Reinforced cathode-garnet interface for high-capacity all-solid-state batteries. (1st December 2022)

• Record Type: Journal Article
• Authors: Zheng, Chenxi; Tang, Shijun; Wen, Fangmei; Peng, Jinxue; Yang, Wu; Lv, Zhongwei; Wu, Yongmin; Tang, Weiping; Gong, Zhengliang; Yang, Yong
• Is Part Of: Materials futures. Volume 1:Number 4(2022)
• Publication Date: 2022-12-01
• Subjects: garnet electrolyte -- all-solid-state battery -- high cathode loading -- interface evolution -- spark plasma sintering; Materials science -- Periodicals; Materials science -- Research -- Periodicals; 620.11
• DOI: 10.1088/2752-5724/aca110
• Languages: English
• ISSNs: 2752-5724

Abstract

Abstract: Garnet-type solid-state electrolytes (SSEs) are particularly attractive in the construction of all-solid-state lithium (Li) batteries due to their high ionic conductivity, wide electrochemical window and remarkable (electro)chemical stability. However, the intractable issues of poor cathode/garnet interface and general low cathode loading hinder their practical application. Herein, we demonstrate the construction of a reinforced cathode/garnet interface by spark plasma sintering, via co-sintering Li6.5 La3 Zr1.5 Ta0.5 O12 (LLZTO) electrolyte powder and LiCoO2 /LLZTO composite cathode powder directly into a dense dual-layer with 5 wt% Li3 BO3 as sintering additive. The bulk composite cathode with LiCoO2 /LLZTO cross-linked structure is firmly welded to the LLZTO layer, which optimizes both Li-ion and electron transport. Therefore, the one-step integrated sintering process implements an ultra-low cathode/garnet interfacial resistance of 3.9 Ω cm 2 (100 °C) and a high cathode loading up to 2.02 mAh cm −2 . Moreover, the Li3 BO3 reinforced LiCoO2 /LLZTO interface also effectively mitigates the strain/stress of LiCoO2, which facilitates the achieving of superior cycling stability. The bulk-type Li|LLZTO|LiCoO2 -LLZTO full cell with areal capacity of 0.73 mAh cm −2 delivers capacity retention of 81.7% after 50 cycles at 100 μ A cm −2 . Furthermore, we reveal that non-uniform Li plating/stripping leads to the formation of gaps and finally results in the separation of Li and LLZTO electrolyte during long-term cycling, which becomes the dominant capacity decay mechanism in high-capacity full cells. This work provides insight into the degradation of Li/SSE interface and a strategy to radically improve the electrochemical performance of garnet-based all-solid-state Li batteries.