Unlocking Li2CO3-Li2SO4 as Cathodes for Li-ion Batteries

Amidst the rapid expansion of the electric vehicle industry, the need for alternative battery technologies that balance economic viability with sustainability has never been more critical. Here, we report that common lithium salts of Li2CO3 and Li2SO4 are transformed into cathode active mass in Li-ion batteries by ball milling to form a composite with Cu2S. The optimal composite cathode comprising Li2CO3, Li2SO4, and Cu2S, with a practical active mass loading of 12.5-13.0 mg/cm2, demonstrates a reversible capacity of 247 mAh/g based on the total mass of Cu2S and the lithium salts, a specific energy of 716 Wh/kg, and a stable cycle life. This cathode chemistry rivals layered oxide cathodes of Li-ion batteries in energy density but at substantially reduced cost and ecological footprint. Mechanistic investigations reveal that in the composite Li2CO3 serves as the primary active mass, Li2SO4 enhances kinetic properties and reversibility, and Cu2S stabilizes the resulting anionic radicals for reversibility as a binding agent. Our findings pave the way for directly using precursor lithium salts as cathodes for Li-ion batteries to meet the ever-increasing market demands sustainably.