Lithium Composite Cathode Surface Layer for High Voltage Stability
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Solution Overview
Problem
Existing methods for improving cycle and rate characteristics of lithium ion secondary battery cathode active materials face challenges such as high energy requirements for drying, agglomeration issues, and excessive alkali content leading to gas generation and inadequate cycle characteristics.
Innovation Solution
A cathode active material with a covering layer comprising specific metal oxides and lithium compounds on lithium-containing composite oxide particles, produced through a process involving controlled aqueous solutions and heating, to enhance surface area and atomic ratios for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a treated surface layer is formed by drying a large amount of water, then the surface layer is formed, but high energy for drying is required and the cathode active material is likely to agglomerate
Solution Approach 1:
The patent changes the chemical composition parameters of the surface layer by controlling the atomic ratio of non-metal elements to metal elements within 5nm of the surface to be 0.05-0.20, and uses specific metal oxides (Al, Y, Ga, In, La, Pr, Nd, Gd, Dy, Er, Yb) to achieve effective surface treatment with reduced water content, thereby reducing drying energy requirements
2Reliability
If a treated surface layer is formed by drying a large amount of water, then the surface layer is formed, but the cathode active material is likely to agglomerate to form coarse particles
Solution Approach 1:
The patent controls the atomic ratio parameters and uses specific metal oxide compositions to form a surface layer that prevents particle agglomeration during the drying process, maintaining fine particle morphology while achieving effective surface treatment
3Ease of manufacture
If alkali is excessive in the cathode active material, then the cathode active material is formed, but gas is generated due to decomposition of carbonate solvent in electrolytic solution
Solution Approach 1:
The patent严格控制 the atomic ratio of non-metal elements to metal elements within 5nm of the surface to be 0.05-0.20, and selects specific metal oxides that do not introduce excessive alkali, thereby preventing gas generation from carbonate decomposition while maintaining ease of manufacture
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 solution achieves excellent cycle and rate characteristics even at high voltages, with improved productivity and reduced agglomeration, while avoiding excessive alkali-related issues.
Implementation Method 1
By the presence of such a lithium compound on the surface of the cathode active material, it functions as a physical barrier, whereby dissolution, into an electrolyte solution, of manganese ions in the lithium-containing composite oxide can be suppressed
Implementation Method 2
it was necessary to dry a large amount of water to form the treated surface layer
Data Source
AI summary
To provide a cathode active material for a lithium ion secondary battery excellent in the cycle characteristics and rate characteristics even when charging is conducted at a high voltage. A cathode active material for a lithium ion secondary battery, which comprises particles (III) having a covering layer comprising a metal oxide (I) containing at least one metal element selected from the group consisting of Al, Y, Ga, In, La, Pr, Nd, Gd, Dy, Er and Yb, and a compound (II) containing Li and at least one non-metal element selected from the group consisting of S and B, on the surface of a lithium-containing composite oxide, wherein the atomic ratio (the non-metal element/the metal element) contained within 5 nm of the surface layer of the particles (III) is within a specific range.