Separator Gasification Coating for Lithium Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to short circuits, pressure increases, and capacity deterioration during overcharging, which can lead to explosion and reduced battery life, especially when gas-generating materials are added to the positive electrode active material.
Innovation Solution
A lithium secondary battery with an electrode assembly that includes a gasification material coated on the separator, which generates gas at a certain voltage to improve safety and prevent overcharging, while maintaining battery capacity and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas-generating materials are added to the positive electrode active material to improve safety during overcharging, then battery safety is improved, but battery capacity deteriorates and resistance increases
Solution Approach 1:
The gas-generating material is separated from the positive electrode active material and relocated to the separator. This segmentation allows the safety function to be independent from the capacity-providing electrode materials, eliminating the trade-off between safety and capacity.
Solution Approach 2:
The separator acts as an intermediary component that hosts the gas-generating material. Instead of adding safety materials directly to the electrodes, the separator mediates the safety function by generating gas at overcharge states, preventing direct contact between electrodes while maintaining battery capacity.
2Reliability
If electrolyte additives such as cyclohexylbenzene and biphenyl are increased to generate more gas during overcharging, then battery safety is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The gas-generating function is extracted from the electrolyte additives and transferred to a coating material applied directly to the separator. This eliminates the need for complex electrolyte compositions containing multiple additives like cyclohexylbenzene and biphenyl, simplifying the overall battery composition.
Solution Approach 2:
The invention changes the location and form of the gas-generating material from dissolved electrolyte additives to a solid coating on the separator. This parameter change allows for controlled gas generation at specific voltages without relying on complex electrolyte chemistry.
3Reliability
If gasification material is coated on the separator surface, then battery safety is improved and capacity deterioration is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The coating material is applied to the separator surface with the understanding that not all coating material needs to be perfectly uniform or complete. The gas-generating function is robust enough that partial coverage or slight variations in coating thickness do not significantly impact safety performance, allowing for more forgiving manufacturing tolerances.
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 battery safety by preventing explosions and maintaining capacity and reducing resistance, ensuring a longer battery life by generating gas at overcharge states and operating a current interrupt device when internal pressure increases.
Implementation Method 1
including a gasification material coated on the surface of the separator and electrolyzed at a certain voltage to generate a gas
Data Source
AI summary
The present invention relates to an electrode assembly including a separator and a lithium secondary battery including the same for improving safety. The electrode assembly including a positive electrode, a negative electrode and a separator further includes a gasification material possibly being electrolyzed at a certain voltage to generate a gas. Since the electrode assembly and the lithium secondary battery including the same include the gasification material possibly being electrolyzed at the certain voltage to generate the gas, the safety of the battery may be increased. Since the gasification material is coated on the surface of the separator not on the electrode, the resistance increase of the battery may be restrained and the capacity lowering of the battery may be remarkably decreased. The lifetime of the battery is good.