Coral-like Ni x Co 1−x Se 2 for Na-ion battery with ultralong cycle life and ultrahigh rate capability

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2019-02, Vol.7 (8), p.3933-3940
• Main Authors: He, Yanyan, Luo, Ming, Dong, Caifu, Ding, Xuyang, Yin, Chaochuang, Nie, Anmin, Chen, Yanan, Qian, Yitai, Xu, Liqiang
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C8TA10114K

Storage technology of electrical energy with ultrafast charge/discharge rates is in high demand for future electronics and electric vehicles. Among them, sodium ion batteries (SIBs) have received much attention, however, the exploration of electrode materials with a high rate capacity and long cycle life still faces great challenges. In this work, we have fabricated coralloid Ni x Co 1−x Se 2 with a hierarchical architecture for the first time, and it presents specific capacities of 321 mA h g −1 after 2000 cycles at 2 A g −1 , corresponding to a capacity decay rate of 0.011% per-cycle, and 277 mA h g −1 even at the high rate of 15 A g −1 , which could be attributed to the enhanced conductivity by Co-doping, the hierarchical architecture preventing the structure from collapsing or crushing, the accelerated electron transmission and the shortened diffusion distance of Na + . The extremely fast electron and Na ion transfer kinetics could be associated with the capacitive contribution. We further reveal the ultrastable and ultrahigh rate Na-ion storage mechanism through systematic analysis including compositional/structure evolution studies and comprehensive electrochemical characterizations. The presented strategy for the design and synthesis of coralloid, Co doped NiSe 2 with a hierarchical architecture could enlighten researchers on the development of electrodes with an ultralong cycle life and ultrahigh rate capability.