Enhanced Protection for Li-Metal Anodes via Al-Li/LiF Layer

Professors Guojie Li (Zhengzhou University), Aoxuan Wang (Tianjin University), and Qibo Deng (Hebei University of Technology) have developed a method for producing a stable Al-Li/LiF artificial interphase for lithium metal batteries. Their findings were published in Frontiers of Chemical Science and Engineering.

Lithium (Li) metal is a widely studied anode material due to its low redox potential (–3.04 V vs. standard hydrogen electrode) and high theoretical capacity (3860 mAh·g–1). However, challenges such as uncontrolled volume expansion and the instability of the solid electrolyte interphase (SEI) often lead to lithium dendrite formation and inactive “dead lithium,” which contribute to capacity loss, reduced Coulombic efficiency, and safety concerns in lithium metal batteries

Firstly, a stable Al-Li/LiF artificial interphase (LAF) with rapid ion transport pathways is created through a one-step chemical pretreatment process. As the artificially generated LiF and Al-Li alloy artificial SEI can eliminate dead lithium and lithium dendrites, deposit lithium in the lower section of the modified interface by promoting ion transport, strengthening the mechanical properties, electrolyte wettability, cycling stability, and capacity retention.

Aoxuan Wang, Professor, Tianjin University

In a two-step study, the researchers first analyzed the morphology, chemical composition, and physical properties of the synthesized Al-Li/LiF artificial interphase. Their results confirmed that aluminum (Al) and fluorine (F) elements were uniformly distributed in the surface layer, forming an aluminum-lithium alloy (Li₉Al₄) and LiF. 

To evaluate electrochemical performance, the team tested a series of LAF||LFP full cells incorporating different Al-Li/LiF artificial interphases. Among them, the LAF-20||LFP full cell exhibited the most stable cycling performance, retaining 75.5 % of its capacity and delivering a discharge capacity of 114.3 mAh·g^–1 after 300 cycles. The chemical composition and surface morphology after 100 cycles were also examined to gain further insight into the interphase’s long-term behavior.

Our research shows that 20 μm of the LAF is the most appropriate modification layer thickness. This hybrid artificial SEI exhibits high ion conductivity, low electron conductivity, and excellent mechanical properties. It effectively inhibits side reactions between the lithium anode and electrolyte, as well as the growth of lithium dendrites, while allowing for rapid lithium ion transport and deposition beneath it.

Qibo Deng, Study Co-Corresponding Author, Hebei University of Technology

Journal Reference:

‌Li, G., et al. (2025) Stable lithium metal batteries enabled by Al-Li/LiF composite artificial interfacial layer. Frontiers of Chemical Science and Engineering. doi.org/10.1007/s11705-025-2539-0.