Low-temperature lithium ion secondary battery

Abstract

The invention discloses a low-temperature lithium ion secondary battery. The low-temperature lithium ion secondary battery comprises a positive electrode, a negative electrode, a diaphragm arranged between the positive electrode and the negative electrode and electrolyte, wherein a positive electrode active material adopted by the positive electrode is prepared by mixing a component A with a component B; a chemical formula of the component A is LiNiCoyMn(1-x-y)O2, wherein x is greater than or equal to 0 and is smaller than or equal to 1, y is greater than or equal to 0 and is smaller than or equal to 1, and the sum of the x and the y is greater than or equal to 0 and is smaller than or equal to 1; the component B is selected from at least one of a lithium-containing compound containing K, Mg, Zr, Zn, Ti, Cr, Al, V or Cu elements; counted by mass percentage, the component B accounts for 10 to 15 percent of the positive electrode active material. Compared with the prior art, the low-temperature lithium ion secondary battery disclosed by the invention has the advantages that the low-temperature discharge ability of a lithium battery is improved while the cycle performance of the lithium battery is guaranteed; 1C discharge is realized under the condition that the temperature is 40DEG C below zero; the discharging efficiency can reach 80 percent or above; in addition, the low-temperature lithium ion secondary battery is low in discharge temperature rise and high in safety coefficient.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a low-temperature lithium ion secondary battery. Background technique [0002] With the rapid development of science and technology and the continuous deterioration of the earth's environment, human demand for green energy products is also increasing. Lithium-ion batteries are widely used in the fields of electronics and new energy vehicles because of their high energy density, good rate performance and safety performance, and environmental protection. However, due to its poor low temperature performance, especially in the environment of -40°C, its discharge performance is poor, or even basically no discharge, which restricts the special application of lithium-ion batteries in some technical fields, such as in drones, Sports cameras or logistics express transportation, outdoor portable electronic products and other fields. For this reason, how to obtain a lithium-...

AI Technical Summary

Problems solved by technology

Specifically, as mentioned in the application number 201110136486.8 (a lithium-ion battery electrolyte and lithium-ion battery for ultra-low temperature discharge), add low-melting additives nitroethane and / or nitropropane to the electrolyte, thereby Eliminates the solidification of solvents at lower temperatures (such as -40°C), which is conducive to the rapid migration of lithium ions, improves the ionic conductivity of the electrolyte in an ultra-low temperature environment of -40°C, and can effectively improve the low temperature of lithium-ion batteries. Discharge performance, specifically, in an environment of -40°C, the discharge rate of 0.2C discharge capacity is above 50%, but its discharge capacity still cannot meet customer needs, and the discharge speed is slow

[0004] In addition, in the application number 201010212504.1 (Lithium-ion battery system and method for improving low-temperature discharge performance of lithium-ion batteries), improvements have been made in three aspects of the positive electrode, negative electrode, and electrolyte of lithium-ion batteries. Specifically, lithium cobalt oxide or cobalt acid Lithium-doped nickel-cobalt lithium manganate ternary material is used as the positive electrode system, graphitized mesocarbon microspheres are used as the negative electrode system, and the organic solvent in the electrolyte system used is a mixed system of DEC, EMC, and EC. The effect is that the prepared lithium-ion battery can significantly improve the low-temperature discharge performance of the battery under the premise of meeting the safety performance, rate performance and cycle performance of conventional lithium-ion batteries, and the discharge capacity retention rate at -20°C can reach more than 85%. ℃ The discharge capacity retention rate is above 90%, but the lithium-ion battery cannot be charged and discharged under the environmental condition of -40 ℃

From this, we can see that although improvements have been made to the positive electrode, negative electrode and even the electrolyte of lithium-ion batteries to improve the low-temperature discharge performance of lithium-ion batteries, the discharge capacity retention rate is still not high and cannot meet the actual needs of customers.

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