Nonaqueous Rechargeable Battery Pressure Tuning for Electrolyte Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte rechargeable batteries, particularly lithium-ion batteries, experience high-rate deterioration due to uneven concentration distribution and electrolyte leakage when used in high-rate charging and discharging cycles, leading to increased internal resistance, which is exacerbated by changes in electrode body pressure during charging and discharging.
Innovation Solution
The battery design and manufacturing process involve setting a specific ratio of spring constants (L/H) for the electrode body by applying pressure only at normal temperatures, ensuring the electrode body is restrained in the thickness-wise direction during certain manufacturing stages to maintain electrolyte retainability and prevent electrolyte leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring constant of the outer roll portion is increased to restrict electrode body bulging, then high-rate deterioration is limited, but the electrode body structure becomes complicated and the manufacturing process becomes complicated
Solution Approach 1:
The patent applies different spring constants to different regions of the electrode body by varying the thickness of the roll portion. The outer roll portion has a greater thickness than the inner roll portion, creating local structural differences that provide the needed mechanical properties without complicating the overall structure. This gradient thickness design allows the outer regions to resist bulging while maintaining simplicity in the manufacturing process.
2Reliability
If pressure is applied to the electrode body during manufacturing, then electrolyte retention is improved, but the electrode body may deform or damage other components
Solution Approach 1:
The patent specifies applying pressure within a precise range of 316 to 210 N/cm² during manufacturing. By controlling the pressure parameter within this specific range, the electrode body achieves adequate electrolyte retention without excessive compression that could cause deformation or damage. This parameter optimization balances the competing requirements of electrolyte retention and structural integrity.
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 approach effectively limits high-rate deterioration by maintaining electrolyte retention and preventing uneven salt concentration, thereby reducing internal resistance and extending battery life under high-rate charging conditions.
Implementation Method 1
When a spring constant of the nonaqueous electrolyte rechargeable battery with a load of 316 to 210 N/cm2 is referred to as a spring constant H and a spring constant of the nonaqueous electrolyte rechargeable battery with a load of 95 to 74 N/cm2 is referred to as a spring constant L
Data Source
AI summary
A nonaqueous electrolyte rechargeable battery includes an electrode body, a nonaqueous electrolyte, and a rectangular box-shaped battery case accommodating the electrode body and the nonaqueous electrolyte. The electrode body includes a positive electrode including a positive base and a positive composite material layer, a negative electrode including a negative base and a negative composite material layer, and a porous resin separator disposed therebetween. The electrode body has a low profile when the positive electrode, the negative electrode, and the separator are laminated and rolled. When spring constant of the nonaqueous electrolyte rechargeable battery with a load of 316 to 210 N/cm2 and 95 to 74 N/cm2 is respectively referred to as spring constant H and spring constant L, the ratio L/H is 0.34 or greater and 0.41 or less. A resistance increase rate between before and after a square wave test is less than or equal to 1.17.