Lei Dai,Tingting Wang,Boxuan Jin,Na Liu,Yifei Niu,Wenhao Meng,Ziming Gao,Xianwen Wu,Ling Wang,Zhangxing He
Zinc is a widely used anode material for zinc-ion batteries. However, the problems of dendrites and side reactions faced by the metal zinc anode limit its cycle stability and service life. Surface modification is a simple and effective strategy for preparing high-performance anodes. Here, we used a simple method to coat the γ-Al 2 O 3 on surface of metal zinc as an artificial protective layer for the anode/electrolyte. γ-Al 2 O 3 coating can guide the uniform deposition of zinc ions . The coating has good hydrophilicity, which is conducive to accelerate ion transmission. In addition, the importance of controlling the thickness of protective layer on surface of zinc metal anode to obtain good electrochemical performance is emphasized. The appropriate thickness of Al 2 O 3 coating ensures the rapid migration of zinc ions and improves the uniformity of zinc plating/stripping, which is conducive to more uniform zinc nucleation and high-quality deposition. Therefore, the discharge capacity of Zn@Al 2 O 3 -15 full cell at a current density of 0.3 A g −1 is 174.3 mAh g −1 , which is much higher than that of bare zinc cell (71.8 mAh g −1 ). This work has certain reference significance for the development of anode coating strategies in zinc-ion batteries.
The use of garnet-type conductors as electrolytes for safe lithium solid-state batteries is impeded by the lack of critical processing strategy to stabilize and densify the cubic lithium garnets. The synthesis and processing of dense cubic lithium garnets are typically depending on solid state reaction as a result of unintentional Al contamination from the alumina crucibles at temperatures up to 1230 °C. High Al concentration is also believed to induce the sluggish migration of lithium ions . Here, we demonstrate an ultrathin, conformal γ-Al 2 O 3 surface coating on garnet solids by a hybrid microemulsion solid-state method for accomplishing rational and controllable synthesis and processing of dense cubic garnets with low Al concentration. The γ-Al 2 O 3 coating demonstrates fast-ion conducting Al-doped Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 phase with low Al concentration (~0.17 mol per formula unit), low tetragonal-to-cubic phase transformation temperature of 500 °C, and total conductivity of ~4.4 × 10 − 4 S cm − 1 . Specifically, the desired microstructures of the sintered pellets with uniform grains are revealed. As a proof-of-concept, we demonstrate that the nanoscale γ-Al 2 O 3 modification garnet conductor Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 is available to suppress lithium dendrites in symmetric Li/γ-Al 2 O 3 coating Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 /Li cells during lithium plating/stripping at room temperature, with current densities of 0.026 to 0.5 mA cm − 2 . The Li/γ-Al 2 O 3 coating Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 /LiNi 0.5 Co 0.2 Mn 0.3 O 2 cell delivered a high initial discharge capacity of ~164.2 mAh g − 1 , more importantly, an outstanding cycling performance with a capacity retention of 90.16% after 30 cycles at 0.1C and room temperature. This new synthesis route and the utilization of nanoscale γ-Al 2 O 3 surface modification could open up new avenue to lithium garnet conductors with reliable synthesis for all-solid-state lithium batteries application.
危险品化学品经营许可证（带存储）