Reinforcing ionic conductivity and alleviating dendrite propagation of dense cubic Ga0.3Li6.1La3Zr2O12via two-step sintering

Garnet-type Li7La3Zr2O12 (LLZO) has emerged as a promising candidate to supersede the liquid electrolytes in lithium-ion batteries. In this work, we thoroughly investigated the relationship between particle uniformity and dendrite resistance by utilizing Ga-doped LLZO. Although Ga doping has promising advantages such as facilitating grain boundary mobility to improve ionic conductivity, it also induces abnormal grain growth (AGG), which leads to lower critical current density (CCD) and dendrite formation. Herein, we propose an enhanced approach for fabricating LLZO samples via the two-step sintering (TSS) method. This enhanced sintering method enables the formation of a more dense microstructure and uniform surface compared to the conventional sintering (CS) method. Due to the enhanced Li+ diffusion facilitated by the dense grain boundaries, the Ga-LLZO sample fabricated using the TSS technique exhibits superior electrochemical properties compared to the CS sample. The TSS effectively alleviates dendrite propagation during long-term cycling. In contrast, the non-uniform LLZO sample exhibits inhomogeneous Li plating/stripping, which accelerates dendrite propagation. Furthermore, multi-elemental mapping of the cycled LLZO sample manifests that dendritic Li generates by-products such as Li2CO3 and La2Zr2O7.