Cellulose Separator Composition for Thermal Runaway Resistance
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Solution Overview
Problem
Current lithium-ion battery separators face challenges in thermal stability, leading to thermal runaway risks due to melting and short circuits, and existing flame-retardant additives compromise electrolyte performance.
Innovation Solution
Incorporation of cellulose fibers with flame retardants, such as inorganic compounds and organophosphorus groups, into the separator structure, either through electrostatic interactions or covalent bonds, to enhance thermal stability without compromising electrolyte performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame-retardant additives are added to electrolytes, then the risk of battery fire is reduced, but electrolyte performance deteriorates due to high viscosity
Solution Approach 1:
The patent extracts the flame-retardant function from the electrolyte by incorporating flame-retardant additives into the separator material instead. This allows the electrolyte to maintain its original performance characteristics while the separator provides the fire protection function, thereby resolving the contradiction between safety and performance.
Solution Approach 2:
The patent applies flame-retardant properties locally to the separator rather than uniformly to the entire battery system. By concentrating the flame-retardant additives in the separator, the solution provides targeted fire protection at the critical interface between electrodes and electrolyte without affecting the bulk electrolyte performance.
2Temperature
If polyimide is used to replace polyethylene or polypropylene separators, then thermal stability is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent creates a composite separator by combining cellulose base material with flame-retardant additives. This composite approach achieves the thermal stability of high-performance materials like polyimide while maintaining the manufacturing simplicity and cost-effectiveness of cellulose-based production methods.
Solution Approach 2:
The patent modifies the thermal properties of the separator by changing the chemical composition parameters - specifically by incorporating flame-retardant additives such as phosphorus-containing compounds or metal hydroxides into the cellulose matrix. This allows achieving high thermal stability through compositional modification rather than switching to difficult-to-manufacture polymers.
3Temperature
If flame retardant is incorporated into polymer separator, then thermal stability is improved, but short circuit risk increases when separator melts
Solution Approach 1:
The patent utilizes the melting of the cellulose separator as a beneficial safety mechanism. When the separator melts at elevated temperatures, it physically blocks the electrodes from contacting each other, creating an automatic shutdown effect that prevents short circuits. The flame-retardant additives enhance this effect by maintaining structural integrity longer and suppressing combustion.
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 proposed solution provides improved thermal stability and reduced risk of thermal runaway while maintaining electrolyte performance, offering a safer and more reliable lithium-ion battery design.
Implementation Method 1
Incorporation of cellulose fibers with flame retardants, such as inorganic compounds and organophosphorus groups, into the separator structure, either through electrostatic interactions or covalent bonds
Implementation Method 2
Incorporation of cellulose fibers with flame retardants, such as inorganic compounds and organophosphorus groups, into the separator structure, either through electrostatic interactions or covalent bonds
Implementation Method 3
The mechanism of action of these flame-retardant additives lies primarily in the chemical scavenging of H• or OH• free radicals released during battery combustion
Data Source
Figure 1
Figure 2a~2d
Figure 3a~3b
AI summary
The present technology relates to a flame retardant, a cellulose fibre separator including the flame retardant, a component including the separator and an electrolyte, and electrochemical cells and accumulators including them and their uses.