Using analytical transmission electron microscopy (TEM) techniques reveal a zigzag layer on surface of the cycled particles of LiNi1/3Co1/3Mn1/3O2 cathode after 300 discharge/charge cycles. The Ni, Mn content in the zigzag layer of the cycled particle has decreased rapidly from interior to edge of the zigzag layer of the cycled particles. The structure of LiNi1/3Co1/3Mn1/3O2 oxide was gradually destructed from hexagonal cell with P3112 at interior region to fcc lattice of α-NaFeO2 at edge of the zigzag layer of the cycled particles. These experimental data provide the compositional and structural origins of the capacity decrease in the Li-ion battery.