WO2018029707A2

WO2018029707A2 - Full cell for lithium ion battery with conversion anode and intercalation cathode

Info

Publication number: WO2018029707A2
Application number: PCT/IN2017/050335
Authority: WO
Inventors: Sagar MITRA; Pavan Srinivas VELURI
Original assignee: Indian Institute Of Technology Bombay
Priority date: 2016-08-10
Filing date: 2017-08-09
Publication date: 2018-02-15
Also published as: WO2018029707A3; WO2018029707A4

Abstract

Embodiments herein provide a full cell with porous iron oxide (Fe₂O₃) nanostructures, synthesized using polyol method, as anode, and powder Lithium Cobalt Oxide (LiCoO₂) as cathode. The full cell includes an electrolyte and a separator. The half cell performance of the Fe₂O₃ exhibits a reversible capacity of 903mAh/g at a current (C) rate of 1C vs. Li metal. The LiCoO₂ (LCO) is having a capacity of 131mAh/g at 1C after 50 cycles vs. Li metal. The full cell is prepared using Fe₂O₃ anode and LiCoO₂ cathode, and the mass loadings are adjusted such that the necessity of pre- activation is prevented. The LCO-Fe₂O₃ full cell is having capacity retention of 91% after 100 charge-discharge cycles at 1C. The capacity based on the anode mass is approximately 800mAh/g after 100 cycles. The prepared full cell is having a high capability at C rates in the range of 2C- 5C.

Description

TITLE OF THE INVENTION

"Full Cell for lithium ion battery with conversion anode and

intercalation cathode"

FIELD OF INVENTION

[0001] The embodiments herein relate to a full cell for Lithium-ion batteries (LIB) with Fe₂0₃ as conversion anode and LiCo0₂ as intercalation cathode. The present application is based on, and claims priority from an Indian Application Number 201621027395 filed on 10^th August, 2016, the disclosure of which is hereby incorporated by reference herein

BACKGROUND OF INVENTION

[0002] Lithium- ion batteries (LIBs) excel in terms of capacity and energy density to power portable electronic devices and have the potential to power Electric Vehicles (EV), Hybrid EVs (HEV), or the like. However, the usage of graphite as anode limits the capacity at the anode of the LIBs to 372Ah/kg or 760Ah/L. Moreover, lithium dendrite formation on graphite surface at high current (C) rates imposes safety hazards.

[0003] Amongst the materials proposed to replace graphite, oxides of iron such as Fe₂0₃ are one of the safest, abundant, and inexpensive conversion based anode material. The theoretical gravimetric and volumetric capacities of Fe₂0₃ are 1007 Ah/Kg and 5300 Ah/L, respectively, which are higher than conventional graphite anode. However, metal oxides such as Fe₂0₃ are not visualized as potential replacement to graphite due to their large volume changes associated with the conversion reaction with lithium, which leads to severe capacity fading upon cycling.

[0004] Thus, there is a need for having a full cell which utilizes Fe₂0₃ as anode with high C-rate capability, in conjunction with cathodes such as LiCo0₂, LiFeP0₄, LiMn₂0₄, or the like. [0005] The above information is presented as background only to help the reader for understanding the present invention. Applicants have made no determination and make no assertion as to whether any of the above might be applicable as Prior Art with regard to the present application.

OBJECT OF INVENTION

[0006] The principal object of the embodiments herein is to construct a full cell for Lithium- ion battery (LIB) using Fe₂0₃ porous nanostructures as an anode and commercial grade LiCo0₂ powder as a cathode.

[0007] Another object of the embodiments herein is to prepare a full cell having a high current (C) rate capability.

[0008] Another object of the embodiments herein is to synthesize Fe₂0₃ porous structures as a high C-rate capable anode in conjunction with LiCo0₂ cathode.

SUMMARY

[0009] Accordingly, the embodiments herein provide a full cell with porous iron oxide (Fe₂0₃) nanostructures, synthesized using polyol method, as anode, and powder Lithium Cobalt Oxide (LiCo0₂) as cathode. The full cell includes an electrolyte and a separator. The half cell performance of the Fe₂0₃ exhibits a reversible capacity of 903mAh/g at a current (C) rate of 1C vs. Li metal. The LiCo0₂ (LCO) is having a capacity of 131mAh/g at 1C after 50 cycles vs. Li metal. The full cell is prepared using Fe₂0₃ anode and LiCo0₂ cathode, and the mass loadings are adjusted such that the necessity of pre-activation on anode side is prevented.

[0010] The LCO-Fe₂0₃ full cell is having capacity retention of 91% after 100 charge-discharge cycles at 1C. The capacity based on the anode mass is approximately 800mAh/g after 100 cycles. The prepared full cell is having a high capability at C rates in the range of 2C-5C. [0011] In an embodiment, the capacity of the full cell at 0.5C is 920mAh/g.

[0012] In an embodiment, the capacity of the full cell at 1C is 800mAh/g.

[0013] In an embodiment, the capacity of the full cell at 2C is

670mAh/g.

[0014] In an embodiment, the capacity of the full cell at 5C is 450mAh/g.

[0015] The full cell can be used for powering a solar lamp by preparing a pouch cell, powering an ultra-bright LED array, or the like.

[0016] Accordingly the embodiments herein provide a method of preparing a full cell. The method includes preparing porous Fe₂0₃ nano structured anode. The method includes preparing an electrolyte in which 2 % LiBOB additive is added to the LP 30 (Merck) electrolyte. Further, the method includes soaking a separator in the electrolyte, wherein the soaked separator is placed on the cathode foil and an anode foil is placed on top of the soaked separator, and sealed in a 2016 coin type cell.

[0017] In an embodiment, capacity of the LiCo0₂ cathode is adjusted for countering irreversible loss of the Fe₂0₃ anode in the first cycle. In an embodiment, capacity of the cell is retained in the range of 0.5C to 5C.

[0018] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF FIGURES

[0019] This method is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0020] FIG. la illustrates X-Ray Diffraction (XRD) pattern of a synthesized iron oxide (Fe₂0₃) porous structure, according to an embodiment as disclosed herein;

[0021] FIG. lb illustrates Field Emission Scanning Electron Microscope (FE-SEM) image of the synthesized Fe₂0₃ porous structure, according to an embodiment as disclosed herein;

[0022] FIG. lc illustrates the Transmission Electron Microscope (TEM) image of the Fe₂0₃ porous structures, according to an embodiment as disclosed herein;

[0023] FIG. Id illustrates XRD pattern of commercial grade Lithium Cobalt Oxide (LiCo0₂) powder, according to an embodiment as disclosed herein;

[0024] FIG. le illustrates FE-SEM image of the commercial grade LiCo0₂ powder, according to an embodiment as disclosed herein;

[0025] FIG. 2a illustrates charge-discharge profiles of Fe₂0₃ porous nanostructures vs. Li metal, according to an embodiment as disclosed herein;

[0026] FIG. 2b illustrates cycling performance of the Fe₂0₃ porous nanostructures vs. Li metal, according to an embodiment as disclosed herein;

[0027] FIG. 2c illustrates discharge profile of the Fe₂0₃ porous nanostructures vs. Li metal at different current (C)-rates, according to an embodiment as disclosed herein; [0028] FIG. 2d illustrates power capability of the Fe₂0₃ porous nanostructures vs. Li metal, according to an embodiment as disclosed herein;

[0029] FIG. 3a illustrates charge-discharge profiles of commercial grade LiCo0₂ vs. Li metal, according to an embodiment as disclosed herein;

[0030] FIG. 3b illustrates cycling performance of the commercial grade LiCo0₂ vs. Li metal, according to an embodiment as disclosed herein;

[0031] FIG. 3c illustrates discharge profile of the commercial grade

LiCo0₂ vs. Li metal at different C-rates, according to an embodiment as disclosed herein;

[0032] FIG. 3d illustrates power capability of the commercial grade LiCo0₂ vs. Li metal, according to an embodiment as disclosed herein;

[0033] FIGS. 4a and 4b illustrate initial half cell charge-discharge profiles of LiCo0₂ and Fe₂0₃ vs. Li metal, according to an embodiment as disclosed herein;

[0034] FIGS. 4c and 4d illustrate experimentally obtained (solid line) and computed (dot line) full cell profiles based on half cell profiles, according to an embodiment as disclosed herein;

[0035] FIG. 5a illustrates charge-discharge profiles of LiCo0₂- Fe₂0₃ full cell, according to an embodiment as disclosed herein;

[0036] FIG. 5b illustrates cycling performance of the LiCo0₂-Fe₂0₃ full cell at 1C, according to an embodiment as disclosed herein;

[0037] FIG. 5c illustrates discharge profiles of the LiCo0₂-Fe₂0₃ full cell at different C-rates, according to an embodiment as disclosed herein;

[0038] FIG. 5d illustrates power capability of the LiCo0₂-Fe₂0₃ full cell, according to an embodiment as disclosed herein; [0039] FIG. 6a demonstrates the solar lamp powered by the LiCo0₂-Fe₂0₃ pouch cell, according to an embodiment as disclosed herein;

[0040] FIG. 6b demonstrates an ultra-bright Light Emitting Diode (LED) array, with 50 LEDs, powered by the LiCo0₂-Fe₂0₃ pouch cell, according to an embodiment as disclosed herein;

[0041] FIG. 7 is a schematic of cell configurations, according to an embodiment as disclosed herein;

[0042] FIG. 8 is a schematic of pouch cell fabrication process, according to an embodiment as disclosed herein; and

[0043] FIG. 9 is a flow diagram illustrating a method for preparing a full cell, according to an embodiment as disclosed herein.

DETAILED DESCRIPTION OF INVENTION

[0045] 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 detailed in the following description. Descriptions of well- known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein, refers to a nonexclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0046] Accordingly embodiments herein provide a conversion anode and intercalation cathode based full cell with a high current (C)-rate capability, for Lithium-ion Battery (LIB) applications. The anode of the full cell is a porous iron oxide (Fe₂0₃) nanostructures, synthesized using polyol method, and the cathode of the full cell is powder lithium cobalt oxide (LiCo0₂). The full cell includes an electrolyte and a separator.

[0047] The half cell performance of Fe₂0₃ exhibits a reversible capacity of 903mAh/g at 1C vs. Li metal. The LiCo0₂ (LCO) is having a capacity of 131mAh/g at 1C after 50 cycles vs Li metal foil. The full cell is prepared using Fe₂0₃ anode and LiCo0₂ cathode, and the mass loadings are adjusted such that the necessity of pre-activation is prevented. In an embodiment, the LCO-Fe₂0₃ full cell is having capacity retention of 91% after 100 charge-discharge cycles at 1C. The capacity based on the anode mass is approximately 800mAh/g after 100 cycles. The C-rate capability of the full cell is high and can withstand currents up to 5C.

[0048] Accordingly the embodiments herein provide a method of preparing a full cell. The method includes preparing porous Fe₂0₃ nanostructure anode. The method includes preparing powdered LiCo0₂ cathode. The method includes preparing an electrolyte in which LiBOB additive is added to LP 30 (Merck) electrolyte. Further, the method includes soaking a separator in an electrolyte, wherein the soaked separator is placed on a cathode foil and an anode is placed on top of the soaked separator, and sealed in a 2016 coin type cell.

[0049] In an embodiment, capacity of the LiCo0₂ cathode is adjusted for countering irreversible loss of the Fe₂0₃ anode in the first cycle. In an embodiment, capacity of the cell is retained in the range of 0.5C to 5C.

[0050] A pouch cell is prepared with Fe₂0₃ anode and LiCo0₂ cathode and the pouch cell is demonstrated to power a solar lamp and a Light Emitting Diode (LED) array. In an example, the LED array consists of 50 ultra-bright LEDs, where the rating of each LED is 3V and 50mA.

[0051] Material synthesis: In a synthesis procedure, 3gms of FeC₂0₄ is dispersed in a 150ml of Ethylene Glycol (EG) with the aid of magnetic stirring. The solution is further refluxed at a temperature of 190°C for 6 hours. A yellow color precipitate is obtained, which is collected, washed with ethanol and water several times, followed by heating at a temperature of 60°C in an oven overnight. Finally, the dried powder is calcined at a temperature of 600°C, in air, for 10 hours to obtain porous Fe₂0₃ nanostructures. Commercial grade LiCo0₂ powder (Gelon LIB Co. Ltd., PR China) is used to prepare slurry for cathode preparation.

[0052] Materials characterization: The phase and structural characterization are carried out using Rigaku X-ray diffractometer with Cu- Κα radiation at 40KV and 40mA. Morphological analysis is carried out using Field Emission Scanning Electron Microscope (FE-SEM, Carl Zeiss Ultra 55) and Field Emission Transmission Electron Microscope (FE-TEM, Jeol, 21 OOF, Japan).

[0053] Half cell tests: Half cell tests are performed using lithium

(Li) metal. Negative electrodes are prepared by mixing 60 wt % of Fe₂0₃ porous structures, 20 wt % of super p carbon, and 20 wt % of sodium alginate binder using water as solvent. Positive electrodes are prepared by mixing 88 wt % of LiCo0₂, 8 wt % of super p carbon, and 4 wt % of Polyvinylidene Fluoride (PVDF) binder using N-methyl Pyrrolidone (NMP) as solvent. For the Fe₂0₃, slurries are coated on a copper foil, and for the LCO, the slurries are coated on an aluminium foil. The coated foils are dried in an oven at a temperature of 100°C for overnight. The dried electrodes are cut into 15mm circular discs for electrochemical measurements with Li. 2032 Coin type cells are used for fabricating the half cells. 1M LiPF₆ in Ethylene Carbonate (EC) and Dimethyl Carbonate (DMC), in a 1:1 ratio of wt %, is used as an electrolyte [LP 30, Merck]. Borosilicate glass fiber is used as a separator (Whatman GF/D). Galvanostatic charge-discharge cycling is carried out at different C-rates. Fe₂0₃ is tested as an anode in the potential window of 0.05V-3V, and LCO is tested as a cathode in the potential window of 4.3V- 3.2V at a temperature of 20°C + 2°C.

[0054] Full cell measurements: The full cell is prepared by matching the capacities of the anode and cathode discs. The active materials loading is lmg/cm 2 on the anode and 8mg/cm 2 on the cathode. In order to fabricate full cells, coin type cells are used with 1M LiPF₆ in EC and DMC, in a 1: 1 ratio of wt % [LP 30, Merck] and 2 wt % of Lithium Bis-(oxalato) Borate (LiBOB) additive as electrolyte, and polypropylene as separator. The fabricated full cell is galvano statically cycled within the potential window of 1V-3.9V, based on the half cells charge-discharge profiles.

[0055] Referring now to the drawings and more particularly to FIGS. 1 to 9, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.

[0056] FIG. la illustrates X-Ray Diffraction (XRD) pattern of a synthesized iron oxide (Fe₂0₃) porous structure, according to an embodiment as disclosed herein. The synthesized Fe₂0₃ porous structure is calcined at a temperature of 600°C. The XRD pattern indicates the formation of a-Fe₂0₃ with a corundum structure.

[0057] FIG. lb illustrates FE-SEM image of the synthesized Fe₂0₃ porous structure, according to an embodiment as disclosed herein. As depicted in the SEM analysis, large pores are formed, post calcination, due to the removal of EG from Fe-EG complex. The magnification image depicted in inset depicts the formation of large pores in the calcined samples at the temperature of 600°C.

[0058] FIG. lc illustrates TEM image of the Fe₂0₃ porous structures, according to an embodiment as disclosed herein. The TEM analysis confirms the porous nature of the as synthesized Fe₂0₃ structures. The average length of the porous structures is approximately 2μιη, which is derived from SEM measurements.

[0059] FIG. Id illustrates XRD pattern of LiCo0₂ powder, according to an embodiment as disclosed herein.

[0060] FIG. le illustrates FE-SEM image of the LiCo0₂ powder, according to an embodiment as disclosed herein. The SEM image reveals the particle size of the LiCo0₂ powder. The average particle size is 12μιη.

[0061] FIG. 2a illustrates charge-discharge profiles of Fe₂0₃ porous nanostructure, according to an embodiment as disclosed herein. Initially, half cells are tested with Li for individual performance of Fe₂0₃ as anode and LiCo0₂ as cathode. The charge-discharge profiles of the Fe₂0₃ porous structure at 0.5C for the 1st cycle and 50th cycle are depicted. The Fe₂0₃ undergoes a conversion reaction, which involves the transfer of six Li ions. The flat plateau at approximately 0.8V in the first discharge process represents the formation of Fe and Li₂0, with an initial discharge capacity of 1596mAh/g. The first charge capacity obtained is 1136mAh/g with an irreversible loss of 28.8%. This is of much significance for full cell fabrication. The high initial discharge capacity (theoretical is approximately 1007mAh/g), is due to decomposition of electrolyte and/or pseudo capacitive surface Li storage.

[0062] FIG. 2b illustrates cycling performance of the Fe₂0₃ porous nanostructure vs. Li metal, according to an embodiment as disclosed herein. The cyclic performance of Fe₂0₃ porous structure is depicted at different C- rates. The capacity retention after 50 charge-discharge cycles at 0.5C is 92%, at 1C is 87%, and at 2C is 80%. The discharge capacities obtained after 50 cycles are 1050mAh/g at 0.5C, 903mAh/g at 1C, and 787mAh/g at 2C. The C-rate capability test reveals the robustness of the Fe₂0₃ porous structure at different C-rates.

[0063] FIG. 2c illustrates discharge profile of the Fe₂0₃ porous nanostructures at different C-rates, according to an embodiment as disclosed herein. FIG. 2d illustrates power capability of the Fe₂0₃ porous nanostructure, according to an embodiment as disclosed herein. The increased polarization by applying high C-rates is due to an increase in the Ohmic resistance. At 5C (5A/g), a discharge capacity of 680mAh/g is obtained, which is twice the capacity of graphite anodes.

[0064] FIG. 3a illustrates charge-discharge profiles of LiCo0₂, according to an embodiment as disclosed herein. LiCo0₂ (LCO) powder is tested as cathode material with Li for half cell performance evaluation in the potential window of 4.3V-3.2V. The charge-discharge profiles of LCO at 0.5C for the 1st cycle and 50th cycle are depicted. The plateau in the potential window of 3.9V-4.3V signifies reinsertion of Li from LCO crystal structure, which is associated with Co^3+/4+ redox couple with an initial charge capacity of 153mAh/g. The discharge plateau in the potential window of 4.3V-3.2V indicates re-insertion of Li with a discharge capacity of 147mAh/g.

[0065] FIG. 3b illustrates cycling performance of the L1C0O₂, according to an embodiment as disclosed herein. The cycling performance is depicted at different C-rates. The capacity retention after 50 cycles at 0.5C is 95%, at 1C is 98%, and at 2C is 95%, respectively. The discharge capacity obtained after 50 cycles at 0.5C is 140mAh/g, at 1C is 131mAh/g, and at 2C is 117mAh/g, respectively.

[0066] FIG. 3c illustrates discharge profile of the LiCo0₂ at different C-rates, according to an embodiment as disclosed herein. The polarization is high at 5C. From C-rate capability test, the robustness is confirmed by determining that the capacity is 60mAh/g at 5C (750mA/g).

[0067] FIG. 3d illustrates power capability of the LiCo0₂, according to an embodiment as disclosed herein.

[0068] FIGS. 4a and 4b illustrate initial half cell charge-discharge profiles of LiCo0₂-Fe₂0₃ corresponding to full cell charge-discharge profiles, according to an embodiment as disclosed herein. The half cell performance reveals that both the Fe₂0₃ porous structure and the LCO have high C-rate capability, and demonstrate stable capacities at high C-rates. The full cell is prepared using Fe₂0₃ as anode and LCO as cathode. No pre- activation step is carried out for the Fe₂0₃ anode. However, the capacity of the LCO cathode is adjusted so that the irreversible loss at the anode is taken care of. Pre-activation is difficult to produce high capacity commercial LIBs. LCO is chosen as cathode due to its stability and high potential plateaus. FIG. 4a depicts initial charge profile of the LCO and discharge profile of the Fe₂0₃, the combination of which results in the charge plateau of the full cell. The combination of discharge profile of the LCO and charge profile of the Fe₂0₃, depicted in the FIG. 4b provides the discharge plateau of the full cell.

[0069] FIGS. 4c and 4d illustrate experimentally obtained (solid line) and computed (dot line) full cell profiles based on half cell profiles, according to an embodiment as disclosed herein.

[0070] The charge-discharge profiles of full cell, calculated from the half cell charge-discharge profiles, match with the experimentally obtained LCO-Fe₂0₃ full cell profiles depicted in the FIGS. 4c and 4d. The charge plateau at approximately 3V represents the reinsertion of Li from the LCO and conversion reaction of Li with Fe₂0₃. The reverse process happens upon discharge at the 1.6V- 2.7V plateau. Galvano static charge - discharge cycling of the full cell is carried out in the potential window of IV- 3.9V based on the capacity matching of the anode and the cathode. It is necessary to limit the higher cut-off voltage during charging process, else excess Li will plate on the anode surface. The full cell is limited at anode due to the fact that capacity loading in terms of mAh of the LCO cathode is higher than that of the Fe₂0₃ anode. This is to utilize the full capacity of the Fe₂0 .

[0071] FIG. 5a illustrates charge-discharge profile of LiCo0₂-Fe₂0₃ full cell, according to an embodiment as disclosed herein. FIG. 5b illustrates cycling performance of LiCo0₂-Fe₂0₃ full cell at 1C, according to an embodiment as disclosed herein. FIG. 5c illustrates discharge profile of the LiCo0₂-Fe₂0₃ full cell at different C-rates, according to an embodiment as disclosed herein. FIG. 5d illustrates power capability of the LiCo0₂-Fe₂0₃ full cell, according to an embodiment as disclosed herein. [0072] The initial charge-discharge process is carried out at 0.1C to allow the formation of stable Solid Electrolyte Interface (SEI) layer. The initial charge capacity and discharge capacity is found to be 1320mAh/g and 918mAh/g, respectively, with an irreversible capacity loss of 30%. This is close to the irreversible loss observed in the Fe₂0₃ half cell. After the first cycle, the cyclic performance is carried out at 1C to demonstrate high C-rate capable conversion (Fe₂0₃) based full cell. The capacity retention is 91 % after 100 charge-discharge cycles at 1C, which is 800mAh/g based on anode mass loading as depicted in FIG. 5b. The capacity retention without LiBOB additive is 47.2% after 100 cycles. The discharge profiles at various C-rates are depicted in FIG. 5c. The polarization observed is due to Ohmic resistance at high C-rates as observed in half cells.

[0073] The C-rate capability of the full cell at different C-rates, i.e., from 0.5C to 5C, is depicted in FIG. 5d. The capacities obtained are: 920mAh/g at 0.5C, 800mAh/g at 1C, 670mAh/g at 2C, and 450mAh/g at 5C. The LCO-Fe₂0₃ full cell is able to retain its original capacities at different C-rates. The inset of FIG. 5d depicts a LED, powered by a prepared 2016 coin type LCO-Fe₂0₃ full cell.

[0074] FIG. 6a demonstrates a solar lamp, according to an embodiment as disclosed herein. FIG. 6b demonstrates an ultra-bright LED array, with 50 LEDs, powered by the LCO-Fe₂0₃ full cell, according to an embodiment as disclosed herein. In order to demonstrate a practical application of the Fe₂0₃ anode, a pouch cell is fabricated with LCO cathode with similar mass loading as in coin type cell (FIG. 5d), in a 3x5cm aluminum pouch with a capacity of 300mAh. The pouch cell fabrication and application of the Fe₂0₃ conversion anode is demonstrated. The prepared pouch cell can be used for various applications. The FIG. 6a depicts the lighting of a solar study lamp (using one 300mAh pouch cell) and the FIG. 6b depicts the powering of 50 ultra-bright LEDs, with each LED having a rating of 3V and 50mA (using two 300mAh pouch cells).

[0075] FIG. 7 illustrates schematic of cell configurations, according to an embodiment as disclosed herein.

[0076] FIG. 8 is a schematic of pouch cell fabrication process, according to an embodiment as disclosed herein.

[0077] FIG. 9 is a flow diagram 900 illustrating a method for preparing the full cell, according to an embodiment as disclosed herein. Referring to the FIG. 9, at step 902, the method includes preparing the porous ferric oxide (Fe₂0₃) nano structured anode. In an embodiment, 3gms of FeC₂0₄ is dispersed in a 150ml of Ethylene Glycol (EG) with the aid of magnetic stirring. The solution is further refluxed at a temperature of 190°C for 6 hours. A yellow color precipitate is obtained, which is washed with ethanol and water several times, followed by heating at a temperature of 60°C in an oven overnight. Finally, the dried powder is calcined at a temperature 600°C, in air, for 10 hours to obtain porous Fe₂0₃ nano structure anode.

[0078] At step 904, the prepared porous Fe₂0₃ is used to make a composite electrode with carbon black additive and alginate binder.

[0079] At step 906, LiCo0₂ powder is used to prepare slurry for preparation of the cathode. The LCO is chosen as cathode due to its stability and high potential plateaus.

[0080] At step 908, the method includes preparing the electrolyte. In order to fabricate full cells, coin type cells are used with 1M LiPF₆ in EC and DMC, in a 1:1 ratio of wt % and 2 wt % of Lithium Bis-(oxalato) Borate (LiBOB) additive as electrolyte.

[0081] At step 910, the method includes soaking the separator in the electrolyte. The soaked separator is placed on a cathode and an anode is placed on top of the soaked separator and is sealed in a 2016 coin type cell. [0082] 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 spirit and scope of the embodiments as described herein.

Claims

STATEMENT OF CLAIMS We claim:

1. A full cell comprising:

a porous ferric oxide (Fe₂0₃) nanostructure anode;

a powdered lithium cobalt oxide (LiCo0₂) cathode;

an electrolyte; and

a separator.

2. The full cell of claim 1, wherein capacity of the full cell at a current rate of 0.5C is 920mAh/g.

3. The full cell of claim 1, wherein capacity of the full cell at a current rate of 1C is 800mAh/g.

4. The full cell of claim 1, wherein capacity of the full cell at a current rate of 2C is 670mAh/g.

5. The full cell of claim 1, wherein capacity of the full cell at a current rate of 5C is 450mAh/g.

6. The full cell of claim 1, wherein the capacity retention rate of the full cell is 91% post 100 charge-discharge cycles at a current rate of 1C.

7. A method of preparing a full cell, the method comprising:

preparing porous ferric oxide (Fe₂0₃) nanostructure anode;

preparing porous ferric oxide (Fe₂0₃) nanostructure electrode; preparing powdered lithium cobalt oxide (LiCo0₂) electrode; preparing an electrolyte; and

soaking a separator in an electrolyte, wherein the soaked separator is placed on a cathode foil and an anode is placed on top of the soaked separator and sealed in a 2016 coin type cell.

8. The method of claim 7, wherein the separator is placed between the prepared porous Fe₂0₃ nanostructure electrode and prepared powdered LiCo0₂ electrode.

9. The method of claim 7, wherein capacity of the L1C0O₂ cathode is adjusted for countering irreversible loss of the Fe₂0₃ anode.

10. The method of claim 7, wherein capacity of the full cell is retained in the range of 0.5C to 5C.