Abstract: A method for screening a lithium ion battery is provided. A number of lithium ion batteries are galvanostatically discharged a to an inflection point voltage at an inflection point of a discharge curve at a first constant current I1. The number of lithium ion batteries are rested for a first rest time T1 to raise an open circuit voltage of the number of lithium ion batteries to U1. U1 is greater than the inflection point voltage. The number of lithium ion batteries are galvanostatically discharged to the inflection point voltage at a second constant current I2, in which I2<<I1. The number of lithium ion batteries are rested for a second rest time T2 and the batteries are screened based on a self-discharge of the number of lithium ion batteries.

Abstract: A method for making a sulfur based cathode composite material is disclosed. Polyacrylonitrile and elemental sulfur are dissolved together in a first solvent to form a first solution. An electrically conductive carbonaceous material is added to the first solution to mix with the polyacrylonitrile and the elemental sulfur. An environment in which the polyacrylonitrile and the elemental sulfur are located in is changed to reduce a solubility of the polyacrylonitrile and the elemental sulfur in a changed environment to simultaneously precipitate the polyacrylonitrile and the elemental sulfur, thereby forming a precipitate having the electrically conductive carbonaceous material. The precipitate is heated to chemically react the polyacrylonitrile with the elemental sulfur. A sulfur based cathode composite material is also disclosed.

Abstract: A method for making a sulfur based cathode composite material is disclosed. Polyacrylonitrile and elemental sulfur are dissolved together in a first solvent to form a first solution. An additive is added to the first solution to mix with the polyacrylonitrile and the elemental sulfur. The additive is at least one of metal and metal sulfide. An environment in which the polyacrylonitrile and the elemental sulfur are located in is changed to reduce a solubility of the polyacrylonitrile and the elemental sulfur in a changed environment to simultaneously precipitate the polyacrylonitrile and the elemental sulfur, thereby forming a precipitate having the additive. The precipitate is heated to chemically react the polyacrylonitrile with the elemental sulfur.

Abstract: A method for screening a lithium ion battery is provided. A number of lithium ion batteries are galvanostatically discharged a to an inflection point voltage at an inflection point of a discharge curve at a first constant current I1. The number of lithium ion batteries are rested for a first rest time T1 to raise an open circuit voltage of the number of lithium ion batteries to U1. U1 is greater than the inflection point voltage. The number of lithium ion batteries are galvanostatically discharged to the inflection point voltage at a second constant current I2, in which I2<<I1. The number of lithium ion batteries are rested for a second rest time T2 and the batteries are screened based on a self-discharge of the number of lithium ion batteries.

Abstract: A method of screening a lithium ion battery is provided. A number of lithium ion batteries are galvanostatically discharged to a discharge cutoff voltage V0 at a first constant current I1. The number of lithium ion batteries are rested for a first rest time T1. The number of lithium ion batteries are galvanostatically charged to a charge cutoff voltage V1 at a second constant current I2. The number of lithium ion batteries are rested for a second rest time T2, and the batteries are screened based on a self-discharge of the plurality of lithium ion batteries.