Cathode Active Material Doping and Coating for High-Temperature Cycle Life
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Solution Overview
Problem
Existing lithium secondary battery positive electrode active materials face challenges with thermal stability, cycle characteristics, and durability due to issues with cobalt-based materials, manganese-based materials, and nickel-based materials, particularly when exposed to high temperatures and moisture.
Innovation Solution
A method involving the preparation of a positive electrode active material for lithium secondary batteries through a two-step calcination process, where a lithium composite transition metal oxide is doped with Zr and Al, and coated with B and Al, controlling the weight ratio of doping and coating elements within a specific range to enhance structural and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then charge-discharge efficiency and lifespan are improved, but high-temperature stability deteriorates and price increases
Solution Approach 1:
The patent uses LiNi0.8Co0.1Mn0.1O2 composite material that combines multiple transition metals to achieve both high capacity and improved thermal stability compared to conventional LiCoO2, resolving the contradiction between lifespan and high-temperature stability
Solution Approach 2:
The patent applies localized coating of Al2O3 on the surface of the active material particles, creating a protective layer that specifically addresses high-temperature stability at the particle surface while maintaining the bulk material's electrochemical properties for charge-discharge efficiency
2Reliability
If LiNi0.8Co0.15Al0.05O2 is used to improve cycle characteristics, then capacity properties are improved, but chemical stability deteriorates causing cell swelling and thermal stability degradation
Solution Approach 1:
The patent modifies the stoichiometric parameters of the LiNi0.8Co0.1Mn0.1O2 material and controls the coating thickness and composition to optimize the balance between cycle characteristics and chemical stability, preventing cell swelling while maintaining capacity
Solution Approach 2:
The patent introduces Al2O3 coating as an intermediary layer between the LiNi0.8Co0.1Mn0.1O2 active material and the electrolyte, which acts as a protective barrier that maintains chemical stability while allowing the underlying material to deliver improved cycle characteristics
3Temperature
If lithium-manganese oxide is used, then thermal stability and price are improved, but capacity and conductivity deteriorate
Solution Approach 1:
The patent creates a composite structure where LiNi0.8Co0.1Mn0.1O2 serves as the core material providing high capacity, while Al2O3 coating provides thermal stability, achieving both requirements simultaneously rather than choosing one material
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 improves the high-temperature lifetime characteristics, capacity, and cycle stability of lithium secondary batteries by stabilizing the active material structure and reducing lithium ion migration resistance.
Implementation Method 1
a lithium composite transition metal oxide which has been doped with a doping element
Implementation Method 2
performing a first calcination treatment thereon to prepare a lithium composite transition metal oxide doped with the doping elements
Implementation Method 3
a coating layer which has been formed with a coating element on the lithium composite transition metal oxide
Implementation Method 4
performing a second calcination treatment thereon to prepare a positive electrode active material for a lithium secondary battery in which a coating layer containing the coating elements is formed on the lithium composite transition metal oxide
Data Source
AI summary
A method for manufacturing a cathode active material for a lithium secondary battery according to the present invention comprises the steps of: mixing a transition metal hydroxide comprising transition metals inclusive of nickel (Ni), cobalt (Co), and manganese (Mn), a lithium-containing raw material, and a doping raw material including at least one doping element selected from the group consisting of Al, Mg, Co, V, Ti, Zr, and W and subjecting the mixture to a first baking process to afford a lithium composite transition metal oxide doped with the doping element; and mixing the lithium composite transition metal oxide and at least one coating element selected from the group consisting of Al, Mg, Co, Ti, Zr, and B and subjecting the mixture to a second baking process to produce a cathode active material for a lithium secondary battery, in which a coating layer comprising the coating element is formed on the lithium composite transition metal oxide, wherein the doping raw material and the coating raw material are fed so that the weight ratio of the doping element to the coating element ranges from 0.3 to 7 in the cathode active material for a lithium secondary battery.