Electrochemical Performance of Electrophoretically Deposited Nickel/ Cobalt Antimony Oxide-Carbon Black Negative Electrodes for Alkali-Ion Batteries

In recent years, the requirement for portable power has increased due to the miniaturization of electronic devices. Developing rechargeable lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), with high power and energy density, long cycle life is the need of the hour. In this present work, nickel antimony oxide (NiSb2O6; NSO) and cobalt antimony oxide (CoSb2O6; CSO), two relatively new conversion-type anode materials have been explored as negative electrodes for both LIB and SIB. Conversion-type anode materials offer many advantages like ease of synthesis, requires inexpensive and abundantly available precursors and exhibit high specific capacities. Besides, relatively higher redox potentials of such anodes minimize the chance of lithium dendrites formation. A simple co-precipitation followed by calcination at 1000◦C leads to formation of tri-rutile phase NSO and CSO powder. The microstructural analysis using scanning electron microscopy of NSO and CSO powder confirms the formation of asymmetric particles having size in the range of 50-100nm. FTIR and Raman results of the calcined NSO and CSO powder indicate the presence of Sb2O6 2- units along with Ni+2/Co+2. The NSO-CB and CSO-CB electrodes are fabricated by facile and reproducible electrophoretic deposition (EPD) technique. EPD is a facile colloidal technique which can be adopted to fabricate different types of materials like conversion, insertion and alloying anode on any complex shaped substrate. Besides being an economical and ecofriendly process, EPD offers excellent reproducibility and control over the deposited film thickness. At a deposition parameter of 100V for 3minutes, well-adhered and uniform coating of NSO-CB and CSO-CB are obtained on the copper current collector. The SEM micrographs of the EPD grown electrodes substantiate the formation of a porous film with uniform distribution of active materials and carbon black (CB). Detailed ex-situ XRD analysis has been carried out to find out the lithium storage mechanism of NiSb2O6 material. It is observed that the NiSb2O6 breaks into NiO and Sb2O5 in the first lithiation step. These oxides further participate in reversible lithiation and de-lithiation reactions in the subsequent cycles. When used as a lithium-ion anode, the NSO-CB and CSO-CB electrode deliver a stable reversible capacity of 594mAhg-1 and 612mAhg-1, respectively, at a specific current of 0.5Ag-1 after 100 cycles (Fig 1(a)). Both the anode material exhibits excellent rate performance delivering a specific capacity of 397mAhg-1 and 510mAhg-1, respectively, at a high specific current of 4Ag-1. On the other hand, as a sodium-ion anode, the NSO-CB and CSO-CB electrodes are able deliver a stable reversible capacity of 255mAhg-1 and 150mAhg-1, respectively, at a specific current of 0.1Ag-1 after 50 cycles (shown in Fig 1(b)). Cyclic voltametric study at different scan rates reveals that the electrochemical reactions of NSO and CSO are mainly dominated by diffusion-controlled behavior. Therefore, both NSO and CSO can be a potential anode material for alkali-ion batteries. Fig 1: Cyclability performance of NSO-CB and CSO-CB electrodes as (a) lithium-ion battery anode, cycled at 0.5mAg-1 specific current and (b) sodium-ion battery anode, cycled at 0.1mAg-1 specific current in the voltage range of 0.01-2.5V. Figure 1