The Influence of Surface Chemistry on Critical Current Density for Garnet Electrolyte

Garnet‐based solid state lithium batteries have attracted a lot of attention due to their potential advantages in safety and energy density. However, the high electrode–electrolyte interfacial resistance and low critical current density (CCD) related with lithium dendrite penetration have seriously hindered their further development and practical application. Here, for garnet‐type solid electrolyte, the surface Li2CO3, interlayer species, lithium wettability, interfacial impedance, and CCD are systematically investigated. It turns out that Li2CO3‐free garnet electrolyte is intrinsically lithiophilic, and the interfacial impedance is mainly affected by the amount of surface Li2CO3. In addition, the CCD values are manipulated by the interfacial impedance rather than the apparent Li wettability. This study provides a comprehensive understanding about the interrelationships among surface chemistry, lithium wettability, interfacial impedance, and critical current density for garnet‐type solid electrolytes. For garnet‐type solid electrolytes, the high interfacial resistance and low critical current density (CCD) related with lithium dendrite penetration have seriously hindered their further development and practical application. Here, the surface Li2CO3, interlayer species, lithium wettability, interfacial impedance, and CCD are systematically investigated. The key to achieving low ASR and high CCD is removing Li2CO3 rather than coating lithiophilic interlayers.