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Cathode active material for lithium secondary battery and lithium secondary battery

A positive electrode active material and lithium secondary battery technology, which is applied in the direction of secondary batteries, lithium batteries, battery electrodes, etc., can solve problems such as insufficient effect, reduced capacity, and reduced structural integrity

Pending Publication Date: 2020-12-29
LG CHEM LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, in the case of Ni-rich NCM-based lithium oxides with a nickel content of 50 atomic % or more, although they provide excellent effects in terms of capacity realization, because the structural and chemical stability of the active material increases with the nickel content Therefore, problems such as deterioration of the structural integrity of the surface of the active material due to repeated charging and discharging, rapid degradation of the structural integrity due to the occurrence of exothermic reactions, and thus degradation of battery stability may occur; or Rapid deterioration of life characteristics due to structural deterioration
In addition, compared with the positive electrode active material with low nickel content, the positive electrode active material whose nickel content accounts for more than 80 atomic % of all transition metals has the following problems: at high temperature, with the acceleration of cation mixing, irreversible phase transition, etc., the lifetime Further deterioration of characteristics
However, the cathode active materials proposed so far still have problems such as: insufficient effect of improving thermal structural stability; capacity drop due to doping elements; and increase in resistance (lifetime characteristics) at high temperature

Method used

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  • Cathode active material for lithium secondary battery and lithium secondary battery
  • Cathode active material for lithium secondary battery and lithium secondary battery
  • Cathode active material for lithium secondary battery and lithium secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0096] By adding Ni 0.90 co 0.08 mn 0.02 (OH) 2 , LiOH, TiO 2 and WO 3 Dry-blended and fired the mixture at 760° C. for 12 hours to prepare Ti and W-doped lithium complex transition metal oxides. In this case, TiO was used in such amounts that Ti and W reached 2000 ppm and 4000 ppm, respectively, based on the entire lithium complex transition metal oxide. 2 and WO 3 .

[0097] After combining the lithium composite transition metal oxide prepared as described above with H 3 BO 3 After mixing, the mixture was heat-treated at 350° C. for 3 hours, thereby preparing a lithium composite transition metal oxide (A) having a B-containing coating layer.

[0098] The lithium composite transition metal oxide (A) prepared as described above was mixed with carbon black conductive material and PVdF binder in a weight ratio of 96.5:1.5:2.0 in N-methylpyrrolidone solvent to prepare the positive electrode mixture, and then The positive electrode mixture was applied to one surface of a...

experiment example 1

[0113] Experimental example 1: Analysis of crystal structure

[0114] At room temperature (25°C), under the condition of 0.005C cut-off, charge each lithium secondary battery of Example 1 and Comparative Examples 1 to 3 with a constant current of 0.2C until fully charged at 4.25V status. After the positive electrode was subsequently separated from the lithium secondary battery, the positive electrode active material layer was scraped off from the positive electrode, thereby collecting a positive electrode active material sample. The collected samples were placed in a radiation accelerator equipped with an in-situ high-temperature XRD instrument and analyzed by XRD, and based on the obtained data, the crystal structure and c parameter of each sample were determined as a function of temperature.

[0115] Show the measurement results in figure 1 and figure 2 middle. figure 1 is a graph showing the crystal structure of each sample as a function of temperature, and figure 2 ...

experiment example 2

[0118] Experimental example 2: Evaluation of initial capacity characteristics

[0119] The initial capacity characteristics of the lithium secondary batteries of Example 1 and Comparative Examples 1 to 3 were evaluated by the following method:

[0120] At room temperature (25° C.), each lithium secondary battery was charged at a constant current of 0.2 C until reaching 4.25 V under a cut-off condition of 0.005 C, and maintained for 20 minutes. Subsequently, its charge capacity was measured. Show the measurement results in image 3 and in Table 1 below.

[0121] [Table 1]

[0122] Charging capacity(mAh / g) Example 1 231.44 Comparative example 1 229.90 Comparative example 2 225.91 Comparative example 3 230.61

[0123] as table 1 and image 3 As shown in , Example 1 exhibited superior capacity characteristics compared to Comparative Examples 1 to 3 despite using a positive electrode active material having a higher doping element content...

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Abstract

The present invention relates to a lithium secondary battery comprising a cathode, an anode, a separation membrane interposed between the cathode and the anode, and an electrolyte, wherein the cathodecomprises, as a cathode active material, lithium composite transition metal oxide powder having a layered structure and having a nickel content of 50 atm% or more of the total content of transition metals, wherein the cathode active material has a phase transition temperature of 300 DEG C or higher at which, in a fully charged state, the layered structure changes into a spinel structure.

Description

technical field [0001] Cross References to Related Applications [0002] This application claims priority and benefit from Korean Patent Application No. 10-2018-0071054 filed on June 20, 2018, the disclosure of which is incorporated herein by reference in its entirety. technical field [0003] The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery having excellent capacity characteristics and excellent thermal stability. Background technique [0004] Recently, as environmental issues become important issues, interest in renewable energy capable of replacing nuclear power generation or fossil fuels has increased. Among such renewable energy sources, demand for secondary batteries that allow charging and discharging and thus have semi-permanent characteristics and allow repeated use is rapidly increasing. [0005] Lithium secondary batteries are the most attractive secondary batteries due to their excellent life ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/525H01M4/505H01M10/052
CPCH01M4/525Y02E60/10H01M2220/20H01M4/62H01M10/0525H01M4/505H01M10/052H01M2004/028
Inventor 朴娜丽尹汝俊潘盛皓严浚浩白贤姬申基喆
Owner LG CHEM LTD
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