| dc.description.abstract | In response to global warming and the continuous advancement of technology, there is a growing demand for sustainable and environmentally friendly energy storage solutions. Consequently, the research focus has turned towards anode-free lithium metal batteries (AFLB) due to their high energy density. However, AFLB research faces challenges, notably the formation of dendritic lithium during lithium deposition, which undermines the stability of the anode and can lead to battery short-circuiting. Recent studies have thus aimed to address this issue by developing an artificial solid electrolyte interphase (ASEI) as a solution. ASEI, typically a functional thin film composed of organic or inorganic materials, is designed to protect the lithium metal anode and enhance its performance. Yet, improving lithium deposition efficiency, material stability, and increasing battery cycle life remains an ongoing challenge.
This study explores a novel approach by employing electrophoretic deposition (EPD) to fabricate a new type of composite multilayer ASEI structure using fluorinated electrochemically exfoliated graphene (FECG) and electrochemically exfoliated graphene (ECG). The upper layer consists of FECG, which exhibits high lithium ion conductivity enabling uniform lithium plating. Transitioning below is the ECG layer, known for its electron conductivity, facilitating efficient electron transfer, with a thin FECG layer at the base ensuring robust adhesion to the copper substrate. Mechanistically, this composite multilayer ASEI facilitates uniform lithium deposition by guiding lithium ions through its conductive layers and gradual transitions, thereby promoting efficient lithium plating and stripping processes at the ECG/FECG interface, maintaining high Coulombic efficiency and structural stability.
The fabricated composite multilayer ASEI membrane demonstrated promising electrochemical characteristics, including low nucleation overpotential (46.1 mV) and reduced polarization (81.8 mV), which diminish with cycling, indicating enhanced lithium plating efficiency. After 325 cycles, the Coulombic efficiency remained high at 97.2 %, underscoring its stability. Polarization curves remained stable for up to 600 hours. In full-cell (NMC-622//ML) testing, the specific capacity exceeded 120 mAh/g after 150 cycles, with capacity retention at 72 % after 160 cycles. Additionally, material analysis of lithium deposition behaviors within the composite ASEI membrane, including microstructural morphology and chemical bonding composition during lithium plating and stripping, elucidated the mechanism behind its performance.
These findings suggest that the application of this composite multilayer ASEI membrane holds promise in addressing the challenges faced by AFLB, potentially advancing safer and higher energy density energy storage batteries. | en_US |