Battery Separator Pore Volume for Stable Electrolyte Infiltration
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Solution Overview
Problem
Existing secondary batteries face issues with insufficient electrolyte infiltration due to separator ion channels being blocked by adhesive coating layers, leading to problems like dark spots and lithium precipitation, and do not adequately consider the cooperation between the separator and electrodes, affecting cycling performance.
Innovation Solution
The secondary battery design ensures a specific ratio of pore volume of the separator to the capacity per unit area of the negative electrode film layer, within the range of 0.05 cm3/Ah to 0.3 cm3/Ah, to maintain both separator infiltration capability and negative electrode capacity, using a negative electrode plate with a negative electrode current collector and a negative electrode film layer, and a separator with a base film and coating layer comprising polymer particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive coating layers are applied to separator ion channels, then electrode adhesion is improved, but electrolyte infiltration is blocked causing dark spots and lithium precipitation
Solution Approach 1:
The patent employs a porous coating layer structure on the separator that maintains open ion channels while providing electrode adhesion. The coating layer contains controlled pores that allow electrolyte infiltration to proceed unblocked, preventing dark spots and lithium precipitation while still achieving the necessary adhesive strength between separator and electrode.
Solution Approach 2:
The patent applies different properties to different regions of the separator coating. The coating layer has localized adhesive properties in contact with the electrode while maintaining porous pathways for electrolyte flow. This spatial differentiation of properties allows simultaneous achievement of good adhesion and unblocked infiltration.
2Reliability
If separator pore volume is increased to improve electrolyte infiltration, then infiltration capability is enhanced, but negative electrode capacity is reduced
Solution Approach 1:
The patent optimizes the pore volume parameter of the separator to a specific range that balances electrolyte infiltration capability with negative electrode capacity. By precisely controlling this parameter, the patent achieves sufficient infiltration without excessive pore volume that would reduce the active material content and capacity of the negative electrode.
Solution Approach 2:
The patent uses a composite separator structure combining base film material with coating layer material that has controlled porosity. This composite approach allows the separator to provide both adequate infiltration pathways and maintain high electrode capacity by optimizing the distribution and volume of pores within the composite structure.
3Manufacturing precision
If separator and electrode design are optimized independently, then individual component performance is improved, but overall cycling performance is limited due to lack of cooperation
Solution Approach 1:
The patent merges the optimization of separator and negative electrode into a coordinated design system. The separator's pore structure, coating layer properties, and the negative electrode's capacity and morphology are designed together as an integrated system, ensuring that both components work cooperatively to achieve superior cycling performance rather than merely summing individual performances.
Solution Approach 2:
The separator acts as an intermediary element that mediates between the electrolyte and the negative electrode. The patent optimizes this intermediary function by designing the separator's coating layer and pore structure to facilitate efficient ion transport while maintaining proper contact with the negative electrode, thereby enabling the two components to cooperate effectively for improved cycling 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
This design enhances the cycling performance of the battery by ensuring effective electrolyte infiltration and maintaining the capacity of the negative electrode, thereby improving overall battery performance.
Implementation Method 1
the pore volume per unit area of the separator being denoted as V
Data Source
AI summary
A secondary battery and a power consuming device comprising same are described. The secondary battery comprises a negative electrode plate and a separator, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector; and with the capacity per unit area of the negative electrode film layer being denoted as C, and the pore volume per unit area of the separator being denoted as V, the secondary battery satisfies: 0.05 cm3/Ah≤V/C≤0.3 cm3/Ah, where C is in mAh, and V is in cm3. The secondary battery has a good cycling performance.