Polymer-Coated Battery Separator for Faster Electrolyte Uptake
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Solution Overview
Problem
Current battery cells exhibit poor cycle performance and storage performance due to slow electrolyte absorption and reabsorption rates, leading to liquid deficiency and increased battery polarization during charge and discharge cycles.
Innovation Solution
A separator with a polymer layer containing a liquid-absorbing polymer, characterized by v/λ>5.00, where λ represents porosity and v represents liquid absorption rate, accelerates electrolyte absorption and transmission between the separator and electrode sheets, forming a uniform high infiltration point and a three-dimensional connected interface to improve cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the structure is simple, but the liquid absorption rate is slow and cycle performance is poor
Solution Approach 1:
The separator is constructed as a composite material system consisting of a base separator and a polymer coating layer. The polymer coating layer contains liquid-absorbing polymer particles dispersed in a binder polymer matrix, creating a multi-phase composite structure that combines the mechanical strength of the base separator with the electrolyte absorption capabilities of the liquid-absorbing polymer particles.
Solution Approach 2:
The liquid-absorbing polymer particles possess a porous internal structure with pore volumes ranging from 0.2 mL/g to 0.8 mL/g. This porous architecture provides extensive internal surface area and void spaces that rapidly absorb and retain electrolyte through capillary action, significantly enhancing the separator's liquid absorption rate and electrolyte retention capacity.
2Speed
If the porosity of the separator is increased to improve electrolyte transmission, then the liquid absorption rate increases, but the mechanical strength decreases
Solution Approach 1:
The separator exhibits spatially differentiated properties: the base separator provides mechanical strength and structural integrity, while the polymer coating layer on the surface provides enhanced electrolyte absorption and transmission. Within the coating layer, the liquid-absorbing polymer particles create localized high-absorption zones that do not compromise the overall structural strength provided by the base separator and binder polymer matrix.
3Productivity
If the liquid absorption rate is increased to reduce liquid deficiency, then the electrolyte reabsorption rate during discharge improves, but the separator complexity increases
Solution Approach 1:
The liquid-absorbing polymer particles within the coating layer automatically absorb electrolyte during charging and release it during discharging through their inherent porous structure and capillary forces. This self-regulating mechanism occurs without external control systems, continuously maintaining electrolyte saturation in the separator and reducing liquid deficiency during battery operation cycles.
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 introduction of the liquid-absorbing polymer enhances electrolyte absorption and reabsorption rates, reduces liquid deficiency, and decreases battery polarization, thereby improving the cycle performance and storage capacity of the battery cell.
Implementation Method 1
The polymer layer includes a liquid-absorbing polymer, v/λ>5.00, where λ represents a porosity of the separator, v represents a liquid absorption rate of the separator
Implementation Method 2
the affinity between the liquid-absorbing polymer and the electrolyte is relatively good, so the infiltration performance of the separator and the electrolyte can be improved
Implementation Method 3
polymer molecular chains are stretched open, and the electrolyte can diffuse between the molecular chains
Implementation Method 4
the contact angle between the polymer layer and the electrolyte is in a range from 5° to 25°, the affinity between the liquid-absorbing polymer and the electrolyte is relatively good, so the infiltration performance of the separator and the electrolyte can be improved
Data Source
AI summary
The present application provides a separator, a battery cell, a battery, and an electrical apparatus. The separator comprises a separator body and a polymer layer provided on at least one surface of the separator body. The separator satisfies: v/λ>5.00, wherein λ represents the porosity of the separator, v represents the liquid absorption rate of the separator, and the unit of the liquid absorption rate is mg/s.