Pouch Secondary Battery Electrolyte Ratio for Impact Resistance
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Solution Overview
Problem
Pouch-type secondary batteries are vulnerable to fire, explosion, and electrolyte leakage due to their lower rigidity and susceptibility to external impacts compared to can-type batteries, which is a concern when used in electric vehicles requiring high safety.
Innovation Solution
The design of a secondary battery with specific conditions for the electrode assembly and electrolyte content, defined by the W/S ratio, to increase frictional force between the electrode assembly and the battery case, minimizing displacement and electrolyte leakage upon impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If pouch-type secondary batteries are used to achieve light weight and high energy density, then weight reduction and space utilization are improved, but impact resistance and safety deteriorate due to vulnerability to fire, explosion, and electrolyte leakage
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative relationships between electrolyte weight per unit capacity (W) and electrode assembly surface area (S) through the equation W/S ≤ 0.15 g/Ah/m². By controlling this critical parameter, the invention increases frictional force between the electrode assembly and pouch inner surface, thereby preventing displacement and electrolyte leakage during impact while maintaining the lightweight pouch-type structure.
2Quantity of substance
If the electrode assembly is made larger to increase capacity, then energy density is improved, but frictional force with the battery case decreases, leading to increased displacement risk upon impact
Solution Approach 1:
The patent resolves this contradiction by changing the parameter relationship between electrolyte amount and electrode size. Instead of simply increasing electrode size, the invention controls the ratio W/S (electrolyte weight per unit capacity divided by electrode surface area) to maintain adequate frictional force even with larger electrode assemblies, thus preventing displacement while achieving higher capacity.
3Quantity of substance
If more electrolyte is added to ensure adequate lubrication and ion conduction, then battery performance is improved, but frictional force between the electrode assembly and battery case decreases, increasing separation risk upon impact
Solution Approach 1:
The patent applies parameter changes by establishing the optimal balance between electrolyte amount and electrode assembly size through the W/S ratio equation. By controlling this parameter, the invention ensures adequate electrolyte for ion conduction while maintaining sufficient frictional force to prevent electrode assembly displacement during impact, thus resolving the contradiction between electrolyte quantity and frictional force.
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 increased frictional force between the electrode assembly and the battery case prevents separation and leakage, enhancing impact resistance and safety, particularly in pouch-type batteries.
Implementation Method 1
increase frictional force between the electrode assembly and a battery case (e.g., pouch), thereby suppressing separation of the electrode assembly and/or leakage of the electrolyte when an external impact is applied
Data Source
AI summary
A secondary battery having improved impact resistance is provided. The secondary battery includes a battery case comprising an electrode assembly and an electrolyte accommodated in an accommodation part of the battery case. The secondary battery satisfies following Equation (1): Equation (1): W/S≤42. In Equation (1), W is an amount of electrolyte per unit capacity of the secondary battery [unit: g/Ah], and S is a product of a total length [unit: m] and a full width [unit: m] of the electrode assembly.