New Polymer Electrolytes for Safe All Solid-State Lithium Metal Batteries

Abstract

Driven by the growing demand in energy and the challenge of finding new green energy sources to replace the excessively used fossil fuels, electrochemical energy storage arises as the key alternative to meet the needs of current society. Among all the available electrochemical storage devices, lithium-ion batteries (LIBs) have been extensively investigated as the most suitable choice. Besides, there has been an increasing interest in the research of rechargeable lithium metal batteries (LMBs), where a higher energy density can be achieved compared to the state of art LIBs technologies, due to the high specific capacity provided by lithium metal electrode. As one of the most critical components, the choice of the electrolyte is very important for preparing safe and high performance LMBs. Most of the commercial batteries are built up with liquid electrolytes based on lithium salts and organic solvents. However, safety concerns such as volatilization, flammability and explosion has tipped the scale in favor of the search of solvent-free solid electrolytes, for which solid polymer electrolytes (SPEs) emerge as one of the most promising choices. In addition to the excellent flexibility, ease of processing and low cost, SPEs can mitigate the Li dendrite growth that takes place in conventional liquid electrolytes, attenuate the interfacial resistance, and improve the electrode-electrolyte compatibility compared to their inorganic solid electrolytes counterparts. Nevertheless, the low Li-ion conductivity, several orders of magnitude lower than those of the conventional liquid electrolytes, remains as the major hindrance towards the practical deployment of all solid-state lithium polymer batteries (ASSLPBs).1,2 Moreover, SPEs are usually characterized by a low lithium-ion transference number (T Li + < 0.5) and consequently are more susceptible to polarization phenomena that eventually limit the power density and cycle life of ASSLPBs.3 Thus, studies on new polymer electrolytes is urgent to improve the performance of ASSLPBs and meet the market requirements. Inspired by these challenges, in this presentation the performance of new flexible and highly conductive SPEs is provided. Furthermore, the role of different additives on the performance of novel single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs) is elucidated.