Copolymer Dispersant for Battery Positive Electrode Paste
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Solution Overview
Problem
Existing methods for producing positive electrodes for nonaqueous electrolyte batteries face challenges in achieving short production times and high adhesiveness to current collectors while maintaining coatability and adhesiveness, often requiring increased temperatures, air volumes, or higher plant investments, which can lead to issues like deteriorated adhesiveness or increased production costs.
Innovation Solution
A positive electrode comprising a copolymer with specific structural units, which reduces viscosity and enhances adhesiveness by aggregating particles into a network, thereby shortening production time and improving adhesiveness to current collectors without compromising coatability or adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the line speed of coating is increased to shorten production time, then productivity is improved, but the retention time in the drying furnace is shortened causing insufficient drying
Solution Approach 1:
The patent changes the chemical composition parameter of the paste by adding a specific dispersant, which fundamentally alters the drying characteristics. This allows the paste to dry properly at higher line speeds without requiring proportional increases in drying furnace temperature or air volume, thus resolving the contradiction between productivity and drying time.
2Loss of time
If the temperature or air volume in the drying furnace is increased to increase drying speed, then drying time is reduced, but the adhesiveness of the positive composite layer deteriorates or flammable gas concentration becomes too high
Solution Approach 1:
The patent introduces a dispersant with specific chemical structure parameters (polyoxyalkylene group with 2-50 repeating units) that changes the paste's rheological properties. This chemical parameter change enables the paste to maintain proper adhesiveness even when drying at higher temperatures or air volumes, thus resolving the contradiction between drying speed and adhesiveness.
Solution Approach 2:
The dispersant acts as an intermediary substance that mediates between the solvent and the positive active material particles. It modifies the interaction between these components during drying, allowing faster drying rates without the harmful effects on adhesiveness that would normally occur. The dispersant protects the paste structure during rapid drying.
3Loss of time
If the mass ratio of solid in the paste is increased to shorten drying time, then drying time is reduced, but the viscosity of the paste is increased causing coatability to deteriorate
Solution Approach 1:
The patent changes the compositional parameters of the paste by introducing a dispersant with specific molecular characteristics (copolymer with hydrophobic and hydrophilic groups). This parameter change fundamentally alters the viscosity-solids content relationship, allowing high solids content pastes to maintain low viscosity and good coatability while drying quickly.
4Device complexity
If a dispersant is added to improve the fluidity of the paste, then viscosity is reduced, but multiple mixing operations are required causing reduction in production efficiency
Solution Approach 1:
The dispersant according to this patent performs multiple functions simultaneously: it disperses the positive active material particles, controls paste viscosity, and enhances adhesiveness during drying. This multi-functionality eliminates the need for separate additives or multiple mixing stages, thereby maintaining high production efficiency while achieving all necessary paste properties.
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 use of a copolymer with specific structural units in the positive electrode paste results in a shorter production time and higher adhesiveness to current collectors, maintaining coatability and adhesiveness, thus enhancing the efficiency and cost-effectiveness of the battery production process.
Implementation Method 1
reduces viscosity and enhances adhesiveness by aggregating particles into a network
Implementation Method 2
allowing the resultant to pass through a drying furnace so as to volatilize and remove the solvent
Implementation Method 3
volatilize and remove the solvent
Implementation Method 4
enhances adhesiveness by aggregating particles into a network, thereby shortening production time and improving adhesiveness to current collectors
Data Source
AI summary
A positive electrode for a battery includes a positive active material, a conductive agent, and a copolymer. The copolymer includes a constituent unit (a) represented by the following general formula (1) and a constituent unit (b) represented by the following general formula (2):(wherein R1, R2, R3, R5, R6, R7 and R9 are the same or different and denote a hydrogen atom, a methyl group or an ethyl group, R4 denotes a hydrocarbon group having 8 to 30 carbon atoms, R8 denotes a linear or branched alkylene group having 2 to 4 carbon atoms, X1 and X2 denote an oxygen atom or NH, and p denotes a number of 1 to 50).