Gel Electrolyte Battery Low-Temperature Ion Conduction
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Solution Overview
Problem
Existing gel electrolyte batteries face challenges with ion conduction properties at low temperatures and cycle characteristics due to uneven gel formation and poor adhesion between electrodes, leading to battery deformation and capacity deterioration.
Innovation Solution
A gel electrolyte battery using a polyvinylidene fluoride copolymerized with hexafluoropropylene and a solvent mixture of ethylene carbonate and low-viscosity linear carbonates, such as dimethyl carbonate, to enhance compatibility and maintain a balance of solvents for improved low-temperature performance and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gel electrolyte is formed by charging an electrolytic solution containing monomers into the battery, then the battery can be produced using conventional methods, but the gel amount at the interface between electrode and separator cannot be appropriately controlled, leading to poor adhesion and lithium deposition
Solution Approach 1:
The gel electrolyte is formed before assembling the battery components. The gel layer is pre-formed on the separator surface, ensuring proper gel amount and uniform distribution before the electrodes are installed. This preliminary formation eliminates the problem of inadequate gel amount at interfaces that occurs when electrolyte is charged after assembly.
Solution Approach 2:
The gel electrolyte formulation is specifically optimized for interfacial adhesion properties. The gel layer is designed with enhanced adhesive characteristics to ensure strong bonding between the electrode and separator, preventing lithium deposition and improving cycle characteristics while maintaining compatibility with conventional production methods.
2Quantity of substance
If the electrolyte is formed at an interface having a large distance between electrode and separator, then the gel amount is sufficient, but the ion conduction properties are lowered due to increased thickness
Solution Approach 1:
The gel electrolyte's physical and chemical parameters are optimized to achieve the right balance. The gel layer thickness, crosslinking density, and composition are carefully controlled to provide sufficient gel amount for adhesion while maintaining thin enough dimensions for good ion conduction. This parameter optimization resolves the contradiction between having enough gel for bonding and keeping the layer thin for ion transport.
3Use of energy by moving object
If a nonaqueous electrolyte is used to achieve lightweight and compact battery design, then the energy density is improved, but the ion conduction properties are poor compared to aqueous electrolytes
Solution Approach 1:
The nonaqueous electrolyte composition is optimized by adjusting the ratios of different carbonate solvents and adding specific additives. This parameter optimization enhances the ion conduction properties of the nonaqueous electrolyte while maintaining its high energy density advantages. The gel formulation compensates for the inherently lower ion conduction of nonaqueous systems compared to aqueous electrolytes.
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 solution results in a battery with enhanced low-temperature characteristics, improved capacity, and stable charge-discharge performance, preventing battery deformation and capacity loss.
Implementation Method 1
a gel electrolyte having a matrix polymer; and a nonaqueous solvent and an electrolytic solution having an electrolyte salt composed of lithium dissolved in the nonaqueous solvent, the matrix polymer being swollen with the electrolytic solution
Implementation Method 2
an electrolytic solution having an electrolyte salt composed of lithium dissolved in the nonaqueous solvent
Data Source
AI summary
A gel electrolyte and a gel electrolyte battery are provided. The gel electrolyte includes a matrix polymer; a nonaqueous solvent; and an electrolytic solution having an electrolyte salt containing lithium dissolved in the nonaqueous solvent, in which the matrix polymer is swollen with the electrolytic solution. The matrix polymer comprises polyvinylidene fluoride copolymerized with at least hexafluoropropylene in an amount of 3 wt % or more and 7.5 wt % or less. The nonaqueous solvent comprises ethylene carbonate; and at least one solvent selected from the group consisting of dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, ethylpropyl carbonate, ethyl butyl carbonate, and dipropyl carbonate. The content of the ethylene carbonate in the nonaqueous solvent is 15 wt % or more and 55 wt % or less, and the total content of the at least one solvent in the nonaqueous solvent is 30 wt % or more and 85 wt % or less.