Ultrathin, Mechanically Robust Quasi-Solid Composite Electrolyte for Solid-State Lithium Metal Batteries
Qingrong Wang, Hongli Xu, Zhongbo Liu, Shang‐Sen Chi, Jian Chang, Jun Wang, Chaoyang Wang, Yonghong Deng
Abstract
Herein, we present the preparation and properties of an ultrathin, mechanically robust, quasi-solid composite electrolyte (SEO-QSCE) for solid-state lithium metal battery (SLB) from a well-defined polystyrene- b -poly(ethylene oxide) diblock copolymer (SEO), Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 nanofiller, and fluoroethylene carbonate plasticizer. Compared with the ordered lamellar microphase separation of SEO, the SEO-QSCE displays bicontinuous phases, consisting of a Li + ion conductive poly(ethylene oxide) domain and a mechanically robust framework of the polystyrene domain. Therefore, the 12 μm-thick SEO-QSCE membrane exhibits an exceptional ionic conductivity of 1.3 × 10 –3 S cm –1 at 30 °C, along with a remarkable tensile strength of 5.1 MPa and an elastic modulus of 2.7 GPa. The high mechanical robustness and the self-generated LiF-rich SEI enable the SEO-QSCE to have an extraordinary lithium dendrite prohibition effect. The SLB of Li|SEO-QSCE|LiFePO 4 reveals superior cycling performances at 30 °C for over 600 cycles, maintaining an initial discharge capacity of 145 mAh g –1 and a remarkable capacity retention of 81% (117 mAh g –1 ) after 400 cycles at 0.5 C. The high-voltage SLB of Li|SEO-QSCE|LiNi 0.5 Co 0.3 Mn 0.2 O 2 displays good cycling stability for over 150 cycles at 30 °C. Moreover, the exceptional robustness of SEO-QSCE enables the high-voltage solid-state pouch cell of Li|SEO-QSCE|LiNi 0.5 Co 0.3 Mn 0.2 O 2 with high flexibility and excellent safety features. The current investigation delivers a promising and innovative approach for preparing quasi-solid electrolytes with features of ultrathin design, mechanical robustness, and exceptional electrochemical performance for high-voltage SLBs.