Nanoengineering of Thin Film V₂O₅ Cathode Interfaces via Atomic Layer Deposition for use with Polymer Gel Ionic Liquid Electrolytes

In this work we show high capacity and cycle-life performance, for electrodeposited, crystalline V₂O₅ thin film cathodes protected by a 1 nm ALD alumina deposit for use with Li-metal and ionic liquid electrolyte based microbatteries. Al₂O₃ coatings thicker than 1 nm are shown to decrease the performance of the V₂O₅ thin film cathodes. The ionic liquid outperforms an organic electrolyte at 1 C rates with an initial capacity of 148 mAh g⁻¹ and capacity retention of 97 % at cycle 50. A polymer gel analogue of the ionic liquid electrolyte in combination with the 1 nm Al₂O₃ coated V₂O₅ had an initial capacity of 139 mAh/g with a capacity retention of 93.5 % to cycle 800, illustrating high capacity and extended cycle life.