CN-122000347-A - Positive electrode active material for lithium secondary battery and lithium secondary battery

Abstract

A positive electrode active material for a lithium secondary battery and a lithium secondary battery, the lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode includes a lithium composite transition metal oxide powder having a layered structure and having a nickel content of 85 atm% or more in all transition metals, and wherein the lithium composite transition metal oxide powder undergoes a lithium-oxygen (Li-O) interlayer distance change of 3% or less in a state of charge (SOC) range of 58% to 72%. The lithium secondary battery of the present invention can exhibit excellent capacity characteristics and excellent high-temperature life characteristics.

Inventors

• Bai Xianji
• PAN SHENGHAO
• YAN JUNHAO
• LIN CAIZHEN
• LI XIANGZHAO
• Pu Nali

Assignees

• 株式会社LG化学

Dates

Publication Date

20260508

Application Date

20190619

Priority Date

20180620

Claims (8)

1. 1. A lithium secondary battery, the lithium secondary battery comprising: A positive electrode; A negative electrode; A separator interposed between the positive electrode and the negative electrode, and An electrolyte is provided, which is a metal-containing electrolyte, Wherein the positive electrode contains, as a positive electrode active material, a lithium composite transition metal oxide powder having a layered structure and having a nickel content of 85 atm% or more in the entire transition metal, Wherein the lithium composite transition metal oxide powder undergoes a lithium-oxygen (Li-O) interlayer distance change of 3% or less in a state of charge (SOC) range of 58% to 72%.
2. 2. The lithium secondary battery according to claim 1, wherein the lithium composite transition metal oxide powder undergoes a Li-O interlayer distance change of 1% or less in an SOC range of 58% to 72%.
3. 3. The lithium secondary battery according to claim 1, wherein in the lithium composite transition metal oxide powder, a Li-O interlayer distance at 100% SOC is greater than or equal to a Li-O interlayer distance at 0% SOC.
4. 4. The lithium secondary battery according to claim 1, wherein the lithium composite transition metal oxide is represented by chemical formula 1: [ chemical formula 1] Li x [Ni a Co b Mn c M d ]O 2 Wherein, in the chemical formula 1, M is one or more elements selected from W, cu, fe, V, cr, ti, zr, zn, al, in, ta, Y, la, sr, ga, sc, gd, sm, ca, ce, nb, mg, B and Mo, and X is more than or equal to 0.9 and less than or equal to 1.2,0.85 and a is more than or equal to 0 0.99,0< b <0.15,0< c <0.15, and 0< d <0.15.
5. 5. The lithium secondary battery according to claim 4, wherein the M contains two or more elements selected from the group consisting of W, zr, al, ti and Mg.
6. 6. The lithium secondary battery according to claim 4, wherein the M contains W and one or more elements selected from the group consisting of Zr, al, ti and Mg.
7. 7. The lithium secondary battery according to claim 1, wherein the lithium composite transition metal oxide comprises a coating layer comprising one or more elements selected from the group consisting of Al, ti, W, B, F, P, mg, ni, co, fe, cr, V, cu, ca, zn, zr, nb, mo, sr, sb, bi, si and S on a surface thereof.
8. 8. A positive electrode active material for a lithium secondary battery, comprising a lithium composite transition metal oxide powder having a layered structure and a nickel content of 85 atm% or more in the entire transition metal, Wherein the lithium composite transition metal oxide powder undergoes a change in Li-O interlayer distance (i.e., liO 6 plate thickness) of 3% or less in the SOC range of 58% to 72%.

Description

Positive electrode active material for lithium secondary battery and lithium secondary battery The present invention is a divisional application of chinese invention patent application, which is entitled "positive electrode active material for lithium secondary battery and lithium secondary battery", based on the application of No. 201980034513.5, no. 2019, no. 6, and 19. Cross Reference to Related Applications The present application claims priority and equity from korean patent application No. 10-2018-007055, filed on date 20 of 2018, whose disclosure is incorporated herein by reference in its entirety. Technical Field The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery that exhibits excellent electrochemical properties even at high temperatures. Background Recently, as environmental problems have become important issues, interest in renewable energy sources capable of replacing nuclear power generation or fossil fuels has increased. Among such renewable energy sources, the demand for secondary batteries that allow charging and discharging and thus have semi-permanent characteristics and allow reuse is rapidly increasing. Lithium secondary batteries are the most attractive secondary batteries because of their excellent life (cycle) characteristics and high energy density. As a positive electrode active material for such a lithium secondary battery, various lithium transition metal oxides have been developed, such as LiCoO2、LiNiO2、LiMnO2、LiMn2O4、LiFePO4、Li(NiaCobMnc)O2 ( where a, b, and c are atomic fractions of transition metals, where 0< a <1,0< b <1,0< c <1, and a+b+c=1, the compounds being hereinafter referred to as NCM-type lithium oxides), and the like. Meanwhile, in recent years, in order to be applied to high-capacity batteries such as batteries for electric vehicles, development of nickel (Ni) -rich (Ni) NCM-based lithium oxides having an increased nickel content for high energy density is actively underway. However, in the case of a lithium secondary battery to which a Ni-rich NCM-type lithium oxide is applied, although excellent effects are provided in terms of capacity realization, problems may occur, such as a decrease in structural integrity of the surface of the active material due to repeated charge and discharge, a decrease in battery stability due to occurrence of exothermic reaction, causing a rapid decrease in structural integrity, or a rapid decrease in life characteristics due to structural deterioration, since structural stability and chemical stability of the active material decrease with increase in nickel content. Such a phenomenon is aggravated under high temperature and/or high voltage conditions, and is particularly remarkable when a positive electrode active material having a nickel content of 80 atm% or more in the entire transition metal is used. Further, the positive electrode active material having a nickel content of 80 atm% or more in all transition metals has a problem that life characteristics are lowered under high temperature conditions because cation mixing, irreversible phase transition, etc. are accelerated, as compared with the positive electrode active material having a low nickel content. In order to solve the above-described problems, a technique of improving the structural stability of the positive electrode active material by doping or coating with a metal element has been attempted. However, the heretofore proposed technology has not been able to sufficiently achieve capacity characteristics and high temperature characteristics. Therefore, there is a need to develop a lithium secondary battery having excellent high-temperature characteristics while satisfying high-capacity requirements. Disclosure of Invention Technical problem The present invention relates to a lithium secondary battery that exhibits excellent life characteristics even at high temperatures while having high capacity characteristics, since it includes a positive electrode active material having a nickel content of 85 atm% or more. Technical proposal An aspect of the present invention provides a lithium secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode includes a lithium composite transition metal oxide powder having a layered structure and having a nickel content of 85 atm% or more in all transition metals as a positive electrode active material, and wherein the lithium composite transition metal oxide powder undergoes a change in lithium-oxygen (Li-O) interlayer distance (i.e., liO 6 plate thickness) of 3% or less, preferably 1% or less in a state of charge (SOC) range of 58% to 72%. In the lithium composite transition metal oxide powder, the Li-O interlayer distance at 100% SOC may be greater than or equal to the Li-O interlayer distance at 0% SOC. Further, the lithium comp