Designing mesostructured bimetallic selenide derived from room-temperature prepared metal–organic frameworks as a sodium-ion battery anode with high performance and fast reaction kinetics

Mesostructured materials are considered to be promising candidates for use in high-performance secondary batteries due to their specific properties, which are beneficial for electrochemical redox and ion diffusion; however, the synergistic mechanism is still unclear, and a general preparation approach is highly needed. Here, we report a mesostructured nitrogen-doped CoNiSe₂ as a high-performance sodium-ion battery anode derived from room-temperature-synthesized CoNi-metal organic frameworks, and in-depth insight into the synergistic effect during charge-discharge is demonstrated. The mesostructure provides three-dimensional ion transport channels, which are conducive to the stable insertion/extraction of Na⁺ ions. <i>In situ</i> Raman spectra and <i>in situ</i> X-ray diffraction patterns verify the good real-time reversibility of the mesostructured CoNiSe₂/NC upon charge-discharge. Moreover, CoNiSe₂/NC shows fast reaction kinetics and enhanced electrical conductivity. The results show that the CoNiSe₂/NC anode displays a high and stable capacity of 498 mAh g^-1 after 600 cycles at 0.2 A g^-1, and 426 mAh g^-1 after being cycled 1500 times at 1 A g^-1, exceeding the performance of many reported anodes. Even at 50 °C or -10 °C, the anode exhibits stable performance. In addition, the full cell provides 270 mAh g^-1 after 500 cycles at 0.5 A g^-1, exhibiting promising potential for practical applications. These findings are important for developing emerging energy-storage materials and will find broad applications in many battery systems.