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.
Much more stable chemistry. In stationary applications, like UPS systems and off grid electrical systems, lead acid is still the standard, due to having stable chemistry, very unlikely to catch fire, and a cost to capacity ratio that is still very good.
The degradation seems pretty bad, but if it’s stable from 300 cycles onwards, you could take 75% as the actual capacity of the battery.