Affiliation:
1. Center of Nanomaterials for Renewable Energy State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 P. R. China
2. College of Chemical and Biological Engineering Zhejiang University Hangzhou Zhejiang 310027 P. R. China
3. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan Hubei 430070 P. R. China
4. School of Optical and Electronic Information-Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan Hubei 430074 P. R. China
5. Jiangsu Jufeng New Energy Technology Co. Ltd. Changzhou Jiangsu 213166 P. R. China
Abstract
AbstractIn spite of the competitive performance at room temperature, the development of sodium‐ion batteries (SIBs) is still hindered by sluggish electrochemical reaction kinetics and unstable electrode/electrolyte interphase under subzero environments. Herein, a low‐concentration electrolyte, consisting of 0.5M NaPF6 dissolving in diethylene glycol dimethyl ether solvent, is proposed for SIBs working at low temperature. Such an electrolyte generates a thin, amorphous, and homogeneous cathode/electrolyte interphase at low temperature. The interphase is monolithic and rich in organic components, reducing the limitation of Na+ migration through inorganic crystals, thereby facilitating the interfacial Na+ dynamics at low temperature. Furthermore, it effectively blocks the unfavorable side reactions between active materials and electrolytes, improving the structural stability. Consequently, Na0.7Li0.03Mg0.03Ni0.27Mn0.6Ti0.07O2//Na and hard carbon//Na cells deliver a high capacity retention of 90.8 % after 900 cycles at 1C, a capacity over 310 mAh g−1 under −30 °C, respectively, showing long‐term cycling stability and great rate capability at low temperature.
Funder
National Natural Science Foundation of China
State Key Laboratory of Electrical Insulation and Power Equipment