Wound Electrode Assembly with Unformed Ends for Battery Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric storage devices face issues with increased resistance due to electrolyte solution supply shortages, particularly when the electrode assembly deforms or is subjected to impact, leading to inadequate absorption and distribution of the electrolyte solution.
Innovation Solution
The electric storage device incorporates a wound electrode assembly with curved and linear portions, where the positive and negative electrodes have unformed portions at their ends, allowing for increased gaps with the separator, enhancing electrolyte solution penetration and retention, even under deformation or impact. The unformed portions are connected to current collectors, creating waves that increase the surface area for solution absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrode assembly is tightly wound to reduce volume, then the device size is reduced, but the electrolyte solution supply to electrodes deteriorates when deformation occurs
Solution Approach 1:
The patent applies preliminary action by pre-forming curved portions at both ends of the electrode assembly before final assembly. These curved portions create initial gaps between electrodes and separator that serve as electrolyte reservoirs, ensuring electrolyte supply is maintained even when the assembly deforms during operation or insertion into the housing.
Solution Approach 2:
The patent applies local quality by creating non-uniform structure in the electrode assembly - specifically, curved portions at the ends with larger gaps versus the tightly wound central portion. This local variation in gap size allows the ends to function as electrolyte reservoirs while maintaining compact overall volume, resolving the contradiction between small size and reliable electrolyte supply.
2Weight of moving object
If the amount of electrolyte solution is reduced to decrease weight, then the device weight is reduced, but the resistance increases due to insufficient electrolyte supply
Solution Approach 1:
The patent utilizes the porous structure of the electrode materials and separator to absorb and retain electrolyte solution within the gaps created by the curved portions. This allows a reduced overall electrolyte volume while maintaining sufficient electrolyte availability at the electrode surfaces, thereby keeping electrical resistance low without requiring excessive electrolyte that would increase device weight.
Solution Approach 2:
By pre-forming the curved portions and gaps before final assembly, the patent ensures that electrolyte distribution is optimized in advance. This preliminary structuring allows minimal electrolyte volume to be effectively distributed throughout the assembly, reducing weight while preventing resistance increases that would occur with insufficient electrolyte supply.
3Device complexity
If the electrode assembly is inserted into the housing to compact the device, then the device compactness is improved, but the electrode assembly deforms causing electrolyte supply shortages
Solution Approach 1:
The patent applies beforehand cushioning by creating excess space in the form of curved portions and gaps between electrodes and separator before the assembly is inserted into the housing. These pre-created spaces act as cushions that accommodate deformation during insertion and operation, ensuring electrolyte supply pathways remain open even when the assembly is compacted into the housing.
Solution Approach 2:
The curved portions are formed in advance before housing insertion, creating a structure that is pre-adapted to withstand compression. This preliminary shaping ensures that when the assembly is inserted into the housing, the pre-formed gaps maintain electrolyte pathways rather than collapsing, thus maintaining reliability during compacting.
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 configuration effectively suppresses resistance increases by ensuring consistent electrolyte solution supply to the electrodes, maintaining performance even under stress or deformation, while also reducing weight and cost by minimizing the required electrolyte solution amount.
Implementation Method 1
a portion, serving to absorb the electrolyte solution, of the electrode assembly deforms
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric storage device includes: a rolled electrode assembly 10 formed by winding a positive electrode, a negative electrode, and a separator so as to have curved portions and linear portions; current collectors 7; and an electrolyte solution 3. A positive electrode substrate has at one end 10A an unformed portion 11E formed without a positive electrode mixture layer, and a negative electrode substrate has at the other end 10B an unformed portion 13E formed without a negative electrode mixture layer. The current collectors 7 are connected respectively to at least part of the linear portions in the unformed portion of the positive electrode at the one end 10A and that of the negative electrode at the other end 10B. The one end 10A in the positive electrode has a length greater than the winding length, and/or the other end 10B in the negative electrode has such a length.