By coating the iron sulfide cathodes in polymers, a research team was able to create transition-metal sulfide-based lithium batteries with stable cycling and high safety. After 300 cycles, a lithium carbide iron disulfide pouch cell retained 72.0% capacity with no capacity degradation after 100 cycles.
Put that on a phone and the battery will degrade almost 30% in one year… seems a lot tbh.
But depending on cost, in my hopeful optimistic universe, that could mean bringing back replaceable batteries.