Claims:1. A Metal-CO2 battery system for Mars exploration comprising:
a) metal anode;
b) candle soot carbon porous cathode utilizing Martian atmosphere gases;
c) electrolyte;
d) catalyst; and
e) separator between the anode and cathode;
characterized in that the positive carbon soot porous cathode is made up of carbon nanoparticles derived from candle soot or other carbon based materials and the catalyst is selected from candle soot carbon-transition metal oxide/ sulfide composite.
2. The battery system according to claim 1, wherein a metal anode is selected from Lithium (Li), Magnesium (Mg), Manganese (Mn) Aluminium (Al), Zinc (Zn), Sodium (Na), Potassium (K), Iron (Fe), Silicon (Si), a combination of these metal or other metal and their compound.
3. The battery system according to claim 1, wherein the transition metal oxide/ sulfide composite in the catalyst can be selected from porous Mn2O3 or MoS2.
4. The battery system according to claim 1, wherein positive carbon soot porous cathode is made up of carbon based materials selected from candle soot carbon or Graphitic pencil composite with carbon soot carbon nanoparticle or carbon based other compounds selected from hard carbon, soft carbon, synthetic graphite, activated carbon (AC), graphene, biomass-derived carbon, carbon nanotube, fullerene or reduced graphene oxide.
5. The battery system according to claim 1, wherein the positive porous carbon electrode may further comprise a catalyst layer comprising candle soot carbon or metal oxide composite or metal or metal oxide or a combination thereof.
6. The battery system according to claim 5, wherein positive porous carbon electrode may further comprise a catalyst layer comprising metal selected from Pt, Au, Ru, Pd, Co or Cr.
7. The battery system according to claim 5, wherein the positive porous carbon electrode may further comprise a catalyst layer comprising metal oxide selected from Mn2O3, MoS2 or TiO2.
8. The battery system according to claim 1, wherein the porous cathode is configured to capture CO2 from Martian atmosphere.
9. The battery system according to claim 1, wherein the electrolyte is either in a liquid state comprising solvent and salt compound or can be an organic and inorganic solid electrolyte (SSE) material having metal-ion conductor.
10. The electrolyte as claimed in claim 9, wherein said solvent is selected from ethylene carbonate (EC), tetraethylene glycol dimethylether (TEGDME), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), poly(ethylene glycol)dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), sulfone, sulfolane, dimethyl carbonate (DMC), methylethyl carbonate (MEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), ethylene glycol dimethyl ether, dimethyl cellosolve, dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DGDE), acetonitrile (AN), 2-ethoxyethyl ether (EEE), ethyl acetate (EA), methyl formate (MF), toluene, methyl acetate (MA), fluoroethylene carbonate (FEC), and combinations of other organic, inorganic and ionic liquid solvent.
11. The electrolyte as claimed in claim 9, wherein said salt can be selected from lithium hexafluorophosphate (LiPF6), sodium perchlorate (NaClO4), potassium perchlorate (KClO4), lithium borofluoride (LiBF4), sodium hexafluorophosphate (NaPF6), potassium hexafluorophosphate (KPF6), sodium borofluoride (NaBF4), potassium borofluoride (KBF4), lithium bis(oxalato)borate (LiBOB), lithium trifluoromethanesulfonimide (LiTFSI), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF3SO3), potassium trifluoro-metasulfonate (KCF3SO3), bis-trifluoromethyl sulfonylimide sodium (NaN(CF3SO2)2), lithium nitrate (LiNO3), sodium trifluoromethanesulfonimide (NaTFSI), bis-trifluoromethyl sulfonylimide potassium (KN(CF3SO2)2), lithium bisperfluoro-ethysulfonylimide (LiBETI), or a combination thereof.

12. The battery system according to claim 1, wherein the electrolyte comprises a ternary, equi-proportion solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) with LiPF6 salt.
13. The battery system according to claim 1, wherein the battery may further comprise adsorption compressor technology for extracting and compressing atmospheric CO2 from the surface of Mars.
14. The battery system according to claim 1, wherein the operating temperature for Metal-CO2 battery is in the range of -160 °C to 60°C, preferably in the range of -140°C to 40°C.
15. The battery system according to claim 1, wherein the operating pressure for Metal-CO2 battery is in the range of 0.001 bar to 5 bar, preferably in the range of 0.005 bar to 1 bar.
16. A method of fabricating metal-CO2 battery, as claimed in claim 1, comprising the steps of:
a) Preparing porous cathode using nickel foam and appropriate carbon based material;
b) Preparing electrolyte;
c) Synthesizing catalyst;
d) cutting metal foil into circular disc for anode;
e) assembling the battery in mesh coin cell case in argon glove box;
f) using separator between carbon electrode and electrolyte;
g) using gasket with a spring; and
h) crimpling the coin cell assembly inside the glove box.
, Description:FIELD OF THE INVENTION
[0001] The present invention relates to energy storage devices. Specifically, the present invention relates to metal-CO2 battery for Mars exploration, comprising porous carbon cathode. The present invention further relates to method of fabricating metal-CO2 battery comprising porous carbon cathode.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Carbon capture, utilization, and sequestration technologies have been extensively studied to utilize carbon dioxide (CO2), a greenhouse gas, as a resource. Metal–CO2 batteries have attracted significant research attention owing to their high energy density, contemporary energy and environmental issues. The metal–CO2 battery platform provides a novel approach for simultaneous capturing of CO2 emissions and producing electrical energy.
[0004] Various metal-CO2 battery systems are reported in the literature which have different sets of battery configuration and utilize either pure CO2 or a mixture of CO2 and oxygen (O2) gas for their electrochemical reaction at earth atmospheric conditions.
[0005] Several different types of metal-CO2 batteries are known, such as Na-CO2 batteries, Li-CO2 batteries, Al-CO2 batteries, K-CO2, and have attracted much attention due to their high energy density and efficient utilization of greenhouse CO2 fixation. Among these metal-CO2 batteries, Li-CO2 batteries possess great promising potential due to their high theoretical specific energy density (1876 Wh/kg) with high discharge potential (~2.8V). In 2011, Takechi et al. (Chem. Commun. (Camb); 2011, 47(12), 3463-5) reported primary Li-CO2/O2 battery using a mixed gas of O2 and CO2, and reported a high discharge capacity, more than three times that of a non-aqueous Li-air (O2) battery. Shaomao Xu et al. in 2013, (RSC Advances; 3.18 (2013), 6656-6660) reported a primary Li-CO2 battery with pure CO2 gas as its cathode. The battery obtained a high discharge capacity of 2500 mAh/g at moderate temperatures and the performance of the battery is temperature-dependent. In 2014, Li and co-workers (Energy & Environmental Science; 7.2 (2014), 677-681) reported first rechargeable Li-CO2 batteries with a Ketjen black (KB) cathode and electrolyte of LiCF3SO3 in TEGDME, wherein the battery demonstrated discharging specific capacities of 1032 mAh/g at 30mA/g. In 2015, Xin Zhang et al. (Chem. Commun.; 51.78 (2015); 14636-14639) developed porous three-dimensional networks of carbon nanotubes (CNTs) with high electrical conductivity air cathodes for rechargeable Li-CO2 batteries. These batteries were tested over 20 cycles at100 mA/g with a cut-off capacity of 1000 mAh/g. In 2019, researchers at the University of Illinois at Chicago (Advanced Materials; 31.40 (2019), 1902518) reported fully rechargeable Li-CO2 battery using an ionic liquid/dimethyl sulfoxide electrolyte with MoS2 nanoflakes as a cathode catalyst. The battery prototype was tested up to 500 cycles for a fixed 500 mAh/g capacity per cycle. Recently, Gang Wu, et al. (J. Mater. Chem. A; 2020,8, 3763-3770) developed nitrogen-doped carbon nanotubes cathode with ultrafine IrO2 nanoparticles electro-catalysts for carbon dioxide reduction and Li2CO3 decomposition. The Li-CO2 batteries with the IrO2-N/CNT cathode were tested for more than 316 charge discharge cycles at 100 mA/g with a fixed capacity of 400 mAh/g.
[0006] For Li-CO2 batteries, many researches have used metals (such as Mo, Ru, Ni, Au, Co etc.) as catalyst while carbon in different morphologies (CNT, GO, RGO etc.) has been used to improve electrical conductivity of the electrode. Y. Hau et al. (Batteries. 2017, 1700564, 1–8) have reported Mo2C as efficient catalyst for conversion of Li and CO2 to Li2CO3 meanwhile CNT was used to improve the conductivity of electrode because of its 3D network which can host Mo2C uniformly on the surface to act as efficient catalyst.The electrochemical performance reveals the excellent catalytic behavior in the voltage window of 2.0-3.8 V. Similarly, X. Li et al. (Adv. Mater.; 2019, 31(48):e1905879) have used COF/CNT as cathode host because of its atomically precise open pore channels and skeleton which act as ideal platform to investigate ion and gas transport meanwhile CNT imparts the electronic conductivity to the electrode. They have used Ru as catalyst to improve the reaction kinetics which is frequently used for CO2 reduction and Li2CO3 reduction. COF-Ru@CNT showed promising result as a cathode for Li-CO2 batteries. B.W. Zhang et al. (Advanced Functional Materials; 2019, 29(49):1904206-1-1904206-7) have used Co atoms on Graphene oxide as an efficient electro catalyst for Li-CO2 batteries. They’ve reported the capacity of 17,358 mAh/g at the current density of 100 mA.g for more than 100 cycles which revealed the excellent electro catalyst behavior of Co. Moreover, unique electronic structure with synergic interaction of Co-C and Co-O binding give the excellent absorption ability for the CO2 capture. In the recent report for K-CO2 batteries, L. Dai et al. (Angewandte Chemie International Edition. 2020, 59, 3470-3474) have reported N-CNT/RGO 3D network cathode. N-CNTs not only prevent the re-staking of RGO sheets but also provide 3D conductive pathways for efficient electron/electrolyte/CO2 gas transport along with sufficient space to accommodate discharge product K2CO3. As fabricated N-CNT/RGO cathode exhibited a cycle life of over 40 and 250 cycles at a limited specific capacity of 500 and 300 mAh.g.
[0007] Over the last two decades, there has been an increase in missions sent for exploration of Mars. In 2004, NASA-JPL landed two rovers “Spirit” and “Opportunity” on Mars. “Spirit” was operational until 2010 but “Opportunity” is still operational and has completed over 13 years of operation. In 2012, NASA-JPL successfully landed another rover “Curiosity” on Mars and it is still operational. Joining the feat of excellence, Indian Space Research Organization (ISRO), the Indian space agency launched its first ever interplanetary mission called Mares Orbiter Mission (MOM) in November 2013 and became not only the first Asian country to reach Martian orbit but also the first ever nation to do so in the very first attempt. The major objectives of MOM were to develop the technology for an interplanetary mission and an exploration of Mars surface and atmosphere features space probe which orbits Mars. ISRO is also planning to send MOM-2 with a lander and rover in to the Mars in 2024. SpaceX is also looking to use Tesla battery packs in new ‘Starship’ Mars vehicle prototype to meet their aspirational goal to land the first humans on Mars by 2024.
[0008] The Li-ion battery chemistry is mostly used for such type of mission for example NASA-JPL developed lithium ion battery consists of meso-carbon microbeads (MCMB) anodes, LiNixCo1-xO2 (NCO) cathodes, and a low temperature ternary carbonate-based electrolyte.
[0009] Exploration missions aimed at exploring Mars, require rechargeable batteries that can operate effectively over a wide temperature range to satisfy the requirements of various applications, including landers, rover, orbiter and penetrators. A robust, highly efficient, high energy density with long cyclic stability rechargeable battery system is required for energy conversion and storage which can also utilize the resources available on the Martian land and operate even in the harsh conditions. Metal-CO2 batteries are an attractive option for Mars exploration as Martian atmosphere comprises mainly 95% of carbon dioxide (CO2) along with some other gases like N2, O2, Ar etc. The development of Metal-CO2 batteries for Mars exploration is justified in terms of significant savings on mass, volume, and more importantly energy density. Currently, there are no reports on the development of any metal-CO2 battery or energy storage system for use in Mars exploration missions, which can utilize the CO2 available from Martian atmosphere. Martian atmosphere is consisting of nearly 95% CO2, and therefore, metal-CO2 battery system seems to be promising technology for energy storage which will also reduce the effective weight of the overall mission spacecraft.
[0010] There is, therefore, a need to develop metal-CO2 batteries, which includes limited energy material supplies brought from earth and utilizing local resource of Mars such as CO2 from its atmosphere to fulfil the energy necessity for the Mars missions, thereby overcoming the deficiencies associated with the known arts. The development of metal CO2 battery face challenges such as low coulombic efficiency and electrolyte degradation caused by high over potential during charge-discharge. Therefore, further efforts are required to design and fabricate the catalysts for metal-CO2 batteries, which can lower the over-potential during charging-discharging operation of metal CO2 batteries. The present invention provides metal-CO2 battery that is capable of utilizing CO2 from Martian atmosphere and provides high rate performance and efficiency.

OBJECTS OF THE INVENTION
[0011] An object of the present invention is to provide metal-CO2 battery system for energy conversion and storage which can utilizes the local resources available on the Martian land such as CO2 and operate in Martian atmosphere.
[0012] Another object of the present invention is to provide metal-CO2 battery system for Mars exploration that comprises appropriate cathode host capable of utilizing large amounts of CO2.
[0013] Yet another object of the present invention is to provide metal-CO2 battery system for Mars exploration that can reduce the effective weight of the overall mission spacecraft.
[0014] Another object of the present invention is to provide metal-CO2 battery system for Mars exploration which is robust, displays high rate performance and has high energy density with long cyclic stability.
[0015] Another object of the present invention is to provide rechargeable metal-CO2 battery system for Mars exploration comprising catalysts at cathode host, which can lower the over-potential during charging-discharging operation of metal CO2 batteries.
[0016] The other objects and preferred embodiments and advantages of the present invention will become more apparent from the following description of the present invention when read in conjunction with the accompanying examples and figures, which are not intended to limit scope of the present invention in any manner.

SUMMARY OF THE INVENTION
[0017] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0018] The present invention relates to energy storage devices. Specifically, the present invention relates to metal-CO2 battery for Mars exploration, comprising porous carbon cathode.
[0019] In one aspect, the present invention relates to a metal-CO2 battery for Mars exploration, comprising:
a) metal anode;
b) candle soot carbon porous cathode utilizing Martian atmosphere gases;
c) electrolyte;
d) catalyst; and
e) separator between the anode and cathode;
characterized in that the positive carbon soot porous cathode is made up of carbon nanoparticles derived from candle soot or other carbon based materials and the catalyst is selected from candle soot carbon - transition metal oxide/ sulfide composite.
[0020] In another aspect, the present invention relates to a metal-CO2 battery, wherein metal anode is selected from but not limited to Lithium (Li), Magnesium (Mg), Manganese (Mn) Aluminium (Al), Zinc (Zn), Sodium (Na), Potassium (K), Iron (Fe), Silicon (Si) or a combination of these metal or their derivatives.

[0021] In one aspect, the present invention relates to a metal-CO2 battery wherein the transition metal oxide/ sulfide composite in the catalyst can be selected from porous Mn2O3 or MoS2.
[0022] In yet another aspect, the present invention relates to a metal-CO2 battery wherein positive carbon soot porous cathode is made up of carbon based materials selected from candle soot carbon or Graphitic pencil composite with carbon soot carbon nanoparticle or carbon based other compounds selected from but not limited to hard carbon, soft carbon, synthetic graphite, activated carbon (AC), graphene, biomass-derived carbon, carbon nanotube, fullerene, reduced graphene oxide and the like.
[0023] In another aspect, the present invention relates to a metal-CO2 battery wherein the metal-CO2 battery of the present invention can be utilized as energy conversion and storage systems with CO2 fixation.
[0024] In one aspect, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising candle soot carbon or metal oxide composite or metal or metal oxide or a combination thereof. The metal or metal oxides used in the catalyst layer can be selected from but not limited to Group II metal (such as alkaline earth, Be, Mg, Zn, Cd or Hg), Group IV metal ( such as Ti, Zr, Hf, Ge, Sn or Pb), Group V metal (such as V, Nb, Ta, As, Sb or Bi), Group VIII metal (such as iron or platinum group), Group I (such as alkali, Ag, Au or Cu) , other metal (such as Cr, Mo, Sc, Y, Al, Ga, In), and their oxide such as Mn2O3, ZnO, NiO, SiO2, TiO2, WO3, MgO, CaCO3, ZrO2, Al2O3, Fe2O3, CO3O4, and the like.
[0025] In another aspect, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising metal selected from but not limited to Pt, Au, Ru, Pd, Co, Cr and the like.
[0026] In another aspect, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising metal oxide selected from but not limited to Mn2O3, MoS2, TiO2 and the like.
[0027] In another aspect, the present invention relates to a metal-CO2 battery wherein the porous cathode is configured to capture CO2 from Martian atmosphere which comprising Carbon dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%, Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08% and other elements.

[0028] In another aspect, the present invention relates to a metal-CO2 battery wherein the electrolyte is either in a liquid state comprising solvent and salt compound or can be an organic and inorganic solid electrolyte (SSE) material having metal-ion conductor. The solid electrolyte material having metal-ion conductor according to embodiments of the present invention can be selected from but not limited to such as LiF, LiCl, LiI, Li2O, Li2S, Li3N, Li3P, LGPS, Li3.5Ge0.25PS4, Li3PS4, Li6PS5Cl, Li7P2S8I, LiPON, LLZO, LLTO, LATP, LAGP, LISICON and the like.
[0029] In another aspect, the present invention relates to a metal-CO2 battery wherein solvent for electrolyte is solvent is selected from but not limited to ethylene carbonate (EC), tetraethylene glycol dimethylether (TEGDME), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), poly(ethylene glycol)dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), sulfone, sulfolane, dimethyl carbonate (DMC), methylethyl carbonate (MEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), ethylene glycol dimethyl ether, dimethyl cellosolve, dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DGDE), acetonitrile (AN), 2-ethoxyethyl ether (EEE), ethyl acetate (EA), methyl formate (MF), toluene, methyl acetate (MA), fluoroethylene carbonate (FEC), or combinations of other organic, inorganic and ionic liquid solvent. The ionic liquid solvents according to an embodiment of the present invention can be selected from but not limited to imidazolium, sulfonium, pyrrolidinium, pyridinium, piperidinium, ammonim, and phosphonium, and different inorganic or organic anions, including halides (chloride [Cl–], bromide [Br–], iodide [I–]), acetate [AcO–], tetrafluoroborate [BF4 –], hexafluorophosphate [PF6 –], tetrachloroaluminate [AlCl4 –], bistriflimide [(CF3SO2)2N]- ,bis(trifluoromethanesulfonyl) imide [TFSI–], ethyl sulfate [EtSO4 –], dicyanamide [N(CN)2 –], and thiocyanate [SCN–], Nitrate (NO3), Amino acid and the like.
[0030] In another aspect, the present invention relates to a metal-CO2 battery wherein salt for electrolyte can be selected from but not limited to lithium hexafluorophosphate (LiPF6), sodium perchlorate (NaClO4), potassium perchlorate (KClO4), lithium borofluoride (LiBF4), sodium hexafluorophosphate (NaPF6), potassium hexafluorophosphate (KPF6), sodium borofluoride (NaBF4), potassium borofluoride (KBF4), lithium bis(oxalato)borate (LiBOB), lithium trifluoromethanesulfonimide (LiTFSI), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF3SO3), potassium trifluoro-metasulfonate (KCF3SO3), bis-trifluoromethyl sulfonylimide sodium (NaN(CF3SO2)2), lithium nitrate (LiNO3), sodium trifluoromethanesulfonimide (NaTFSI), bis-trifluoromethyl sulfonylimide potassium (KN(CF3SO2)2), lithium bisperfluoro-ethysulfonylimide (LiBETI), or a combination thereof.
[0031] In a preferred aspect, the present invention relates to a metal-CO2 battery wherein the electrolyte comprises a ternary, equi-proportion solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) with LiPF6 salt.
[0032] In yet another aspect, the present invention relates to a metal-CO2 battery wherein said electrochemical system can be used for the applications selected from Rover, lander, orbiter, robotic, and human to mars missions.
[0033] In another aspect, the present invention relates to a metal-CO2 battery, wherein the operating temperature for Metal-CO2 battery is in the range of -160°C to 50°C, preferably in the range of -140°C to 30°C.
[0034] In another aspect, the present invention relates to a metal-CO2 battery, wherein the operating pressure for Metal-CO2 battery is in the range of 0.001 bar to 5 bar, preferably in the range of 0.005 bar to 1 bar.
[0035] The present invention further relates to method of fabricating metal-CO2 battery comprising porous carbon cathode.
[0036] In another aspect, the present invention relates to a method of fabricating metal-CO2 battery, comprising the steps of:
a) Preparing porous cathode using nickel foam and appropriate carbon based material;
b) Preparing electrolyte;
c) Synthesizing catalyst;
d) cutting metal foil into circular disc for anode;
e) assembling the battery in mesh coin cell case in argon glove box;
f) using separator between carbon electrode and electrolyte;
g) using gasket with a spring; and
h) crimpling the coin cell assembly inside the glove box.
[0037] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

BRIEF DESCRIPTION OF DRAWINGS THE INVENTION
[0038] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
Figure 1: illustrates a schematic representation of Metal-CO2 battery configuration, specifically Li-CO2 battery for Martian atmosphere comprising 1: Porous cathode, 2: Electrolyte, 3: catalyst, 4: martin atmosphere comprising 95% CO2 along with other gases.
Figure 2: Illustrates preparation of porous candle soot carbon cathode for Metal-CO2 battery, in accordance with embodiments to the present disclosure.
Figure 3: illustrates a schematic diagram of fabricating Metal-CO2 battery wherein metal-CO2 battery comprises Lower porous case (1); porous cathode (2); electrolyte (3) containing salt and solvent solution; glass fiber separator (4); metal anode (5); spacer (6); spring (7) and upper closing case (8), in accordance with embodiments to the present disclosure.
Figure 4: illustrates a) First cycle charging/discharging characteristics of Li-CO2 battery operated at pure CO2 atmosphere; b) First cycle charging/discharging characteristics of Li-CO2 battery operated using Mars atmospheric gases; c-d) Comparative performance of first cycle charging/discharging characteristics of Li-CO2 battery operated at pure CO2 atmosphere and at Mars atmosphere gases, in accordance with embodiments to the present disclosure.

DETAILED DESCRIPTION
[0039] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0040] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0041] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0042] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0043] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0044] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0045] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0046] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
[0047] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0048] It should also be appreciated that the present disclosure can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0049] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0050] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0051] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing..
[0052] The present invention relates to energy storage devices. Specifically, the present invention relates to metal-CO2 battery for Mars exploration, comprising porous carbon cathode, utilizing Martian atmospheric gases.
[0053] In one embodiment, the present invention relates to a metal-CO2 battery for Mars exploration, comprising:
a) metal anode;
b) candle soot carbon porous cathode utilizing Martian atmosphere gases;
c) electrolyte;
d) catalyst; and
e) separator between the anode and cathode;
characterized in that the positive carbon soot porous cathode is made up of carbon nanoparticles derived from candle soot or other carbon based materials and the catalyst is selected from candle soot carbon - transition metal oxide/ sulfide composite.
[0054] In another embodiment, the present invention relates to a metal-CO2 battery, wherein metal anode is selected from but not limited to Lithium (Li), Magnesium (Mg), Manganese (Mn) Aluminium (Al), Zinc (Zn), Sodium (Na), Potassium (K), Iron (Fe), Silicon (Si) or a combination of these metal or their derivatives.
[0055] In one embodiment, the present invention relates to a metal-CO2 battery wherein the transition metal oxide/ sulfide composite in the catalyst can be selected from porous Mn2O3 or MoS2.
[0056] In another embodiment, the present invention relates to a metal-CO2 battery wherein the transition metal oxides/ sulfide, selected from porous Mn2O3 and MoS2, can be synthesized by using simple, versatile and low-cost hydrothermal method and flame synthesis, well-known to a person skilled in the art.
[0057] In another embodiment, the present invention relates to a metal-CO2 battery wherein the candle soot used in oxide and sulfide (Mn2O3 and MoS2) composite catalyst provides the conductive nature to the metal oxide or metal sulfide and act as a functional catalyst which is very essential for the better performance of the device.
[0058] In yet another embodiment, the present invention relates to a metal-CO2 battery wherein positive carbon soot porous cathode is made up of carbon based materials selected from candle soot carbon or Graphitic pencil composite with carbon soot carbon nanoparticle or carbon based other compounds selected from but not limited to hard carbon, soft carbon, synthetic graphite, activated carbon (AC), graphene, biomass-derived carbon, carbon nanotube, fullerene, reduced graphene oxide and the like.
[0059] The metal–CO2 batteries, utilizing CO2 at cathode, possess great promising potential in both reversible greenhouse CO2 fixation and energy storage fields. It has been also observed that the cathode reaction over-potential (CO2 reduction/evolution) is much higher than that of the anode reaction (discharging) in metal-air/CO2 battery chemistry. This limits the overall charge and discharge rate of the battery. Therefore, the development of high rate performance, porous cathode in metal CO2 batteries need to carried out.
[0060] According to another embodiment of the present invention, the present invention utilizes carbon nanoparticles derived from candle soot and other carbon based material (such as pencil graphite) in order to overcome the rate performance issue of metal-CO2 battery.
[0061] In another embodiment, the present invention relates to a metal-CO2 battery wherein the metal-CO2 battery of the present invention can be utilized as energy conversion and storage systems with CO2 fixation.
[0062] According to one embodiment of the present invention, the metal-CO2 battery is open to the atmosphere, wherein the candle soot derived carbon nanoparticles act as cathode, unlike the alkali-ion battery, which is a completely closed system, wherein candle soot derived carbon nanoparticles act as anode and take actively part in electrochemical reaction with the alkali-ions (Li, K, Na).
[0063] In one embodiment, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising candle soot carbon or metal oxide composite or metal or metal oxide or a combination thereof. The metal or metal oxides used in the catalyst layer according to an embodiment of the present invention can be selected from but not limited to Group II metal (such as alkaline earth, Be, Mg, Zn, Cd or Hg), Group IV metal ( such as Ti, Zr, Hf, Ge, Sn or Pb), Group V metal (such as V, Nb, Ta, As, Sb or Bi), Group VIII metal (such as iron or platinum group), Group I (such as alkali, Ag, Au or Cu) , other metal (such as Cr, Mo, Sc, Y, Al, Ga, In), and their oxide such as Mn2O3, ZnO, NiO, SiO2, TiO2, WO3, MgO, CaCO3, ZrO2, Al2O3, Fe2O3, CO3O4, and the like.
[0064] In another embodiment, the present invention relates to a metal-CO2 battery wherein the separator can be selected from PTFE, Glass separator, PO Membranes, Ceramic filled Nonwovens, Ceramic coated Membranes, Freudenberg Ceramic filled PET Nonwoven, polyethylene (PE), polypropylene (PP), and their combinations such as PE/PP and PP/PE/PP. According to an embodiment of the present invention, the separator material can also be selected from other polymers such as isotactic poly(4-methyl-1-pentene), polyoxymethylene, PE-PP blend, polystyrene (PS)-PP blend and poly(ethylene terephthalate (PET)-PP blend polymers.
[0065] In a preferred embodiment, the present invention relates to a metal-CO2 battery wherein the separator is selected from PTFE or Glass separator.
[0066] In another embodiment, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising metal selected from but not limited to Pt, Au, Ru, Pd, Co, Cr and the like.
[0067] In another embodiment, the present invention relates to a metal-CO2 battery wherein the positive porous carbon electrode may further comprise a catalyst layer comprising metal oxide selected from but not limited to Mn2O3, MoS2, TiO2 and the like.
[0068] In another embodiment, the present invention relates to a metal-CO2 battery wherein the porous cathode is configured to capture CO2 from Martian atmosphere which comprising Carbon dioxide (CO2) - 95.32% ; Nitrogen (N2) - 2.7%, Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08% and other elements.
[0069] In another embodiment, the present invention relates to a metal-CO2 battery wherein the electrolyte is either in a liquid state comprising solvent and salt compound or can be an organic and inorganic solid electrolyte (SSE) material having metal-ion conductor. The solid according to embodiments of the present invention can be selected from but not limited to such as LiF, LiCl, LiI, Li2O, Li2S, Li3N, Li3P, LGPS, Li3.5Ge0.25PS4, Li3PS4, Li6PS5Cl, Li7P2S8I, LiPON, LLZO, LLTO, LATP, LAGP, LISICON and the like.
[0070] In another embodiment, the present invention relates to a metal-CO2 battery wherein solvent for electrolyte is solvent is selected from but not limited to ethylene carbonate (EC), tetraethylene glycol dimethylether (TEGDME), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), poly(ethylene glycol)dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), sulfone, sulfolane, dimethyl carbonate (DMC), methylethyl carbonate (MEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), ethylene glycol dimethyl ether, dimethyl cellosolve, dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DGDE), acetonitrile (AN), 2-ethoxyethyl ether (EEE), ethyl acetate (EA), methyl formate (MF), toluene, methyl acetate (MA), fluoroethylene carbonate (FEC), or combinations of other organic, inorganic and ionic liquid solvents. The ionic liquid solvents according to an embodiment of the present invention can be selected from but not limited to imidazolium, sulfonium, pyrrolidinium, pyridinium, piperidinium, ammonim, and phosphonium, and different inorganic or organic anions, including halides (chloride [Cl–], bromide [Br–], iodide [I–]), acetate [AcO–], tetrafluoroborate [BF4 –], hexafluorophosphate [PF6 –], tetrachloroaluminate [AlCl4 –], bistriflimide [(CF3SO2)2N]- ,bis(trifluoromethanesulfonyl) imide [TFSI–], ethyl sulfate [EtSO4 –], dicyanamide [N(CN)2 –], and thiocyanate [SCN–], Nitrate (NO3), Amino acid and the like.
[0071] In another embodiment, the present invention relates to a metal-CO2 battery wherein salt for electrolyte can be selected from but not limited to lithium hexafluorophosphate (LiPF6), sodium perchlorate (NaClO4), potassium perchlorate (KClO4), lithium borofluoride (LiBF4), sodium hexafluorophosphate (NaPF6), potassium hexafluorophosphate (KPF6), sodium borofluoride (NaBF4), potassium borofluoride (KBF4), lithium bis(oxalato)borate (LiBOB), lithium trifluoromethanesulfonimide (LiTFSI), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF3SO3), potassium trifluoro-metasulfonate (KCF3SO3), bis-trifluoromethyl sulfonylimide sodium (NaN(CF3SO2)2), lithium nitrate (LiNO3), sodium trifluoromethanesulfonimide (NaTFSI), bis-trifluoromethyl sulfonylimide potassium (KN(CF3SO2)2), lithium bisperfluoro-ethysulfonylimide (LiBETI), or a combination thereof.
[0072] In a preferred embodiment, the present invention relates to a metal-CO2 battery wherein the electrolyte comprises a ternary, equi-proportion solvent mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and diethyl carbonate (DEC) with LiPF6 salt. This electrolyte mixture provides good low temperature performance of the battery which is required for batteries used in Mars planetary exploration missions, especially landers and rovers as these batteries experience low temperatures approaching -30°C.
[0073] In another aspect, the present invention relates to a metal-CO2 battery, with CO2 as an energy carrier for mars mission with configuration as illustrated in Figure 1, specifically Li-CO2 battery for Martian atmosphere comprising 1: Porous cathode, 2: Electrolyte, 3: catalyst, 4: martin atmosphere comprising 95% CO2 along with other gases.
[0074] In still another embodiment, the present invention relates to a metal-CO2 battery wherein the battery may further comprise adsorption compressor technology for extracting and compressing atmospheric CO2 from the surface of Mars. The technology is used for extracting and compressing atmospheric CO2 from the Martian surface. The technology includes Mars Atmosphere Acquisition & Compression (MAAC) system wherein the compression is achieved by alternately cooling and heating a sorbent material.
[0075] In yet another embodiment, the present invention relates to a metal-CO2 battery wherein said electrochemical system can be used for the applications selected from Rover, lander, orbiter, robotic, and human to mars missions.
[0076] In yet another embodiment, the present invention relates to a metal-CO2 battery for energy storage which leads to reduction in the effective weight of the overall mission spacecraft.
[0077] In another aspect, the present invention relates to a metal-CO2 battery, wherein the operating temperature for Metal-CO2 battery is in the range of -160 °C to 60°C, preferably in the range of -140°C to 40°C.
[0078] In another aspect, the present invention relates to a metal-CO2 battery, wherein the operating pressure for Metal-CO2 battery is in the range of 0.001 bar to 5 bar, preferably in the range of 0.005 bar to 1 bar.
[0079] The present invention further relates to method of fabricating metal-CO2 battery comprising porous carbon cathode.
[0080] In another aspect, the present invention relates to a method of fabricating metal-CO2 battery, comprising the steps of:
a) Preparing porous cathode using nickel foam and appropriate carbon based material;
b) Preparing electrolyte;
c) Synthesizing catalyst;
d) cutting metal foil into circular disc for anode;
e) assembling the battery in mesh coin cell case in argon glove box;
f) using separator between carbon electrode and electrolyte;
g) using gasket with a spring; and
h) crimpling the coin cell assembly inside the glove box.
[0081] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
[0082] The present invention is further explained in the form of following examples. However, it is to be understood that the following examples are merely illustrative and are not to be taken as limitations upon the scope of the invention.
[0083] Example 1: Preparation of cell components
[0084] Preparation of porous cathode using candle soot: The candle soot was deposited on a porous nickel foam substrate (purity > 99.99%, Thickness 1.6 mm) that was placed on top of the outer flame as illustrated in Figure 2. The obtained product on Nickle foam is fractal-like interconnected network of carbon nanoparticles. This method is binder free and is more advantageous than conventional methods.
[0085] Preparation of porous cathode using pencil graphite: This preparation process involved sticky slurry formation by ultra-sonication of active carbon material (70-90%), catalyst material (candle soot with graphite pencil, 1-10%), 10-15 mg of PTFE and 0.25 mg of Nafion® dispersion reagent in a solution containing distilled water and isopropanol in ratio of 1:1 (v/v). The prepared slurry sputtered onto nickel foam (10-25 mm in diameter). The water and organic content was removed by heating the product obtained at 105 °C for 3 hours.
[0086] Preparation of Electrolyte: Electrolyte was prepared by mixing appropriately selected salt in solvent. Different weight ratios of salt in solvent were used for electrolyte preparation such as: 5:5, 4:6, 3:7, and 2:8.
[0087] Metal anode: Commercially available metal foil was used as metal anode. The metal foil used had a diameter in the range of 10-25 mm.
[0088] Preparation of catalyst: The candle soot carbon-porous Mn2O3 or MoS2 composite catalyst was synthesized by using simple, versatile and low-cost hydrothermal method, known to a person skilled in the art.
[0089] Example 2: Metal-CO2 battery cell assembly
[0090] The mesh coin cell case of CR2032 was used as housing for the Metal CO2 battery. The positive side of cell case has uniform drilled holes to provide inlet of carbon dioxide to the battery. Metal foil die-cut into circular disc (10-25 mm in diameter) having active area acts as an anode. The metal-CO2 battery coin cell assembly is carried out in argon filled glove box with moisture and oxygen content < 0.1ppm. During assembly, PTFE / micro-glass separator (10-25mm) was placed on top of the air carbon electrode bonded on positive-side of coin-cell case. Appropriate amount of prepared electrolyte to completely soak the separator was added onto the separator, followed by placing a piece of single metal foil and then placing the cover with a PP gasket along with spring. The coin-cell assembly prepared was then crimped inside the glove-box with a crimping force of about 10MPa. The overall cell configuration has been illustrated in Figure 3, wherein metal-CO2 battery comprises: Lower porous case (1), porous cathode (2), electrolyte (3) containing salt and solvent solution, glass fiber separator (4), metal anode (5), spacer (6), spring (7) and upper closing case (8).
[0091] Open-circuit voltage (OCV) was measured inside the glove-box using multimeter to ensure proper functioning of the battery. The electrochemical performance of Metal-CO2 battery was evaluated with cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS).
[0092] Example 3: Testing
[0093] The electrochemical performance of the battery was measured using in-house built Metal-CO2 battery testing. The mesh coin cells were assembled in a glass chamber filled with argon gas (O2 and H2O content <0.1 ppm) container in a glove box. The gas container was locked properly in ordered to avoid other gas contamination. After the cell assembly was completed, the glass container was taken out from the glovebox. For the test in CO2 ambient, the inlet of glass container with metal-CO2 cell was attached with the CO2 gas cylinder directly. Further, pure CO2 flowed through the glass chamber to replace the argon gas present initially during assembly. To perform the electrochemical measurement, glass container was attached with the potentiostat/galvanostat.
[0094] In this non limiting example, the metal CO2 battery comprising candle soot deposited porous nickel foam substrate along with traced pencil graphite was used. The device was fabricated as per described methodology in Example 3. The Li-CO2 battery cell assembly was carried out as depicted in Figure 3. The Li-CO2 battery setup was placed in simulated Martian atmosphere which consisted of Carbon dioxide (CO2) - 95.32%, Nitrogen (N2) - 2.7%, Argon (Ar) - 1.6%; Oxygen (O2) - 0.13%; Carbon Monoxide (CO) - 0.08% and other elements. The device performance was tested with the first cycle charging/discharging characteristics. The Galvanostatic discharge/charge tests were conducted in the voltage range of 2.0-5.0V (vs.Li+/Li) using battery tester. All the specific capacity and current densities reckoned with reliant to weight of active cathode material.
[0095] The device performance operated at Martian atmosphere was compared with pure CO2 environment for further analysis. The device operatingat pure CO2 environment exhibits a discharge capacity of around 215 mAh/g and charge capacity of 143.5 mAh/g with a coulombic efficiency of 67%, as shown in Figure 4a.
[0096] For the Mars exploration and practical application, the device was electrochemically tested for the galvanostatic discharge/charge performance and the results are depicted in Figure 4b. The battery demonstrated the discharge and charge capacity of 269 mAh/g and 263 mAh/g, respectively, with a higher coulombic efficiency of 98%. Galvanostatic discharge/charge performance of device operated at Martian atmosphere compared with pure CO2 environment, are depicted in Figures 4c and 4d. The device operating at Martian atmosphere shows better electrochemical performance in terms of specific capacity and overpotential. The impressive electrochemical performance may be due to the existence of Martian atmosphere with other electrochemically active species such Oxygen and Carbon Monoxide.
[0097] The foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.

ADVANTAGES OF THE PRESENT INVENTION
[0098] The present invention provides a metal-CO2 battery system for energy conversion and storage which can utilizes the local resources available on the Martian land such as CO2 and operate in Martian atmosphere.
[0099] The present invention provides a metal-CO2 battery system for Mars exploration that comprises appropriate cathode host capable of utilizing large amounts of CO2.
[00100] The present invention provides a metal-CO2 battery system for Mars exploration that can reduce the effective weight of the overall mission spacecraft.
[00101] The present invention provides a metal-CO2 battery system for Mars exploration which is robust, displays high rate performance and has high energy density with long cyclic stability.
[00102] The present invention provides a rechargeable metal-CO2 battery system for Mars exploration comprising catalysts, which can lower the over-potential during charging-discharging operation of metal CO2 batteries.