NOVELTY - A lithium ion battery comprises a positive pole, negative pole and a diaphragm, where the positive pole comprises positive active material, conductive agent and binder, the negative pole comprises negative active material, conductive agent and binder, the positive active material includes lithium-nickel-cobalt-manganese oxide and/or lithium manganate, the negative active material includes hard carbon and/or soft carbon, the conductive agent is carbon fiber, flake graphite and/or carbon nanotube, and the binder is butadiene styrene rubber and/or hydroxypropyl/carboxymethyl cellulose.    USE - Lithium ion battery.    ADVANTAGE - The lithium ion battery has better charging and discharging characteristics, and high stability.    DETAILED DESCRIPTION - A lithium ion battery comprises a positive pole, negative pole and a diaphragm, where the positive pole comprises 80-98 wt.% positive active material, 1-19 wt.% conductive agent and 1-19 wt.% binder, the negative pole comprises 80-98 wt.% negative active material, 1-19 wt.% conductive agent and 1-19 wt.% binder, the positive active material includes lithium-nickel-cobalt-manganese oxide and/or lithium manganate, the negative active material includes hard carbon and/or soft carbon, the conductive agent is superconducting carbon black, carbon fiber, crystalline flake graphite and/or carbon nanotube, and the binder is Kynar (RTM: fluoropolymer resin), butadiene styrene rubber, sodium carboxymethylcellulose and/or hydroxypropyl/carboxymethyl cellulose. An INDEPENDENT CLAIM is also included for a method for preparing lithium ion battery which involves mixing positive pole raw materials into mixed slurry, coating slurry on an aluminum foil uniformly, drying and rolling to obtain positive pole piece, mixing negative pole raw materials into mixed slurry, coating slurry on a copper foil, drying and rolling to obtain negative pole piece, stacking prepared positive pole and negative pole into a battery core, where the positive pole and negative pole are separated by membrane, packing into dry battery core, injecting a dry battery in the electrolyte to obtain finished product.