Cylindrical Li-Ion Cell Contact Layout for Low Resistance Charging
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Solution Overview
Problem
Existing lithium-ion cells face challenges in achieving high energy density, homogeneous power distribution, low internal resistance, and improved manufacturing and safety features, particularly during quick charging which can lead to heat-related issues and performance losses.
Innovation Solution
The energy storage cell design includes an electrode separator network in the form of a cylindrical wrap with a specific sequence of anode, separator, and cathode, housed in a metallic tube-shaped housing part with a contact element that serves both for electrical contact and as a housing part, reducing internal resistance and enhancing manufacturing simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cell is designed with conventional electrode contact arrangements, then the structure is simple, but the internal resistance is high and power distribution is non-uniform
Solution Approach 1:
The contact element transitions from conventional point or line contact to a two-dimensional surface contact by extending radially along the inner circumference of the housing. This dimensional expansion creates a larger contact area with the current collector, reducing contact resistance and improving current distribution uniformity across the electrode surface.
Solution Approach 2:
The contact element serves multiple functions simultaneously: it provides electrical contact with the current collector, acts as a structural component of the cell housing, and functions as a current distribution bus. This multi-functionality reduces the need for separate components, simplifying the overall structure while improving electrical performance.
2Productivity
If quick charging is implemented to improve charging speed, then productivity increases, but heat generation and safety issues worsen
Solution Approach 1:
The invention converts the potentially harmful concentrated current flow into a beneficial distributed current pattern. By spreading the electrical contact over a large radial surface area, the current density is reduced, minimizing resistive heating while maintaining high charging rates. The heat that would otherwise concentrate at contact points is distributed across the entire contact surface.
Solution Approach 2:
The contact element creates locally optimized current distribution zones across different radial positions of the electrode. Each region of the contact surface provides tailored current entry points, ensuring uniform current density across the entire electrode area. This local quality control prevents hot spots and enables safe quick charging.
3Quantity of substance
If energy density is increased to improve energy storage capacity, then the amount of active material increases, but homogeneous power distribution becomes more difficult to achieve
Solution Approach 1:
The contact strategy moves from one-dimensional or point contact to two-dimensional surface contact along the radial direction. This dimensional expansion allows the current to enter the electrode uniformly across a large area, ensuring homogeneous power distribution even in high-capacity cells with large amounts of active material.
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 achieves improved energy density, homogeneous power distribution, reduced internal resistance, and enhanced manufacturing and safety features, effectively addressing the challenges of quick charging and heat management in lithium-ion cells.
Implementation Method 1
the cell comprises an at least partially metallic contact element which is in direct contact with one of the first longitudinal edges and which is connected to this longitudinal edge
Implementation Method 2
which is connected to this longitudinal edge, preferably by welding
Data Source
Figure 1A~2
Figure 3~4
Figure 5~6B
AI summary
The invention relates to an energy storage cell (100) which has an assembly (104) of strip-shaped electrodes and separators in the form of a cylindrical winding with two end faces (104b, 104c) and a winding lateral surface (104a) therebetween. The electrodes each have current collectors (115, 125) and are offset from each other in the assembly, so that a longitudinal edge of a negative electrode emerges from one of the end faces (104b, 104c), and a longitudinal edge of a positive electrode emerges from the other end face. The assembly (104) is oriented axially in a housing, which comprises a metallic, tubular housing part (101) with a circular opening (101c) at the end, so that the winding lateral surface (104a) bears against the inside (101b) of the tubular housing part (101). In preferred embodiments, the winding lateral surface is formed by the separator or by a separate plastic strip and is thus insulated from the housing part (101). The cell (100) comprises a contact element (110) for electrically contacting one of the electrodes, said contact element being in direct contact with one of the longitudinal edges (115a, 125a) which emerges from one end face and being connected to said longitudinal edge, preferably by welding. According to the invention, a contact element (110) with a circular edge is used, and the circular opening (101c) at the end of the tubular housing part (101) is closed with the contact element (110).