Molecular Surface Coating of High-Voltage Cathodes in LPSCl-Based All-Solid-State Lithium Metal Batteries

Despite their improved safety, high energy density when paired with Li metal anode, all-solid-state batteries (ASSBs) continue to face significant challenges, notably the interface with the cathode active material (CAM), which is prone to both physical and (electro-)chemical degradation during cycling, especially when employing high-Ni CAMs. To address this issue, here, we introduced an organic surface anchoring strategy to stabilize the CAM surface and CAM-solid electrolyte interface using trifluoroacetamide (TFAA). A weak acid–base interaction between the CAM and TFAA creates a passivating layer, incorporating in situ generated LiF, as a highly competitive alternative to conventional sol–gel-applied inorganic coating, i.e., LiNbO3 (LNO). Comparative electrochemical and physicochemical characterization of pristine, LNO-coated, and TFAA-coated NMC811 verified the efficiency of the organic anchoring strategy. Furthermore, we observed significant suppression in the formation of POx, SOx, and P–Sn–P species, indicating efficient mitigation of the (electro-)chemical oxidation of LPSCl at the interface, thus enabling an improved capacity retention of 95% after 100 cycles at 0.1 C.