A High Energy Density Li-ion Battery Cathode Using Only Industrial Elements

Li-ion batteries are crucial for the global energy transition to renewables, but their scalability is limited by the supply of key elements used in commercial cathodes (e.g., Ni, Mn, Co, P). Therefore, there is an urgent need for next-generation cathodes composed of widely available and industrially scalable elements. Here, we introduce a Li-rich cathode based on the known material Li2FeS2, composed of low-cost elements (Al, Fe, S) that are globally mined and refined at industrial scale. The substitution of redox-inactive Al3+ for Fe2+ achieves remarkably high degrees of anion redox, which in turn yields high gravimetric capacity ~450 mAh/g) and energy density (~1000 Wh/kg). We show that Al3+ enables high degrees of delithiation by stabilizing the delithiated state, suppressing phase transformations that would otherwise prevent deep delithiation and extensive anion redox. This mechanistic insight offers new possibilities for developing scalable, next-generation Li-ion battery cathodes to meet pressing societal needs.