Electroplating lithiated transition metal oxides using low purity starting precursors

Abstract

A method for electroplating (or electrodeposition) a lithiated transition metal oxide composition using low purity starting precursors. The method includes electrodepositing the electrochemically active material onto an electrode in an electrodeposition bath containing a non-aqueous electrolyte. The lithiated metal oxide can be used for various applications such as electrochemical energy storage devices including high power and high-energy lithium-ion batteries.

Claims

1. A method of forming a lithiated transition metal oxide onto the surface of a working electrode comprising the steps of: (a) immersing a working electrode into a non-aqueous electrolyte comprising a lithium source and a transition metal source, wherein said lithium and transition metal sources have a purity ranging from about 50% to about 95% by weight; (b) electrodepositing a lithiated transition metal oxide onto a surface of the working electrode from the electrolyte at a temperature in excess of the melting temperature of the non-aqueous electrolyte; (c) removing the working electrode from the bath and; (d) rinsing the electrodeposited lithiated transition metal oxide.

2. The method of claim 1 wherein the low purity lithium and transition metal sources have a purity ranging from about 50% to about 85% by weight.

3. The method of claim 1 wherein the low purity lithium source is selected from the group consisting of LiOH, Li.sub.2CO.sub.3 LiF, LiCI, LiBr, LiI, LiNO.sub.3, LiNO.sub.2, Li.sub.2SO.sub.4, and combinations thereof.

4. The method of claim 1 wherein the low purity transition metal source is selected from the group consisting of MnCl.sub.2, MnSO.sub.4, Mn.sub.2O.sub.3, MnO.sub.2, Mn.sub.3O.sub.4, Mn(NO.sub.3).sub.2, CoO, Co.sub.2O.sub.3, Co.sub.3O.sub.4, CoOH.sub.2, CoCl.sub.2, CoSO.sub.4, Co(NO.sub.3).sub.2 and combinations thereof.

5. The method of claim 1 wherein the non-aqueous electrolyte comprises an inorganic molten salt.

6. The method of claim 5 wherein at least 50% of the ions comprised by the inorganic molten salt electrolyte are inorganic ions.

7. The method of claim 5 wherein the inorganic molten salt electrolyte comprises a hydroxide salt, a halide salt, a sulfate salt, a nitrate salt, a nitrite salt, and combinations thereof.

8. The method of claim 7 wherein the inorganic molten salt electrolyte comprises a hydroxide salt selected from the group consisting of Li.sub.2SO.sub.4, LiOH, KOH, NaOH, RbOH, and CsOH, a halide salt selected from the group consisting of LiCI, LiF, KF, KCl, NaCl, NaF, LiBr, NaBr, KBr, LiI, NaI, KI, a nitrate salt selected from the group consisting of LiNO.sub.3, NaNO.sub.3, and KNO.sub.3, a nitrite salt selected from the group consisting of LiNO.sub.2, NaNO.sub.2, KNO.sub.2, a Li.sub.2SO.sub.4 sulfate salt, and combinations thereof.

9. The method of claim 8 wherein the inorganic molten salt electrolyte comprises a hydroxide salt selected from the group consisting of LiOH, KOH, NaOH, and combinations thereof.

10. The method of claim 8 wherein the inorganic molten salt electrolyte comprises a Li.sub.2SO.sub.4 sulfate salt.

11. The method of claim 1 wherein the working electrode comprises an electrically conductive material selected from the group consisting of metals, metal alloys, metallic ceramics, electrically conductive carbon, electrically conductive polymers, and electrically conductive composite materials.

12. The method of claim 11 wherein the working electrode is a planar foil with thickness ranging from 1 m to 100 mm.

13. The method of claim 11 wherein the working electrode is a porous foam with porosity ranging from 1% to 99% porosity.

14. The method of claim 11 wherein the working electrode is a metal or metal alloy selected from the group consisting of aluminum, copper, chromium, cobalt, manganese, nickel, silver, gold, tin, platinum, palladium, zinc, tungsten, tantalum, rhodium, molybdenum, titanium, iron, zirconium, vanadium, and hafnium, and the alloys thereof.

15. The method of claim 1 wherein the source of the transition metal in the plating bath comprises an oxide, halide or sulfate of at least one transition metal.

16. The method of claim 1 wherein the transition metal source is selected from the group consisting of cobalt, manganese, nickel, copper, iron, chromium, vanadium, titanium, molybdenum, tungsten, and combinations thereof.

17. The method of claim 1 wherein the lithiated transition metal oxide is electrodeposited onto the surface(s) of a three-dimensional working electrode having an open pore porous structure.

18. The method of claim 1 wherein the lithiated transition metal oxide is conformally coated onto the working electrode.

19. The method of claim 1 wherein the thickness of the electrodeposited lithiated transition metal oxide ranges from about 10 nm to about 500 m.

20. The method of claim 1 wherein the electrodeposited lithiated transition metal oxide is lithium cobalt oxide characterized by an XRD spectrum containing a doublet peak at approximately between 63 and 70 2 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. Cyclic voltammetry of LiOH (98%)/KOH, LiOH (90%)/KOH, LiOH (85%)/KOH baths containing Co(OH).sub.2 at 5 mV/s scan rate at 260 C.

(2) FIG. 2. XRD patterns of electroplated LiCoO.sub.2 powders obtained from LiOH (98%)/KOH, LiOH (90%)/KOH, LiOH (85%)/KOH eutectic baths containing Co(OH).sub.2.

(3) FIG. 3. HRSEM figure of LiCoO.sub.2 particles obtained from LiOH (98%)/KOH, LiOH (90%)/KOH, LiOH (85%)/KOH eutectic baths containing Co(OH).sub.2.

(4) FIG. 4A. Discharge profiles of LiCoO.sub.2 cathode active materials obtained from LiOH (98%)/KOH, LiOH (90%)/KOH, LiOH (85%)/KOH eutectic baths containing Co(OH).sub.2. The cells were cycled between 4.25 and 3V at C/5 rate.

(5) FIG. 4B. dQ/dV plot along with its charge-discharge profile for LiCoO.sub.2 cathode obtained regular LiOH/KOH eutectic bath containing Co(OH).sub.2.

(6) FIG. 5. Cyclic voltammetry of LiCl (97%)/KOH, LiCl (85%)/KOH, LiCl (70%)/KOH, LiCl (50%)/KOH baths containing Co(OH).sub.2 at 5 mV/s scan rate at 320 C.

(7) FIG. 6. Discharge profiles of LiCoO.sub.2 cathode active materials obtained from LiCl (97%)/KOH, LiCl (85%)/KOH, LiCl (70%)/KOH, LiCl (50%)/KOH baths containing Co(OH).sub.2 at 320 C. The cells were cycled between 4.25 and 3V at C/5 rate.

(8) FIG. 7. Cyclic voltammetry of Li.sub.2SO.sub.4 (98%)/KOH and Li.sub.2SO.sub.4 (85%)/KOH baths containing Co(OH).sub.2 at 5 mV/s scan rate at 350 C.

(9) FIG. 8. Discharge profiles of LiCoO.sub.2 cathode active materials obtained from Li.sub.2SO.sub.4 (98%)/KOH and Li.sub.2SO.sub.4 (85%)/KOH baths containing Co(OH).sub.2 at 350 C. The cells were cycled between 4.25 and 3V at C/5 rate.

(10) FIG. 9. Cyclic voltammetry of LiOH/KOH baths containing 98% pure Co(OH).sub.2 and 85% pure Co(OH).sub.2 at 5 mV/s scan rate at 260 C.

(11) FIG. 10. Discharge profiles of LiCoO.sub.2 cathode active materials obtained from LiOH/KOH baths containing 98% pure Co(OH).sub.2 and 85% pure Co(OH).sub.2 at 260 C. The cells were cycled between 4.25 and 3V at C/5 rate.

(12) FIG. 11. Cyclic voltammetry of LiOH/KOH baths containing 95% pure Co(SO).sub.4 at 5 mV/s scan rate at 260 C.

(13) FIG. 12. Discharge profiles of LiCoO.sub.2 cathode active materials obtained from LiOH/KOH baths containing 98% pure Co(OH).sub.2 and 95% pure Co(SO).sub.4 at 260 C. The cells were cycled between 4.25 and 3V at C/5 rate.

DETAILED DESCRIPTION OF THE INVENTION

(14) In general, the present invention relates to a method of forming a lithiated transition metal oxide comprising the steps of (a) immersing a working electrode into a non-aqueous electrolyte comprising a lithium source and a transition metal source, wherein the lithium and transition metal source are both of low purity; (b) electrodepositing a lithiated transition metal oxide onto a surface of the working electrode from the electrolyte at a temperature in excess of the melting temperature of the non-aqueous electrolyte; (c) removing the working electrode from the bath and; (d) rinsing the electrodeposited lithiated transition metal oxide.

(15) In a preferred embodiment, the electrodeposition is done by applying a constant voltage ranging from 0.6V to 1.4V versus Cobalt wire reference electrode or by applying constant current ranging from 1 uA/cm2 to 100 A/cm2, or applying a voltage and/or current pulses intermittently.

(16) In a preferred embodiment, the low purity lithium source is selected from the group consisting of LiOH, Li.sub.2CO.sub.3 LiF, LiCl, LiBr, LiI, LiNO.sub.3, LiNO.sub.2, Li.sub.2SO.sub.4, and combinations thereof.

(17) In a preferred embodiment, the low purity transition metal source is selected from the group consisting of MnCl.sub.2, MnSO.sub.4, Mn.sub.2O.sub.3, MnO.sub.2, Mn.sub.3O.sub.4, CoO, Co.sub.2O.sub.3, Co.sub.3O.sub.4, CoOH.sub.2, CoCl.sub.2, CoSO.sub.4, and combinations thereof.

(18) The low purity lithium and transition metal sources have a purity ranging from about 50% to about 98% by weight, more preferably from about 50% to about 95% by weight, and most preferably from about 50% to about 85% by weight.

(19) Preferably the non-aqueous electrolyte comprises an inorganic molten salt, wherein at least 50%, and preferably 99% of the ions comprised by the inorganic molten salt electrolyte are inorganic ions. The inorganic molten salt electrolyte can comprise a hydroxide salt, a halide salt, a nitrate salt, a sulfate salt or a combination thereof. In a preferred embodiment, the inorganic molten salt electrolyte comprises a hydroxide salt selected from the group consisting of LiOH, KOH, NaOH, RbOH, and CsOH, a halide salt selected from the group consisting of LiCl, LiF, KF, KCl, NaCl, NaF, LiBr, NaBr, KBr, LiI, NaI, KI, a nitrate salt selected from the group consisting of LiNO.sub.3, NaNO.sub.3, and KNO.sub.3, a nitrite salt selected from the group consisting of LiNO.sub.2, NaNO.sub.2, KNO.sub.2, a Li.sub.2SO.sub.4 sulfate salt, and combinations thereof.

(20) In one embodiment, the inorganic molten salt electrolyte comprises a nitrite salt selected from the group consisting of LiNO.sub.2, NaNO.sub.2, KNO.sub.2, and combinations thereof.

(21) In another embodiment, the inorganic molten salt electrolyte comprises a hydroxide salt selected from the group consisting of LiOH, KOH, NaOH, CsOH, and combinations thereof.

(22) In another embodiment, the inorganic molten salt electrolyte comprises a Li.sub.2SO.sub.4 sulfate salt.

(23) The electrodeposited lithiated transition meal oxide is preferably conformally coated onto the working electrode. In a preferred embodiment, the working electrode is a three-dimensional porous nanostructured structure. The three-dimensional porous working electrode preferably has a void volume fraction (porosity) between 1% and 99%.

(24) The working electrode comprises an electrically conductive material selected from the group consisting of metals, metal alloys, metallic ceramics, electrically conductive carbon, electrically conductive polymers, and electrically conductive composite materials. In a preferred embodiment, the working electrode is a metal or metal alloy selected from the group consisting of aluminum, copper, chromium, cobalt, manganese, nickel, silver, gold, tin, platinum, palladium, zinc, tungsten, tantalum, rhodium, molybdenum, titanium, iron, zirconium, vanadium, and hafnium, and the alloys thereof.

(25) In another preferred embodiment, the working electrode is a planar foil with thickness ranging from 1 um to 100 mm or a porous foam with porosity ranging from 1% to 99% porosity.

(26) The thickness of the electrodeposited lithiated transition metal oxide preferably ranges from about 10 nm to about 500 m. The electrodeposited lithiated transition metal oxide material can also be in the form of a powder, and wherein the powder can be scraped off.

(27) The electrodeposition is carried out at relatively low temperatures ranging from 100 C. to 600 C. Preferably, the electrodeposition temperature is from about 300 C. to about 500 C.

(28) The electrodeposition can be carried out in an ambient or an inert atmosphere.

(29) In a preferred embodiment, the electrodeposited lithiated transition metal oxide is lithium cobalt oxide characterized by an XRD spectrum containing a doublet peak at approximately between 63 and 70 2 degrees.

(30) Electroplating of a lithiated transition metal oxide was carried out using a 3-electrode system where a working electrode, a counter (Ni foil), and a pseudo reference (Co metal) electrode were immersed into a eutectic solution, which is also called a molten salt, containing a transition metal and Li ions source. Preferably, the transition metal source comprises an oxide, hydroxide, halide or sulfate of at least one transition metal. The transition metal can be aluminum, copper, chromium, cobalt, manganese, nickel, silver, gold, tin, platinum, zinc, tungsten, tantalum, rhodium, molybdenum, titanium, iron, zirconium, vanadium, hafnium, and the alloys thereof. The Li source can be LiOH, Li.sub.2SO.sub.4, LiCl, LiI, LiBr, LiNO.sub.3, LiNO.sub.2, LINO and mixtures thereof.

(31) The eutectic system can provide a relative low synthesis temperature (100-800 C.). The eutectic temperature is known as the melting point which is lower than any composition made up of the mixture. Above the eutectic temperature, the liquid phase is generally called molten salt. For electrodepositing on a working electrode, a molten salt system should have low temperature to protect the working electrode and possess high solubility of transition metal sources. Low-temperature molten salt is usually selected by checking the eutectic points in the phase diagrams. Molten salt bath is prepared with at least one of chemicals including hydroxides (KOH, NaOH, RbOH, CsOH etc), halides (KF, KCl, NaCl, NaF, NaBr, KBr, NaI, KI, AlCl.sub.3 etc), nitrate (NaNO.sub.3, KNO.sub.3), nitrite (NaNO.sub.2, KNO.sub.2), and sulfates (Na.sub.2SO.sub.4, K.sub.2SO.sub.4). The Ni crucible was used as the reaction vessel and glass lid was used to hang the abovementioned electrodes into the eutectic solution. All three electrodes were connected to a power supply which provides sufficient voltage or current densities where electrochemically active lithiated transition metal oxide materials were produced. These materials are of great interest to the Li-ion battery industry. FIG. 1 shows the cyclic voltammetries (CVs) of several KOH/LiOH molten salt systems containing different percentages of LiOH impurities (98%, 90% and 85%) which all of the baths contain CoOH.sub.2 species as Co source. The 90% and 85% pure LiOH powders were prepared by grinding appropriate percentages of Li.sub.2CO.sub.3 and Li.sub.2SO.sub.4 with 98% pure LiOH. As can be seen from CV profiles, in all cases Co.sup.2+ ions start to be oxidized at relatively similar potentials i.e. 0.7V. All three profiles in FIG. 1 resemble each other suggesting that there are most likely no electrochemically active impurities present during electroplating. The sharp increase in current appearing above 1.2V is due to the oxidation of OH groups originating from KOH and LiOH salts which are the major components of the molten salt. To further support this, the inset figure in FIG. 1 also shows the CV of the KOH/LiOH bath without the presence of Co source which demonstrates that there is only one oxidation peak which corresponds to anion oxidation. The potentials shift after Co oxidation is minor which could be due to the water content of the molten salt. As seen in FIG. 1 (inset) the eutectic bath is stable for plating LiCoO.sub.2 nano-flakes to 1.4 V vs. Co/Co.sup.2+. We found the optimum voltage pulse to be 1.2V versus Co reference electrode. All voltage values are reported versus Co/Co.sup.2+ pseudo reference electrode. As can be seen from FIG. 2, all LiCoOh.sub.2 powders have very similar XRD patterns irrespective of the starting material impurity percentages. They all possess R3m phase of layered structure and have similar lattice parameters. Every diffraction peak can be assigned to Joint Committee on Powder Diffraction Standards (JCPDS) card no 50-0653 indicating that the materials made from these impure starting materials are crystallographically identical to standard lithium cobalt oxide. Of particular importance, the presence of the doublet peak in all patterns around 65-70 2 degrees suggest that layered feature of the crystal structure is preserved regardless of the impurity percentages. High resolution scanning electron microscopy images exhibited in FIG. 3 shows that the LiCoO.sub.2 particles have very similar morphological features. This set of images demonstrates that the raw material impurities present in LiOH do not affect the morphology of the final product.

(32) In one example, 120 g of KOH, 20 g LiOH, and 5 g CoOH.sub.2 are added to the bath and monitored that they are dissolved thoroughly. The color of the melt changed from transparent color to blue as the divalent Co.sup.2+ ions are coordinated by hydroxide ions. This is followed by immersing the 3-electrode lid into the molten salt. Afterwards, 1.2V (versus cobalt wire reference electrode) potential pulses were applied. The pulse range is from 1 s to 20 s where a SSF, Ni foil and Co wire are used as working, counter, and pseudo reference electrodes, respectively. Between pulses, there was an open circuit voltage period (ranging from 1 s to 60 minutes). This resting period allows ions to move into the voids of SSF thereby conformal deposition is achieved. Number of deposition cycles (duty cycle refers to on/off time) determines the loading of the sample. Constant voltage or current densities will also lead to the formation of the metal oxide however the electroplated material will not cover the 3D substrate conformally. Nevertheless, one can use this method to obtain powder form of the lithiated metal oxide. By simply changing the transition metal to a Mn source, one can also produce Li.sub.xMn.sub.yO.sub.z material.

(33) After electroplating LiCoO.sub.2 on the working electrode, the electrode quickly is rinsed with deionized water thoroughly to ensure no residual KOH or LiOH salts remain. Since CoOH.sub.2 is not soluble in water, a chelating agent, such as citric acid, would help to dissolve Co.sup.2+. If CoOH.sub.2 traces are not removed, during heat treatment this would form Co.sub.3O.sub.4 particles that are not formed during electroplating. Removal of Co.sup.2+ ions can be simply done by immersing the lithiated transition metal oxide electrode into an approximately 0.4M citric acid aqueous solution for 1 minute.

(34) In one experiment, we employed stainless steel fibers (SSF) as the 3D scaffold working electrode. The plating procedure is as follows: 1.2V (versus Co/Co.sup.2+) voltage pulses for 1 s on-time followed by 2 minutes rest between each voltage pulses. This ensured ions to diffuse inner pores of 3D scaffold leading to conformal LCO plating. Approximately, 20 cycles of these pulse plating procedures resulted in a 2 mAh/cm.sup.2 loaded electrodes with around 145 mAh/g specific capacities, standard values in the literature. The electrochemical performances of the LiCoO.sub.2 electrodes were tested and discharge profiles of LiCoO.sub.2 obtained from different purity of LiOH precursor were plotted in FIG. 4A. The coin cell was constructed with LiCoO.sub.2 cathode deposited onto SSF versus Li foil and separated with a commercially available 20 um polymer separator. The electrolyte was a traditional LiPF.sub.6 dissolved in organic solvents. All of the LiCoO.sub.2 electrodes in FIG. 4A delivered very identical capacities (145 mAh/g) and voltage profiles resemble each other well. This electrochemical data further proves that neither 85% nor 90% pure LiOH have any negative effect on the characteristic of LiCoO.sub.2 electrochemical discharge profile. FIG. 4B exhibits charge-discharge capacities of the LiCoO.sub.2 electrode obtained from a regular molten salt bath. The plateaus indicated with the circles in FIG. 4B are indicative of a high level of crystallinity. During charging at 4.06V and 4.18V regions, a phase transformation takes place concomitant with the removal of Li ions from monoclinic and hexagonal phases, respectively (see Microemulsion-based synthesis and electrochemical evaluation of different nanostructures of LiCoO.sub.2 prepared through sacrificial nanowire templates, Gautam Ganapati Yadav, Anand David, Huazhang Zhu, James Caruthers and Yue Wu, Nanoscale, 2014, 6, 860). These regions are considered a direct correlation with the quality of LiCoO.sub.2 powders. Good crystallinity is desired as it is responsible for good performance characteristics like lifetime and high temperature storage resistance.

(35) In another example, FIG. 5 shows the cyclic voltammetries (CVs) of several KOH/LiCl molten salt systems containing different percentages of LiCl impurities (97%, 85% 70% and 50%) in which all of the baths contain CoOH.sub.2 species as Co source. The bath temperature was set to 320 C. and the plating procedure was as follows: 1.2V (versus Co/Co.sup.2+) voltage pulses for 1 s on-time followed by 2 minutes rest between each voltage pulses. This ensured ions to diffuse inner pores of 3D scaffold, SSF working electrode, leading to conformal LCO plating. Approximately, 20 cycles of these pulse plating procedures resulted in a 2 mAh/cm.sup.2 loaded electrodes with around 145 mAh/g specific capacities, bode well with the standard values in the literature. The 85%, 70% and 50% pure LiCl powders were prepared by mixing appropriate percentages of NaCl, KCl and CaCl with 97% pure LiCl. These impurities were selected as LiCl is usually refined through brines which contain alkali chloride ions heavily (see Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation: A comprehensive review, Pratima Meshram, B. D. Pandey, T. R. Mankhand, Hydrometallurgy 150 (2014) 192-208). The weight percentages of the impurities were set as NaCl/KCl/CaCl w/w 1/0.5/0.5, respectively. The Pt foil working electrode is employed to evaluate if there are any side reactions stemming from impurities of LiCl precursors. As can be seen from CV profiles, in all cases Co.sup.2+ ions oxidize at relatively similar potentials i.e. 0.6V. All three profiles in FIG. 1 resemble each other suggesting that there are most likely no electrochemically active impurities present during electroplating. The intensity of the oxidation peak around 1V could correspond to complexed [Co(OH).sub.6].sup.4 and appears to decrease as the impurity percentages increase due to some cation hindrance. This however does not affect the final product as will be discussed below. From these results the eutectic bath is stable for plating LiCoO.sub.2 up until 1.4 V vs. Co/Co.sup.2+. We find the optimum voltage pulse to be 1.2V versus Co reference electrode. All voltage values are reported versus Co/Co.sup.2+ pseudo reference electrode. As can be seen from FIG. 6, discharge capacities of LiCoO.sub.2 electrodes obtained from different impurity ranges of LiCl delivered identical values which was around 145 mAh/g. The voltage profiles also resembled each other suggesting that NaCl, KCl and CaCl impurities do not have adverse effect on LiCoO.sub.2.

(36) In another example, FIG. 7 shows the CVs of two KOH/Li.sub.2SO.sub.4 molten salt systems containing different percentages of Li.sub.2SO.sub.4 impurities (98% and 85%) in which both of the baths contain CoOH.sub.2 species as Co source. The bath temperature was set to 350 C. and the plating procedure was as follows: 1.2V (versus Co/Co.sup.2+) voltage pulses for 1 s on-time followed by 2 minutes rest between each voltage pulses. This ensured ions to diffuse inner pores of 3D scaffold, SSF working electrode, leading to conformal LCO plating. Approximately, 20 cycles of these pulse plating procedures resulted in a 2 mAh/cm.sup.2 loaded electrodes with around 145 mAh/g specific capacities, standard values in the literature. The 85% pure Li.sub.2SO.sub.4 powders were prepared by mixing appropriate percentages of Al.sub.2O.sub.3 and SiO.sub.2 with 98% pure Li.sub.2SO.sub.4. Al.sub.2O.sub.3 and SiO.sub.2 were reported as common impurities of Li.sub.2SO.sub.4 in literature. These impurities were selected as Li.sub.2SO.sub.4 is usually refined through an ore which contains spodumene, known as lithium-aluminum-silicate (see Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation: A comprehensive review, Pratima Meshram, B. D. Pandey, T. R. Mankhand. Hydrometallurgy 150 (2014) 192-208). The weight percentages of the impurities were set as Al.sub.2O.sub.3/SiO.sub.2 w/w 1/1, respectively. In addition to these two major impurities there are other impurities present in Li.sub.2SO.sub.4. These impurities are at the ppm level and consisted of the following elements: Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Zn and Cl. The Pt foil working electrode is employed to evaluate if there are any side reactions stemming from impurities of Li.sub.2SO.sub.4 precursors. As can be seen from CV profiles, in all cases Co.sup.2+ ions start to oxidize at relatively similar potentials i.e. 0.6V. All three CV profiles in FIG. 7 resemble each other suggesting that no electrochemically active impurities are present during electroplating. From these results the eutectic bath is stable for plating LiCoO.sub.2 nano-flakes to 1.4 V vs. Co/Co.sup.2+. We find the optimum voltage pulse to be 1.2V versus Co reference electrode. All voltage values are reported versus Co/Co.sup.2+ pseudo reference electrode. As can be seen from FIG. 8, discharge capacities of LiCoO.sub.2 electrodes obtained from different impurity ranges of Li.sub.2SO.sub.4 delivered identical values which is around 145 mAh/g. The voltage profiles also resembled each other suggesting that Al.sub.2O.sub.3 and SiO.sub.2 impurities and other ppm level of impurities do not have adverse effect on LiCoO.sub.2.

(37) In another example, FIG. 9 shows the CVs of two KOH/LiOH molten salt systems containing different purity percentages of Co(OH).sub.2 impurities (98% and 85%) in which the bath temperature was set to 260 C. and the plating procedure was as follows: 1.2V (versus Co/Co.sup.2+) voltage pulses for 1 s on-time followed by 2 minutes rest between each voltage pulses. This ensured ions to diffuse inner pores of 3D scaffold, SSF working electrode, leading to conformal LCO plating. Approximately, 20 cycles of these pulse plating procedures resulted in a 2 mAh/cm.sup.2 loaded electrodes with around 145 mAh/g specific capacities, standard values in the literature. The 85% pure Co(OH).sub.2 powders were prepared by mixing 98% Co(OH).sub.2 powders with the appropriate percentages of CoSO.sub.4 and Mg(OH).sub.2, commonly found impurities in Co(OH).sub.2 (see Processing Considerations for Cobalt Recovery from Congolese Copperbelt Ores, B Swartz, S. Donegan, S. Amos, Hydrometallurgy Conference 2009, The Southern African Institute of Mining and Metallurgy, 2009). The weight percentages of the CoSO.sub.4 and Mg(OH).sub.2 impurities were 1/1. The Pt foil working electrode is employed to evaluate if there are any side reactions stemming from impurities of Co(OH).sub.2 precursors. As can be seen from CV profiles, in all cases Co.sup.2+ ions are started to be oxidized at relatively similar potentials i.e. 0.6V. All three CV profiles in FIG. 9 resemble each other suggesting that no electrochemically active impurities are present during electroplating. From these results the eutectic bath is stable for plating LiCoO2 nano-flakes to 1.4 V vs. Co/Co.sup.2+. We find the optimum voltage pulse to be 1.2V versus Co reference electrode. All voltage values are reported versus Co/Co.sup.2+ pseudo reference electrode. As can be seen from FIG. 10, discharge capacities of LiCoO.sub.2 electrodes obtained from different impurity ranges of Co(OH).sub.2 delivered identical values which is around 145 mAh/g. Voltage profiles, an indication of structural integrity, also resembled each other suggesting that CoSO.sub.4 and Mg(OH).sub.2 impurities and other ppm level of impurities do not have adverse effect on LiCoO.sub.2.

(38) In another example, FIG. 11 shows the CVs of two KOH/LiOH molten salt systems containing low purity (95% pure) percentage of Co(SO).sub.4 in which the bath temperature was set to 260 C. and the plating procedure was as follows: 1.2V (versus Co/Co.sup.2+) voltage pulses for 1 s on-time followed by 2 minutes rest between each voltage pulses. This ensured ions to diffuse inner pores of 3D scaffold, SSF working electrode, leading to conformal LCO plating. Approximately, 20 cycles of these pulse plating procedures resulted in a 2 mAh/cm.sup.2 loaded electrodes with around 145 mAh/g specific capacities, standard values in the literature. The Pt foil working electrode is employed to evaluate if there are any side reactions stemming from impurities of Co(SO).sub.4 precursors. As can be seen from CV profiles, in all cases Co.sup.2+ ions are started to be oxidized at relatively similar potentials i.e. 0.6V. CV profile in FIG. 11 resemble CoOH.sub.2 based eutectic bath suggesting that CoSO.sub.4 can also be utilized as Co source. As can be seen from FIG. 12, discharge capacities of LiCoO.sub.2 electrodes obtained from different Co source, namely CoOH.sub.2 and CoSO.sub.4 delivered identical values which is around 145 mAh/g. Voltage profiles, an indication of structural integrity, also resembled each other suggesting that using either CoOH.sub.2 or CoSO.sub.4 do not have adverse effect on LiCoO.sub.2.