Maximizing interface stability in all-solid-state lithium batteries through entropy stabilization and fast kinetics
Xiangkun Kong, Run Gu, Zongzi Jin, Lei Zhang, Chi Zhang, Wenyi Xiang, Li Cui, Kang Zhu, Yifan Xu, Huang Huang, Xiaoye Liu, Ranran Peng, Chengwei Wang
Abstract
The positive electrode|electrolyte interface plays an important role in all-solid-state Li batteries (ASSLBs) based on garnet-type solid-state electrolytes (SSEs) like Li6.4La3Zr1.4Ta0.6O12 (LLZTO). However, the trade-off between solid-solid contact and chemical stability leads to a poor positive electrode|electrolyte interface and cycle performance. In this study, we achieve thermodynamic compatibility and adequate physical contact between high-entropy cationic disordered rock salt positive electrodes (HE-DRXs) and LLZTO through ultrafast high-temperature sintering (UHS). This approach constructs a highly stable positive electrode|electrolyte interface, reducing the interface resistance to 31.6 Ω·cm2 at 25 °C, making a 700 times reduction compared to the LiCoO2 | LLZTO interface. Moreover, the conformal and tight HE-DRX | LLZTO solid-state interface avoids the transition metal migration issue observed with HE-DRX in liquid electrolytes. At 150 °C, HE-DRXs in ASSLBs (Li|LLZTO | HE-DRXs) exhibit an average specific capacity of 239.7 ± 2 mAh/g at 25 mA/g, with a capacity retention of 95% after 100 cycles relative to the initial cycle—a stark contrast to the 76% retention after 20 cycles at 25 °C in conventional liquid batteries. Our strategy, which considers the principles of thermodynamics and kinetics, may open avenues for tackling the positive electrode|electrolyte interface issue in ASSLBs based on garnet-type SSEs. The positive electrode/electrolyte interface is crucial for the performance of all-solid-state lithium batteries. Here, authors use a sintering technique to form a conformal interface between high-entropy disordered rock salt electrodes and garnet-type electrolytes to reduce interfacial resistance.