Cylindrical Battery Anode Contact Stability via Graphite Control
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Solution Overview
Problem
Cylindrical batteries with exposed negative electrode cores experience unstable contact states between the electrode assembly and the exterior can, leading to significant variations in internal resistance values.
Innovation Solution
Incorporating graphite particles with 5% or less internal porosity and 25 MPa to 55 MPa breaking strength as the negative electrode active material, which stabilizes the contact state by controlling the repulsive force and expansion of the negative electrode within the exterior can.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional graphite particles are used as negative electrode active material, then the battery structure is simple, but the contact state between the electrode assembly and exterior can becomes unstable
Solution Approach 1:
The patent applies parameter changes by precisely controlling the internal porosity (5% or less) and breaking strength (25-55 MPa) of graphite particles. These parameter specifications transform the graphite particles from a conventional loose material into a structurally controlled component that maintains stable contact pressure with the exterior can, resolving the contact state stability issue while managing the complexity through defined parameter ranges.
Solution Approach 2:
The patent applies local quality by creating an exposed part on the outer peripheral surface of the electrode assembly where the negative electrode core is exposed. This localized structural modification ensures stable contact with the interior surface of the exterior can at the critical interface region, while the rest of the battery structure remains conventional.
2Reliability
If graphite particles with low internal porosity and high breaking strength are used, then the contact state stability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for graphite particles (internal porosity ≤5%, breaking strength 25-55 MPa) that balance manufacturing feasibility with performance requirements. These parameter definitions provide clear manufacturing targets while achieving the goal of reducing internal resistance variation through stable contact maintenance.
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 approach maintains a stable contact state between the electrode assembly and the exterior can, thereby reducing the variation in internal resistance values of the cylindrical battery.
Implementation Method 1
graphite particles having 5% or less of internal porosity and 25 MPa to 55 MPa of breaking strength
Implementation Method 2
controlling the repulsive force and expansion of the negative electrode within the exterior can
Data Source
AI summary
A cylindrical battery, as one example according to an embodiment of the present disclosure, is provided with: an electrode body formed by spirally winding a positive electrode and a negative electrode with a separator interposed therebetween; and a bottomed cylindrical exterior can for accommodating the electrode body. The negative electrode has a negative-electrode core body and a negative-electrode mixture layer provided on a surface of the negative-electrode core body. An exposed area in which the surface of the negative-electrode core body is exposed is formed on an outer circumferential surface of the electrode body, and the exposed area is in contact with the inner surface of the exterior can. The negative-electrode mixture layer contains, as a negative-electrode active material, graphite particles having an internal porosity of 5% or less and a fracture strength of 25-55 MPa.