Cylindrical Battery Current Collector Plates for Kinetic Balance
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Solution Overview
Problem
Existing cylindrical secondary batteries face challenges in controlling the movement speed of lithium ions and achieving a kinetic balance between the positive and negative electrodes, particularly during rapid charging, which can lead to heat generation and potential ignition, and the design of the current collector plates is inefficient, leading to poor current collection efficiency and safety concerns during rapid charging.
Innovation Solution
The solution involves a design where the positive electrode current collector plate is designed with a positive electrode and a negative electrode plate, which are connected to the positive and negative electrode uncoated portions respectively, with a smaller coupling area for the positive electrode than the negative electrode, and the current collector plates are welded directly to these portions to improve current collection efficiency and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current collector tab is used to electrically connect the electrode assembly and external electrode terminal, then the electrode assembly can be connected, but current is concentrated in the current collector tab causing large resistance and heat generation
Solution Approach 1:
The current collector plate is divided into multiple welding portions (first welding portion and second welding portion) that are distributed across different locations on the electrode plate. This segmentation distributes the current flow across multiple connection points, preventing current concentration in a single tab and reducing both resistance and heat generation.
Solution Approach 2:
The invention transitions from a single-point tab connection to a distributed multi-point plate connection, effectively moving from one-dimensional tab connection to two-dimensional plate-wide current collection. The welding portions are arranged at different radial positions and angles on the electrode plate, creating a spatial distribution of current pathways that reduces current density and heat generation.
2Speed
If the composition of the active material layer is adjusted to control lithium ion movement speed, then the movement speed can be controlled within a narrow range, but the controllable range is very limited
Solution Approach 1:
Different welding portions are designed with different areas, allowing local adjustment of current collection characteristics. The first welding portion and second welding portion can have different sizes and shapes, enabling independent optimization of lithium ion movement control in different regions of the electrode plate, thereby expanding the controllable range beyond what uniform composition adjustment can achieve.
Solution Approach 2:
The invention changes the control parameter from chemical composition (which has limited adjustment range) to geometric parameters of the welding portions (area, shape, position). By varying the area and configuration of different welding portions, the lithium ion movement speed can be controlled over a much wider range, as geometric parameters offer greater design flexibility than chemical composition constraints.
3Stability of the object's composition
If the coupling area between positive electrode uncoated portion and positive electrode current collector plate is made smaller than that of negative electrode, then kinetic balance is improved, but the design complexity increases
Solution Approach 1:
The current collector plate is designed with asymmetric welding portions where the first welding portion (positive electrode) has a different area than the second welding portion (negative electrode). This asymmetric design creates different coupling areas that compensate for the inherent differences in lithium ion movement characteristics between positive and negative electrodes, achieving kinetic balance. The asymmetry is intentionally designed to create the required difference in coupling areas while maintaining manufacturing feasibility through standard welding 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
This design allows for improved kinetic balance, rapid charging, and enhanced cycle characteristics, reducing resistance and heat generation, making it suitable for large-sized batteries and vehicles.
Implementation Method 1
a positive electrode current collector plate coupled to the positive electrode uncoated portion by a positive electrode welding portion; and a negative electrode current collector plate coupled to the negative electrode uncoated portion by a negative electrode welding portion
Data Source
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AI summary
A cylindrical secondary battery according to the present disclosure includes a jelly-roll type electrode assembly having a structure in which a positive electrode plate and a negative electrode plate having a sheet shape and a separator interposed therebetween are wound in one direction, the positive electrode plate including a positive electrode uncoated portion exposed to the outside of the separator at a long side end, the negative electrode plate including a negative electrode uncoated portion exposed to the outside of the separator at a long side end; a positive electrode current collector plate coupled to the positive electrode uncoated portion by a positive electrode welding portion; and a negative electrode current collector plate coupled to the negative electrode uncoated portion by a negative electrode welding portion, wherein a coupling area (S 1) between the positive electrode uncoated portion and the positive electrode current collector plate is smaller than a coupling area (S2) between the negative electrode uncoated portion and the negative electrode current collector plate. According to the present disclosure, by improving the positive electrode current collector plate and the negative electrode current collector plate, it is possible to secure the kinetic balance between the positive electrode and the negative electrode, improve the energy density and strengthen the coupling force between components.