Thixotropic Battery Electrolyte for Dendrite-Safe Cell Interfaces
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Solution Overview
Problem
Current liquid and all-solid electrolytes in secondary batteries face issues such as dendrite formation leading to short circuits and poor interfacial contact, respectively, failing to meet the safety and performance requirements of new electrochemical systems.
Innovation Solution
A non-Newtonian fluid electrolyte composition exhibiting thixotropic behavior, transitioning from a flowable to a solid state under external force, which includes organic solvents, electrolyte salts, ionic liquids, and suspended particles, enhancing safety and impact resistance while reducing ohmic and interface resistances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used, then good interfacial contact with electrode plate is achieved, but dendrites are generated on negative electrode during cycling causing short circuit and safety hazards
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to semi-solid by incorporating gel-forming polymers (such as polyacrylonitrile, carboxymethyl cellulose, or starch) and suspended particles into the liquid electrolyte system. This parameter change transforms the electrolyte's flow characteristics while maintaining its ionic conductivity, thereby preventing dendrite formation without sacrificing interfacial contact quality.
Solution Approach 2:
The patent creates a composite electrolyte system combining liquid electrolyte components (lithium salt, solvent) with gel-forming polymers and suspended particles. This composite structure provides both the fluidity needed for good electrode contact and the mechanical strength to suppress dendrite growth, resolving the contradiction between safety and interfacial contact.
2Reliability
If all-solid electrolyte is used, then dendrite formation is suppressed, but excellent interfacial contact with electrode plate cannot be formed
Solution Approach 1:
The patent adjusts the solid content parameter of the electrolyte to create a semi-solid state rather than complete solidification. By controlling the concentration of gel-forming polymers and suspended particles, the electrolyte maintains sufficient fluidity for good electrode contact while having enough structural integrity to suppress dendrites, thus resolving the contradiction between interfacial contact and safety.
3Object-generated harmful factors
If high viscosity electrolyte is used, then gas production is suppressed, but ohmic resistance and interface resistance increase
Solution Approach 1:
The patent optimizes the viscosity parameter by carefully selecting the type and concentration of gel-forming polymers and suspended particles. The semi-solid state achieves just enough viscosity to suppress gas production during cycling while maintaining sufficient ionic conductivity through proper selection of lithium salts and solvents, thus balancing gas suppression with energy efficiency.
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 non-Newtonian fluid electrolyte composition improves safety against short-circuiting and impact resistance, simplifies battery assembly, and enhances cycle performance by suppressing gas production and reducing stacking pressure.
Implementation Method 1
The non-Newtonian fluid electrolyte composition exhibits a thixotropic behavior in response to an applied external force, thereby transitioning from a flowable state to a solid state
Implementation Method 2
The non-Newtonian fluid electrolyte composition in this application is a shear thickening liquid with a viscosity increasing with the increase of the shear rate or shear time
Data Source
AI summary
This application provides an electrolyte composition, a secondary battery, a battery module, a battery pack, and an electrical device. The electrolyte composition is a non-Newtonian fluid electrolyte composition. The electrolyte composition can improve the impact resistance and safety of the battery by a thixotropic action that occurs in response to an applied external force.