Lithium ion secondary battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly discloses a lithium ion secondary battery. The lithium ion secondary battery comprises a cathode, an anode, an isolation membrane and electrolyte, wherein the cathode comprises cathode active substance, adhesive and conductive carbon; the anode comprises a lithium titanate active material, adhesive and conductive carbon; base materials for a cathode plate and an anode plate are aluminum foils; and the ratio of the anode capacity to the cathode capacity is 0.70 to 1.00. The lithium ion secondary battery comprises the following activation steps of: 1, charging the battery with constant current of 0.2C to 5C to change lithium titanate into Li4+xTi5O12 from Li4Ti5O12, wherein the x is more than 0.09 and less than or equal to 2.50; 2, charging the battery changed in the first step with constant current of 0.1C to 5C so that the x in the Li4+xTi5O12 is more than 2.50 and less than or equal to 3.00; and 3, charging the battery changed in the second step with constant voltage for 0.2 to 12 hours, and pumping the gas generated in each step until vacuum. The lithium ion secondary battery has excellent electrochemical performance, and meanwhile, the circulation performance and the high-temperature storage performance of the lithium ion secondary battery are improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium ion secondary battery using lithium titanate as a negative electrode. Background technique [0002] With the low-carbon economy in the ascendant, lithium-ion secondary batteries are also actively developing in the direction of power vehicles and grid energy storage, and the development of fast-charging and discharging lithium-ion batteries is becoming the focus of research. Spinel lithium titanate Li 4 Ti 5 o 12 , due to its three-dimensional channels that can quickly deintercalate lithium ions and high safety, the lithium ion secondary battery prepared using it has high rate charge and discharge and high safety performance, and has attracted much attention. Studies have shown that the fabrication process of lithium-ion batteries is closely related to the electrochemical performance. The control conditions of battery production will directl...

AI Technical Summary

Problems solved by technology

However, since the lithium intercalation platform potential of lithium titanate is about 1.55V, which is higher than the formation potential of the SEI film, the SEI film cannot be formed.

Due to the lack of SEI film, the lithium titanate after lithium intercalation is in direct contact with the electrolyte, and catalyzes the decomposition of the electrolyte, resulting in the generation of a large amount of gas, which in turn affects the gram capacity and cycle performance of the active material.

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