Li metal secondary batteries known for their high energy and power density are the much-awaited energy storage systems owing to the high specific capacity of Li metal. However, due to the instability of Li metal with common Li-ion battery electrolytes, a combination with a polymer electrolyte seems to be an effective strategy to alleviate the safety issues of employing Li metal and provide design conformity to the system. Current trends show improvements in different aspects, such as improving ionic conductivity, single-ion conductivity, mechanical stability, and electrochemical stability. A combination of all these properties has been a bottleneck for the development of polymer electrolytes for safe and efficient operation of all solid-state batteries. Herein, a multifunctional polysalt has been synthesized from green and sustainable materials, namely, ethyl cellulose, plasticized with adiponitrile, that contributes to meeting the critical properties enabling high compatibility with Li metal and a quasi-single-ion-conducting property while simultaneously acting as a matrix/filler for efficient operation of the cells. This multifunctional polymer matrix inhibits further decomposition of nitrile-based plasticizers on Li metal anodes with the formation of a favorable Li metal anode interface, thus enabling the utilization of high-voltage stable nitrile-based plasticizers (4.2 V) to be implemented as an electrolyte component for realization of high-voltage Li metal anode polymer batteries.
Keywords: Li metal interface; Li metal polymer; functionalized cellulose matrix; high-voltage electrolytes; plasticized polymer electrolytes; single-ion conducting polysalt; solid-state batteries.