Positive Electrode Additive Film for High-Temperature Li Battery Stability
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Solution Overview
Problem
Rechargeable lithium batteries face issues with non-uniform coating of the positive electrode slurry composition, leading to electrode deformation and active material peeling during charging and discharging, which affects high-temperature performance and storage characteristics.
Innovation Solution
Incorporation of a specific additive, represented by Chemical Formula 1 or Chemical Formula 2, which forms a protective film on the positive electrode surface, preventing electrochemical reactions and enhancing high-temperature stability by suppressing the collapse of the positive electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode slurry composition is coated to increase energy density, then the battery capacity increases, but the coating becomes non-uniform causing electrode deformation and active material peeling
Solution Approach 1:
The patent applies preliminary action by adding a viscosity stabilizer to the slurry composition before coating. This stabilizer pre-establishes viscosity stability that prevents agglomeration of active materials during storage and coating processes, ensuring uniform coating even at high solid content levels that increase energy density.
Solution Approach 2:
The patent changes the parameter of slurry viscosity stability through the addition of specific viscosity stabilizers (polymer compounds with specific molecular weights and structures). This parameter change allows the slurry to maintain stable viscosity over time and under varying conditions, enabling both high energy density and uniform coating quality.
2Quantity of substance
If the positive electrode active material is increased to improve capacity, then the battery performance increases, but the material collapses at high temperature causing resistance increase and gas generation
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a protective coating formulation containing specific polymers and additives that form a protective layer on the positive electrode active material surfaces. This protective layer acts as a cushion against thermal degradation, preventing material collapse and associated problems (resistance increase, gas generation) during high-temperature storage and operation.
Solution Approach 2:
The patent uses composite materials by creating a composite structure where the positive electrode active material is combined with a protective coating matrix consisting of specific polymer compounds (such as carboxymethyl cellulose derivatives, styrene-butadiene rubber, or carboxylated polyvinyl chloride). This composite structure maintains the high capacity of the active material while providing thermal stability and structural integrity at elevated temperatures.
3Stability of the object's composition
If the slurry viscosity is increased to reduce material agglomeration, then the dispersion uniformity improves, but the coating process becomes difficult and productivity decreases
Solution Approach 1:
The patent optimizes the viscosity parameter by selecting polymer compounds with specific molecular weights (e.g., carboxymethyl cellulose with degree of substitution 0.7-1.3 and viscosity 5-500 mPa·s at specific concentrations). This parameter optimization achieves the right balance: high enough viscosity to prevent agglomeration and ensure uniform dispersion, but low enough to maintain good coating processability and productivity.
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 additive improves high-temperature characteristics and storage stability by reducing resistance and gas generation, while maintaining electrode integrity and preventing electrochemical reactions.
Implementation Method 1
A positive electrode film may be further included on the surface of the positive electrode, and the positive electrode film may be formed by coordinating the additive represented by Chemical Formula 1 or Chemical Formula 2 to the positive electrode active material.
Data Source
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AI summary
Provided are a positive electrode including a positive electrode active material, a binder, a conductive material, and an additive represented by Chemical Formula 1 or Chemical Formula 2, and a rechargeable lithium battery including the same. Details of Chemical Formula 1 and Chemical Formula 2 are as described in the specification.