Positive Electrode Copolymer Dispersant for High-Voltage Stability
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Solution Overview
Problem
Conventional dispersants for positive electrodes in power storage devices decompose at high voltages, leading to battery degradation due to lack of resistance, resulting in gas generation and reduced energy density.
Innovation Solution
A copolymer dispersant with a constitutional unit A and at least one constitutional unit B, where the total content of these units is 80% by mass or more, is used to improve dispersibility and reduce decomposition, comprising specific monomers that enhance adsorption on conductive materials and control solubility, thereby reducing direct current resistance and maintaining battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dispersants are used in positive electrodes, then dispersibility of conductive materials is achieved, but decomposition occurs at high voltages leading to battery degradation
Solution Approach 1:
The dispersant is designed as a copolymer combining two distinct constitutional units: Unit A (with hydrocarbon group R4 having 16-30 carbon atoms) provides high-voltage stability and resistance to decomposition, while Unit B (with hydroxyl, carboxyl, or amide groups) ensures dispersibility of conductive materials. This composite structure resolves the contradiction by integrating both functions into a single molecular architecture, preventing gas generation and battery degradation at high voltages while maintaining effective dispersibility.
Solution Approach 2:
The copolymer dispersant exhibits local quality differentiation through its two constitutional units: Unit A with long hydrocarbon chains (16-30 carbon atoms) provides localized high-voltage stability and electrochemical inertness, while Unit B with polar groups (hydroxyl, carboxyl, or amide) provides localized dispersibility and interaction with conductive materials. This spatial differentiation of functional properties within the single dispersant molecule resolves the contradiction between stability and dispersibility.
2Quantity of substance
If energy density is improved through higher voltage, then power storage capacity increases, but dispersant decomposition leads to reduced reliability
Solution Approach 1:
The copolymer dispersant with Unit A (hydrocarbon group R4, 16-30 carbon atoms) and Unit B (polar groups) enables high-voltage operation for improved energy density while Unit A simultaneously provides resistance to decomposition, preventing battery capacity degradation and maintaining reliability throughout the charge-discharge cycles.
Solution Approach 2:
The invention changes the chemical composition parameters of the dispersant by specifying Unit A with 16-30 carbon atoms in the hydrocarbon group and Unit B with specific polar groups, enabling the system to operate reliably at higher voltages (improving energy density) while maintaining capacity retention through the stabilizing effect of Unit A.
3Reliability
If conductive materials are dispersed in paste, then electrical conductivity is improved, but decomposition at high voltage generates harmful gases
Solution Approach 1:
The copolymer dispersant combines Unit A (hydrocarbon group R4, 16-30 carbon atoms) which prevents decomposition and gas generation at high voltages, with Unit B (polar groups) which ensures effective dispersibility of conductive materials, thereby achieving improved electrical conductivity without harmful gas evolution.
Solution Approach 2:
The copolymer dispersant acts as an intermediary substance that mediates between conductive materials and the high-voltage environment: Unit B interacts with conductive materials to ensure dispersibility and conductivity, while Unit A shields the system from high-voltage-induced decomposition and gas generation.
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 proposed dispersant effectively reduces battery degradation by minimizing decomposition at high voltages, enhancing energy density and maintaining capacity retention, as evidenced by improved dispersibility and reduced direct current resistance.
Implementation Method 1
the dispersant is a copolymer that contains a constitutional unit A... and at least one constitutional unit B... The content of the constitutional unit A in all constitutional units of the copolymer is 35% by mass or more
Implementation Method 2
a copolymer that contains a constitutional unit A represented by the following general formula (1) and at least one constitutional unit B selected from the group consisting of a constitutional unit B1 represented by the following general formula (2) and a constitutional unit B2 represented by the following general formula (3)
Data Source
AI summary
The present invention relates to a dispersant for a positive electrode of a power storage device. The dispersant is a copolymer that contains a constitutional unit A represented by the following general formula (1) and at least one constitutional unit B selected from the group consisting of a constitutional unit B1 represented by the following general formula (2) and a constitutional unit B2 represented by the following general formula (3). The total content of the constitutional unit A and the constitutional unit B in the copolymer is 80% by mass or more. The content of the constitutional unit A in all constitutional units of the copolymer is 35% by mass or more.