Separator Polymer Properties for Longer Battery Cycle Life
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Solution Overview
Problem
Existing electrochemical devices, such as secondary batteries, have a limited number of cycles before exhibiting a parasitic condition, leading to device failure, and there is a need to extend the cycle life.
Innovation Solution
An electrochemical device comprising an anode, a cathode, and a separator with specific material properties, including a linear polymer with a kinetic friction coefficient of up to 2.0, elongation at break of at least 240, and a modulus of elasticity of up to 270 MPa, along with a lithium-chalcogen battery configuration, which allows for increased cycle durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separators are used in electrochemical devices, then the device can operate, but the device exhibits parasitic conditions after limited cycles leading to failure
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the separator material. Specifically, it uses linear polymer materials with controlled molecular weight (at least 200,000 g/mol), specific linearity (at least 70%), and defined mechanical properties (elongation at break of at least 240%, modulus of elasticity of up to 270 MPa). These parameter modifications enable the separator to withstand repeated charging cycles without exhibiting parasitic conditions, thereby extending device cycle life from limited operations to at least 2 full cycles.
2Duration of action of stationary object
If the separator material is made more durable to extend cycle life, then the number of cycles increases, but the material properties become more complex to control
Solution Approach 1:
The patent applies local quality by focusing durability enhancements specifically on the separator component rather than the entire electrochemical device. By concentrating material property optimizations on the separator alone (linear polymer with specific molecular weight, linearity, elongation, and modulus), the invention achieves extended cycle life without requiring complex modifications across all device components. This localized approach manages complexity by isolating the durability solution to a single component with well-defined specifications.
Data Source
AI summary
An electrochemical device including: an anode, a cathode, an electrolyte, and a separator separating the anode from the cathode. The separator includes a material that includes at least one of: a linear polymer; a kinetic friction coefficient of up to 2.0; an elongation of at least 240, elongation defined as elongation at break; a ratio of elongation to thickness of at least 10; and/or a modulus of elasticity of up to 270 MPa.