Combating Phase Segregation in Earth-Abundant Pyrite Cathodes for High-Energy-Density Lithium–Metal Batteries

The pursuit of sustainable electrification calls for advanced batteries that deliver high energy density, intrinsic safety, and a sustainable material supply. Conversion-type chemistries enable multielectron transfer and high energy density, yet their reversibility is fundamentally limited by phase segregation of conversion products, driven by agglomeration-induced deactivation and the dissolution of soluble intermediates. In this work, we overcome this central bottleneck in the natural pyrite (FeS 2 ) by introducing a partitioned ionic-cluster electrolyte. This tailored chemical environment suppresses polysulfide dissolution, resulting in a homogeneous nanoscale phase distribution during cycling. Such suppression of phase segregation enables the pyrite cathode to deliver a specific energy of ∼1300 Wh kg –1 over 500 cycles and to retain 72.4% of its capacity after 10,000 cycles at 10C. Moreover, scalable pouch cells demonstrate a competitive energy density of 511 Wh kg –1 and intrinsic safety after nail penetration. This study highlights that electrolyte-enabled phase-segregation suppression is crucial for unlocking the practical potential of earth-abundant conversion-type electrodes.