Positive Electrode Active Material Coating with Steam-Rise Heat Treatment
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Solution Overview
Problem
The existing methods for preparing high-Ni-based positive electrode active materials for lithium secondary batteries face issues with residual lithium by-products on the surface, leading to gas generation, swelling, and reduced capacity and coating efficiency due to surface damage and non-uniform coating layers.
Innovation Solution
A preparation method involving the mixing of a positive electrode active material precursor and a lithium-containing raw material, followed by calcination, and then a heat treatment with a temperature-rising phase and vapor-adding phase, followed by a maintenance phase, without washing, to form a uniform coating, to form a coating layer, and a uniform coating, to form a uniform coating, to form a uniform coating, to form a uniform coating, to form a uniform coating, to form a uniform coating, to form a uniform coating, to form a uniform coating layer on the lithium composite transition metal oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a washing process is adopted to remove residual lithium by-products, then the amount of residual lithium is reduced, but the surface of the positive electrode active material is damaged causing reduction in capacity characteristics and rate capability
Solution Approach 1:
The patent applies preliminary action by conducting the coating process before the material is fully dried after calcination. The coating raw material is applied to the wet surface immediately after washing, allowing the coating to form before the surface dries and becomes susceptible to damage. This timing strategy prevents surface damage while still removing residual lithium by-products through the washing step.
2Object-generated harmful factors
If a washing process is adopted to remove residual lithium by-products, then the amount of residual lithium is reduced, but the process becomes complicated
Solution Approach 1:
The patent merges the washing process with the coating process into a single integrated operation. The coating raw material is applied during the washing step itself, combining two separate processes (washing to remove by-products and coating to protect the surface) into one simultaneous operation, thereby reducing process complexity while achieving both objectives.
3Productivity
If heat treatment is performed to form a coating layer, then coating efficiency is improved, but residual lithium by-products remain on the surface
Solution Approach 1:
The patent applies preliminary action by performing the washing step before the heat treatment and coating process. Residual lithium by-products are removed through washing while the material is still in a wet state, before the heat treatment that forms the coating layer. This sequencing ensures by-products are eliminated before coating, preventing them from being trapped in the final coating structure.
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
This method reduces surface by-products, improves coating efficiency, and ensures a uniform coating layer, enhancing the capacity and stability of the positive electrode active material.
Implementation Method 1
performing a heat treatment to form a coating layer on the lithium composite transition metal oxide
Implementation Method 2
a vapor-adding phase is included only during the temperature-rising phase
Data Source
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AI summary
The present invention relates to a method for manufacturing a positive electrode active material and, more specifically, to a method for manufacturing a positive electrode active material, the method comprising the steps of: (A) preparing a lithium composite transition metal oxide by mixing a positive electrode active material precursor and a lithium (Li)-containing raw material and then firing the mixture; and (B) forming a coating layer on the lithium composite transition metal oxide by mixing the lithium composite transition metal oxide and a coating raw material and heat-treating same, wherein the heat treatment includes a temperature increasing section for increasing the temperature and a maintaining section for maintaining the temperature, and includes a section for injecting steam only in the temperature increasing section.