失效石墨负极材料包覆修复技术的进展与挑战

Progress and challenges in material cladding repair technology for failed graphite anodes

  • 摘要: 新能源汽车行业的快速发展对高性能电池需求大增,锂电池凭借其优势在该领域广泛应用,石墨负极作为其关键组成部分,需求也随之上升. 石墨凭借其低成本、高能量密度、优异的导电性和良好的循环稳定性成为了商业化锂电池中最主要的负极材料. 然而,随着锂电池循环次数的增加,石墨负极表面会逐渐形成固体电解质(SEI)界面层和锂枝晶,导致石墨结构受损,电化学性能下降,这会导致大量的石墨资源浪费. 为了实现石墨的可持续利用,需要对失效石墨负极进行再生修复,重新投入使用. 本文综述了材料包覆技术在修复失效石墨负极中的应用进展和挑战,介绍了失效石墨负极的除杂方法,着重介绍了沥青包覆修复、金属氧化物包覆修复和聚合物包覆修复这三种方法对失效石墨负极的修复作用. 这些包覆技术能够有效修复失效石墨受损的结构,恢复电化学性能. 最后,本文提出了目前材料包覆技术所面临的挑战,并对未来研究方向提出了展望,以促进新能源电池产业的可持续发展.

     

    Abstract: Rapid growth of the new-energy vehicle industry has significantly increased the demand for high-performance batteries. Among various energy storage technologies, lithium-ion batteries (LIBs) have become the dominant choice owing to their high energy density, long cycle life, and environmental advantages. Graphite, a critical component of LIBs, has been widely adopted as the primary anode material in commercial batteries because of its low cost, high energy density, excellent electrical conductivity, and superior cycling stability. However, as LIBs undergo repeated charge-discharge cycles, the graphite anode gradually degrades. This degradation primarily results from the formation of a solid electrolyte interphase (SEI) layer and the growth of lithium dendrites on the graphite surface. The SEI layer, though initially necessary for battery operation, becomes excessively thick over time, thereby impeding lithium-ion transport. Simultaneously, lithium dendrites can penetrate the separator, causing internal short circuits and safety hazards. These issues lead to structural damage in the graphite anode, reducing its electrochemical performance and ultimately resulting in battery failure. Consequently, large quantities of spent graphite anodes are discarded, leading to resource wastage and environmental concerns. To address these challenges and promote the sustainable use of graphite, researchers have focused on developing techniques to restore failed graphite anodes. Among various regeneration strategies, material coating technology has emerged as highly effective. By applying a protective or functional layer onto the degraded graphite surface, structural defects can be repaired and the electrochemical performance can be restored. This article reviews the recent advancements in material coating techniques for regenerating failed graphite anodes. First, we discuss the necessary pretreatment steps, including impurity removal methods, such as acid leaching, thermal treatment, and solvent extraction, essential for preparing degraded graphite for regeneration. Next, this study examines three key coating strategies: (1) Asphalt coating – asphalt, a carbon-rich material, is carbonized at high temperatures to form a conductive layer that repairs surface cracks and enhances electrical conductivity. (2) Metal oxide coating materials, such as Fe2O3, TiO2 and TiNb2O7 have been applied to stabilize the SEI layer and suppress lithium dendrite growth. (3) Polymer coating: conductive polymers and functional polymers (e.g., biofilms) improve the mechanical strength and interfacial stability. These coating methods have proven effective in restoring the structural integrity and electrochemical performance of graphite anodes, thereby enabling their reuse in LIBs. However, some challenges remain, including the need for scalable production methods, cost optimization, and long-term stability under high-voltage conditions. Future research should focus on developing multifunctional composite coatings that combine the advantages of different materials as well as exploring green and low-cost coating techniques to improve sustainability. Additionally, integrating advanced process control methods, such as artificial intelligence and automation, can enhance the consistency and efficiency of graphite regeneration. In conclusion, the material coating technology offers a promising solution for the regeneration of failed graphite anodes, contributing to the sustainable development of the LIB industry. By refining these techniques and addressing existing limitations, we can improve resource utilization, reduce environmental impact, and support the continued growth of the new energy sector.

     

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