Winding Core Geometry for Uniform Pressure in Cylindrical Cells
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Solution Overview
Problem
Existing electrochemical energy storage cells with helically wound composite bodies experience irregularities and non-uniform pressure distributions due to changes in electrode strip thickness and ends, leading to mechanical stress, ion exchange hindrance, and lithium plating, which can cause short circuits.
Innovation Solution
A cylindrical electrochemical energy storage cell design featuring a winding core with localized deviations from a cylindrical shape to compensate for irregularities in the helical structure, ensuring uniform pressure distribution and preventing lithium plating by spatially assigning these deviations to regions of defects in the helical structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a helically wound composite body is used in the energy storage cell, then the structural integrity and mechanical strength are improved, but local irregularities and non-uniform pressure distributions occur due to changes in electrode strip thickness and ends
Solution Approach 1:
The patent introduces local deviations in the winding core geometry (such as varying radial distance, axial position, or winding angle) to compensate for local irregularities in the helical structure. This allows different regions of the winding core to have different functional properties, ensuring uniform pressure distribution despite variations in electrode strip thickness and ends.
2Quantity of substance
If the electrode strips are wound helically around the winding core, then the energy storage capacity is increased, but mechanical stress and ion exchange hindrance occur due to non-uniform pressure distribution
Solution Approach 1:
The patent modifies geometric parameters of the winding core (radial distance, axial position, winding angle) to optimize the pressure distribution throughout the helical structure. By carefully controlling these parameters, the system maintains high energy storage capacity while ensuring uniform pressure that facilitates efficient ion exchange and reduces mechanical stress.
3Ease of manufacture
If the winding core maintains a constant radial distance from the winding axis, then the manufacturing simplicity is improved, but local irregularities cause lithium plating and short circuits
Solution Approach 1:
The patent deliberately introduces asymmetric deviations in the winding core geometry, where the radial distance from the winding axis varies locally. This asymmetric design compensates for irregularities in the helical structure, preventing lithium plating and short circuits while remaining manufacturable through standard winding processes.
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 design enhances the reliability and service life of the energy storage cell by reducing mechanical stress and preventing ion exchange hindrance, thereby minimizing the risk of lithium plating and short circuits.
Implementation Method 1
an electrochemical reaction takes place and is composed of two partial reactions that are electrically coupled to one another, but are spatially separate from one another
Implementation Method 2
electrons are released at the negative electrode by virtue of an oxidation process
Implementation Method 3
a reduction process therefore takes place at the positive electrode
Implementation Method 4
at least one positive electrode and at least one negative electrode that are separated from one another by a separator
Implementation Method 5
an ion current corresponding to the electrode reaction results inside the electrochemical cells. This ion current crosses the separator and is ensured by an ion-conducting electrolyte
Implementation Method 6
a wound composite body shaped in a hollow cylindrical manner is arranged in the interior space and has a helical structure including at least two electrode strips helically wound around a winding axis
Implementation Method 7
winding core with localized deviations from a cylindrical shape to compensate for irregularities in the helical structure, ensuring uniform pressure distribution
Data Source
AI summary
An energy storage cell includes a cylindrical housing that encloses an interior space and a housing casing, a wound composite body arranged in the interior space and having a helical structure including at least two electrode strips and at least one separator strip arranged between the electrode strips, each including a strip-shaped current collector having an active material coating, the wound composite body includes two terminal end faces, a circumferential outer composite body lateral surface and a circumferential inner composite body lateral surface, the inner composite body lateral surface defines an axially oriented cavity, a winding core having a substantially cylindrical or hollow cylindrical shape and has an outer circumferential surface that rests flat on the inner composite body lateral surface, and the winding core has a local deviation from the cylindrical or hollow cylindrical shape in at least one region of the outer circumferential surface.