Ce in situ tuning control in Ga‐LLZO: overcoming pore formation and lithium filament growth for high‐performance solid‐state batteries

Abstract The Ga‐doped Li 7 La 3 Zr 2 O 12 (Ga‐LLZO) system currently exhibits the highest ionic conductivity among garnet‐type solid‐state electrolytes and faces persistent challenges including pore formation—arising from high‐temperature disproportionation reactions and elevated sintering activity—as well as lithium filament growth and short‐circuit failure at pores and grain boundaries. Effectively addressing these issues while retaining high ionic conductivity remains a major obstacle. In this study, Ce was introduced into the Ga‐LLZO lattice via an in situ tuning strategy, which significantly reduced internal pore retention and suppressed the reduction of migrating Li + into dead lithium. The optimized Ce in situ tuning controlled Ga‐LLZO achieved an ionic conductivity exceeding 1 mS cm −1 at 25 °C, while the critical current density (CCD) in lithium symmetric cells reached 0.7 mA cm −2 —twice that of unmodified Ga‐LLZO. Remarkably, no short‐circuiting occurred even after 2700 h of cycling at 0.3 mA cm −2 , in contrast to the unmodified Ga‐LLZO, which failed after only 50 h. The corresponding full cells also demonstrated excellent cycling stability and ultra‐high capacity retention, significantly outperforming unmodified Ga‐LLZO. Compared with recent electrolyte modification strategies, the Ce in situ tuning controlled Ga‐LLZO delivers outstanding overall performance. Moreover, it holds strong potential for synergistic integration with other advanced modification techniques, offering broad prospects for further development and practical implementation in next‐generation all‐solid‐state batteries (ASSBs).