Energy Storage Science and Technology ›› 2023, Vol. 12 ›› Issue (5): 1500-1509.doi: 10.19799/j.cnki.2095-4239.2023.0001

• Special Issue on Key Materials and Recycling Technologies for Energy Storage Batteries • Previous Articles     Next Articles

Role of CoS2/NC in ether-based electrolytes as high-performance anodes for sodium-ion batteries

Yuhua BIAN(), Zhaomeng LIU, Xuanwen GAO(), Jianguo LI, Da WANG, Shangzhuo LI, Wenbin LUO   

  1. Northeastern University, Shenyang 110819, Liaoning, China
  • Received:2023-01-03 Revised:2023-01-13 Online:2023-05-05 Published:2023-05-29
  • Contact: Xuanwen GAO E-mail:2001520@stu.neu.edu.cn;gaoxuanwen@mail.neu.edu.cn

Abstract:

Developing high-performance sodium-ion battery anode materials is imminent. Transition metal sulfides have the advantages of high sodium storage capacity and good redox reaction reversibility but rapid capacity decay during charging and discharging exists. Improving the electrochemical performance of electrodes by optimizing the electrolyte is a more convenient, environmentally friendly, and effective strategy than modifying electrode materials. This study investigates CoS2/NC as anode materials for sodium-ion batteries and their electrochemical and reaction kinetic differences between two electrolytes: ethylene glycol dimethyl ether (DME) and ethylene carbonate/diethyl carbonate (EC/DEC). The results show that the DME electrolyte, which has few side reactions with the intermediate Na2S6, exhibits excellent multiplicative and cycling performance. The higher stability of Na2S6 in DME electrolytes was demonstrated using UV spectroscopy. The electron transport and ion diffusion rates of the electrode materials were analyzed using electrochemical impedance spectroscopy and cyclic voltammetry tests at different sweep rates. The results demonstrated that the side reactions of CoS2/NC with the electrolyte arise from the reaction of the intermediate sodium polysulfide with the electrolyte. Furthermore, the difference in the stability of the intermediate in the electrolyte is one of the main reasons affecting the electrochemical performance of CoS2/NC. This study investigates the differences in electrochemical performance owing to the stability of sodium polysulfide in two typical electrolytes, adding new insights into the interactions between TMS anodes and electrolytes.

Key words: CoS2, sodium polysulfide, electrolyte, sodium ion battery anode

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