Recent advances in organic-inorganic composite solid electrolytes for all-solid-state lithium batteries

With excellent safety and potentially high energy density, all-solid-state lithium batteries (ASSLBs) are expected to meet the needs of large-scale energy storage applications, and widely regarded as the next-generation battery technology to replace traditional lithium-ion batteries (LIBs). As one of the most important components in ASSLBs, solid-state electrolytes (SSEs) are the key to promoting the commercialization of ASSLBs. Ideal SSEs should at least possess excellent mechanical and electrochemical properties to enable ASSLBs to operate safely and stably for a long time at a relatively high rate. Unfortunately, solid polymer electrolytes (SPEs) and inorganic solid electrolytes (ISEs) are excluded because of their significant deficiency in electrochemical or mechanical properties. In contrast, organic-inorganic composite solid electrolytes (O-ICSEs) derived from incorporating inorganic fillers into SPEs can well balance the two properties through the synergy between the components, which are the most promising candidates for ASSLBs. Therefore, a timely summary of the latest research progress in the field of O-ICSEs is of great significance for designing O-ICSEs with better performance and early realizing the commercialization of ASSLBs. In this review, the enhancement mechanisms of the electrochemical performance for O-ICSEs are firstly discussed in detail, and the basic characteristics of effective fillers are determined. Then the latest research progress in recent five years of O-ICSEs based on polyethylene oxide (PEO), polyacrylonitrile (PAN) and polycarbonate matrix are highlighted, covering various fillers types, rational structural designs and main performance parameters. Finally, the existing problems and future research directions of O-ICSEs are summarized.