The invention discloses a high-voltage high-energy-density lithium ion battery which comprises a positive pole piece, a negative pole piece, a diaphragm, electrolyte and a shell, wherein the positive pole piece comprises a positive active material, a conducting agent, an adhesive and a current collector, and the weight percents of the positive active material, the conducting agent and the adhesion are 92 to 97%: 2 to 3.5%: 1 to 6%; the negative pole piece comprises a negative material, a conducting agent, an adhesive and a current collector, and the weight percents of the negative material, the conducting agent and the adhesive are respectively 90 to 96%, 1 to 5% and 4 to 10%; the lithium ion battery is prepared by adopting modified lithium cobalt oxides (LiCoO2) as the positive active material and the artificial graphite or natural graphite as the negative material and matching the corresponding ceramic diaphragm, high-voltage electrolyte, adhesive and conducting agent. The lithium ion battery not only has high energy density and high discharging platform, but also is good in chemical performance and safety performance and is applicable to the commercialized mass production.