Highly Tough, Li-Metal Compatible Organic-Inorganic Double-Network Solvate Ionogel

Ionogels are considered promising electrolytes for safe lithium-ion batteries (LIBs) because of their low flammability, good thermal stability, and wide electrochemical stability window. Conventional ionic liquid-based ionogels, however, face two main challenges; poor mechanical property and low Li-ion transfer number. In this work, a novel solvate ionogel electrolyte (SIGE) based on an organic-inorganic double network (DN) is designed and fabricated through nonhydrolytic sol-gel reaction and in situ polymerization processes. The unprecedented SIGE possesses high toughness (bearing the deformation under the pressure of 80 MPa without damage), high Li-ion transfer number of 0.43, and excellent Li-metal compatibility. As expected, the LiFePO4/Li cell using the newly developed SIGE delivers a high capacity retention of 95.2% over 500 cycles, and the average Coulombic efficiency is as high as 99.8%. Moreover, the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811)/Li cell based on the modified SIGE achieves a high Coulombic efficiency of 99.4%, which outperforms previous solid/quasi-solid-state NCM811-based LIBs. Interestingly, the SIGE-based pouch cells are workable under extreme conditions (e.g., severely deforming or clipping into segments). In terms of those unusual features, the as-obtained SIGE holds great promise for next-generation flexible and safe energy-storage devices.