FeS2-Imbedded Mixed Conducting Matrix as a Solid Battery Cathode

A new concept of pairing an active material and a mixed conductor is explored as a solid‐state battery electrode. By imbedding nano‐FeS2 domains into an amorphous LiTiS2 matrix, a hybrid power‐energy system is achieved while additionally improving upon many common solid electrode design flaws. High‐resolution transmission electron microscopy is used to probe the active material/mixed conductor interface over the course of cycling. Arguably the most beneficial development is enhancement of charge transfer, manifesting in a significantly increased exchange current as captured in a Tafel analysis. By developing a solution to active material isolation and creating a more homogenous electrode design, cycling at a high rate of C/2 for 500 cycles is obtained. Additionally, the electrode can recover full capacity simply by reducing system rate. Capacity recovery implicates a lack of active material isolation, a common problem in solid‐state batteries. A new concept of pairing an active material and a mixed conductor is explored as a solid‐state battery electrode. By imbedding nano‐FeS2 domains into an amorphous LiTiS2 matrix, a hybrid power‐energy system is achieved. The new cathode retains 62% capacity after 500 cycles at C/2 but also can recover full capacity once rate is reduced.