An optimized Al2O3 layer for enhancing the anode performance of NiCo2O4 nanosheets for sodiumion batteries

Herein, an ultrathin Al2O3 layer was coated onto NiCo2O4 nanosheets via an atomic layer deposition (ALD) method, and the NiCo2O4 coated with an ALD-derived Al2O3 material was successfully used as an anode material for sodium-ion batteries (SIBs). This kind of electrode exhibited enhanced cycling performance with a reversible capacity of 395 mA h g(-1) after 50 cycles, and good rate capability with the discharge capacities of 350, 320, and 294 mA h g(-1) at the various current densities of 100, 200, and 400 mA g(-1), respectively. Interestingly, remarkable prevention of the reactions between the electrode and electrolyte was observed. The performance improvement is due to the protection of the NiCo2O4 coated with an ALD-derived Al2O3 layer from the electrochemical active materials. These results demonstrate the great potential of NiCo2O4 coated with an ALD-derived Al2O3 material as anodes in SIBs.