Construction of ion–electron conduction network on FeS2 as high-performance cathodes enables all-solid-state lithium batteries

The all-solid-state lithium batteries (ASSLBs) with high energy density are considered to be one of the most promising candidates for next-generation lithium battery systems. Nevertheless, the low ionic and electronic conduction inside the cathode and the poor interfacial contact of the cathode/electrolyte seriously impede the large-scale application of ASSLBs. In this work, a novel multiple ion-electron conductive network is constructed on the FeS2 cathode to realize a high-energy all-solid-state battery. The internal disordered carbon matrix acts as electronic network to accelerate the electronic transmission. Meanwhile, reduced graphene oxide (rGO) tightly wrapping FeS2/C microspheres' surface serves as external electronic pathway. Moreover, the in-situ formed Li7P3S11 electrolyte infiltrates into the nanoparticles to improve lithium-ion transport kinetics. Therefore, the dual-carbon framework and Li7P3S11 coating layer strategies significantly enhance ion-electron transport kinetics and improve interfacial contact during cycling. As expected, the FeS2@C/rGO@Li7P3S11 cathode exhibits excellent rate capability and cycling stability, showing a reversible discharge capacity of 350.3 mAh/g at 0.5C after 200 cycles. More importantly, ex-situ XPS and dQ/dV results reveal that the synergistic effect of dual-carbon frameworks and Li7P3S11 coating layer not only provides fast electron-ion transfer channels, but also wraps the reaction products with poor electrochemical activity such as Fe0, FeSy, and S to accelerate the reaction kinetics and strengthens the reaction reversibility. This work provides valuable insights for improving the electrochemical performance and understanding the reaction mechanism of the conversion-type metal sulfide cathodes in ASSLBs.