LiNiMnCoO2 Electrode Active Material for Low-Temperature Rate Characteristics
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Solution Overview
Problem
Lithium-nickel-manganese-cobalt composite oxide electrodes used in nonaqueous electrolyte secondary batteries exhibit insufficient rate characteristics in low-temperature environments.
Innovation Solution
A lithium-nickel-manganese-cobalt composite oxide with a hexagonal, layered rock-salt type crystal structure, represented by the formula Li1−α[NixMnyCoz]O2, where α is between 0.1 and 0.3, and the molar ratio of Ni to Mn is between 0.5 and 0.9, with a peak intensity ratio of diffraction peaks within specific ranges, and optionally containing tungsten, is used to enhance stability and reduce internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-nickel-manganese-cobalt composite oxide is used as electrode active material, then safety and cost are improved compared to cobalt composite oxides, but rate characteristics in low-temperature environment deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratios of nickel, manganese, and cobalt in the composite oxide formula Li1−α[NixMnymCoz]O2, where x+y+z=1.0. Specifically, nickel content is controlled at 0.3-0.6, manganese at 0.1-0.3, and cobalt at 0.1-0.3, with additional constraints on their ratios. This optimization of compositional parameters achieves both improved safety and enhanced rate characteristics in low-temperature environments.
Solution Approach 2:
The patent employs composite materials by creating a lithium-nickel-manganese-cobalt composite oxide that combines four different metal elements in specific proportions. This multi-element composite approach leverages the beneficial properties of each element: nickel for capacity, manganese for stability and safety, and cobalt for electrochemical performance, achieving a balance between safety and low-temperature rate characteristics that single-element or simpler composite materials cannot provide.
2Ease of manufacture
If lithium-nickel-manganese-cobalt composite oxide is used as electrode active material, then cost is reduced compared to cobalt composite oxides, but rate characteristics in low-temperature environment deteriorate
Solution Approach 1:
The patent optimizes the compositional parameters of the composite oxide to achieve both cost-effectiveness and performance. By controlling nickel content at 0.3-0.6 (reducing expensive cobalt while maintaining capacity) and optimizing the ratios of all elements, the material achieves low-temperature rate characteristics comparable to or better than cobalt-rich compositions, thereby reducing cost without sacrificing productivity.
Solution Approach 2:
The four-element composite oxide structure allows for cost optimization by replacing a portion of expensive cobalt with more affordable nickel and manganese while maintaining electrochemical performance. The synergistic interaction between the four elements ensures that rate characteristics in low-temperature environments are preserved despite the reduced cobalt content, achieving both cost reduction and maintained productivity.
3Reliability
If nickel composite oxide is used as electrode material, then safety is improved and cost is reduced, but crystal structure stability deteriorates
Solution Approach 1:
The patent uses a four-element composite oxide (lithium-nickel-manganese-cobalt) where manganese plays a crucial role in stabilizing the crystal structure. The presence of manganese (0.1-0.3 in molar ratio) and cobalt (0.1-0.3) alongside nickel provides structural reinforcement through their combined effects, preventing the crystal structure degradation that occurs in pure nickel composite oxides, while maintaining the safety and cost advantages of nickel-based materials.
Solution Approach 2:
The patent stabilizes the crystal structure by optimizing the compositional parameters, specifically controlling the nickel content at 0.3-0.6 and the ratios between nickel, manganese, and cobalt. This parameter optimization ensures that the crystal structure remains stable during charge-discharge cycles, preventing degradation while maintaining the inherent safety and cost benefits of nickel-based composite oxides.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described electrode active material improves rate characteristics in low-temperature environments by maintaining a stable crystal structure and reducing internal resistance, leading to enhanced battery performance.
Implementation Method 1
secondary batteries using lithium ions or other alkali metal ions as charged carriers, in which the electrochemical reaction accompanying the transfer of charge is utilized
Implementation Method 2
lithium ion secondary batteries have spread widely
Data Source
AI summary
An electrode active material that contains a lithium-nickel-manganese-cobalt composite oxide having a hexagonal, layered rock-salt type crystal structure that belongs to the space group R3m. The lithium-nickel-manganese-cobalt composite oxide is represented by the general formula Li1+α[NixMnyCoz]O2 (wherein α satisfies 0.1<α<0.3, and x, y, and z satisfy x+y+z=1, 0.075<z<0.250, and 0.50<x/y<0.90). In the powder X-ray diffraction analysis of a powder of the lithium-nickel-manganese-cobalt composite oxide using a CuKα ray, the peak intensity ratio (A/B) of the diffraction peak intensity (A) observed near 2θ=18.6±0.2° to the diffraction peak intensity (B) observed near 2θ=44.3±1.0° is more than 0 and less than 1.0.