Authors: Feng Jin, Ingeborg Sellæg Ellingsen, Laras Fadillah, Quoc Hung Nguyen, Henrik Rotvær Bratlie, Daniel Knez, Gerald Kothleitner, Mir Mehraj Ud Din, Sverre M. Selbach, Günther J. Redhammer, Daniel Rettenwander
Published: 2025-05-30
DOI: 10.1002/eem2.70047
Source: Full article
Solid‐state batteries are attracting considerable attention for their high‐energy density and improved safety over conventional lithium‐ion batteries. Among solid‐state electrolytes, sulfide‐based options like Li6PS5Cl are especially promising due to their superior ionic conductivity. However, interfacial degradation between sulfide electrolytes and high‐voltage cathodes, such as LiCoO2, limits long‐term performance. This study demonstrates that a LiBF4‐derived F‐rich coating on LiCoO2, applied by immersing LiCoO2 particles in a LiBF4 solution followed by annealing, can significantly enhance performance in Li6PS5Cl‐based solid‐state batteries. This coating enables stable high‐voltage (4.5 V vs Li+/Li) operation, achieving an initial specific capacity of 153.82 mAh g−1 and 87.1% capacity retention over 300 cycles at 0.5C. The enhanced performance stems from the F‐rich coating, composed of multiple phases including LiF, CoF2, LixBFyOz, and LixBOy, which effectively suppresses side reactions at the LiCoO2|Li6PS5Cl interface and improves lithium‐ion diffusivity, thereby enabling greater Li capacity utilization. Our findings provide a practical pathway for advancing solid‐state batteries with high‐voltage LiCoO2 cathodes, offering substantial promise for next‐generation energy storage systems.