Wide Negative Electrode SEI Formation for Thermal-Stable Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte solution secondary batteries with higher capacity face challenges in uniform film formation on the negative electrode active material layer, leading to uneven reactivity and decreased thermal stability, particularly at the central part of the electrode, resulting in increased heat generation during overcharging.
Innovation Solution
Incorporating a boron element into the negative electrode active material layer and employing a specific manufacturing and inspection method that includes initial charging and aging steps under controlled temperature conditions to adjust the black unevenness index to 12 or less, ensuring uniform film formation and improved thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode body width is increased to 15 cm or more to achieve higher capacity, then the battery capacity is improved, but the additive permeation becomes insufficient in the central part, causing uneven film formation and decreased thermal stability
Solution Approach 1:
The patent applies preliminary action by performing an aging process before the battery is put into service. During this aging process, the battery is held at a temperature of 40°C or higher for a specific period, which promotes uniform film formation across the entire electrode surface, including the central part that would otherwise have insufficient additive permeation. This preliminary treatment ensures uniform reactivity and thermal stability before the battery enters normal operation.
2Quantity of substance
If the electrode body width is increased to 15 cm or more to achieve higher capacity, then the battery capacity is improved, but the film formation uniformity decreases due to reduced additive permeation in the central part
Solution Approach 1:
The patent applies preliminary action by performing an aging process before the battery is put into service. During this aging process, the battery is held at a temperature of 40°C or higher for a specific period, which promotes uniform film formation across the entire electrode surface, including the central part that would otherwise have insufficient additive permeation. This preliminary treatment ensures uniform reactivity and thermal stability before the battery enters normal operation.
3Ease of manufacture
If conventional electrolyte composition is used in large-capacity batteries, then the manufacturing cost is reduced, but the central part of the electrode exhibits high reactivity and low thermal stability
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition to include a specific additive at a concentration of 0.01 wt% or higher. This compositional change, combined with the aging process at elevated temperature, ensures uniform film formation and consistent thermal stability across the entire electrode, including the central part, without significantly increasing manufacturing cost.
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
The method effectively suppresses heat generation and enhances thermal stability by ensuring uniform film formation across the negative electrode, providing a battery with improved reliability and reduced temperature increases during overcharging.
Implementation Method 1
at initial charging, a part of the nonaqueous electrolyte solution is decomposed and a film including a decomposition product thereof (solid electrolyte interface film: SEI film) is deposited on a surface of a negative electrode active material layer
Implementation Method 2
a surface of the negative electrode is photographed with a camera so as to include a central part of the negative electrode active material layer in a width direction and photographed image data expressed in an RGB color model is acquired
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A nonaqueous electrolyte solution secondary battery (100) disclosed herein includes an electrode body (20) that includes a positive electrode (22) including a positive electrode active material layer (22a) and a negative electrode (24) including a negative electrode active material layer (24a), and a nonaqueous electrolyte solution. The negative electrode active material layer (24a) has a width of 15 cm or more and includes a film containing a boron element, and a black unevenness index is 12 or less.