Many battery applications target fast charging to achieve an 80 % rise in state of charge (SOC) in < 15 min. However, in the case of all-solid-state batteries (SSBs), they typically take several hours to reach 80 % SOC while retaining a high specific energy of 400 W h kgcell−1. We specify design strategies for fast-charging SSB cathodes with long cycle life and investigate the fast-charging capability of a sulfide-based single crystal Li-Ni-Mn-Co oxide composite cathode. At 30 °C and charging at 15 mA cm−2, a specific capacity of 150 mA h g−1 was achieved in ∼8 min, with 81 % capacity retention after 3000 cycles. Critically, a 3-electrode arrangement was used to avoid the common problem of overcharging at high current densities. By following the design strategy and optimized manufacturing, a 210 µm thick cathode was able to be charged at an extraordinary current density of 50 mA cm−2 to reach an areal capacity of 8 mA h cm−2 in only 10 min, suggesting practical cathodes for SSBs with 400 W h kgcell−1 may be within reach.
