Flexible Secondary Battery Electrode Stack for Uniform Bending
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Solution Overview
Problem
Flexible secondary batteries with multiple positive and negative electrode current collectors tend to degrade in capacity and cycle characteristics when curved due to variations in distance between collectors, leading to local highly and slightly curved portions and uneven battery reaction rates.
Innovation Solution
A flexible secondary battery structure is introduced, where a polymer electrolyte and separator are placed between positive and negative electrode current collectors, and surfaces without active material layers are in contact to reduce friction and maintain constant distance, preventing the formation of highly and slightly curved portions and variations in reaction rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple positive and negative electrode current collectors are stacked to increase capacity, then the battery capacity increases, but the distance variation between collectors causes uneven reaction rates and degrades cycle characteristics when curved
Solution Approach 1:
A flexible packaging structure is employed to encapsulate the stacked electrode assemblies. This flexible packaging allows the battery to be curved while maintaining structural integrity and preventing excessive distance variation between collectors, thus preserving cycle characteristics during bending while accommodating increased capacity through multiple stacked collectors
Solution Approach 2:
The packaging structure is designed to distribute mechanical stress uniformly across all electrode collectors when curved. By ensuring equipotential stress distribution, the distance variation between collectors is minimized, preventing uneven reaction rates and maintaining reliable cycle characteristics even with multiple stacked collectors increasing overall capacity
2Adaptability or versatility
If the secondary battery is curved to achieve flexibility for wearable devices, then adaptability to body contours improves, but highly curved and slightly curved portions form causing variation in distance between collectors
Solution Approach 1:
The flexible packaging structure is specifically engineered to accommodate curvature while maintaining internal geometry. The packaging allows the battery to conform to body contours for wearable applications while preventing the formation of highly curved and slightly curved portions that would cause distance variation between collectors
Solution Approach 2:
The packaging structure incorporates stress-distributing features that preemptively compensate for curvature-induced deformation. By designing the packaging to beforehand cushion against bending stresses, the structure prevents excessive local curvature and maintains uniform distance between collectors even when the battery is curved for wearable device integration
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 structure enhances the stability and performance of flexible secondary batteries by reducing stress and maintaining consistent reaction rates, thereby improving capacity and cycle characteristics when curved.
Implementation Method 1
Since a polymer can be gelled, a distance between a positive electrode current collector and a negative electrode current collector can be kept constant more easily
Data Source
AI summary
A gel electrolyte and a separator are provided between the positive electrode current collector and the negative electrode current collector. The plurality of positive electrode current collectors and the plurality of negative electrode current collectors are stacked such that surfaces of negative electrodes with which active material layers are not coated or surfaces of positive electrodes with which active material layers are not coated are in contact with each other.