Ultrastable LiF/carbon nanocomposites as sacrificial additives for enhancing the lifespan of anode-free lithium metal batteries

Abstract

Prelithiation is key to extending the lifespan of anode-free lithium-metal batteries (AFLMBs) by compensating for irreversible lithium loss. However, current prelithiation agents suffer from poor processability and sensitivity to temperature and humidity, limiting their use in conventional manufacturing. In this study, we introduce a novel high-prelithiation-capacity (720 mA h g⁻¹), ambient environment stable LiF/carbon nanocomposite as the sacrificial agent, specifically designed to stabilize high-energy, ampere-hour-level anode-free lithium-metal batteries. The nanocomposite's design, with LiF nanodots embedded in a carbon matrix, balances high lithium retrievability with compatibility with existing battery manufacturing processes. Additionally, the carbon matrix facilitates the delithiation process of the LiF nanocrystals. In an Ah-level anode-free pouch cell (LiNi_1.5Mn_0.5O₄ cathode paired with bare Cu foil) the nanocomposite enabled an energy density of 278.2 W h kg⁻¹ and 76.2% capacity retention after 200 cycles. Operando transmission-mode X-ray diffraction analysis reveals the lithium-supplementation process of the LiF/C agent, as well as enhanced reversibility of the phase transition during cycling. These findings suggest that the nanocomposite is a promising material for energy-dense, anode-free cell development.