The allure of spherical lithium deposition—realizing the stable cycle of anode-free lithium-metal batteries

Abstract

The deepening electrification of society and the wide application of electric vehicles have raised the demand for high-energy-density batteries. The anode-free lithium-metal battery (AFLMB), which relies on a simple internal structure of the battery to bring about high energy density, has a broad application prospect. The lack of surplus Li metal at the anode restricts the active material in AFLMB to only the cathode and electrolyte, resulting in a more concentrated distribution within the batteries. Thus, most AFLMBs encounter a rapid decline in capacity after 100 cycles, presenting a significant challenge. Maximizing the effectiveness of the limited active substances is the breakthrough to improve the cycling performance of AFLMB. Based on the latest research findings, this paper presents a comprehensive analysis of the factors for the capacity decline in the AFLMB cycling process, specifically focusing on the behavior of Li deposition on the anode. We explore the relationship between the lithophilic nature of the substrate and Li deposition morphology, along with methods for characterization, and propose optimal spherical deposition. Furthermore, it discusses strategies for optimizing Li deposition behavior through current collector modification, electrolyte modification, and improvement of test conditions. Ultimately, this evaluation of optimization strategies for Li deposition morphology aims to offer insights for advancing AFLMB development and enhancing its long-cycle stability.