Crosslinked Hydrogel Electrolyte for High-Temperature Alkaline Strength
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Solution Overview
Problem
Alkaline secondary battery hydrogels face challenges with low mechanical strength under high temperature conditions due to low crosslinking and interaction between gels, and polyvinyl alcohol-based polymers experience strength degradation from salting-out effects.
Innovation Solution
A hydrogel comprising water, a polyvinylsulfonic acid-based polymer, and a polymer matrix with specific monomers and molecular weight ranges, forming a crosslinking network structure that enhances mechanical strength and resistance to alkaline environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a polymer hydrogel electrolyte with low crosslinking is used, then water content and electric conductivity are improved, but mechanical strength deteriorates under high temperature alkaline conditions
Solution Approach 1:
The patent uses a composite hydrogel system combining polyvinylsulfonic acid-based polymer with a copolymer network (acrylic acid-methacrylic acid copolymer crosslinked with divinylbenzene). This composite structure allows the hydrogel to maintain high water content (80-95 wt%) and electric conductivity while achieving sufficient mechanical strength through the synergistic interaction between the different polymer components and crosslinking network.
2Strength
If polyvinyl alcohol-based polymer is added as strength reinforcing material, then mechanical strength is improved under ambient conditions, but strength degradation occurs under high temperature alkaline conditions due to salting-out effect and main chain decomposition
Solution Approach 1:
The patent changes the polymer chemistry from polyvinyl alcohol to polyvinylsulfonic acid-based polymer, which has different chemical properties that prevent salting-out effect and main chain decomposition under alkaline conditions. The polyvinylsulfonic acid-based polymer maintains its structural integrity and mechanical strength even at high temperatures (60°C) and high alkali concentrations (7M KOH) over extended periods (1 week immersion), whereas polyvinyl alcohol-based polymers degrade.
3Strength
If crosslinking density is increased to improve mechanical strength, then strength is improved, but swelling ratio increases under alkaline conditions
Solution Approach 1:
The patent creates a heterogeneous crosslinking structure where divinylbenzene provides localized crosslinking points within the copolymer network. This localized crosslinking approach creates a balanced network structure that provides mechanical strength while maintaining appropriate swelling characteristics. The crosslinking density is optimized at 0.1 to 5 parts by mass of polymer derived from polyfunctional monomer per 100 parts by mass of copolymer, achieving both strength and controlled swelling.
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 hydrogel maintains high mechanical strength and reduced swelling in alkaline solutions at high temperatures, with improved piercing strength and swelling ratios, ensuring stability and performance in alkaline secondary batteries.
Implementation Method 1
a copolymer of a monofunctional monomer having one ethylenically unsaturated group and a polyfunctional monomer having 2 to 6 ethylenically unsaturated groups
Implementation Method 2
the copolymer has a hydrophilic group binding to its main chain, the polymer matrix is contained in an amount of 2 to 80 parts by mass in 100 parts by mass of the hydrogel
Implementation Method 3
the polyvinylsulfonic acid-based polymer has a weight average molecular weight of 200,000 to 3,000,000
Implementation Method 4
a polyvinylsulfonic acid-based polymer, and a polymer matrix containing the water and the polyvinylsulfonic acid-based polymer
Implementation Method 5
the hydrogel maintains high mechanical strength and reduced swelling in alkaline solutions at high temperatures
Implementation Method 6
since a polyvinyl alcohol-based polymer that is a strength reinforcing material takes a contracted state due to the salting-out effect under ambient temperature alkaline conditions
Data Source
AI summary
A hydrogel containing water, a polyvinylsulfonic acid-based polymer, and a polymer matrix containing the water and the polyvinylsulfonic acid-based polymer, in which the polymer matrix contains a copolymer of a monofunctional monomer having one ethylenically unsaturated group and a polyfunctional monomer having 2 to 6 ethylenically unsaturated groups, the copolymer has a hydrophilic group binding to its main chain, the polymer matrix is contained in an amount of 2 to 80 parts by mass in 100 parts by mass of the hydrogel, a polymer derived from the polyfunctional monomer is contained in a proportion of 0.1 to 5 parts by mass in 100 parts by mass of the copolymer, the polyvinylsulfonic acid-based polymer is contained in an amount of 0.1 to 150 parts by mass in 100 parts by mass of the polymer matrix, and the polyvinylsulfonic acid-based polymer has a weight average molecular weight of 200,000 to 3,000,000.