A solid-like succinonitrile-based polymer electrolyte with superior mechanical strength for high performance lithium metal batteries

• Published in: Journal of energy storage Vol. 91; p. 112016
• Main Authors: Bao, Dequan, Zhao, Wei, Li, Zixuan, Tao, Yi, Zhong, Yihong, Tang, Zikun, Gao, Zhenqiu, Wang, Haibo, Zhang, Hao, Sun, Xuhui
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.06.2024
• Subjects: Ionic conductivity; lithium metal batteries; Mechanical strength; Solid-like; Succinonitrile-based polymer electrolyte; Succinonitrile-based polymer electrolyte; Solid-like; Mechanical strength; Ionic conductivity; lithium metal batteries
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2024.112016

Succinonitrile (SN)-based electrolytes provide an attractive candidate for solid electrolytes because of their high room-temperature ionic conductivity and favorable interfacial contact with electrodes. However, the mechanical strength of SN will suffer from a significant decrease when complexing with lithium salts, which results in excessive plastic and even liquid-like behavior and hence impedes its further application as a self-supporting electrolyte film in solid lithium metal batteries (LMBs). Here, a robust solid-like succinonitrile (SN)-based polymer electrolyte (SNPE) is proposed to address this issue through a facile film casting strategy, which is fabricated by mixing PVDF with SN and introducing dual-salt (LiTFSI-LiBOB) and FEC to suppress the side reactions of SN. By adjusting the weight ratio of SN to PVDF, the optimized SNPE (SN PVDF = 3:5) not only exhibited comparable ionic conductivity (0.97 mS cm−1) at room temperature but also exhibited superior mechanical robustness (15.7 MPa). As a result, the Li symmetric cell using the SNPE prevents itself from short-circuiting for >1500 h under a current density of 0.1 mA cm−2. Moreover, the LiFePO4 (LFP)|Li cell assembled with SNPE delivers long-term cycling stability under 2C at room temperature, with a high capacity retention of 87.8 % over 1000 cycles. This design proves to be an effective approach for enhancing the mechanical strength of SN-based electrolytes, broadening their application in LMBs. [Display omitted] •SNPE shows superior stress strength (15.7 MPa) solving the drawback of poor mechanical property of SN-based electrolytes.•High mechanical strength of SGPE inhibits lithium dendrite growth and promotes uniform lithium deposition.•Li|Li cells exhibit stable cyclability at 0.1 mA cm-2 with low overpotential over 1500 hours.•Li|LFP batteries display high performance reaching high capacity retention of 87.8% over 1000 cycles at 2 C.