Electrode Overhang Layout for Higher-Density Lithium-Ion Cells
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Solution Overview
Problem
Existing electrochemical apparatuses, such as lithium-ion batteries, face challenges in efficiently utilizing the negative electrode active substance due to the larger size of the negative electrode compared to the positive electrode, leading to decreased energy density.
Innovation Solution
The electrochemical apparatus is designed with a specific configuration where the negative electrode active substance layer extends beyond the positive electrode active substance layer in a controlled manner, with a defined ratio and width difference, to optimize current density distribution and reduce lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode is designed to be significantly larger than the positive electrode to ensure safety and reduce lithium precipitation, then safety performance is improved, but the utilization of negative electrode active substance decreases
Solution Approach 1:
The patent applies local quality by creating asymmetric overhang configurations where only specific portions of the negative electrode extend beyond the positive electrode. The first and second overhang widths (OH1 and OH2) are independently controlled, allowing different local regions to serve different functions: one side provides safety margin while the other optimizes active substance utilization, resolving the contradiction between safety and energy efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the electrode configuration by defining specific ranges for OH1 and OH2 (where 0.1mm ≤ OH1 + OH2 ≤ 5mm and 0.01 ≤ OH1/OH2 ≤ 0.9). This parameter optimization allows the design to achieve both safety performance and high active substance utilization by precisely controlling the extent of negative electrode overhang on each side.
2Reliability
If the negative electrode is made larger to prevent lithium precipitation, then safety is improved, but energy density decreases
Solution Approach 1:
The patent implements local quality by differentiating the overhang behavior on opposite sides of the electrode assembly. By controlling OH1 and OH2 independently within specific ranges, the design ensures safety through controlled overhang while minimizing the total area of non-active negative electrode material, thus maintaining high energy density.
Solution Approach 2:
The patent employs asymmetry by allowing OH1 and OH2 to have different values within defined constraints (0.01 ≤ OH1/OH2 ≤ 0.9). This asymmetric configuration optimizes the balance between safety requirements and active substance utilization, preventing lithium precipitation while maximizing energy density by avoiding excessive symmetric overhang on both sides.
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 enhances the utilization of the negative electrode active substance, improves energy density, and prevents lithium precipitation, thereby ensuring safety and efficiency of the electrochemical apparatus.
Implementation Method 1
Electrochemical apparatuses, such as lithium-ion batteries, are widely used as portable chemical energy
Implementation Method 2
a capacity per gram of a material can be improved
Implementation Method 3
A higher current density generates heat and accelerates diffusion of lithium ions in the electrode
Implementation Method 4
A higher current density generates heat
Data Source
AI summary
An electrochemical apparatus including an electrode assembly, where the electrode assembly includes a positive electrode, a negative electrode, and tabs, and the tabs extend out of a housing in a first direction. A positive electrode active substance layer has a first positive electrode active substance layer side and a second positive electrode active substance layer side opposite to the first positive electrode active substance layer side in the first direction. A negative electrode active substance layer has a first negative electrode active substance layer side and a second negative electrode active substance layer side opposite to the first negative electrode active substance layer side in the first direction. The tabs includes a positive tab and a negative tab, the positive tab is provided at the first positive electrode active substance layer side and the negative tab is provided at the first negative electrode active substance layer side.