Versatile Inorganic/Polymer Composite Electrolyte Added with 2‑Methylsuccinic Anhydride via a Solvent-Free Preparation Method for High-Performance All-Solid-State Li-Metal Batteries: High Voltage, Long Cycle Life, and Room-Temperature Operation

Solid-state Li-metal batteries (LMBs) with a high room-temperature
energy density, long cycle life, and remarkable flexibility and safety
are necessary for practical energy-storage applications. In this study,
2-methylsuccinic anhydride was used as a novel additive to fabricate
a series of all-solid-state inorganic/polymer composite electrolytes
(IPCEs) using a completely solvent-free hot-pressing process instead
of the conventional solution-casting method. This electrolyte comprises
a poly(ethylene oxide) framework that is hybridized with a Li6.4Al0.24La3Zr2O12 inorganic filler. The freestanding IPCE membrane exhibited long-term
stability against Li metal and a high ion conductivity of 2.4 ×
10–4 S cm–1 at 25 °C, showing
an appreciable transference number of 0.87. All-solid-state LMBs (ASSLBs)
fabricated using this IPCE, high-voltage LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, and lithium
foil anode achieved a specific capacity of 163 mA h g–1 at 0.5C and 25 °C. The IPCE inhibited lithium dendrite growth
and eventually delivered an excellent battery cycling performance
beyond 400 cycles. Moreover, this ASSLB performed well even at 15
°C and showed notable rate performance at 35 °C, at which
a capacity of 143 mA h g–1 at 2C was realized for
133 cycles. Remarkably, a pouch cell based on this system exhibited
good electrochemical performance, flexibility, and safety. This ASSLB
holds great promise for practical energy-storage applications.