Multi-Stage Firing for High-Nickel Cathode Materials
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Solution Overview
Problem
The existing methods for manufacturing lithium composite compounds with high nickel content for lithium ion secondary batteries face challenges in achieving sufficient oxidation and purity, leading to reduced charge-discharge capacity and increased manufacturing costs due to high oxygen supply costs and impurity issues during the firing process.
Innovation Solution
A method involving a multi-stage firing process with controlled temperature and oxygen concentration, where a lower oxygen concentration is used at a lower temperature stage and a higher oxygen concentration at a higher temperature stage, along with a firing apparatus that recycles gas from the higher temperature stage to the lower temperature stage to optimize nickel oxidation and crystal purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solid phase process is used to manufacture lithium composite compound with high nickel content, then the manufacturing cost is reduced, but insufficient oxidation of nickel occurs causing cation mixing and decreased electrochemical activity
Solution Approach 1:
The firing process is divided into multiple stages with different oxygen concentrations. The first firing stage uses an oxidizing atmosphere with 80% or more oxygen concentration to ensure complete nickel oxidation, while the second firing stage uses a different atmosphere to prevent cation mixing. This segmentation allows each stage to optimize for its specific purpose, resolving the contradiction between cost and oxidation completeness.
Solution Approach 2:
The first firing stage performs preliminary oxidation of nickel at high oxygen concentration before the second firing stage. This preliminary action ensures that nickel is fully oxidized before the compound is cooled, preventing cation mixing in subsequent processing while maintaining manufacturing efficiency.
2Manufacturing precision
If high oxygen concentration is maintained throughout the firing process to ensure sufficient nickel oxidation, then oxidation completeness is improved, but manufacturing cost increases due to high oxygen supply costs
Solution Approach 1:
The firing process is divided into two stages with different oxygen concentrations. The first stage uses high oxygen concentration (80% or more) to ensure complete nickel oxidation, while the second stage uses a different atmosphere. This segmentation allows high oxygen concentration to be applied only where necessary, reducing overall oxygen consumption and manufacturing cost while maintaining oxidation completeness.
Solution Approach 2:
High oxygen concentration is applied partially only in the first firing stage where it is most needed for nickel oxidation, rather than being maintained throughout the entire firing process. This partial application reduces oxygen supply costs while still achieving sufficient oxidation of nickel.
3Manufacturing precision
If multi-stage firing with different oxygen concentrations is implemented to optimize oxidation and reduce cost, then manufacturing precision and cost are improved, but device complexity increases
Solution Approach 1:
The firing process is segmented into two distinct stages with different atmospheric conditions. The first stage uses an oxidizing atmosphere with 80% or more oxygen concentration for complete nickel oxidation, while the second stage uses a different atmosphere to prevent cation mixing. This segmentation achieves high crystal purity through targeted atmospheric control at each stage, while the complexity is managed by using a straightforward two-stage process with clear functional differentiation.
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 results in a lithium composite compound with higher crystal purity and charge-discharge capacity while reducing manufacturing costs by optimizing the firing atmosphere and gas usage.
Implementation Method 1
it is necessary to sufficiently oxidize nickel used as a starting material and fire a crystal having higher purity
Data Source
AI summary
A method for manufacturing a cathode active material for a lithium ion secondary battery comprises mixing lithium carbonate and a compound containing a metal element other than Li, and a firing step. The firing step includes at last two stages of controlling firing to different temperatures. The at least two stages include controlling a firing temperature to a lower temperature and controlling a firing temperature to a higher temperature. The firing is controlled is such that the former stage has a lower oxygen concentration in an atmosphere than the latter stage. The firing apparatus comprises at least two firing furnaces of controlling firing temperatures to different temperatures. The at least two firing furnaces include controlling a firing temperature to a lower temperature and controlling firing temperature to a higher temperature. The latter firing furnace has a gas outlet being in communication with the former firing furnace.