Abstract: This paper gives a general introduction on xEVs(HEV，PHEV and EV) and Li-ion batteries. Developing of xEVs will remarkably reduce the consumption of oils and improve the air quality in cities. Advanced Li-ion batteries supports the industrialization of xEVS. Cathode materials with high energy density, long cycling life and low cost is developing and the range per charge for EVs is expected to be doubled in few years. The energy, service life and safety of a battery are very much dependent on its materials choice and cell design. "Good" battery can be obtained with good understanding and good intention.