Accelerating ionic–electronic percolation pathways via catecholate coordination of bioinspired-polymer dopamine in all-solid-state composite cathode

All-solid-state batteries (ASSBs) are becoming recognized as encouraging energy storage solutions due to their great energy density and superior safety features with sulfide-based solid-state electrolytes (SSEs). However, a major challenge is the unstable interface between conductive additives and SSEs, leading to a performance degradation. To overcome this obstacle, there is an urgent need to enhance ionic conductivity at the SSE–conductive additive interface and control interfacial kinetics to prevent undesired side reactions. Herein, we investigate the critical roles of self-polymerized dopamine coated vapor-grown carbon fibers (PDA@VGCF) in optimizing ionic–electronic percolation pathways in composite cathodes. The electrochemical properties, charge transfer kinetics, and interfacial side reactions of the composite cathodes consisting of LiNi_0.8Co_0.15Al_0.05O₂–Li₆PS₅Cl and VGCF as a conductive additive are thoroughly examined. In practice, the composite cathode employing PDA@VGCF exhibits superior to discharge capacity of 165.5 mAh g⁻¹ (3.81 mAh cm⁻²) with outstanding capacity retention (≥96 %) at a current density of 0.1C (0.46 mA cm⁻²) compared to the composite cathode with VGCF (118.7 mAh g⁻¹) over 100 cycles. The enhancement can be appropriate to the integration of a PDA surface layer onto VGCF, enhancing both Li⁺ diffusivity and the distribution of cathode components while suppressing undesirable capacity fading. This work proposes a promising approach for the surface modification of conductive additives in composite cathodes, thereby enhancing the electrochemical performance of sulfide-based ASSBs.