Weak Coordination and Structural Stability Synergistically Suppress Structural Relaxation and Achieve Stable Ion Transport in High‐Performance All‐Solid‐State Batteries

ABSTRACT PEO‐based composite solid electrolyte has attracted wide attention due to its good safety and processability, but its strong coordination and significant structural relaxation behavior limit the transmission performance of Li + . Here, Succinonitrile (SN) and Li 0.35 La 0.55 Ti 0.9 Al 0.1 O 3 (LLTO‐Al 0.1 ) are introduced into polyethylene oxide (PEO). The weak coordination and structural stability synergistic strategy introduced by the two, SN inhibits the coupling of PEO and Li + through weak coordination, while Al enables stable transport by increasing the stability of the overall electrolyte, which can be confirmed by molecular dynamics (MD) and in situ EIS, so that the Li||Li symmetrical battery remains stable at 0.1 mA·cm −2 cycle for 1800 h, achieving rapid lithium ion migration ( t Li+ = 0.71) and conductivity (2.76 × 10 −4 S·cm −1 at 30°C). In addition, its Li||LFP battery still has 83% capacity retention rate after 850 cycles at 5 C. The synergistic strategy of weak coordination and structural stability introduced by Al 3+ /SN to suppress structural relaxation provides some insights into high‐performance solid electrolytes.