The improved cycling stability of nanostructured NiCo2O4 anodes for lithium and sodium ion batteries

Abstract

Developing the high-capacity anode materials such as conversion-type metal oxides which possess both Li and Na storage activity is very practical for the high-energy LIBs/SIBs. Herein, we use NiCo 2 O 4 anodes as a model to investigate the morphology evolution which accounts for the poor cycling performance and understand the effect of structure optimization on the electrochemical performance. Three NiCo 2 O 4 samples with different morphologies of microspheres, nanospheres and nanosheets are synthesized.Firstly, the serious structural degradation of NiCo 2 O 4 microspheres is observed whether it works as a LIB or SIB anode. In addition, a signi cant difference between the lithiation and sodiation capacity of NiCo 2 O 4 materials reveals Na + ions only partially intercalated in NiCo 2 O 4 and the conversion reaction limited by the strain. Next, NiCo 2 O 4 nanosheets on Ni foam as a binder-free anode for LIBs are investigated which suggest the positive effect of 3D nanostructures on the morphology stability. As a result, NiCo 2 O 4 nanosheets deliver a high lithiation capacity of 1092 mAh g − 1 after 100 cycles at 0.5 A g − 1 and an excellent rate capacity of 643 mAh g − 1 at 4 A g − 1 . Finally, NiCo 2 O 4 nanospheres are evaluted as a SIB anode which indicate the smaller particle size of active materials is bene cial to the release of stress and structure stability during discharge-charge processes. A rational design of the electrode' architecture is very important for the conversion-type 3d transition metal oxide anodes for advanced LIBs and SIBs.