Abstract: 18650 type Li ion secondary cells were developed using carbon as anode material and LiNi1/3Co1/3·Mn1/3O2 as cathode material. The discharge performance of the C/LiNi1/3Co1/3Mn1/3O2 cell was studied through such methods as charge and discharge cycle, hybrid pulse power characterization (HPPC) and area-specific impedance (ASI) test. Study was also performed on the impact of such factors as material particle and morphology, discharge temperature and electrolyte on the discharge performances of the C/LiNi1/3Co1/3Mn1/3O2 cell, especially on its discharge performance under big currents. The results show that the C/LiNi1/3Co1/3Mn1/3O2 cell presents more stable charge/discharge cycles as well as better discharge performance under big currents with smaller original particle of LiNi1/3Co1/3·Mn1/3O2. It is also demonstrated that elevated discharge temperature prominently improves the discharge performance of the C/LiNi1/3Co1/3Mn1/3O2 cell, with its output power density at late discharge period growing by a large margin. Electrolyte with high conductivity also improves the cell’s long-termcycle performance under big discharge currents.