Sun Haiming, Liu Qiunan, Chen Jingzhao, Li Yanshuai, Ye Hongjun, Zhao Jun, Geng Lin, Dai Qiushi, Yang Tingting, Li Hui, Wang Zaifa, Zhang Liqiang, Tang Yongfu, Huang Jianyu
Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 567-0047, Japan.
School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105, PR China.
ACS Nano. 2021 Dec 28;15(12):19070-19079. doi: 10.1021/acsnano.1c04864. Epub 2021 Sep 8.
The two biggest promises of solid-state lithium (Li) metal batteries (SSLMBs) are the suppression of Li dendrites by solid-state electrolyte (SSE) and the realization of a high-energy-density Li anode. However, LMBs have not met their expectations due to Li dendrite growth causing short-circuiting. In fact, Li dendrites grow even more easily in SSE than in liquid electrolyte, but the reason for this remains unclear. Here we report transmission electron microscopy observations of Li dendrite penetration through SSE and "dead" Li formation dynamics in SSLMBs. We show direct evidence that large electrochemomechanical stress generates cracks in the SSE and drives Li through the SSE directly. We revealed that fresh Li nucleation sites emerged in every discharge cycle, creating new "dead" Li in the following charging cycle and becoming the dominant Coulombic efficiency decay mechanism in SSLMBs. These results indicate that engineering flaw size and reducing electronic conductivity in SSEs are essential to improve the performance of SSLMBs.
固态锂金属电池（SSLMBs）的两大最大优势在于通过固态电解质（SSE）抑制锂枝晶以及实现高能量密度锂负极。然而，由于锂枝晶生长导致短路，锂金属电池尚未达到预期效果。事实上，锂枝晶在固态电解质中比在液体电解质中更容易生长，但其原因尚不清楚。在此，我们报告了通过透射电子显微镜对锂枝晶穿透固态电解质以及固态锂金属电池中“死”锂形成动力学的观察结果。我们展示了直接证据，即大的电化学机械应力会在固态电解质中产生裂纹，并直接驱使锂穿过固态电解质。我们发现，在每个放电循环中都会出现新的锂成核位点，在随后的充电循环中产生新的“死”锂，并成为固态锂金属电池中库仑效率衰减的主要机制。这些结果表明，控制固态电解质中的缺陷尺寸并降低其电子电导率对于提高固态锂金属电池的性能至关重要。
