Li Tong, Gu Sichen, Chen Likun, Zhang Lihan, Qin Xianying, Huang Zhijia, He Yan-Bing, Lv Wei, Kang Feiyu
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, P. R. China.
Department of Materials Science, Shenzhen MSU-BIT University, Shenzhen, 518172, P. R. China.
Small. 2022 Aug;18(33):e2203273. doi: 10.1002/smll.202203273. Epub 2022 Jul 24.
Using 3D host is an effective way to solve the dendrite growth problem and accommodate volume changes of lithium (Li) metal anode. However, the preferred Li deposition on the top surface leads to the Li metal agglomeration at the surface. In addition, the large weight of the 3D host also greatly decreases the capacity based on the whole anode. Herein, a bidirectional lithiophilic gradient modification, including a top-down ZnO gradient and a bottom-up Sn gradient, is applied to an ultralight 3D carbon nanofiber host (density: 0.1 g cm ) and ensures the evenly filling lithium deposition in the 3D host. ZnO transforms into highly ionic conductive Li-Zn alloy and Li O during cycling, enhancing the Li-ion transportation from top to bottom. The metallic Sn also lowers the Li nucleation potential, guiding the preferential Li deposition from the bottom. With such a host, a stable CE of 97.5% over 100 cycles at 1 mA cm and 3 mAh cm is achieved, and the full battery also delivers good cycling stability over 300 cycles with a high CE of 99.8% coupled with high loading LiFePO cathode (10 mg cm ) and low N/P ratio (≈3).
使用三维主体是解决锂金属阳极枝晶生长问题并适应其体积变化的有效方法。然而，锂在顶表面的优先沉积会导致锂金属在表面团聚。此外，三维主体的大重量也会极大地降低基于整个阳极的容量。在此，一种双向亲锂梯度修饰，包括自上而下的氧化锌梯度和自下而上的锡梯度，被应用于超轻三维碳纳米纤维主体（密度：0.1 g/cm³），并确保锂在三维主体中均匀填充沉积。氧化锌在循环过程中转变为高离子导电的锂锌合金和氧化锂，增强锂离子从顶部到底部的传输。金属锡也降低了锂的成核电位，引导锂从底部优先沉积。使用这样的主体，在1 mA/cm²和3 mAh/cm²的条件下，100次循环中实现了97.5%的稳定库仑效率，并且全电池在300次循环中也具有良好的循环稳定性，库仑效率高达99.8%，同时采用了高负载磷酸铁锂正极（10 mg/cm²）和低氮/磷比（≈3）。
