Cellulose Separator Coating for Compression-Resistant Li-Ion Batteries
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Solution Overview
Problem
Lithium ion battery separators made from cellulose non-woven fabrics suffer from compression issues during charging and discharging cycles, leading to increased impedance and reduced battery life due to lack of elasticity.
Innovation Solution
A porous carrier with a cellulose substrate coated with an organic polymer elastic filler and a polymer binder, providing improved compression resistance and recovery, is used as an electrochemical device separator to prevent electrode-separator gaps and maintain battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cellulose non-woven fabric is used as separator material, then ionic conductivity and wettability are improved, but compression resistance and elasticity deteriorate
Solution Approach 1:
The patent applies composite materials by combining cellulose fibers with polyolefin fibers to create a non-woven fabric separator. The cellulose component provides excellent ionic conductivity and wettability, while the polyolefin component contributes compression resistance and elasticity. This composite structure resolves the contradiction by integrating the advantages of both materials without sacrificing either ionic conductivity or mechanical strength.
2Reliability
If cellulose non-woven fabric is used as separator material, then wettability is improved, but elasticity deteriorates
Solution Approach 1:
The composite structure combines hydrophilic cellulose fibers that enhance wettability with elastic polyolefin fibers that provide recovery capability. The cellulose ensures excellent electrolyte penetration and contact, while the polyolefin matrix maintains structural integrity and elastic recovery after compression, thus resolving the contradiction between wettability and elasticity.
Solution Approach 2:
The patent applies local quality by distributing different fiber types throughout the non-woven fabric structure. Cellulose fibers are positioned to maximize contact with electrolyte for enhanced wettability, while polyolefin fibers are distributed to provide localized elastic support and compression resistance, creating regions with specialized functions within the overall separator structure.
3Reliability
If pure cellulose is used as separator, then ionic conductivity is improved, but recovery after compression deteriorates
Solution Approach 1:
The patent uses a composite of cellulose and polyolefin fibers where cellulose provides the ionic conductivity necessary for battery operation, while polyolefin provides the elastic recovery needed to maintain separator-electrode contact over extended cycling. This composite approach extends service life by preventing the permanent compression that would otherwise occur with pure cellulose separators.
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 porous carrier with enhanced compression resistance and recovery extends the life of lithium ion batteries by minimizing impedance increases during charging and discharging cycles.
Implementation Method 1
a functional layer including an organic polymer elastic filler and a polymer binder
Data Source
AI summary
A porous carrier including a cellulose substrate and a functional layer is provided. The functional layer is located on at least one surface of the cellulose substrate, wherein the functional layer includes an organic polymer elastic filler and a polymer binder. An electrochemical device separator including the porous carrier is also provided.