Cylindrical Li-Ion Cell Collector Welding for Lower Internal Resistance
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Solution Overview
Problem
Existing lithium-ion energy storage cells face limitations in achieving higher energy density and efficient current handling due to internal resistance and housing constraints, particularly in cylindrical round cells used for high-energy applications.
Innovation Solution
The energy storage cell design features a band-shaped electrode-separator composite with free edge strips that are welded to the contact element or housing cup, eliminating the need for a separate electrical conductor, which reduces internal resistance and allows for increased active material volume, thereby enhancing energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate electrical conductor is used to connect current collectors to the housing, then electrical connection is achieved, but internal resistance increases and energy density decreases
Solution Approach 1:
The current collector is integrated directly with the housing structure, eliminating the need for separate electrical conductors. The housing itself serves as the electrical connection path, reducing internal resistance and improving energy efficiency while maintaining reliable electrical connection.
2Quantity of substance
If more active material is loaded into the cell, then energy density increases, but the cell volume and housing size increase
Solution Approach 1:
The current collector is nested within the housing structure rather than occupying separate space. This integrated design allows the electrical connection components to be embedded within the existing cell volume, freeing up additional space that can be utilized for loading more active material and increasing energy density.
3Device complexity
If the current collector design is simplified to eliminate separate conductors, then manufacturing complexity decreases, but electrical connection reliability may be compromised
Solution Approach 1:
The housing structure is designed to serve multiple functions simultaneously: it provides mechanical containment, thermal management, and electrical connection pathways. This multi-functional design simplifies the overall structure by eliminating separate components while maintaining or enhancing electrical connection reliability through the integrated housing-current collector interface.
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 design reduces internal resistance, allows for better heat dissipation, and increases the usable volume for active material, resulting in higher energy density and improved performance in high-energy applications.
Implementation Method 1
The free marginal strip extending along the first longitudinal edge of the anode current collector or the free edge strip extending along the first longitudinal edge of the cathode current collector is welded to the contact element of the cover assembly
Implementation Method 2
They are based on the use of lithium, which can migrate back and forth between the cell's electrodes in the form of ions
Implementation Method 3
the electrode-separator assembly is formed or processed into a coil... wound helically in the coil with the sequence positive electrode / separator / negative electrode
Implementation Method 4
Lithium-ion cells typically use electrolytes consisting of solutions of lithium salts such as lithium hexafluorophosphate (LiPF6) in organic solvents (e.g., ethers and esters of carbonic acid)
Data Source
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AI summary
An energy storage cell (100) is proposed in which a free edge strip (109a) of a cathode current collector (109) is welded to a contact element (112) of a cover assembly (102). Furthermore, a method for manufacturing such energy storage cells is proposed.