Claims:We claim:
1. A method for producing a processed carbon additive (110), the method comprising:
mixing activated carbon (104) with a binder (106) to form a carbon paste;
mixing the carbon paste with a solvent in an ultrasonicator (108) to form a slurry;
drying the slurry to evaporate the solvent; and
collecting the processed carbon additive (110).

2. The method as claimed in claim 1, wherein the carbon paste comprises activated carbon (104) in a range between 90-95 wt. %, wherein the activated carbon (104) further comprises one or more of conductive carbon and an additional component.

3. The method as claimed in claim 1, wherein the carbon paste comprises binder (106) in a range of 5-10 wt. %.

4. The method as claimed in claim 1, wherein the carbon paste comprises conductive carbon in a range of 0.1-10 wt. %.

5. The method as claimed in claim 1, wherein the carbon paste is mixed in the ultrasonicator (108) for five minutes.

6. The method as claimed in claim 1, wherein the carbon additive (110) comprises one or more of graphene, Single Walled Carbon Nanotube (SWNT), Multi Walled Carbon Nanotube (MWNT), and carbon nano particles in a weight percentage of 5 to 30 wt.%.

7. The method as claimed in claim 1, wherein the solvent is one or more of dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and water.

8. The method as claimed in claim 1, wherein the solvent is recovered from the carbon slurry; and wherein the solvent is an organic solvent.

9. A method of producing an electrode (306) using a carbon additive (110), the method comprising:
producing a processed carbon additive (110)
mixing the processed carbon additive (110) with electrode material (304) to produce the electrode (306).

10. The method as claimed in claim 9, wherein the binder (106) is one or more of polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).
, Description:FIELD OF INVENTION
[001] The field of invention generally relates to the field of electrochemical cells; and more specifically, the field of invention relates to the field of making processed carbon additives for electrochemical cells.

BACKGROUND
[002] Batteries play an important role in reusable and rechargeable cell technology due to their reliable performance and ease of access to raw materials. Lead-acid batteries find applications in various spheres of technology such as heavy-duty machinery, hybrid or electric vehicles and are required to be devised in a way such that they are durable and long lasting.
[003] Batteries finding applications in different technologies further require electrodes that have enhanced conductive nature, better charge acceptance and meet requisite power requirements along with extended battery life.
[004] Currently, the existing battery systems do not succeed in providing efficient systems with prolonged battery life. While efficiency of the battery is an important aspect, cycle life of the battery also plays an important role in determining battery performance.
[005] Other existing systems have tried to address this problem. However, their scope was limited to addition of an added component in the battery system. Existing systems have not been fully successful in devising an efficient battery system without altering part or whole of said system.
[006] Altering the structural design of the battery system to accommodate a feature further requires structural changes in production lines or at places where the battery system would be used.
[007] Therefore, there is a long, unresolved need for a battery system that requires few to no changes in structure in order to improve efficacy.
[008] Thus, in light of the above discussion, it is implied that there is a need for a system and method for an effective and productive battery, which is reliable and does not suffer from the problems discussed above.

OBJECT OF INVENTION
[009] The principal object of this invention is to provide a method of making processed carbon additive.
[0010] Another object of the invention is to provide a method of producing a carbon additive to be used in creating efficient electrodes.
[0011] A further object of the invention is to provide a method of increasing electrochemical processes at an electrode comprised in a battery.

BRIEF DESCRIPTION OF FIGURES
[0012] This invention is illustrated in the accompanying drawings, throughout which, like reference letters indicate corresponding parts in the various figures.
[0013] The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0014] Fig. 1 depicts/illustrates a method of making a processed carbon additive, in accordance with an embodiment;
[0015] Fig. 2 depicts/illustrates a method of recovering solvent from the carbon slurry in accordance with an embodiment;
[0016] Fig. 3 depicts/illustrates a process of using the processed carbon additive in electrode material, in accordance with an embodiment;
[0017] Fig. 4 depicts/illustrates a method of producing an electrode comprising a carbon additive, in accordance with an embodiment;
[0018] Fig. 5 depicts/illustrates a second method of producing an electrode comprising a carbon additive, in accordance with an embodiment;
[0019] Fig. 6 illustrates a method of deriving the carbon additive, in accordance with an embodiment.

STATEMENT OF INVENTION
[0020] The present invention discloses a method of making a processed carbon additive from an organic carbon source. In the present invention, an organic source of carbon is exposed to pyrolysis to derive activated carbon. The derived activated carbon is further mixed with a preferable solvent to form a carbon paste.
[0021] The carbon paste obtained from the mixture of the activated carbon with or without conductive carbon and the solvent is then mixed in an ultrasonicator to form a slurry, and the slurry is dried at a required temperature to dry the solvent. In the present invention, processing of the carbon is made cost-effective with the recovery of especially organic solvents. Thereafter, a dry powder thus obtained from the drying process is a processed carbon additive that is further added to an electrode material to construct an electrode.
[0022] Electrodes constructed using the processed carbon additive exhibit enhanced efficacy.

DETAILED DESCRIPTION
[0023] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and/or detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0024] The present invention discloses a method of producing a processed carbon additive, wherein the carbon additive may be derived by exposing activated carbon to various processes. The carbon additive thus derived is used in constructing an electrode and improving efficacy of an electrochemical cell.
[0025] In the context of the present invention, an electrochemical cell may be any electrochemical cell commonly known in the art such as a lead-acid battery or a lithium battery. The electrochemical cell may be herein further referred to as a lead-acid battery for the purpose of the present invention.
[0026] Throughout this description, a method for producing a processed carbon additive has been explained with the help of an illustrative process. This embodiment should not be read as a limitation of this invention and the scope of this description covers other embodiments wherein the disclosed method of processed carbon additives may be utilized.
[0027] Referring now to the drawings, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0028] Fig. 1 depicts/illustrates a method of producing a processed carbon additive to make a carbon additive 110, in accordance with an embodiment of the present invention as depicted at 100.
[0029] In this method, an organic carbon source 102 is selected. Activated carbon 104 is prepared from the carbon source 102. In an embodiment of the invention, the carbon source 102 may be any carbonaceous source material such as, but not limited to, bamboo, coconut husk, willow peat, wood, coir, lignite, coal, and petroleum pitch.
[0030] Activated carbon 104 is derived from the carbon source 102 using pyrolysis techniques. Any person skilled in the art will realize that pyrolysis is a process of decomposing materials at elevated temperatures. Pyrolysis brings about an irreversible change in chemical composition of materials.
[0031] In other embodiments of the invention, any other processes for deriving activated carbon 104 from the carbon source 102 may be used.
[0032] In an embodiment of the invention, the activated carbon 104 may be in the form of graphite, nanoforms of carbon such as, but not limited to, multi-walled or single-walled carbon nanotubes (MWCNTs/SWCNTs). The activated carbon 104 thus derived from the organic carbon source also has a high specific surface area.
[0033] Further, in a preferred embodiment, the activated carbon 104 is mixed with a binder 106 to form a carbon paste.
[0034] In an embodiment of the invention, the activated carbon 104 may be mixed with conductive carbon, or in an alternate embodiment, the activated carbon 104 may not be mixed with conductive carbon.
[0035] The high surface area carbon, i.e., the activated carbon 104 is mixed in a range of approximately 90-95 wt. %, whereas the binder is present in a range of approximately 5-10 wt. %.
[0036] In an embodiment of the invention, the BET surface area of the activated carbon 104 is approximately 1000 m2/g and the mesh size is approximately 325.
[0037] As is commonly known in the art, BET is a technique used to measure specific surface area of any given sample including a pore-size distribution of the sample, and mesh size refers to the openings between the sieve wires per inch in an activated carbon sample.
[0038] The binder 106 used in making the carbon paste may comprise approximately 5-10 wt.% of polyvinylidene difluoride (PVDF) dissolved in a dimethylformamide (DMF) solvent. It is necessary to ensure that the binder 106 does not affect the conductive nature of the carbon.
[0039] In an embodiment of the invention, the binder 106 may be water-soluble or soluble in organic solvents.
[0040] In an exemplary embodiment of the invention, approximately 5.0 grams of PVDF is dissolved in approximately 200 mL of DMF. Thereafter, approximately 95 grams of activated carbon to form the aforementioned carbon paste. The activated carbon added here may comprise high surface area carbon with UCSL, 325 Mesh.
[0041] In other embodiments of the invention, the activated carbon may be fixed with conductive carbon in the range 0 to 5 wt.%.
[0042] In other embodiments of the invention, the solvent may be any one of dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) or water.
[0043] Further, in a preferred embodiment of the invention, the carbon paste is mixed in an ultrasonicator 108 for approximately five minutes.
[0044] In other embodiments of the invention, the carbon paste may be mixed in the ultrasonicator 108 for more than five minutes.
[0045] After the paste has been mixed in the ultrasonicator 108, a slurry is formed. The slurry is further dried at approximately 80oC to evaporate the solvent present in the slurry.
[0046] Another objective of drying the slurry is to deprive the slurry of all moisture in order to form a dry powder.
[0047] Thus, once the solvent present in the slurry has been dried off, a dry powder of a processed carbon additive 110 is formed.
[0048] An advantageous benefit of the processed carbon additive 110 is that since the carbon additive 110 is in a powder form, it can be used in multiple applications where a powder form of said additive 110 may be required.
[0049] In the present invention, an additional component may be chosen to be added to the aforementioned process. The additional component is chosen in a way such that said component is inert to an electrolyte that may be present in the electrochemical cell (not shown in the figure), viz., the electrolyte present in a lead-acid battery. In an embodiment, the additional component may be lead oxide and zinc oxide.
[0050] Further, the additional component is also required to be stable at electrochemical potentials of electrodes that are present in electrochemical cells and should coat only a small portion of the activated carbon surface.
[0051] In a preferred embodiment of the invention, a binder 106 may be chosen from multiple different binders such as, but not limited to, polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).
[0052] An important advantage of a polymeric binder is that a polymeric binder provides a stable, low-resistance bonding, particle-to-particle contact, and provides mechanical integrity to the electrode.
[0053] Depending upon the type of application, binder 106 is chosen appropriately based upon binder properties and electrochemical cell properties.
[0054] An advantage of using a binder 106 is that the binder 106 provides strong adhesion and cohesion between active and conductive materials thereby resulting in stronger interfaces and enhanced performance.
[0055] In one embodiment, commercially available emulsion comprising 60% PTFE may be used as a binder. An appropriate amount of emulsion is used in order to ensure that the weight percentage of PTFE is maintained between approximately 5-10 wt.%.
[0056] Fig. 2 depicts a method of recovering solvent from the carbon slurry in accordance with an embodiment of the invention with an apparatus setup as depicted at 200.
[0057] In a preferred embodiment, the slurry is transferred into a round bottom flask 202. The round bottom flask 202 is placed on a heating mantle 204. Any person skilled in the art will realize that a heating mantle 204 is a laboratory equipment devised to apply heat to containers or devised to be an alternative to a heated bath.
[0058] Structure of the round bottom flask 202 comprises an outlet connecting the flask 202 to a condenser 206. In a preferred embodiment of the invention, the condenser 206 has a provision for circulation of ice-cold water. Solvent collected from the condenser 206 is sent to a solvent recovery flask 210.
[0059] In order to ensure that thorough condensation of the solvent present in the slurry takes place, the solvent recovery flask 210 and a solvent trap 212 are placed in such a way that said apparatus are immersed in glass beakers comprising a mixture of salt and crushed ice. Low temperatures offered by a mixture of salt and crushed ice aids better condensation in the solvent recovery process.
[0060] A water circulation pump 208 attached to a low temperature device is present in the invention to ensure proper circulation of cold water for condensation of solvent vapour into the solvent recovery flask 210. Further, a vacuum pump 214 is also present in the invention. A person skilled in the art will realize that the vacuum pump 214 present in an embodiment accomplishes a commonly known function of removing gas molecules from a sealed volume. In a preferred embodiment, the vacuum pump 214 may aid in recovering the solvent efficiently from the carbon slurry.
[0061] In a preferred embodiment of the invention, the collected solvent is reused for further processes for processing fresh batches of carbon.
[0062] Fig. 3 depicts/illustrates a process of using the processed carbon additive 110 in electrode material 304, in accordance with an embodiment of the invention, as depicted at 300.
[0063] In an embodiment of the invention, the processed carbon additive 110 is mixed with an electrode material 304 to construct an electrode 306.
[0064] The electrode material 304 may either be positive electrode material for constructing a positive electrode 306 or may be negative electrode material for constructing a negative electrode 306.
[0065] Fig. 4 illustrates a method of deriving the carbon additive, in accordance with an embodiment, as depicted at 400.
[0066] Initially, a step 402, activated carbon is mixed with a binder and solvent to form a carbon paste.
[0067] In an embodiment of the invention, the binder may also be in an emulsion form.
[0068] Further, at step 404, the carbon paste is mixed in an ultrasonicator for a predetermined amount of time.
[0069] At step 406, the slurry formed in the ultrasonicator is dried at a predetermined temperature.
[0070] Once the slurry has been dried to evaporate the solvent, a processed carbon additive is obtained in a powder form.
[0071] Fig. 5 illustrates a method of producing an electrode comprising a carbon additive, in accordance with an embodiment of the invention as depicted at 400.
[0072] In the present invention, at step 502, high surface area carbon, i.e., the activated carbon is mixed with a solvent. In a preferred embodiment, 90-95 wt.% activated carbon is mixed with 5-10 wt.% PVDF in DMF solvent to form a carbon paste.
[0073] Further, at step 504, the carbon paste is mixed in an ultrasonicator for a predetermined amount of time. In the present invention, the carbon paste is mixed for five minutes to obtain a slurry.
[0074] The slurry is then dried at 80oC to dry the solvent present in the slurry, as depicted at step 506.
[0075] Finally, at step 508, the dried and processed carbon additive is mixed with a positive or negative active material to produce positive or negative electrodes respectively.
[0076] Fig. 6 depicts/illustrates a second method of producing an electrode comprising a carbon additive, in accordance with an embodiment of the invention as depicted at 600.
[0077] In this method, initially, at step 602, activated carbon is mixed with Polytetrafluoroethylene (PTFE) emulsion to form a carbon paste.
[0078] In an embodiment of the present invention, 90-95 wt.% of high surface area carbon, i.e., the activated carbon derived from the process described in Fig. 1, is mixed with 5-10 wt.% of PTFE in the form of an emulsion.
[0079] In one embodiment, commercially available emulsion comprising 60% PTFE may be used. An appropriate amount of emulsion is used in order to ensure that the weight percentage of PTFE is maintained between 5-10 wt.%.
[0080] Further, at step 604, the carbon paste is mixed with distilled water in an ultrasonicator for five minutes. In other embodiments of the invention, the carbon paste may be mixed for longer than five minutes.
[0081] Once the carbon paste has been mixed in the ultrasonicator, a slurry is formed which is further dried at 80oC to evaporate the solvent, as depicted at step 606. Drying the solvent at high temperature reduces the slurry to a powder form, i.e., a processed carbon additive.
[0082] Finally, at step 608, the processed carbon additive thus formed is used with positive or negative electrode material to further construct positive or negative electrodes respectively, for producing electrochemical cells.
[0083] Further, in a preferred embodiment, gassing may occur at the positive or negative electrodes in an aqueous electrolyte present in the battery system, especially a lead-acid battery. This may occur due to active carbon present in the processed carbon additive.
[0084] In order to prevent an occurrence of gassing, oxides of lead or zinc may be introduced in the battery system.
[0085] A major advantage of the processed carbon additive is that it can be used in positive or negative electrodes or in both of electrochemical cells to improve the efficacy of the electrochemical cells.
[0086] The present method of mixing a processed carbon additive in the electrode material has advantages over merely mixing conventional carbon in the electrode material since presence of a processed carbon additive prevents shedding of carbon particles during usage.
[0087] A main reason for this is also the presence of a binder used along with the processed carbon additive that offers compact binding of composite materials and mechanical strength in the electrode.
[0088] Further, the presence of carbon additives increases electroactive surface of an electrode. Processed carbon additives also improve rate of electrochemical processes occurring at an electrode.
[0089] Moreover, carbon additives present in electrodes restrict the growth of undesirable sulfate crystals at the electrodes; thereby increasing the amount of energy that can be stored in an electrical double layer of the electrode.
[0090] Applications of the current invention include hybrid or electric vehicles or forklifts, UPS, microgrids and the like.
[0091] Further advantageous benefits of the processed carbon additive include prevention of shedding during high rates of charge or discharge and suppression of gas evolution for aqueous systems.
[0092] Additional benefits of the processed carbon additive are that it is easier to produce and less expensive. Moreover, incorporation of such a battery system does not require structural changes, thereby increasing simplicity of the system.
[0093] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described here.