Polymer Pouch Battery Pack Structure for Moisture Barrier and Low Weight
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Solution Overview
Problem
Secondary batteries, particularly those using pouch-type cells, face challenges in achieving high energy density due to the use of metal components for moisture and impact resistance, which increase weight and reduce efficiency.
Innovation Solution
The use of non-metallic polymer-based pouch films and spacers, along with a rigid case, to create a secondary battery pack that maintains energy density, impact resistance, and prevents moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal materials are used in pouch-type cells to prevent moisture permeation and enhance impact resistance, then reliability is improved, but weight increases and energy density decreases
Solution Approach 1:
The invention extracts and removes the metal layer from the pouch film structure, transitioning from a metal-polymer composite film to a purely polymer-based film. This extraction eliminates the weight penalty associated with metal while maintaining the essential functions of moisture barrier and mechanical strength through optimized polymer material selection and multi-layer construction.
Solution Approach 2:
The invention employs composite polymer materials consisting of multiple polymer layers with different functions. The outer layers provide mechanical strength and impact resistance, while inner layers provide moisture barrier properties. This composite structure achieves the reliability previously provided by metal without the weight penalty, as each polymer layer is optimized for its specific function.
2Adaptability or versatility
If pouch-type cells are used instead of cylindrical or prismatic cells, then adaptability to volume changes is improved, but energy density is reduced due to metal content
Solution Approach 1:
By removing the metal layer from the pouch film, the invention eliminates the weight that was reducing energy density. The resulting all-polymer pouch film maintains the adaptability to volume changes inherent in pouch-type cells while significantly reducing the non-active mass, thereby improving energy density to levels comparable with or exceeding traditional cylindrical and prismatic cells.
3Weight of moving object
If the pouch film is made thinner to reduce weight, then energy density is improved, but impact resistance and moisture barrier performance deteriorate
Solution Approach 1:
The invention uses a multi-layer composite polymer structure where different layers have specialized functions. Thinner overall film thickness is achieved while maintaining reliability because each layer is optimized for its specific function: some layers provide mechanical strength and impact resistance, others provide moisture barrier properties, and still others provide adhesion and sealing. The synergistic combination of these specialized thin layers achieves better overall performance than a single thicker layer.
Solution Approach 2:
Different regions and layers of the pouch film are designed with locally optimized properties. The outer surfaces have enhanced mechanical strength for impact resistance, the inner layers have optimized moisture barrier properties, and the bonding layers have optimized adhesion characteristics. This local optimization allows the film to be thinner overall while maintaining or improving reliability in each specific function.
Data Source
AI summary
Aspects of the present disclosure provide a secondary battery pack having at least one pouch-type cell; and a case having an interior space to receive the at least one pouch-type cell, wherein the at least one pouch-type cell includes an electrode assembly and a pouch film to receive the electrode assembly, wherein the pouch film consists of a polymer or a polymer and adhesive.