Cathode Active Material Metal Oxide Coating Thermal Stability
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Solution Overview
Problem
Current cathode active materials for secondary batteries face challenges such as low structural stability, high raw material costs, environmental pollution, low electrical conductivity, rapid electrode degradation at high temperatures, and poor cycle characteristics, limiting their suitability for high-capacity batteries, especially for electric vehicles.
Innovation Solution
A method of manufacturing a cathode active material with a uniform metal oxide coating layer using a metal glycolate solution, involving steps like preparing a metal glycolate solution, mixing with lithium-containing transition metal oxide particles, drying, and heat treatment, to form a metal composite oxide coating layer that enhances thermal stability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If LiCoO2 is used as cathode active material, then high voltage and high energy density are achieved, but structural stability is low and manufacturing cost is high
Solution Approach 1:
The patent uses LiCoO2 as the core material and coats it with a metal oxide shell formed from metal glycolate solution. This composite structure combines the high voltage characteristics of LiCoO2 with the structural stability of the metal oxide coating, resolving the contradiction between achieving high power and maintaining structural stability during cycling.
Solution Approach 2:
The metal oxide coating is applied locally on the surface of LiCoO2 particles, creating a core-shell structure where the core maintains high voltage characteristics and the shell provides structural stability. This local modification allows the material to simultaneously exhibit both high power and improved stability.
2Ease of manufacture
If lithium manganese oxide is used as cathode active material, then manufacturing cost is reduced, but electrical conductivity is low and capacity is low
Solution Approach 1:
The patent creates a composite structure with lithium manganese oxide core and metal oxide shell. The metal oxide coating improves the electrical conductivity of the inherently conductive lithium manganese oxide, while maintaining the cost advantage of using manganese-based materials instead of expensive cobalt.
Solution Approach 2:
The metal oxide coating modifies the surface properties and electronic structure of lithium manganese oxide, changing parameters such as surface conductivity and charge transfer characteristics, thereby improving overall electrical conductivity without changing the bulk composition.
3Quantity of substance
If lithium-containing nickel oxide is used as cathode active material, then discharge capacity is high, but cycle characteristics are low
Solution Approach 1:
The patent forms a composite structure with lithium-containing nickel oxide core and metal oxide shell. The metal oxide coating protects the nickel oxide core from structural degradation during cycling, thereby improving cycle characteristics while preserving the high discharge capacity of nickel-based materials.
Solution Approach 2:
The metal oxide coating is applied in advance to protect the lithium-containing nickel oxide from harmful effects during cycling, such as Jahn-Teller distortion and surface degradation, thereby cushioning against capacity fade and improving long-term reliability.
4Ease of manufacture
If conventional coating methods are used, then manufacturing process is simple, but metal oxide layer thickness is non-uniform
Solution Approach 1:
The patent changes the physical state parameter of the coating solution from liquid to paste by controlling water content. This paste state allows the coating material to adhere uniformly to the cathode active material particles and be evenly distributed, achieving uniform thickness while maintaining process simplicity.
Solution Approach 2:
The metal glycolate solution is prepared as a paste that can be uniformly applied and copied onto the cathode active material particles. This paste coating method ensures consistent thickness and composition across all particles, reproducing uniform coating quality.
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 method achieves improved charge and discharge efficiency, thermal stability, and cycle characteristics by forming a uniform metal oxide layer on the cathode active material, addressing the limitations of existing materials and enhancing battery performance.
Implementation Method 1
a third step of drying the paste-state mixture
Implementation Method 2
a fourth step of performing a heat treatment on the dried mixture
Implementation Method 3
a third step of drying the paste-state mixture; a fourth step of performing a heat treatment on the dried mixture
Data Source
Figure 1
AI summary
Provided are a method of manufacturing a cathode active material including a first step of preparing a metal glycolate solution, a second step of mixing lithium-containing transition metal oxide particles and the metal glycolate solution and stirring in a paste state, a third step of drying the paste-state mixture, and a fourth step of performing a heat treatment on the dried mixture, a cathode active material including a metal oxide layer which is manufactured by the above method, and a secondary battery composed of a cathode including the cathode active material.