Battery Separator and Cyano Electrolyte for Thermal Runaway Prevention
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Solution Overview
Problem
Lithium ion batteries face safety hazards due to gas and heat generation during overcharge and high temperature conditions, leading to potential thermal runaway, explosions, or fires, necessitating improved overcharging and hot box performance while maintaining energy density and cycle life.
Innovation Solution
The combination of a specific electrolyte containing 2 to 3 cyano groups and a composite separator with distinct pore closing temperatures and materials, including inorganic particles and polymers, enhances overcharging, hot box, and cycle performance by reducing electrolyte decomposition and lithium ion transfer during temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional batteries are used under overcharge conditions, then battery capacity is maintained, but gas and heat generation occur causing safety hazards
Solution Approach 1:
The separator is designed with dual pore-closing temperatures to preemptively prevent thermal runaway before it occurs. The first pore-closing temperature (105-145°C) provides initial safety protection, while the second higher temperature (120-160°C) provides backup protection, creating a preliminary defense mechanism against overheating and gas generation
Solution Approach 2:
The separator uses composite material structure with different polymer layers (first porous layer and second porous layer) having different pore-closing temperatures. This composite structure combines the advantages of both materials to provide multi-stage thermal protection, preventing both moderate and extreme overheating scenarios
2Temperature
If electrolyte is used under high temperature conditions, then battery operation is maintained, but side effects increase resulting in thermal runaway
Solution Approach 1:
The electrolyte contains additives (0.1-5 wt% of specific compounds) that preemptively form protective films on electrode surfaces before thermal runaway can occur. These additives activate at elevated temperatures to suppress harmful side reactions and prevent the chain reaction leading to thermal runaway
Solution Approach 2:
The electrolyte composition is modified by adding specific additives that change the chemical parameters of the electrolyte system. These additives alter the decomposition temperature and reaction kinetics of the electrolyte, raising the threshold for thermal runaway and improving high-temperature stability
3Reliability
If separator with single pore closing temperature is used, then manufacturing is simplified, but overcharging and hot box performance are insufficient
Solution Approach 1:
The separator is segmented into two functional layers: the first porous layer with lower pore-closing temperature (105-145°C) and the second porous layer with higher pore-closing temperature (120-160°C). Each layer performs a specific thermal protection function, with the first layer providing primary protection and the second layer providing backup protection against more severe overheating
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 combination effectively prevents thermal runaway by suppressing lithium ion transfer and forming protective films, improving safety and energy density while maintaining battery performance.
Implementation Method 1
the pore closing temperature of the first porous layer is different from the pore closing temperature of the second porous layer
Implementation Method 2
an electrolyte, including at least one compound containing 2 to 3 cyano groups
Data Source
AI summary
The present application relates to an electrochemical device comprising a separator and an electrolyte, wherein the separator comprises a first porous layer and a second porous layer; and the electrolyte comprises at least one compound containing 2 to 3 cyano groups.