凝胶聚合物电解质（GPEs）被认为是开发具有高能量密度和高安全性的锂金属电池（LMBs）的有希望的候选材料，然而大多数报道的GPEs是易燃的，使得LMBs仍然面临巨大的安全风险。
近日，西安交通大学丁书江教授和高国新副教授等人在Science China Materials发表研究论文，使用甲基膦酸二甲酯（DMMP）作为功能性阻燃剂和增塑剂，用于聚偏二氟乙烯（PVDF）基质，开发了一种新型的不易燃PVDF-DMMP GPEs用于LMBs。
本文要点
1) 这种DMMP不仅极大地增强了PVDF-DMMP GPEs的阻燃性，还有效提高了锂盐的解离效率和锂离子的快速传输，同时还有助于形成稳定且坚固的CEI/SEI层。2) 超薄的PVDF-DMMP GPEs（约20微米）展现出卓越的阻燃性、高离子导电性（在30°C下为1.34×10−3 S cm−1）、快速的锂离子迁移（在30°C下tLi+=0.59）、在30–80°C下具有宽的电化学稳定性电压窗口（超过4 V）以及均匀的锂沉积.3) 当用于Li||Li对称电池、Li||LiFePO4（LFP）和Li||LiNi0.8Co0.1Mn0.1O2全电池时，不易燃的PVDF-DMMP GPEs能够使这些电池同时具有长期循环稳定性、高倍率性能、宽温度工作范围(从−20到80°C)和高安全性。即使在遭受严苛的破坏性测试时，Li|PVDFDMMPGPEs|LFP软包电池仍然正常工作，没有任何安全风险。实际的软包电池能量密度高达508 Wh kg−1。Figure 1. (a) Schematic diagram of the large-area preparation process of SPE membranes. (b) Physical drawing of SPE membranes. (c) Scanning electron microscopy (SEM) images of PVDF-DMMP SPE and energy-dispersive spectroscopy (EDS) of P and S elements (d). (e) Electrolyte contact angles of PP membrane, PVDF SPE, and PVDF-DMMP SPE. (f) Combustion process diagram of PVDF-DMMP SPE on the flam.![]()
Figure 2. (a) Electrochemical impedance plots of PVDF-DMMP GPEs at different temperatures. (b) Temperature dependence of conductivity of PP membranes, PVDF GPEs and PVDF-DMMP GPEs. (c) Voltage-constant current-time curves of PVDF-DMMP GPEs at 30°C with a polarisation voltage of 10 mV, and inset shows impedance spectra before and after the polarization. Raman partial spectra of (d) PVDF SPE and (e) PVDF-DMMP SPE in the range 725–765 cm−1. (f) Fourier-transform infrared spectra of different compositions in the wave number range of 4000–400 cm−1. (g) HOMO and LUMO energy level calculations of different compositions. (h) LSV curves of PVDF-DMMP GPEs at 30, 60, and 80°C.![]()
Figure 3. (a, b) Long-term cycle performance of Li||LFP full cells using PVDF GPEs and PVDF-DMMP GPEs at (a) 30°C and 1 C, and (b) 30°C and 5 C. (c, d) High-resolution N 1s and P 2p XPS plots of (c) PVDF GPEs and (d) PVDF-DMMP GPEs after etched for 0, 60 and 120 s. (e–h) FESEM images of (e, g) the surface and (f, h) the cross-section of lithium metal anodes in the cycled Li||Li symmetrical cells using (e, f) PVDF GPEs and (g, h) PVDF-DMMP GPEs.![]()
Figure 4. (a) The schematic diagram of the dual-functional role of DMMP additive. Besides its flame-retardant function, DMMP also contributes to the formation of more uniform and robust SEI/CEI layers at the electrode/electrolyte interface of LMBs. (b) Performance comparison radar chart of this work with other related studies. (c) Long-cycle performance of Li||LFP pouch cells at 30°C and 1 C. (d) Destructive exhibition of Li|PVDF-DMMP GPEs|LFP pouch cells, which can still light up the LED strip normally upon being clipped by a scissor arbitrarily. (e) Cycling performance of the Ah-level Li||NCM811 pouch cells in PVDF-DMMP GPEs at 0.1 C. The single-side mass loading of NCM811 in the pouch cells is 25.0 mg cm−2. (f) Charge–discharge voltage–capacity curves of the Ah-level Li||NCM811 pouch cells for the 1st and 20th cycles at 30°C and 0.1 C.Yuanjun Zhao, Xinyu Da, Yanyang Qin, Xin Jia, Xuetian Deng, Shujiang Ding, Junqiao Xiong, Qiang Rong, Xiangpeng Kong, Guoxin Gao. Nonflammable PVDF-based gel polymer electrolytes modified by dimethyl methylphosphate for wide temperature range, long cycle-life and high-safety lithium metal batteries. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3130-y
![]()
点击左下角“阅读原文”，阅读以上文章PDF原文
![]()
