LiCoO2 Stoichiometry Control via Lithium Buffer Co-firing
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Solution Overview
Problem
The high cost and variability of lithium cobalt oxide (LiCoO2) in mass production for lithium rechargeable batteries due to sensitivity to process parameters and difficulty in maintaining stoichiometric composition, leading to performance fluctuations and impurity issues.
Innovation Solution
A method involving co-firing LiCoO2 with a solid state lithium buffer material to equilibrate the lithium chemical potential, ensuring a consistent stoichiometric composition and reducing sensitivity to process variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LiCoO2 is prepared by conventional heating methods, then the material can be produced, but the lithium chemical potential fluctuates and stoichiometric composition cannot be maintained
Solution Approach 1:
A solid state lithium buffer material is introduced as an intermediary substance during the heating process. This buffer material acts as a mediator that regulates the lithium chemical potential, enabling the LiCoO2 to achieve and maintain stoichiometric composition by controlling lithium diffusion and preventing composition drift during sintering.
Solution Approach 2:
The invention changes the chemical potential parameter of the lithium in the system by introducing the lithium buffer material. This parameter change allows the system to maintain a stable lithium chemical potential throughout the heating process, thereby achieving consistent stoichiometric composition in the final LiCoO2 product.
2Reliability
If strict quality management and process control are implemented to maintain stoichiometric composition, then performance reproducibility is improved, but production cost increases
Solution Approach 1:
The lithium buffer material enables the system to self-regulate the lithium chemical potential during the heating process. This self-service mechanism automatically maintains stoichiometric composition without requiring complex external monitoring and control systems, thereby reducing quality management efforts and production costs while ensuring performance reproducibility.
3Ease of manufacture
If excess lithium is present in LiCoO2, then the material can be easily prepared, but Li2CO3 impurities form and degrade storage properties
Solution Approach 1:
The invention converts the harmful effect of excess lithium (which would form Li2CO3 impurities) into a beneficial process. The lithium buffer material provides a controlled source of excess lithium that prevents Li2CO3 formation by regulating the chemical potential, thereby allowing easy preparation of stoichiometric LiCoO2 without the harmful impurity formation associated with conventional methods.
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 approach stabilizes the lithium chemical potential within a preferred range, enhancing high-voltage cycling and storage properties while reducing production costs and quality control efforts.
Implementation Method 1
co-firing LiCoO2 with a solid state lithium buffer material to equilibrate the lithium chemical potential
Implementation Method 2
heating the resulting mixture to make an equilibrium of a lithium chemical potential
Data Source
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AI summary
The present invention provides a LiCoO2-containing powder comprising LiCoO2 having a stoichiometric composition via heat treatment of a lithium cobalt oxide and a lithium buffer material to make equilibrium of a lithium chemical potential therebetween; a lithium buffer material which acts as a Li acceptor or a Li donor to remove or supplement Li-excess or Li-deficiency, coexisting with a stoichiometric lithium metal oxide; and a method for preparing a LiCoO2-containing powder. Further, provided is an electrode comprising the above-mentioned LiCoO2-containing powder as an active material, and a rechargeable battery comprising the same electrode. The present invention enables production of a LiCoO2electrode active material which has improved high-temperature storage properties and high-voltage cycling properties, and is robust in composition fluctuation in the production process. Therefore, the present invention provides advantages such as reduction of time and labor required for quality control and process management in the mass-production of the electrode active material, and decreased production costs of LiCoO2.