Deshielding anions enable solvation chemistry control of LiPF6-based electrolyte toward low-temperature lithium-ion batteries

• Main Authors: Yuan, Song, Cao, Shengkai, Chen, Xi, Wei, Jiaqi, Lv, Zhisheng, Xia, Huarong, Li, Jiaofu, Zhang, Hang, Liu, Lin, Tian, Changhao, Chen, Lixun, Zhang, Wei, Xing, Zhenxiang, Li, Haicheng, Li, Shuzhou, Zhu, Qiang, Feng, Xue, Chen, Xiaodong
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Engineering; Deshielding anions; Lithium-ion batteries
• Online Access: https://hdl.handle.net/10356/174646
• Institution: Nanyang Technological University

Severe capacity decay under subzero temperatures remains a significant challenge for lithium-ion batteries (LIBs) due to the sluggish interfacial kinetics. Current efforts to mitigate this deteriorating interfacial behavior rely on high-solubility lithium salts (e.g., Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium bis(fluorosulfonyl)imide (LiFSI))-based electrolytes to construct anion participated solvation structures. However, such electrolytes bring issues of corrosion on the current collector and increased costs. Herein, the most commonly used Lithium hexafluorophosphate (LiPF6 ) instead, to establish a peculiar solvation structure with a high ratio of ion pairs and aggregates by introducing a deshielding NO3 - additive for low-temperature LIBs is utilized. The deshielding anion significantly reduces the energy barrier for interfacial behavior at low temperatures. Benefiting from this, the graphite (Gr) anode retains a high capacity of ≈72.3% at -20 °C, which is far superior to the 32.3% and 19.4% capacity retention of counterpart electrolytes. Moreover, the LiCoO2 /Gr full cell exhibits a stable cycling performance of 100 cycles at -20 °C due to the inhibited lithium plating. This work heralds a new paradigm in LiPF6 -based electrolyte design for LIBs operating at subzero temperatures.