Expandable Particle Separator for Thermal Runaway Prevention
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Solution Overview
Problem
The diversification of applications for electrochemical devices has led to a need for new techniques to inhibit thermal runaway and ensure higher safety by preventing short-circuiting between electrodes, which existing technologies have not adequately addressed.
Innovation Solution
The use of an additive for electrochemical devices with a specific range of volume expansion ratios and limited content of certain elements, combined with azo or melamine compounds, improves safety by enhancing slurry stability, peel strength, and inhibiting Joule heat release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separators are used to prevent short-circuiting, then basic safety is improved, but thermal runaway and internal short circuits cannot be effectively inhibited
Solution Approach 1:
The expandable particles are incorporated into the separator during manufacturing, preparing the separator in advance to activate its safety function when thermal runaway occurs. The particles remain dormant during normal operation but automatically expand when exposed to high temperatures, physically blocking potential short-circuit paths before they can cause damage.
Solution Approach 2:
The separator utilizes the phase transition of expandable particles (from compact state to expanded foam state) in response to temperature changes. When the battery experiences thermal runaway and temperature rises, the expandable particles undergo a phase transition by absorbing moisture and expanding, transforming the separator's structure from a compact filtration medium to an expanded barrier that physically prevents internal short circuits.
2Reliability
If expandable particles with low expansion temperature are used, then thermal runaway response is improved, but electrode decomposition and performance degradation occur
Solution Approach 1:
The invention carefully selects and controls the expansion temperature parameter of the expandable particles, specifying that it should be between 150°C and 400°C. This parameter optimization ensures the particles activate only when genuine thermal runaway occurs, rather than during normal operation or minor temperature fluctuations, thereby preventing premature activation that would degrade electrode performance while still providing effective thermal runaway response.
Solution Approach 2:
The invention converts the potentially harmful effect of expandable particle activation (which could decompose electrodes) into a beneficial selective protection mechanism. By optimizing the expansion temperature to match the thermal runaway threshold, the particles only activate when truly needed, transforming what could be a source of electrode damage into a precise safety mechanism that distinguishes between normal operation and dangerous conditions.
3Reliability
If separator structure is modified to improve safety, then internal short circuit prevention is enhanced, but manufacturing complexity increases
Solution Approach 1:
The invention merges the safety function into the existing separator structure by incorporating expandable particles during the separator manufacturing process. Rather than adding a separate safety mechanism layer, the expandable particles are integrated into the separator matrix itself, combining the filtration function and thermal runaway protection function into a single unified structure, thereby avoiding increased manufacturing complexity.
Solution Approach 2:
The separator achieves multi-functionality by simultaneously providing its original filtration function and gaining thermal runaway protection through the incorporated expandable particles. This universal approach allows a single separator component to perform multiple safety functions without requiring additional separate layers or structures, maintaining manufacturing simplicity while enhancing safety performance.
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
This approach ensures a high level of safety for electrochemical devices by preventing internal short circuits and maintaining performance under high temperatures, as evidenced by improved rate characteristics and capacity retention.
Implementation Method 1
a temperature at which a volume expansion ratio of the additive for an electrochemical device reaches a factor of 2 or more is higher than 150° C. and lower than 400° C.
Data Source
AI summary
Provided is an additive for an electrochemical device that can ensure a high level of safety of an electrochemical device. The additive for an electrochemical device is an additive for an electrochemical device that is used in an electrochemical device, for which a temperature at which a volume expansion ratio thereof reaches a factor of 2 or more is higher than 150° C. and lower than 400° C., and in which the content of (A) each element belonging to group 2 of the periodic table is less than 100 mass ppm, the content of (B) each element belonging to group 17 of the periodic table is less than 100 mass ppm, and the content of (C) each element among Cr, Mn, Fe, Co, Ni, Cu, and Zn is less than 5 mass ppm.