Mixed-Conductive FeS<sub>2</sub> Composite Cathode for High Areal Capacity Thin-Film Lithium Batteries.

Zhang, Boqing; Xue, Lu; Ke, Bingyuan; Zhang, Jie; Pan, Hanqing; Yang, Ming; Liu, Yongming; Liu, Zongnian et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Pyrite (FeS<sub>2</sub>) thin-film cathode holds great potential for all-solid-state thin-film lithium batteries (ASSTFBs) due to its high theoretical volumetric capacity. However, fabricating FeS<sub>2</sub> thin films using conventional physical vapor deposition techniques presents significant challenges including low deposition rates and limited areal capacities. Herein, a simple tape-casting process is novelly employed to fabricate FeS<sub>2</sub>-based composite thin-film cathodes with superior mixed ionic-electronic conductivity (MIEC-FeS<sub>2</sub> cathode). Benefiting from the inhibitory effect of lithium-phosphorus-oxynitride thin-film solid electrolyte on the shuttle effect of Li-polysulfides, along with its excellent ionic conductivity and interfacial contact, the MIEC-FeS<sub>2</sub> cathode can deliver a high areal capacity of 277.3 μAh cm<sup>-2</sup> at 20 μA cm<sup>-2</sup> and outstanding cycling stability of up to 3000 cycles in a solid-state system. More importantly, the MIEC-FeS<sub>2</sub> based ASSTFBs could deliver a high areal capacity of 180.1 μAh cm<sup>-2</sup>. This work paves the way for the scalable, low-temperature fabrication of stable ASSTFBs with high areal capacities.