An inbuilt and unreactive Zr-Te framework enable durable, high-capacity CoTe2 anode for sodium ion storage

Metal tellurides (MTs) as potential electrode materials for sodium-ion battery suffer from detrimental volume expansion, followed by severe capacity degradation. Herein, an inbuilt Zr Te framework is introduced into CoTe 2 to boost the overall electrochemical performance of sodium ion storage. The ex-situ XPS results suggest that the Zr Te framework is unreactive, which can counteract the volume expansion due to the large size of Zr atom. In addition, the suitable introduction of Zr shall decrease the adsorption energy and diffusion barrier of Na + ion, proved by density functional theoretical calculations. As a result, Zr-CoTe 2 with the inbuilt and unreactive Zr Te framework can deliver a maximum capacity of 357 mAh g −1 at 0.05 A g −1 , an outstanding rate capability (121 mAh g −1 at 5 A g −1 ), and an enhanced cyclability (85% retention after 1000 cycles at 1 A g −1 ).