Soft Pack Battery Shell Forming with Corner Compensation Preforms
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing manufacturing process for soft pack battery shells using aluminum-plastic film faces challenges such as incomplete sealing, cracking, poor yield rates, and excessive thinning, especially when the depth-thickness ratio exceeds 30 and local thickness thinning rates are high.
Innovation Solution
A method involving a two-stage process: preforming and final-forming, using fluid pressure to deform the thin sheet material. This method includes a material-left design and the formation of compensation portions to manage deformation and thinning, ensuring a depth-thickness ratio of at least 75 and a local thinning rate of no more than 30%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cold pressing is used to form the aluminum-plastic film shell, then the manufacturing process is simple, but the shell is easy to have flaws such as thinning, pinholes, and cracks
Solution Approach 1:
The patent applies preliminary action by performing a pre-forming step before the final forming operation. During pre-forming, compensation portions are created at the corners of the shell, which store extra material that prevents thinning and cracking during the subsequent final forming process. This preliminary preparation of material distribution resolves the contradiction between simple manufacturing and shell integrity.
2Quantity of substance
If the depth-thickness ratio is increased to achieve higher energy density, then the battery capacity increases, but the shell is easy to crack when depth-thickness ratio is no less than 30
Solution Approach 1:
The patent applies local quality by creating compensation portions specifically at the corner areas of the shell where stress concentration occurs. These compensation portions have different material distribution compared to other areas, providing extra material reserve exactly where needed to prevent cracking. This localized material reinforcement allows the shell to achieve higher depth-thickness ratios while maintaining strength.
3Reliability
If single mold cavity is used instead of double mold cavity, then welding difficulties are avoided and leakage problems are reduced, but the deformation is complicated and local over-thinning or breakage occurs easily
Solution Approach 1:
The patent applies preliminary action by performing pre-forming to create compensation portions before the final forming operation. This preliminary material distribution preparation enables the single mold cavity to achieve complex deformations without local over-thinning or breakage, while maintaining the sealing reliability benefits of the single cavity design.
4Reliability
If materials with good elongation are used to avoid incomplete sealing or crack, then the shell integrity improves, but the yield rate of complicated shapes is poor
Solution Approach 1:
The patent applies parameter changes by introducing compensation portions that alter the material distribution parameters during forming. This changes the stress and strain parameters during deformation, allowing materials with good elongation to be fully utilized without causing defects. The compensation portions ensure uniform material flow, improving both shell integrity and yield rate for complicated shapes.
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 increases the yield rate by preventing excessive thinning and breakage, while achieving a higher depth-thickness ratio and maintaining a low local thinning rate, thus improving the reliability and efficiency of soft pack battery shell production.
Implementation Method 1
a first fluid pressure is generated on the first surface of the thin sheet material while a second fluid pressure is generated on the second surface of the thin sheet material. There is a first pressure difference between the first fluid pressure and the second fluid pressure. Owing to the first pressure difference, the thin sheet material is deformed
Implementation Method 2
the thin sheet material is deformed from the first surface toward the second surface until the second surface is in contact with the preform mold cavity to form a preform
Data Source
AI summary
A method of forming a shell of a soft pack battery is provided. The method includes steps of adjusting temperature of a thin sheet material for the shell to a working temperature, applying a difference of fluid pressure to the thin sheet material as forming pressure, and a two-stage forming step. In a first-stage preforming step, a preform with a first depth is formed by the thin sheet material and at least one compensation portion is formed on the preform. In a second-stage final-forming step, the perform is molded into the final formed part with a second depth. Thereby the shell with a higher depth-thickness ratio is manufactured and the thin sheet material is uniformly deformed. The compensation portion is used for compensation of deformation at corners of the bottom of the final molded part. Thus thinning rate is less than 30% and yield rate is increased.