Gel Electrolyte Viscosity Tuning for Safer Secondary Batteries
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Solution Overview
Problem
Current secondary batteries face issues with liquid electrolytes that react with metallic negative electrodes, leading to performance decline and safety hazards such as dendrite formation and battery explosions, while all-solid electrolytes struggle with poor ionic conductivity and interface kinetics.
Innovation Solution
A gel electrolyte composition with a viscosity of 500 mPa·s to 100000 mPa·s is developed, combining the fluidity of liquid electrolytes with the safety of solid electrolytes, incorporating specific solvent, electrolyte salt, and polymer ratios to enhance ionic conductivity and interface wettability, and including a supersaturated gel electrolyte with crystallized electrolyte salt for improved mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used, then ionic conductivity is improved, but safety performance deteriorates due to parasitic reactions with metallic negative electrode and dendrite formation
Solution Approach 1:
The patent uses a composite gel electrolyte system combining polymer matrix (for safety and structural integrity) with liquid electrolyte components (for ionic conductivity). This composite approach allows the electrolyte to simultaneously achieve the safety benefits of solid electrolytes and the high ionic conductivity of liquid electrolytes, resolving the contradiction between safety and conductivity.
Solution Approach 2:
The patent modifies the physical state of the electrolyte by transforming it from a purely liquid phase to a gel phase through polymer incorporation. This parameter change in the electrolyte's physical state allows it to maintain fluidity and ionic mobility while gaining the safety characteristics of solid materials, thereby reducing parasitic reactions and dendrite formation.
2Object-generated harmful factors
If all-solid electrolyte is used, then safety performance is improved, but ionic conductivity and interface kinetics deteriorate
Solution Approach 1:
The gel electrolyte creates a composite structure that incorporates liquid electrolyte components within a polymer network. This composite design enables the electrolyte to provide the high ionic conductivity characteristic of liquid electrolytes while maintaining the safety and low gas production characteristics of solid electrolytes.
Solution Approach 2:
The polymer gel acts as an intermediary between purely liquid and purely solid electrolyte states. It provides a semi-solid matrix that facilitates ion transport like liquid electrolytes while offering the mechanical stability and safety of solid electrolytes, thus mediating between the two extremes to achieve both high conductivity and safety.
3Reliability
If viscosity of gel electrolyte is increased, then safety performance is improved, but interface wettability and kinetics deteriorate
Solution Approach 1:
The patent optimizes the viscosity parameter of the gel electrolyte to fall within a specific range (500-100,000 mPa·s) that balances safety and wettability. By carefully controlling this physical parameter, the electrolyte achieves sufficient viscosity for safety while maintaining adequate fluidity for interface contact and ion transport kinetics.
Solution Approach 2:
The gel electrolyte exhibits dynamic properties that allow it to adapt its viscosity and flow characteristics based on operational conditions. This dynamic behavior enables the electrolyte to maintain good interface wettability during battery operation while providing the viscosity necessary for safety and structural stability.
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 gel electrolyte composition improves ionic conductivity, reduces gas production, enhances Coulombic efficiency, and broadens the temperature range of battery applicability, while ensuring safety and reliability, particularly at high temperatures.
Implementation Method 1
providing an ion transport channel and improving the ionic conductivity
Implementation Method 2
increasing the interface wettability of the battery and the interface kinetics of the gel electrolyte composition
Data Source
AI summary
A gel electrolyte composition, a secondary battery, a battery module, a battery pack, and an electrical device are disclosed. A viscosity of the gel electrolyte composition at 25° C. is 500 mPa·s to 100000 mPa·s. The gel electrolyte composition falls within an appropriate viscosity range, thereby increasing the interface wettability of the battery and the ionic conductivity of the gel electrolyte composition at a room temperature and a high temperature, and on the other hand, alleviating interface side reactions of the gel electrolyte composition and improving the Coulombic efficiency of the battery.