DESC:
FIELD OF THE INVENTION
The present invention generally relates to electrodes for batteries. More specifically, the invention relates to anodes for lithium-ion batteries.

BACKGROUND OF THE INVENTION
Presently, Lithium-ion batteries (LIBs) are the most dominant power source for electric vehicles technology. Usually, ‘Graphite’ is used as standard anode electrode material in LIBs with theoretical capacity of 372 mAh/g. It can be reversibly charged and discharged under intercalation potentials with this maximum feasible specific capacity. The low theoretical capacity (372 mAh/g) of currently used graphite anode in LIB limits its applications for higher range or long driving distance of the EV. Among various anode materials, transition metal oxides and sulfides attract extensive research attention due to their stable chemical states and high specific capacities significantly higher that of the conventional graphite anode material (372 mAh/g). Si and Sn based materials have practical application of their oxides for lithium-ion batteries, but this is significantly impeded by its poor cycling stability and rate capability resulting from the severe volume expansion and contraction during the alloying–dealloying cycles with Li+.

To improve cycling and high-rate performances, various strategies have been used to effectively tune performances and properties of oxide-based electrode materials including fabrication of hierarchical structures, modifications of surface, and tuning phase and elemental composition. However, to meet the increasing demand for high capacity or for solving the current range anxiety in EVs, there is an urgent need to explore new high-performance anode materials for next-generation LIBs.

OBJECT OF THE INVENTION
The object of the present invention is to attain a higher energy density in Lithium-Ion batteries through innovation in anode electrode with respect to the conventional Graphite electrode in current Lithium ion batteries.

SUMMARY OF THE INVENTION
The object of the invention is achieved by an electrode for a battery which includesa reduced graphene oxide and Bismuth Tin oxide.

According to another embodiment of the electrode, wherein Bismuth Tin oxide is placed homogeneously on Graphene sheets. This act as spacers to effectively prevent the agglomeration of graphene sheets, keeping their high active surface. In turn, the graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during discharge/charge process. Bi2Sn2O7/graphene as electrode delivers the charge capacity of 1000 mAh/g, whichis much enhanced than capacities of 230 mAh/g for Bi2Sn2O7O and of 470mAh/g for graphene. The proposed technology/method can hence lead to enhanced energy density of Lithium ion batteries.

According to yet another embodiment of the electrode, wherein the electrode is as an anode. The battery is Li-ion battery assembled with the anode and Lithium Iron Phosphate coated cathode.

According to one another embodiment of the electrode, wherein the battery is assembled with the anode and the cathode and additive of the electrolyte with 10 percentage of fluoroethylene carbonate (FEC).

According to another embodiment of the electrode, wherein the battery is assembled with the anode and the cathode, along with Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in the ratio 80:10:10.

The object of the invention is also achieved by a process of making an electrode for a battery. The process steps includes
preparation of graphene oxide, synthesis of Bismuth Tin Oxide, and
preparation of a composite of Bismuth Tin Oxide and reduced graphene oxide composite,
forming of the electrode using the composite formed in previous step.

According to another embodiment of the process of making the electrode, wherein the sub-steps for the preparation of graphene oxide are:
-supplementing the mixture of 27 ml of sulphuric acid and 3 ml of phosphoric acid in the ratio 9:1with0.225 g of graphite powder,
-stirring for six hours after adding gradually 1.32 g of KMnO4 to the mixture,
-agitating the mixture using Hydrogen peroxide (0.675ml),
-adding 10ml of hydrochloric acid and 30ml of deionised water to the mixture,
-centrifugation of the mixture at 5000 rpm for 10 minutes, and
-precipitation of the mixture is kept to dry at 90 degree for 24 hours, after repeating the above processes thrice.

According to yet another embodiment of the process of making the electrode, wherein the sub-steps for the synthesis of Bismuth Tin Oxide are:
-dissolving 4mmol of Sodium stannate trihydrate and 4mmol of Bismuth Nitrate Pentahydrate in 35ml of deionizer water,
-obtaining a homogeneous mixture by adding Sodium Stannate solution and Bismuth Trinitrate solution and stirring the homogeneous mixture for 30 minutes,
-adjusting the pH value of the solution to 14 by using 5 M Sodium Hydroxide of aqueous solution,
-heating the mixture at 170 degree Celsius in an oven for 24 hours by pouring the mixture in 50 ml Teflon lined autoclave,
-washing the precipitant by deionised water and ethanol thrice separately, after cooling it to the room temperature, and
-drying the mixture at 80 degree Celsius in a vacuum oven.

According to one embodiment of the process of making the electrode, wherein the preparation of Bismuth Tin Oxide and reduced graphene oxide composite includes following sub-steps:
-heating the mixture comprising 50mg of Bismuth Tin Oxide and 50mg of Graphene Oxide with 35ml of deionised water in the 50ml Teflon lined autoclave kept in hot air oven at 120 degree Celsius for 24 hours,
-filtering and washing the mixture with deionised water and ethanol, after cooling it to the room temperature, and
-grounding the mixture, after drying the mixture at 80 degree Celsius for 10 hours.

The object of the invention is also achieved by a method for forming a battery. The method steps comprising
- using a composite of Bismuth Tin Oxide and reduced graphene oxide, Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in a ratio of 80:10:10 to form an active component of anode,
- using a Lithium Iron Phosphate, Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in a ratio of 80:10:10 to form an active component of cathode,
- forming separate uniform slurries of the above active components of anode and cathode respectively using N-Methyl -2-pyrrolidone,
- drying the slurries of the anode and the cathode for 18 hours at 80 degree Celsius in a vacuum oven after applying the uniform slurry to a copper foil and the Aluminium foil respectively to form the anode and the cathode respectively, and
- placing the anode, the cathode, glass fibre as separator and one mole of electrolyte Lithium hexafluorophosphate solution in ethylene carbonate or dimethyl carbonate in the ratio 1:1in a glove box filled with high pure Argon gas.

BRIEF DESCRIPTION OF DRAWINGS
The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:
Figure 1 shows the discharge/charge curves of electrodes of type rGO cycled at 0.1 A g_1.
Figure 2 shows the discharge/charge curves of electrodes of type Bi2Sn2O7 cycled at 0.1 A g_1.
Figure 3 shows the discharge/charge curves of electrodes of type Bi2Sn2O7/RGO cycled at 0.1 A g_1.
Figure 4a shows the cycling stability of GBSO composite samples at 0.1 A g_1.
Figure 4b shows the Columbic efficiency of the electrode at 0.1.
Figure 5 shows the comparison of the electrochemical performance of the anode electrodes disclosed in this invention to that of current graphite electrode in conventional Lithium Ion batteries.
Figure 6 shows the specific arrangement of placement of electrodes (both anode and cathode) in the Lithium Ion battery coin cell architecture. This is a currently well adopted and conventional way of placement of electrodes in the lithium ion batteries.
Figure 7 shows the four ways of common packaging technologies or formats for Lithium ion cells. The four ways are represented as coin, cylindrical, prismatic, and pouch cells.
Figure 8 shows the process steps of making an electrode.
Figure 9 shows the method steps of forming a battery using the electrode made in the present invention.

DETAILED DESCRIPTION OF THE INVENTION
For promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other, sub-systems, elements, structures, components, additional sub-systems, additional elements, additional structures, or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.

Embodiments of the present invention will be described below in detail with reference to the accompanying figures.

The present invention provides for an electrode for the battery and a processof making an electrode and a method for forming a battery with rGO/Bi2Sn2O7 composites leading to their higher electrochemical performance (capacity of over 1000 mAh/g) in Lithium-Ion battery device in contrast with Graphite (372mAh/g) and also Graphene (470 mAh/g) and even the Bi2Sn2O7 based anodes. Graphene-Bi2Sn2O7 composite electrode operates on synergistic effects between Graphene and Bi2Sn2O7 oxide, where reduced graphene oxide (rGO) can work as an excellent conducting layer for better charge transport and strong adhesion of the Bi2Sn2O7 oxide with the oxygen functional groups of rGO. Although graphene has high surface area with excellent electrical conductivity, graphene sheets usually aggregate, due to van der Waal’ forces reducing the overall surface area as well as the properties. Bi2Sn2O7O particles are then synthetically attached to the rGO sheets preventing the aggregation of the graphene sheets to improve capacity, cyclic stability, and rate capability of the anode materials.

Figure1 shows the discharge/charge curves of electrodes of type rGO cycled at 0.1 A g_1. Figure 2 shows the discharge/charge curves of electrodes of type Bi2Sn2O7 cycled at 0.1 A g_1. Figure 3 shows the discharge/charge curves of electrodes of type Bi2Sn2O7/RGO cycled at 0.1 A g_1.VirginrGO nanomaterial electrode exhibits the specific capacities of 580, 460 and 460 mAh/g in 1st, 2nd and 10th cycles respectively. Anodes employing bare oxide nanomaterial of Bi2Sn2O7 displayed the specific capacities of 1000, 800 and 200 mAh/g in 1st, 2nd and 10th cycles respectively. In contrast, the composite electrodes of Bi2Sn2O7/rGO gave the improved specific capacities of 1500, 1150 and 1000 mAh/g at the same number of cycles i.e., 1st, 2nd and 10th cycle respectively. For the pure Bi2Sn2O7 particles, low conductivity, volume expansion and aggregation during the lithiation/delithiation process result in the low initial discharge/charge capacities and poor cycling stability. In contrast, introducing graphene restrains the volume expansion and aggregation, and increase the conductivity, thus showing the enhanced electrochemical performance.

Figure 2 shows the discharge/charge curves of electrodes of type Bi2Sn2O7 cycled at 0.1 A g_1.

Figure 3 shows the discharge/charge curves of electrodes of type Bi2Sn2O7/RGO cycled at 0.1 A g_1.

Figure 4a shows the cycling stability of GBSO composite samples at 0.1 A g_1.

Figure 4b shows the Columbic efficiency of the electrode at 0.1. Bi2Sn2O7/RGO shows the higher initial discharge/charge capacities of1115/1061 mAh/g in the initial cycles and leading to identical discharge/charge capacities of 617/617 mAh/g after 110 cycles. It is seen that there is no capacity fade beyond 50th cycle. The measurements revealed good cycling performance after 110 cycles with a capacity retention of 80.7%.

Figure 5 shows the comparison of the electrochemical performance of the anode electrodes disclosed in this invention to that of current graphite electrode in conventional Lithium-Ion batteries.

Figure 6 shows the specific arrangement of placement of electrodes (both anode and cathode) in the Lithium Ion battery coin cell architecture. This is a currently well adopted and conventional way of placement of electrodes in the lithium ion batteries.

Figure 7 shows the four ways of common packaging technologies or formats for Lithium ion cells. The four ways are represented as coin, cylindrical, prismatic, and pouch cells.

Figure 8 shows the process steps of making an electrode. These process steps of making an electrode comprises of three steps
• Preparation of graphite oxide.
• Synthesis of Bismuth Tin Oxide.
• Preparation of Bismuth Tin Oxide and Graphite Oxide composite.

These steps are explained in detain below.

Preparation of graphite oxide (GO):
Graphene oxide (GO) was typically prepared from pure graphite powder using a modified Hummers process. This procedure involved mixing and stirring for several minutes, 27 ml of sulfuric acid and 3 ml of phosphoric acid (9:1 volume ratio). The mixture was then supplemented with 0.225 g of graphite powder with constant stirring. Then, 1.32 g of KMnO4 was gradually added to the mixture and the solution turned dark green after six hours of stirring. Hydrogen peroxide (0.675 mL) was added gradually and agitated for 10 minutes to remove the excess KMnO4. After cooling, 10 mL of hydrochloric acid and 30 mL of deionized water were added followed by centrifugation at 5000rpm for 10 min. This process was repeated thrice, and the precipitation was kept for drying at 90 °C for 24 hours.

Synthesis of Bi2Sn2O7 (BSO):
In a typical synthesis, 4 mmol of Na2SnO3.3H2O and 4 mmol of Bi(NO3)3.5H2O were dissolved separately in 35 ml of deionized water. Then, Na2SnO3 solution was added to the Bi(NO3)3 solution and the solution was stirred for 30 min to get a homogeneous mixture. 5 M NaOH aqueous solution was used to adjust the pH value to 14. The mixture was then poured into a 50 ml Teflon-lined autoclave (70% full) and kept at 170 °C in an oven for 24 h. The autoclave was cooled to room temperature naturally, and the resultant precipitate was collected and washed by using deionized water and ethanol three times separately. It was then dried at 80 °C in a vacuum oven to obtain Bi2Sn2O7.

Preparation of Bi2Sn2O7/rGO (GBSO) composite:
About 50 mg of Bi2Sn2O7 and 50 mg of GO were taken in 35 ml of deionized water which then transferred to a 50 mL Teflon lined autoclave. It was placed in a hot air oven at 120 °C for 24 h. After cooling to room temperature, the product was filtered and washed with deionized water followed by ethanol several times and kept for drying at 80 °C for 10 h. The final product was ground well and stored in an airtight vial for further use.

Figure 9 shows the method steps for forming the battery using the electrode made from the above process steps. The method steps for forming battery is explained below in detail.

Electrode Making:
Active material (BSO oxide or GBSO composite or LiFePO4), acetylene black as a conductive additive, and polyvinylidene fluoride (PVDF) binder (80:10:10 w%) make up the working electrode's active components. A considerable amount of NMP was utilized as the mixture's solvent to create a uniform slurry. The uniform slurry was then applied to the Cu/ Al foil surface acting as the anode/ cathode, which was subsequently dried for 18 hours at 80 °C in a vacuum oven. Coin cell (CR2032) were put together in a glove box (Jacomex, O2 < 1 ppm and H2O < 1 ppm) filled with high pure Ar gas. The as-prepared anode, counter electrode (Li foil), separator (glass fibre, Whatmann), and electrolyte (1 M LiPF6 in EC/DMC (1:1 vol%)) make up the half-cells for LIBs. Full cells were assembled with oxide coated anode and LiFePO4 coated cathode and 10% fluoroethylene carbonate (FEC) was used as additive in the electrolyte.

The composition range of Active material (oxide or composite or LiFePO4), acetylene black as a conductive additive, and polyvinylidene fluoride (PVDF) binder (80:10:10 w%) make up the working electrode's active components. The another embodiment which hasranges like 90:5:5 and similar ratios in such a way that total adds up to 100% can also be used in the present invention.

Using the Biologic MPG 205 (Biologic, France), all the electrochemical measurements like galvanostatic discharge-charge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) were performed. All EIS measurements were performed in 100 kHz–100 mHz frequency range at open circuit potential in this invention.

Using the above process steps for making electrode and method steps for forming the Lithium ion battery with the electrode formed in the present invention using Bi2Sn2O7O particles which are synthetically attached to the rGO sheets preventing the aggregation of the graphene sheets to improve capacity, cyclic stability, and rate capability of the anode materials, enhanced energy density in the conventional Lithium ion batteries achieves the very object of the invention.

ADVANTAGE OF INVENTION
The present disclosure helps in enhancing the specific capacity of anode of LIB thus increasing the overall energy density of LIB which would result into extra range of EV. This is first demonstration of such electrodes. Higher anode capacity demonstrated here will certainly help appropriately the mass balancing of the anode and the cathode material also improving the volumetric capacity.
,CLAIMS:1. An electrode for a battery comprising:
- a reduced graphene oxide; and
- Bismuth Tin oxide.

2. The electrode as claimed in claim 1, wherein Bismuth Tin oxide is placed homogeneously on Graphene sheets.

3. The electrode as claimed in claim 1, wherein the electrode is an anode, and the battery is Li-ion battery assembled with the anode and Lithium Iron Phosphate coated cathode.

4. The electrode as claimed in claim 3, wherein the battery is assembled with the anode and the cathode and additive of the electrolyte with 10 percentage of fluoroethylene carbonate (FEC).

5. The electrode as claimed in claim 3, wherein the battery is assembled with the anode and the cathode, along with Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in the ratio 80:10:10.

6. A process of making an electrode for a battery comprising:
preparation of graphene oxide,
synthesis of Bismuth Tin Oxide, and
preparation of a composite ofBismuth Tin Oxide and reduced graphene oxide composite,
forming of the electrode using the composite formed in previous step.

7. The process of making an electrode as claimed in claim 6, wherein the preparation of graphene oxide, comprising:
supplementing the mixture of 27 ml of sulphuric acid and 3 ml of phosphoric acid in the ratio 9:1with0.225 g of graphite powder,
stirring for six hours after adding gradually 1.32 g of KMnO4 to the mixture,
agitating the mixture using Hydrogen peroxide (0.675ml),
adding 10ml of hydrochloric acid and 30ml of deionised water to the mixture,
centrifugation of the mixture at 5000 rpm for 10 minutes, and
precipitation of the mixture is kept to dry at 90 degree for 24 hours, after repeating the above processes thrice.

8. The process of making an electrode as claimed in claim 6, wherein the synthesis of Bismuth Tin Oxide, comprising:
dissolving 4mmol of Sodium stannate trihydrate and 4mmol of Bismuth Nitrate Pentahydrate in 35ml of deionizer water,
obtaining a homogeneous mixture by adding Sodium Stannate solution and Bismuth Trinitrate solution and stirring the homogeneous mixture for 30 minutes,
adjusting the pH value of the solution to 14 by using 5 M Sodium Hydroxide of aqueous solution,
heating the mixture at 170 degree Celsius in an oven for 24 hours by pouring the mixture in 50 ml Teflon lined autoclave,
washing the precipitant by deionised water and ethanol thrice separately, after cooling it to the room temperature, and
drying the mixture at 80 degree Celsius in a vacuum oven.

9. The process of making an electrode as claimed in claim 6, wherein the preparation of Bismuth Tin Oxide and reduced graphene oxide composite, comprising:
heating the mixture comprising 50mg of Bismuth Tin Oxide and 50mg of Graphene Oxide with 35ml of deionised water in the 50ml Teflon lined autoclave kept in hot air oven at 120 degree Celsius for 24 hours,
filtering and washing the mixture with deionised water and ethanol, after cooling it to the room temperature, and
grounding the mixture , after drying the mixture at 80 degree Celsius for 10 hours.

10. A method for forming a battery comprising:
using a composite of Bismuth Tin Oxide and reduced graphene oxide, Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in a ratio of 80:10:10 to form an active component of anode,
using a Lithium Iron Phosphate, Acetylene black as a conductive additive, and Polyvinylidene Fluoride as binder combined in a ratio of80:10:10 to form an active component of cathode,
forming separate uniform slurries of the above active components of anode and cathode respectively using N-Methyl -2-pyrrolidone,
drying the slurries of the anode and the cathode for 18 hours at 80 degree Celsius in a vacuum oven after applying the uniform slurry to a copper foil and the Aluminium foil respectively to form the anode and the cathode respectively, and
placing the anode, the cathode, glass fibre as separator and one mole of electrolyte Lithium hexafluorophosphate solution in ethylene carbonate or dimethyl carbonate in the ratio 1:1in a glove box filled with high pure Argon gas.