Photonic surface engineering of conductive additives via flash lamp annealing for interfacial stabilization and homogeneous electron pathways in all-solid-state batteries

Abstract

All-solid-state batteries (ASSBs) are emerging as the next-generation batteries due to their high safety and high energy density. However, sulfide-based solid electrolytes (SEs) suffer from undesirable side reactions with carbon conductive additives (CAs), as well as from the inhomogeneous distribution of CAs, both of which accelerate sluggish Li-ion kinetics and capacity fading, thereby limiting their practical applications. Here, we introduce an ultrafast and scalable flash lamp annealing (FLA) process that reduces oxygen-containing functional groups from vapor-grown carbon fiber (VGCF) and modifies its surface properties, thereby weakening inter-fiber cohesive forces. This surface functionality directly promotes more uniform distribution of the modified VGCF (F-VGCF) within the dry-processed cathode and enables the formation of a continuous electron percolation network. The improved microstructural homogeneity not only enhances electronic pathways but also suppresses SE decomposition at the CA/SE interface, thereby enhancing interfacial stability. As a result, ASSBs employing NCM/F-VGCF cathode exhibit a higher reversible capacity of 5.7 mAh cm−2 at 0.1C compared to those with NCM/bare VGCF cathode and maintain stable cycle retention of 71.5 % at 0.3C after 160 cycles (areal capacity of 7.5 mAh cm−2). The FLA process provides an ultrafast and cost-effective strategy for the surface modification of CA, enabling a scalable and commercially viable approach for high-performance ASSBs.