Qin Zhiwei, Xie Yuming, Meng Xiangchen, Qian Delai, Mao Dongxin, Zheng Zhen, Wan Long, Huang Yongxian
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
ACS Appl Mater Interfaces. 2022 Sep 14;14(36):40959-40966. doi: 10.1021/acsami.2c10027. Epub 2022 Aug 31.
Solid-state lithium batteries (SSLBs) based on Ta-doped LiLaZrTaO (LLZTO) suffer from lithium dendrite growth, which hinders their practical application. Herein, first principles simulations indicate that the Ta element prefers to segregate along grain boundaries in the form of TaO precipitates due to a high energy difference induced by Ta doping. Grain boundary engineering is employed to regulate the distribution of the Ta element and enhance the density of LLZTO by introducing the LaO additive. The sufficient LaO additive reacts with the TaO precipitates, while the residual LaO nanoparticles fill up void defects, promoting the homogeneous distribution of the Ta element and improving the relative density to ∼98%. Critical current density of the symmetric Li battery reaches 2.12 mA·cm at room temperature with the solid-state electrolyte (LLZTO + 5 wt % LaO), which increases by 41% compared to pure LLZTO. SSLBs with the LiFePO cathode achieve a stable cycling performance with a discharge capacity of 138.6 mA·h·g after 400 cycles at 0.2 C. This work provides theoretical insights into the distribution of Ta-doped LLZTO and inhibits lithium dendrite growth through grain boundary engineering.
基于钽掺杂的锂镧锆钽氧化物（LLZTO）的固态锂电池（SSLBs）存在锂枝晶生长问题，这阻碍了它们的实际应用。在此，第一性原理模拟表明，由于钽掺杂引起的高能量差，钽元素倾向于以TaO析出物的形式沿晶界偏析。通过引入LaO添加剂，采用晶界工程来调节钽元素的分布并提高LLZTO的密度。足够的LaO添加剂与TaO析出物反应，而残留的LaO纳米颗粒填充孔隙缺陷，促进钽元素的均匀分布并将相对密度提高到约98%。使用固态电解质（LLZTO + 5 wt% LaO）时，对称锂电池在室温下的临界电流密度达到2.12 mA·cm，与纯LLZTO相比提高了41%。具有LiFePO正极的SSLBs在0.2 C下循环400次后实现了稳定的循环性能，放电容量为138.6 mA·h·g。这项工作为钽掺杂LLZTO的分布提供了理论见解，并通过晶界工程抑制了锂枝晶生长。
