Battery Separator Coating for Passive Impact Resistance
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Solution Overview
Problem
Advanced high energy battery technologies face challenges in the stability and safety of electrolyte systems due to volatility and flammability issues, particularly with shear thickening electrolytes that do not flow properly during fabrication, leading to uneven distribution and increased viscosity, which can result in catastrophic combustion.
Innovation Solution
A method is developed to create a passively impact-resistant composite electrolyte and separator layer using shear thickening enabling particles with specific properties, such as ceramic materials and solvents, applied through a roll-to-roll process to ensure uniform distribution and increased viscosity upon impact, while maintaining porosity for ion transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear thickening electrolyte is injected into the cell using normal electrolyte injection process, then the electrolyte will not flow properly due to increased viscosity, but this prevents proper pore filling and homogeneous distribution
Solution Approach 1:
The patent applies preliminary action by pre-coating the separator with shear thickening particles before electrolyte assembly. This allows the particles to be positioned in advance within the separator structure, avoiding the need to inject already-thickened electrolyte. The separator is prepared with particle layers that will later form the shear thickening electrolyte system, enabling proper distribution before the thickening effect occurs.
Solution Approach 2:
The patent inverts the conventional approach by building the shear thickening electrolyte system from the separator outward, rather than injecting electrolyte into an assembled cell. Instead of injecting liquid electrolyte containing particles, the method coats the separator with particle suspensions that form solid or semi-solid layers, which then interact with subsequently added electrolyte to create the shear thickening effect in place.
2Reliability
If shear thickening particles are added to electrolyte to improve impact resistance, then stability and safety are enhanced, but the electrolyte viscosity increases and prevents proper flow during fabrication
Solution Approach 1:
The patent segments the shear thickening electrolyte system into two separate components: shear thickening particles coated on the separator, and liquid electrolyte added separately. This segmentation allows each component to be prepared and handled in its optimal state - particles as a coating and electrolyte as a liquid - avoiding the need to handle high-viscosity mixed electrolyte during fabrication. The components interact to create shear thickening behavior only when needed.
Solution Approach 2:
The separator acts as an intermediary structure that hosts the shear thickening particles while allowing liquid electrolyte to permeate through it. The separator mediates between the solid particles and liquid electrolyte, enabling the particles to provide shear thickening protection while the liquid electrolyte maintains proper flowability for fabrication and ion transport. The separator structure facilitates the interaction between particles and electrolyte without requiring them to be mixed in advance.
3Reliability
If particles are distributed in the electrolyte to create shear thickening effect, then impact resistance is improved, but uneven distribution occurs leading to safety issues
Solution Approach 1:
The patent applies preliminary action by pre-coating the separator with shear thickening particles before electrolyte assembly. This allows the particles to be positioned in advance within the separator structure, avoiding the need to inject already-thickened electrolyte. The separator is prepared with particle layers that will later form the shear thickening electrolyte system, enabling proper distribution before the thickening effect occurs.
Solution Approach 2:
The patent utilizes the porous structure of the separator to achieve uniform particle distribution. The separator's pore network provides a framework that distributes particles evenly as the particle suspension is applied. The pores guide the suspension flow and ensure particles are deposited uniformly throughout the separator structure, preventing aggregation and ensuring homogeneous distribution of shear thickening particles.
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 enhances the stability and safety of battery electrolytes by preventing mechanical damage and ensuring homogeneous distribution of particles, reducing the risk of combustion and improving thermal safety without compromising cell performance.
Implementation Method 1
a portion of the shear thickening particles and suspension solvent penetrate the pores
Implementation Method 2
The suspension solvent is evaporated from the separator material
Implementation Method 3
A passively impact resistant composite electrolyte composition undergoes a passive shear thickening phenomenon upon application of an external force
Implementation Method 4
providing a porous separator material having pores and a surface
Data Source
AI summary
A method of making a passively impact resistant battery includes the steps of providing a porous separator material having pores and a surface, and providing a suspension composition including shear thickening enabling particles and a particle suspension solvent for suspending the shear thickening enabling particles. The shear thickening particles have a polydispersity index of no greater than 0.1, an average particle size of in a range of 50 nm to 1 um, and an absolute zeta potential of greater than ±40 mV. The suspension composition is applied to the separator material, wherein a portion of the particles and suspension solvent penetrate the pores. The suspension solvent is evaporated from the separator material. An anode layer and a cathode layer are applied. An electrolyte composition is applied between the anode layer and the cathode layer. The electrolyte composition includes an electrolyte solvent and an electrolyte salt.