Composite Electrode Sheet Thermal Runaway Protection
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Solution Overview
Problem
Lithium-ion batteries with high energy density face safety risks due to irreversible electrochemical side reactions leading to thermal runaway, and existing methods to improve high-temperature resistance are insufficient in preventing temperature increases and ensuring battery safety.
Innovation Solution
A composite electrode sheet for lithium-ion batteries is developed, featuring a functional coating made from melamine cyanurate, pentaerythritol melamine phosphate, ammonium polyphosphate, or polydimethylsiloxane, combined with an adhesive, applied to the surface of the electrode sheet, which absorbs excess heat and generates a protective coat to inhibit temperature increases and passivate the active materials, thereby enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high energy density is increased to improve endurance mileage, then energy storage capacity is improved, but safety risk increases due to thermal runaway
Solution Approach 1:
The patent applies preliminary action by pre-coating the electrode sheet with a functional coating containing fire-retardant substances (melamine cyanurate, ammonium polyphosphate, etc.) before battery assembly. This protective layer is prepared in advance to prevent thermal runaway and safety accidents that could occur during battery operation, thereby enabling high energy density while maintaining safety.
2Temperature
If physical properties are improved by coating aluminium oxide on the electrode sheet surface, then high-temperature resistance is improved, but safety cannot be ensured efficiently as temperature increase is not prevented
Solution Approach 1:
The patent converts the harmful effect of high temperature into a beneficial outcome by using fire-retardant substances that undergo endothermic decomposition reactions when exposed to heat. These substances (melamine cyanurate, ammonium polyphosphate, pentaerythritol melamine phosphate) absorb excess heat through chemical reactions, generating protective char layers that prevent further temperature increase and convert the thermal hazard into a safety mechanism.
Solution Approach 2:
The patent changes the chemical composition parameters of the coating by using organic fire-retardant substances with specific molecular structures (melamine cyanurate, ammonium polyphosphate, etc.) instead of conventional inorganic coatings. These substances have specific decomposition temperatures and reaction characteristics that enable them to absorb heat and form protective layers, fundamentally changing the temperature response behavior of the electrode sheet.
3Reliability
If a functional coating is applied to the electrode sheet surface, then safety is improved by absorbing excess heat, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functional coating preparation with the existing electrode sheet manufacturing process. The fire-retardant substances are mixed with adhesive and coating assistants to form a slurry that is applied to the electrode sheet surface in the same production line, combining multiple functions (protection, adhesion, coating) into a single integrated process, thereby reducing manufacturing complexity despite the added functionality.
Solution Approach 2:
The patent uses adhesive and coating assistants as intermediary substances to facilitate the application of fire-retardant materials to the electrode sheet. These intermediaries enable uniform coating distribution, ensure proper adhesion to the electrode surface, and simplify the manufacturing process by providing a ready-to-apply slurry formulation, thereby reducing the complexity of implementing the safety coating.
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 composite electrode sheet effectively prevents further temperature increases, ensuring battery safety and reducing production costs by minimizing process losses, while maintaining superior electrochemical performance with a capacity retention ratio greater than 85% within 1500 cycles and over 95% at a 3C discharge rate.
Implementation Method 1
the functional coating is prepared from a functional substance selected from one or more of melamine cyanurate, pentaerythritol melamine phosphate, ammonium polyphosphate, polydimethylsiloxane and melamine pyrophosphate... When the temperature of the lithium-ion battery increases, the functional coating can quickly absorb excess heat of the battery, regard the excess heat as reaction entropy, spontaneously respond to a chemical reaction, and generate a protecting coat
Data Source
AI summary
A composite electrode sheet for a lithium-ion battery is provided by the disclosure, which includes a battery electrode sheet and a functional coating composited on a surface of the battery electrode sheet. The functional coating is prepared from a functional substance and an adhesive, the functional substance is selected from one or more of a phosphorus-containing compound, a nitrogen-containing compound and an inorganic silicon-based compound, and the battery electrode sheet is a positive electrode and/or a negative electrode of a battery. According to the composite electrode sheet for the lithium-ion battery provided by the disclosure, the functional coating is coated on the surface of the battery electrode sheet. When the temperature of the lithium-ion battery increases, the functional coating can quickly absorb excess heat of the battery, regard the excess heat as reaction entropy, spontaneously respond to a chemical reaction, and generate a protecting coat on the surface of the battery electrode sheet, which can effectively inhibit further increasement in the temperature of the battery on the one hand and can passivate an active coating of a cathode and an anode of the battery on the other hand, thereby, controlling the safety risk of the battery at root and ensuring the safety of the battery.