Engineering Detrimental Functional Groups in Conductive Additives Toward High-Performance All-Solid-State Batteries

Conductive additives are of great importance for the adequate utilization of active materials in all-solid-state lithium batteries by establishing conductive networks in the composite cathode. However, it usually causes severe interfacial side reactions with solid electrolytes, especially sulfide electrolytes, leading to sluggish ion transportation and accelerated performance degradation. Herein, a simple hydrogen thermal reduction process is proposed on a commonly used conductive additive Super P, which effectively removes the surface oxygen functional groups and weakens the interfacial side reactions with sulfide. With a small amount of 1 wt % reduced Super P, ASSLBs demonstrates a competitive capacity of 180.2 mAh g-1, which is much higher than the 130.8 mAh g-1 of untreated Super P. Impressively, reduced Super P based ASSLBs also exhibit a higher capacity retention of 81.8 % than 64.6 % of untreated Super P. The cathode interfacial chemical evolutions reveal that reduced Super P could effectively alleviate the side reactions of sulfide. Reduced Super P shows better reversible capacity compared to reduced carbon nanofiber with almost no loss of capacity retention, due to its more complete conductive network. Our results highlight the importance of oxygen-containing functional groups for conductive additives, lightening the prospect of low-cost 0D conductive additives for practical ASSLBs. Hydrogen thermal reduction process removed oxygen-containing functional groups on the surface of Super P, thereby weakening interface side reactions with sulfide benefits Li-ion migration. Only 1 wt % reduced Super P based ASSLBs exhibited better reversible capacity of 180.2 mA g-1 at 0.1 C and high capacity retention of 81.8 % after 40 cycles, and 130.8 mAh g-1 64.6 % for Super P. image