In a recent breakthrough, researchers from iChEM, led by Professor Wang Yonggang from Fudan University, have developed a novel lithium-ion battery system using a simple pre-lithiation method. The system consists of Li₂V₂(PO₄)₃ as the cathode and LixC as the anode, showcasing high power, long cycle life, and excellent low-temperature performance.
With the rapid growth of electric vehicles powered by lithium-ion batteries, the challenge of maintaining performance in cold environments has become increasingly significant. Lithium-ion batteries typically suffer from reduced capacity and efficiency at low temperatures, which limits their usability in winter or high-altitude areas.
Traditional graphite anodes face limitations in low-temperature performance due to the slow diffusion of lithium ions into and out of the graphite structure. To address this, the research team replaced the conventional graphite anode with a pre-lithiated hard carbon anode, paired with a lithium vanadium phosphate (Li₂V₂(PO₄)₃) cathode, creating a new battery configuration.
Prelithiated hard carbon has shown promise in hybrid lithium-ion capacitors, but its production often involves complex and costly processes, including the use of metallic lithium, which poses safety risks. In this study, the team cleverly used the multi-step delithiation process of Li₃V₂(PO₄)₃ to achieve pre-lithiation of the hard carbon anode without relying on pure lithium electrodes.
During the initial charging cycle, lithium ions are extracted from the cathode material, forming Li₂V₂(PO₄)₃, while the released lithium ions are embedded into the hard carbon anode, resulting in a pre-lithiated LixC anode. This combination forms a stable lithium-ion battery system that exhibits supercapacitor-like performance, delivering high power and long cycle life.
Despite using a conventional electrolyte, LB303, the battery demonstrated remarkable low-temperature performance. At -40°C, it retained 67% of its capacity compared to room temperature, significantly outperforming traditional lithium-ion batteries. This is attributed to the nano-carbon-coated Li₂V₂(PO₄)₃ cathode and the fast kinetics of the pre-lithiated hard carbon anode at low temperatures.
However, there are still challenges. Only a portion of the Li₃V₂(PO₄)₃ capacity is utilized in the system, limiting the energy density, making it more suitable for start-stop applications. Additionally, as temperature decreases, the electrolyte’s ionic conductivity drops, increasing internal resistance and causing noticeable polarization. Future work should focus on developing advanced low-temperature electrolytes to further enhance the battery’s performance under extreme conditions.
This innovation marks a significant step forward in the development of reliable, high-performance batteries for electric vehicles and other low-temperature applications.
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