Polymer Sheet HF Scavenger for Secondary Battery Safety
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Solution Overview
Problem
Existing secondary battery casings fail to effectively scavenge hydrogen fluoride (HF) generated during charging/discharging, leading to safety issues and performance degradation due to HF breaking the solid electrolyte interphase layer and reducing lithium ion mobility when inorganic additives are used directly in the battery.
Innovation Solution
A casing with a polymer sheet containing a hydrogen fluoride scavenger, capable of dissolving at pH 3 or less, is integrated into the inner surface, which includes materials like lithium cobalt oxide, activated carbon, or zeolite to adsorb HF without affecting battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic HF-scavenger additives are incorporated directly into electrodes, separators, or electrolyte, then HF scavenging capability is improved, but lithium ion mobility is reduced and conductivity is decreased
Solution Approach 1:
The HF scavenger is segmented from the electrode structure by being disposed on a separate polymer sheet that is attached to the electrode surface. This segmentation allows the scavenger to be spatially separated from the active electrode materials, enabling HF scavenging without blocking lithium ion pathways in the electrode pores.
Solution Approach 2:
The polymer sheet acts as an intermediary carrier between the electrode and the HF scavenger. The polymer matrix provides a support structure that holds the scavenger particles while maintaining ion transport pathways, mediating between the need for HF scavenging and the need for high ion conductivity.
2Reliability
If inorganic HF-scavenger additives are incorporated directly into electrodes, separators, or electrolyte, then HF scavenging capability is improved, but battery performance is degraded
Solution Approach 1:
The scavenger function is segmented into a separate polymer sheet component, allowing the electrode structure to maintain its optimized design for high performance while the attached polymer sheet provides the scavenging function. This prevents the scavenger from interfering with electrode electrochemical performance.
Solution Approach 2:
The HF scavenger is locally concentrated on the polymer sheet surface that contacts the electrolyte and electrode interface, where HF generation occurs. This local placement provides effective scavenging at the critical interface without dispersing scavenger material throughout the entire electrode volume, preserving electrode performance.
3Reliability
If a polymer sheet with HF scavenger is disposed on the inner surface of the casing, then HF scavenging is achieved without affecting electrode function, but the structure becomes more complex
Solution Approach 1:
The polymer sheet integrating HF scavenger, polymer matrix, and binding assistant is merged into a single functional component that is attached to the electrode. This combining of multiple functions into one element adds minimal structural complexity while achieving comprehensive HF scavenging without affecting electrode performance.
4Reliability
If inorganic HF-scavenger additives are used, then HF is captured, but side reactions are generated and battery life is reduced
Solution Approach 1:
The polymer sheet serves as an intermediary that controls the interaction between the HF scavenger and the battery environment. The polymer matrix protects the inorganic scavenger particles from direct contact with electrolyte and electrode materials, preventing side reactions while still allowing HF capture at the polymer-electrolyte interface.
Solution Approach 2:
The polymer sheet with bound scavenger acts as a sacrificial component designed to remain stable during battery operation. The polymer matrix provides a stable, inert environment that prevents degradation of the scavenger and eliminates side reactions, allowing the scavenger to function throughout the battery lifecycle without generating harmful byproducts.
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 polymer sheet effectively removes HF, preventing side reactions and maintaining battery performance and life characteristics by adsorbing HF without degrading the electrolyte or electrodes, thus enhancing safety and longevity.
Implementation Method 1
the polymer sheet includes a hydrogen fluoride (HF) scavenger contained therein or disposed on a surface thereof... which includes materials like lithium cobalt oxide, activated carbon, or zeolite to adsorb HF
Implementation Method 2
the polymer sheet is capable of dissolving at pH of 3 or less
Data Source
Figure 1~2
Figure 3~5a
Figure 5b~6
AI summary
The present disclosure relates to a casing for a secondary battery shaped to receive an electrode assembly, and a secondary battery including the same. The casing for a secondary battery functions to scavenge hydrogen fluoride (HF) generated during the charging/discharging of a battery. In an embodiment, the casing for a secondary battery includes a casing material which is arranged such that an inner surface of the casing material defines has a receiving portion corresponding to the shape of an electrode assembly, and a polymer sheet disposed on the inner surface of the casing material, wherein the polymer sheet having a hydrogen fluoride (HF) scavenger contained therein or disposed on a surface thereof, and wherein the polymer sheet is capable of dissolving at pH 3 or less.