Electrophoretic Deposition of Poly(ethylene oxide) Gel-Polymer Electrolyte for 3D NiO/Ni Foam Anode Based Lithium-Ion Batteries

The goal to further increase energy and power density of conventional 2D structured lithium-ion batteries is driving research towards more complex 3D batteries with large surface area and accordingly high active material mass loading. So far, many attempts have been implemented to prepare 3D structured LIBs. However, the hindrance of the realization comes with removing the separator which requires conformally and homogeneously coating the scaffolded areas of the electrode. The conformal coating of polymer electrolyte without any defects on the surface of the electrode is one of the most essential and challenging problems to solve to avoid the short circuit between the anode and cathode compartments of the 3D LIBs. In this paper, electrophoretic deposition technique was successfully used for the first time to coat the 3D NiO on the nickel foam anode with polyethylene oxide (PEO) gel-polymer electrolyte. The resulting polymer electrolyte was thin and uniform with the thickness range of 2.5-3.0 μm. The developed NiO@Ni foam anode coated by PEO gel-polymer electrolyte exhibited outstanding cycling stability of 100 cycles at 0.1 C rate, delivering a capacity of 406 mAh g⁻¹. This simple coating approach allowed a cell operation at room temperature without a commercial separator, which is an excellent result for further developing high-energy-density 3D batteries.