A method for cycling a sulfur composite lithium ion battery includes a step of charging and discharging the sulfur composite lithium ion battery at a first voltage range between a predetermined highest voltage and a predetermined lowest voltage. The lithium ion battery includes an electrode active material. The electrode active material includes a sulfur composite. The step of charging and discharging satisfies at least one conditions of (1) and (2): (1) the predetermined lowest voltage of the first voltage range is larger than a discharge cutoff voltage of the sulfur composite; and (2) the predetermined highest voltage of the first voltage range is smaller than a charge cutoff voltage of the sulfur composite. A method for using a sulfur composite as an electrode active material of a lithium ion battery is also disclosed.