Semi-solid alkali metal electrodes enabling high critical current densities in solid electrolyte batteries

The need for higher energy-density rechargeable batteries has generated interest in alkali metal electrodes paired with solid electrolytes. However, penetration and electrolyte fracture at low current densities have emerged as fundamental barriers. Here we show that pure metals the Li–Na–K system, critical scale inversely to mechanical deformation resistance. Furthermore, demonstrate two electrode architectures which presence of a liquid phase enables high while it preserves shape retention packaging advantages electrodes. First, biphasic Na–K alloys K+ (with K-??-Al2O3 electrolyte) exceed 15 mA cm?2. Second, introducing wetting interfacial film between Li Li6.75La3Zr1.75Ta0.25O12 doubles density permits cycling areal capacities 3.5 mAh These design approaches hold promise overcoming electrochemomechanical stability issues heretofore limited performance solid-state batteries. A challenge use anodes is their inability sustain structural stability, especially currents. authors examine properties an effective semi-solid approach practically relevant conditions.