Positive Electrode Dispersant Copolymer for High-Temperature Slurry Stability
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Solution Overview
Problem
The viscosity of the slurry increases with temperature during the dispersion of carbon material-based conductive materials, leading to decreased dispersion efficiency and increased resistance in positive electrodes of power storage devices, as existing dispersants fail to maintain effective adsorption and dispersibility at elevated temperatures.
Innovation Solution
A dispersant copolymer containing specific constitutional units, including hydrocarbon groups and functional groups like pyridinyl or cyano groups, which maintains adsorption and dispersibility even at high temperatures, reducing viscosity and enhancing handleability of the conductive material slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional dispersant is used during carbon material dispersion, then the dispersant provides initial dispersibility in the slurry, but the viscosity increases with temperature leading to decreased dispersion efficiency
Solution Approach 1:
The patent modifies the chemical structure of the dispersant by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups) with defined含量的 ranges. This parameter change in the dispersant's molecular structure enables it to maintain effective adsorption and dispersibility at elevated temperatures, directly addressing the temperature-dependent viscosity increase problem
Solution Approach 2:
The dispersant is designed as a copolymer containing multiple functional units including hydrocarbon groups (for adsorption on carbon material surfaces) and polar functional groups (for temperature stability and solubility control). This composite molecular structure combines the advantages of different functional groups to achieve both initial dispersibility and high-temperature stability
2Ease of operation
If the slurry viscosity increases with temperature, then the handleability of the slurry deteriorates, but maintaining low viscosity requires additives that may affect electrode performance
Solution Approach 1:
The patent changes the rheological parameters of the slurry by introducing a dispersant with specific functional group content (0.1-10 mmol/g). This parameter modification enables the slurry to maintain appropriate viscosity and handleability across a wide temperature range (25-80°C), eliminating the need for additional viscosity-control additives
3Reliability
If existing dispersants are used, then they provide dispersibility at room temperature, but adsorption effectiveness decreases at elevated temperatures leading to increased resistance
Solution Approach 1:
The dispersant combines hydrocarbon groups (which adsorb on carbon material surfaces through van der Waals forces) with polar functional groups (which provide thermal stability and prevent aggregation). This composite structure ensures reliable adsorption effectiveness from room temperature to elevated processing temperatures, maintaining low electrode resistance
Solution Approach 2:
The patent optimizes the functional group content parameter (0.1-10 mmol/g) to achieve the right balance between adsorption strength and temperature stability. This parameter optimization ensures that the dispersant maintains effective adsorption on carbon materials across the full processing temperature range
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 dispersant composition ensures low viscosity and improved dispersion of carbon material-based conductive materials, resulting in reduced resistance values and enhanced performance of positive electrodes in power storage devices.
Implementation Method 1
a functional group X1 is a functional group contained in a monomer unit of a homopolymer that is represented by the formula (2) and is adsorbed on a carbon material-based conductive material at an adsorption percentage of 10.0% or more
Data Source
AI summary
An aspect of the present disclosure relates to a dispersant for a positive electrode of a power storage device, the dispersant being a copolymer containing a constitutional unit represented by the following formula (1), a constitutional unit represented by the following formula (2), and a constitutional unit represented by the following formula (3). Also, an aspect of the present disclosure relates to a dispersant composition, a conductive material slurry for a battery and a method for producing the conductive material slurry a positive electrode paste for a battery or a positive electrode for a battery, each of which contains the dispersant for a positive electrode of a power storage device.