Energy Storage Science and Technology ›› 2024, Vol. 13 ›› Issue (7): 2161-2170.doi: 10.19799/j.cnki.2095-4239.2024.0117

• Special Issue on Low Temperature Batteries • Previous Articles     Next Articles

Diethyl ethylphosphonate-based flame-retardant wide-temperature-range electrolyte in lithium-ion batteries

Shuping WANG1(), Xiankun YANG2,3(), Changhao LI1, Ziqi ZENG2, Yifeng CHENG1, Jia XIE2   

  1. 1.State Grid Anhui Electric Power Research Institute, Anhui Province Key Laboratory of Electric Fire and Safety Protection (State Grid Laboratory of Fire Protection for Transmission and Distribution Facilities), Hefei 230601, Anhui, China
    2.State Key Laboratory of Advanced Electromagnetic Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology
    3.School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430000, Hubei, China
  • Received:2024-02-05 Revised:2024-02-29 Online:2024-07-28 Published:2024-07-23
  • Contact: Shuping WANG, Xiankun YANG E-mail:wangshuping516@126.com;yxk0222@163.com

Abstract:

Lithium-ion batteries are extensively used in various applications such as electric vehicles and electrochemical energy storage systems. However, safety concerns related to flammability and low flash point of commercial carbonate electrolytes limit their broad application. The incorporation of nonflammable flame-retardant diethyl ethylphosphonate (DEEP) into carbonate electrolytes has been shown to effectively reduce the risk of battery fires and explosions by mitigating electrolyte combustion. Nonetheless, the strong interaction between DEEP and Li+ leads to the infiltration of DEEP into the first solvated shell layer of Li+, contributing to the formation of solid electrolyte interphase (SEI) on the graphite anode. The SEI formed through the reductive decomposition of DEEP provides inadequate electron shielding, failing to halt the ongoing decomposition at the interface and leading to the failure of graphite anodes in DEEP-modified carbonate electrolytes. To address this issue, this study adopts a synergistic strategy, using ethylene carbonate as a strong ligand solvent and linear carbonate as a weak ligand solvent. This approach aims to diminish the interaction strength between DEEP and Li+, decrease the proportion of DEEP in the first solvated shell layer of Li+, and reduce the decomposition of DEEP on the anode. In the developed DEEP-modified carbonate electrolyte with a conventional concentration (~1.15 mol/L), the graphite anode shows an impressive capacity retention of 95.6% after 150 cycles. In addition, the electrolyte remains fluid at -60 ℃, and the graphite/LiFePO4 battery retains 49.3% of its capacity after 50 cycles at -20 ℃.

Key words: lithium-ion battery, phosphate, graphite electrode, non-flammable electrolyte, low temperature performance

CLC Number: