Lithium salt regulation enabling 3D printed solid-state electrolytes to achieve ultra-long cycle performance of LiNi0.8Mn0.1Co0.1O2

Solid-state lithium batteries (SLBs) based on LiNi0.8Mn0.1Co0.1O2 (NCM811) have attracted much attention due to their high energy density, but the cycle instability of NCM811 in SLB limits its practical application. Here, we prepared PEO-Li1.3Al0.3Ti1.7(PO4)3 hybrid solid electrolytes with LiTFSI, LiFSI and LiBOB salts by 3D printing method, and utilized the synergistic effect of various lithium salts to construct robust and stable cathode/electrolyte interface (CEI) and anode/electrolyte interface (SEI) inhibiting the decay of NCM811 and the formation of dendrites. The synergistic effect of three salts increased the amorphous region of PEO matrix, improved the ion conductivity and lithium migration number. The SLB assembled with NCM811 could be cycled 4000 times at 2 C. Through DFT calculation and XPS, TEM and SEM analysis of cycled batteries, it is revealed that CEI and SEI rich in LiF, Li-B-O and B-O can increase the stability of NCM811/solid electrolyte interface, prevent NCM811 particles from cracking, inhibit the generation of lithium dendrites and improve the cycle stability. This effective strategy can form robust and reliable CEI and SEI, improve the electrolyte/electrolyte and Li/electrolyte interface stability, and provide a reliable route for the realization of long-life SLBs.