锂离子电池富镍正极基础科学问题:材料失稳机制及改性策略

Basic Scientific Problems of Nickel-Rich Cathode for Lithium-Ion Battery: Destabilization Mechanism and Modification Strategies

  • 摘要: 层状富镍锂过渡金属氧化物因其高容量、高工作电压等优势是长续航动力电池广泛采用的正极材料。然而,由于不稳定的晶体结构和较差的热力学性,富镍正极材料在反复Li+脱嵌过程中稳定性差,进而导致电池难以长周期服役。本文分析了富镍正极材料表面残锂、阳离子混排、气体释放、不可逆相变、微裂纹等各种导致材料失稳降解的机制,总结了近年来为解决上述问题而采用的元素掺杂、表面涂层、单晶化、浓度梯度结构设计和引入电解质添加剂等改性策略,并展望了未来材料改性策略的方向和应用前景。

     

    Abstract: Nickel-rich layered cathodes with high discharge capacity and high voltage platform are recognized as positive materials used for long-life power batteries. However, due to the fragile lattice and poor thermal property, Ni-rich cathode materials have poor stability during repeated lithiation/delithiation, which makes it difficult for batteries to serve for a long period. In this paper, the mechanism of degradation of stability caused by residual lithium, cationic mixing, gas release, irreversible phase change and micro-cracks for nickel-rich cathode materials is analyzed. The modification strategies adopted in recent years to solve the above problems are summarized, such as element doping, surface coating, single crystallization, concentration gradient structure design and introduction of electrolyte additives. Moreover, the future direction and application prospect of those modification strategy are also discussed.

     

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