Gel Polymer Electrolyte Battery Cell for Swelling-Induced Wettability Loss
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Solution Overview
Problem
Lithium-ion batteries face challenges in cycling performance due to electrolyte being squeezed out during negative electrode swelling, leading to poor wettability and lithium precipitation, which affects cycle life and capacity.
Innovation Solution
A battery cell design using a gel polymer electrolyte with high elasticity, formed by in-situ curing between positive and negative electrode plates, mitigates pressure from swelling and maintains electrolyte wettability, reducing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used in conventional lithium-ion batteries, then ionic conductivity is achieved, but electrolyte is squeezed out during negative electrode swelling leading to poor wettability and lithium precipitation
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to gel polymer form. This parameter change allows the electrolyte to maintain its ionic conductivity while gaining the ability to resist being squeezed out during electrode swelling, thereby preventing electrolyte loss and maintaining wettability throughout cycling.
Solution Approach 2:
The patent uses a gel polymer electrolyte that combines the properties of polymers (elasticity, structural integrity) with ionic conductivity. This composite material approach allows the electrolyte to both conduct ions effectively and mechanically withstand the swelling pressure of the negative electrode during cycling.
2Quantity of substance
If negative electrode plate swells during charging, then lithium insertion capacity is improved, but pressure is generated that squeezes out electrolyte and causes lithium precipitation
Solution Approach 1:
The gel polymer electrolyte serves as a cushioning medium that anticipates and absorbs the swelling pressure of the negative electrode during lithium insertion. Its elastic nature allows it to deform with the electrode while maintaining continuous contact, preventing electrolyte expulsion and subsequent lithium dendrite formation.
Solution Approach 2:
The gel polymer electrolyte acts as an intermediary between the swelling negative electrode and the rigid battery structure. It mediates the mechanical stress by deforming elastically while maintaining ionic conductivity, thereby preventing both electrolyte loss and lithium precipitation.
3Reliability
If gel polymer electrolyte with high elasticity is used, then pressure from electrode swelling is alleviated and wettability is maintained, but manufacturing complexity increases due to in-situ curing process
Solution Approach 1:
The gel polymer electrolyte system is designed to self-cure within the battery structure through in-situ polymerization. The curing process occurs automatically under controlled conditions (temperature, catalyst presence) without requiring external intervention, thereby maintaining manufacturing simplicity while achieving the desired elastic properties.
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 gel polymer electrolyte effectively alleviates pressure from negative electrode swelling, maintaining high electrolyte wettability throughout the charge-discharge cycle, improving cycling performance and reducing lithium dendrite growth.
Implementation Method 1
forming the gel polymer electrolyte with high elasticity by in-situ curing between the positive electrode plate and the negative electrode plate
Implementation Method 2
the wettability of the electrolyte to the negative electrode plate remains high throughout an entire charge-discharge cycle
Implementation Method 3
the electrolyte gasifies and detaches from the negative electrode plate within the temperature range of 25° C. to 180° C.
Data Source
AI summary
A battery cell includes: a negative electrode plate having a first and second end, a length of a in a first direction, and a gel polymer electrolyte. When a capacity of the battery cell is less than or equal to 90% of a nominal capacity of the battery cell, a first region exists on the negative electrode plate, a distance between a point in the first region farthest from the first end and the first end is110a,a second region exists on the negative electrode plate, and a distance between a point in the second region farthest from the second end and the second end is110a;and in a temperature range of 25° C. to 180° C., a heat loss amount in the first region is m, and a heat loss amount located in the second region is n, where m/n is greater than or equal to 50%.