Understanding the degradation mechanism of Lithium-ion batteries (LIBs) is critical in developing high-performance LIBs, and the investigation of their electrical conductivity evolution during cycling can lead to a better understanding of the degradation mechanism of the cathode materials for Li-ion batteries (LIBs). Here, we studied the evolution of the electrical conductivity of LiNi_0.8Co_0.15Al_0.05O₂ (NCA) particles for LIB cathodes using scanning spreading resistance microscopy (SSRM). After 300 charge/discharge cycles, stepwise-increasing resistance distributions toward the centers of the secondary particles are observed. These distributions correspond to the degenerated granular structures of the secondary particles caused by the formation of microcracks. In addition, the correlation between the electrical conductivity and microstructure of the NCA cathode is established to explain the observed decay of the NCA discharge capacity. Our findings can provide an insight into the debatable degradation mechanism of LIB cathode materials such as NCA and NMC (LiNi_xMn_yCo_zO₂, x + y + z = 1).

了解锂离子电池（LIB）的降解机理对于开发高性能LIB至关重要，研究其在循环过程中的电导率演变可以更好地理解锂离子电池正极材料的降解机理。 （LIB）。在这里，我们研究了LiNi _0.8 Co _0.15 Al _0.05 O _2的电导率的演变。LIB阴极的（NCA）颗粒，使用扫描扩展电阻显微镜（SSRM）。在300次充/放电循环后，观察到朝向次级颗粒中心的电阻逐步增大。这些分布对应于由微裂纹的形成引起的次级颗粒的退化的颗粒结构。另外，建立了NCA阴极的电导率和微观结构之间的相关性，以解释观察到的NCA放电容量的衰减。我们的发现可以提供对LIB阴极材料如NCA和NMC（LiNi _x Mn _y Co _z O ₂，x + y + z = 1）的有争议的降解机理的见解。