An intricately designed poly(vinylene carbonate-acrylonitrile) copolymer electrolyte enables 5 v lithium batteries

Despite their attractive properties such as high operating voltages and considerable rate capabilities, the commercialization of LiNi_0.5Mn_1.5O₄ cathodes is plagued by rapid capacity fading that stems from the severe parasitic side reactions with conventional liquid carbonate based electrolytes at a high voltage exceeding 4.5 V (vs. Li⁺/Li). In this work, a poly(vinylene carbonate-acrylonitrile) based gel polymer electrolyte (PVN-GPE) is intricately designed by copolymerizing acrylonitrile with vinylene carbonate. The intricately designed PVN-GPE can exhibit superior compatibility with LiNi_0.5Mn_1.5O₄ cathodes, in order to address the above-mentioned severe parasitic side reactions. When evaluating the electrochemical properties of LiNi_0.5Mn_1.5O₄/graphite full cells assembled with the PVN-GPE, an outstanding cycling stability (with a capacity retention of 93.2% after 200 cycles) has been achieved, which is far more superior to that of conventional liquid electrolytes. It is noted that the introduction of vinylene carbonate endows the PVN-GPE with improved interfacial compatibility towards lithium anodes, which can efficiently suppress the formation of lithium dendrites and enables excellent cycling performance (with a capacity retention of 90% after 200 cycles) of LiNi_0.5Mn_1.5O₄/Li metal batteries. Our work presents an intriguing 5 V class high-voltage polymer electrolyte with superior performance and will boost the development of high-energy-density lithium batteries.