Surface modification of Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes by polymethylsiloxane-based polymer for all-solid-state lithium batteries

Lithium all-solid-state batteries (LASSBs) face the challenge of poor performance, interface contact between electrodes, limiting voltage window of solid electrolytes, side reactions between cathode/solid electrolyte, anode/solid electrolyte and so on. To motivate the pursuit of advanced solutions, one of the efficient approaches is to design all-solid-state inorganic/polymer composite electrolytes. This study addresses limitations associated with Li1.3Al0.3Ti1.7(PO4)3 (LATP) as an inorganic solid electrolyte, including instability and short cycle life, by introducing organic-based ethylene glycol methyl ether methacrylate-co-acrylate acid functional groups (AAM950) polymer as a protective interphase between LATP pellet and Li metal. The synergistic effects of LATP pellet and AAM950 reduces the interfacial resistance between LATP pellet and Li metal and significantly suppresses lithium dendrite growth during charge and discharge processes. The ionic conductivity of LATP/AAM950 solid electrolyte exhibits ionic conductivity of 9.3 × 10−4 S/cm at room temperature, while Li stripping/plating tests demonstrates overpotential below 0.2 V over 100 cycles at a current density of 0.63 mA/cm2. Furthermore, the modified LATP/AAM950 solid electrolyte can withstand a current density of 249 mA/cm2 at room temperature, which was a dramatic improvement compared to the LATP pellet's one of only 3 mA/cm2. Finally, we assemble an all-solid-state full cell by using NCM622@LATP||AAM950/LATP/AAM950||Li, which delivers an initial discharge capacity of 165.4 mAh/g and remain 132.9 mAh/g after 100 cycles at 0.1C, achieving a remarkable 80.4 % retention. These advancements contribute significantly to the field of Li all-solid-state batteries, fostering innovation in the energy industry.