Curved Anode Current Collector Radius for Silicon Battery Fracture
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Solution Overview
Problem
Secondary batteries with silicon-based anode materials face challenges in preventing fracture due to volume expansion during charging and discharging, which can lead to reduced energy density and increased costs due to thicker current collectors.
Innovation Solution
The design of an anode with a silicon-based active material and a rounded portion on the current collector, where the radius of curvature satisfies a specific equation, disperses stress and prevents fracture without increasing the current collector thickness, incorporating a tab connection and shoulder portion with a conductive and binder material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a silicon-based active material is used in the anode to increase capacitance, then the energy density is improved, but the current collector undergoes fracture due to volume expansion during charging and discharging
Solution Approach 1:
The patent applies curvature to the transition region between the electrode formation and tab connection portion by forming a rounded portion with a specific radius of curvature (0.5mm to 2.0mm). This curved geometry distributes the stress generated during silicon-based anode expansion, preventing stress concentration that would lead to current collector fracture while maintaining the high energy density benefits of silicon-based active materials
2Strength
If the current collector thickness is increased to prevent fracture, then the strength is improved, but the energy density decreases due to reduced active material proportion
Solution Approach 1:
The patent applies local quality by providing different structural characteristics at different locations of the current collector. The transition region has a rounded portion with increased thickness and curvature radius to withstand stress, while the rest of the current collector maintains its original thin profile (15μm to 30μm), thereby preventing fracture without sacrificing overall energy density
3Strength
If a rounded portion with specific radius of curvature is formed to disperse stress, then the current collector fracture resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent implements a rounded portion with a specifically controlled radius of curvature (0.5mm to 2.0mm) in the transition region. This curvature design is integrated into the existing current collector manufacturing process through controlled deformation or forming techniques, adding fracture resistance through geometry rather than material changes, thus minimizing manufacturing complexity while effectively dispersing stress
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 effectively suppresses anode current collector fracture, maintains high energy density, and ensures excellent lifespan characteristics while maintaining a thin current collector thickness, thus enhancing the economic feasibility and performance of secondary batteries.
Implementation Method 1
the rounded portion has a radius of curvature satisfying a specific equation, disperses stress and prevents fracture
Data Source
AI summary
Anodes and secondary batteries including the anodes are disclosed. In some embodiments of the disclosed technology, an anode includes: an anode current collector; and an anode mixture layer disposed on at least one surface of the anode current collector. The anode mixture layer includes a silicon-based active material, the anode current collector includes a tab connection portion, a shoulder portion, and a rounded portion located therebetween, the rounded portion has a radius of curvature satisfying a value R measured in millimeter (mm) in a range according to Equation expressed as:(p×A+q)−r<R≤(p×A+q)+r, wherein A is a value corresponding to a weight ratio measured in weight percent (wt %) of the silicon-based active material to the anode mixture layer, p is a value ranging from 0.05 to 0.2, q is a value ranging from 0.1 to 1, and r is a value ranging from 0.1 to 1.