Lithium Metal Composite Oxide Cooling Rate for Sheath Crack Control
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Solution Overview
Problem
Existing methods for producing lithium metal composite oxides face challenges in controlling the cooling rate, which can lead to cracking of ceramic sheaths and affect the quality of the lithium metal composite oxide, impacting the initial, output, and charge characteristics of lithium secondary batteries.
Innovation Solution
A method involving calcining a mixture of lithium and metal composite compounds at 600°C or higher, followed by controlled cooling to 150°C or lower, and subsequent pulverization to achieve a BET specific surface area of 0.90 to 1.55 m2/g, using a rotary kiln and cooler to manage cooling rates and prevent sheath cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid cooling is applied to the calcined product, then the productivity and initial characteristics of lithium secondary batteries are improved, but the ceramic sheath box may crack due to thermal stress
Solution Approach 1:
A cooling medium (gas or liquid) is introduced as an intermediary to control the heat transfer process. The cooling medium absorbs heat from the calcined product at a controlled rate, preventing thermal shock to the ceramic sheath box while achieving the desired cooling effect. This mediator enables rapid cooling without direct thermal stress on the sheath box structure.
Solution Approach 2:
The cooling rate parameter is optimized to a specific range that balances productivity improvement with sheath box protection. By changing the cooling rate from excessive values to a controlled optimal range, the patent achieves both high productivity and maintains sheath box integrity, resolving the contradiction between rapid cooling and structural reliability.
2Manufacturing precision
If the cooling rate is controlled to improve battery characteristics, then the initial and output characteristics are enhanced, but the process complexity increases due to precise temperature control requirements
Solution Approach 1:
The system utilizes the natural thermal properties of the calcined product and the cooling medium to achieve controlled cooling. The exothermic nature of the calcined product combined with the heat capacity of the cooling medium creates a self-regulating cooling process that reduces the need for complex active temperature control systems, thereby lowering device complexity while maintaining manufacturing precision.
Solution Approach 2:
The cooling process is implemented in periodic stages with different cooling rates. By dividing the cooling process into multiple phases (e.g., initial rapid cooling phase followed by a slower cooling phase), the system achieves precise temperature control without requiring continuously complex control mechanisms, thus balancing manufacturing precision with device complexity.
3Manufacturing precision
If the calcining temperature is increased to improve crystal structure, then the peak area ratio is enhanced, but the energy consumption and risk of sheath box damage increase
Solution Approach 1:
The calcined product undergoes preliminary cooling and stabilization before subsequent processing steps. By pre-cooling the product to a controlled temperature range, the patent reduces the thermal load on subsequent operations, thereby lowering overall energy consumption while maintaining the high-quality crystal structure achieved during calcining.
Solution Approach 2:
The high calcining temperature, which could potentially damage the sheath box, is converted into a benefit by using the thermal energy to enhance crystal formation and then rapidly cooling the product to lock in the desired crystal structure. The harmful thermal stress is transformed into a useful crystallization process followed by controlled cooling that preserves the sheath box.
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 enhances the initial, output, and charge characteristics of lithium secondary batteries by ensuring a high peak area ratio and improved crystal structure, leading to better battery performance.
Implementation Method 1
a step of cooling the calcined product from a calcining temperature in the step of obtaining the calcined product to 150° C. or lower to obtain a cooled product
Implementation Method 2
an average cooling rate in a temperature range from 600° C. to 150° C. is 150 to 3500° C./h
Data Source
AI summary
A method for producing a lithium metal composite oxide including a step of calcining, at 600° C. or higher, one of a mixture of a lithium compound and a metal composite compound containing at least Ni and a reactant obtained by preliminarily calcining the mixture to obtain a calcined product, a step of cooling the calcined product from a calcining temperature in the step of obtaining the calcined product to 150° C. or lower to obtain a cooled product, and a step of pulverizing the cooled product such that a BET specific surface area becomes 0.90 to 1.55 m2/g, in which, in the step of obtaining the cooled product, an average cooling rate in a temperature range from 600° C. to 150° C. is 150 to 3500° C./h.