Unveil the origin of voltage oscillation for sodium- ion batteries operating at-40 °C

• 成果类型: Article
• 署名作者: Que, Lanfang; Yu, Fuda; Wu, Jihuai; Lan, Zhang; Feng, Yutong; Zhao, Ruizheng; Sun, Zhihao; Yang, Zhuo; Luo, Hao; Chao, Dongliang
• 署名单位: Huaqiao University; Fudan University; Xiamen University of Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10693
• DOI: 10.1073/pnas.2311075121
• 发表日期: 2024-04-23
• 关键词: cathode; DYNAMICS

摘要

Voltage oscillation at subzero in sodium - ion batteries (SIBs) has been a common but overlooked scenario, almost yet to be understood. For example, the phenomenon seriously deteriorates the performance of Na3V2(PO4)3 (NVP) cathode in PC (propylene carbonate)/EC (ethylene carbonate) - based electrolyte at -20 degrees C. Here, the correlation between voltage oscillation, structural evolution, and electrolytes has been revealed based on theoretical calculations, in- /ex - situ techniques, and cross- experiments. It is found that the local phase transition of the Na3V2(PO4)3 (NVP) cathode in PC/EC-based electrolyte at -20 degrees C should be responsible for the oscillatory phenomenon. Furthermore, the low exchange current density originating from the high desolvation energy barrier in NVP-PC/EC system also aggravates the local phase transformation, resulting in severe voltage oscillation. By introducing the diglyme solvent with lower Na- solvent binding energy, the voltage oscillation of the NVP can be eliminated effectively at subzero. As a result, the high capacity retentions of 98.3% at -20 degrees C and 75.3% at -40 degrees C are achieved. The finding provides insight into the abnormal SIBs degradation and brings the voltage oscillation behavior of rechargeable batteries into the limelight.