Curved Electrode Cell Design for Li-Ion Battery Corner Stability
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Solution Overview
Problem
Lithium-ion batteries with thin and light designs experience electrolyte depletion at the corners of the cell structure, affecting their high-temperature cycling performance.
Innovation Solution
The electrochemical device features a cell with a curved and straight portion ratio of 5 ≤ L/D ≤ 10, using an electrolyte containing 4% to 10% dinitrile compound, and optionally includes propionate, trinitrile, and lithium salt, to enhance electrolyte stability and reduce depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the battery is designed to be thin and light, then the specific energy and portability are improved, but the electrolyte depletion at corner regions occurs, worsening the high-temperature cycling performance
Solution Approach 1:
The patent applies local quality by modifying the electrolyte composition specifically for corner regions through the curved portion design. The electrolyte contains dinitrile compound (4-10% by mass) and propionate (20-60% by mass) that preferentially accumulate and form protective films at the corner regions where electrolyte depletion occurs, providing localized protection without changing the overall battery weight.
Solution Approach 2:
The patent applies curvature by designing the outermost electrode with a curved portion having a radius D (1-5mm) and straight portion with length L, where L/D ratio is controlled at 5-10. This curved configuration prevents electrolyte depletion at corner regions by eliminating sharp corners where electrolyte would otherwise be squeezed out, while maintaining the thin and light overall battery structure.
2Volume of moving object
If the battery is designed to be thin and light, then the volume and weight are reduced, but the electrolyte consumption at negative electrode interface increases, worsening the cycling stability
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition parameters - specifically adding dinitrile compound at 4-10% by mass and propionate at 20-60% by mass. These compositional parameter changes enable the electrolyte to form stable protective films that reduce consumption, allowing thin and light battery design while minimizing electrolyte loss at the negative electrode interface.
3Reliability
If the curved portion radius is increased, then the electrolyte depletion is suppressed, but the battery width increases, affecting the thin profile
Solution Approach 1:
The patent applies curvature with optimized parameters - the curved portion has radius D (1-5mm) which is sufficient to prevent electrolyte depletion, and the straight portion length L is controlled to maintain L/D ratio at 5-10. This curvature design suppresses electrolyte depletion at corners while keeping the battery width W (10-40mm) within acceptable thin profile limits.
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 configuration significantly improves the high-temperature cycling performance of lithium-ion batteries by suppressing electrolyte depletion and enhancing electrode stability.
Implementation Method 1
Using an electrolyte containing a specific percentage of the dinitrile compound can enhance the stability of the negative electrode, reduce the consumption of electrolyte at the negative electrode interface
Implementation Method 2
Adding a specific percentage of the propionate can significantly reduce the viscosity of the electrolyte, improve the fluidity of the electrolyte, and enable rapid replenishment of electrolyte in regions with local electrolyte depletion
Implementation Method 3
Electrochemical devices (for example, lithium-ion batteries) have characteristics such as high specific energy, high operating voltage, low self-discharge rate
Data Source
Figure 1
AI summary
The present application relates to an electrochemical device and an electronic device. Specifically, the present application provides an electrochemical device including a cell, where the cell includes a positive electrode, a negative electrode, an electrolyte, and a separator, an outermost electrode of the cell has a curved portion and a straight portion, a length of the straight portion is L mm, a radius of the curved portion is D mm, and 5 ≤ L/D ≤ 10; and the electrolyte includes a dinitrile compound, and based on a mass of the electrolyte, a percentage of the dinitrile compound is A%, and 4 ≤ A ≤ 10. The electrochemical device of the present application has significantly improved high-temperature cycling performance.