Negative Electrode Sheet Heat-Release Profile for Thermal Runaway Control
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Solution Overview
Problem
Current secondary batteries, such as lithium-ion and sodium-ion batteries, face significant safety concerns due to thermal runaway, which can lead to smoking, combustion, and explosion. Specifically, the exothermic characteristics and indexes of carbon material negative electrodes, particularly graphite, remain unclear, making it challenging to develop safe negative active materials that can prevent thermal runaway.
Innovation Solution
A negative electrode sheet is developed, comprising a current collector and a negative active material layer with a specific particle diameter and/or specific surface area. The negative active material layer exhibits a controlled heat release profile when analyzed using differential scanning calorimetry (DSC), with defined exothermic peaks to ensure appropriate solid electrolyte interface (SEI) formation and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional secondary batteries are used to achieve high energy density, then energy storage capacity is improved, but thermal safety deteriorates due to thermal runaway risks
Solution Approach 1:
The patent applies parameter changes by precisely controlling the heat release characteristics of the negative active material layer across different temperature ranges. By adjusting the exothermic peak parameters (first peak at 120-150°C with 2-50 J/g, second peak at 220-260°C with 20-100 J/g, third peak at 260-310°C with 200-600 J/g), the invention modifies the thermal behavior of the battery to prevent thermal runaway while maintaining high energy density.
Solution Approach 2:
The patent implements beforehand cushioning by designing a negative active material layer with controlled exothermic peaks that act as thermal buffers. The first and second exothermic peaks at lower temperatures serve as preliminary heat absorption mechanisms that prevent the third peak from triggering thermal runaway, thereby cushioning against catastrophic failure before it occurs.
2Quantity of substance
If negative active material is used to achieve high capacity, then battery capacity is improved, but thermal stability deteriorates due to uncontrolled exothermic reactions
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for exothermic peak temperatures and heat release quantities. The negative active material layer is designed to exhibit three distinct exothermic peaks with controlled parameters: first peak (120-150°C, 2-50 J/g), second peak (220-260°C, 20-100 J/g), and third peak (260-310°C, 200-600 J/g). This precise parameter control enables high capacity while maintaining thermal stability.
3Use of energy by moving object
If high energy density materials are used, then energy storage is improved, but heat release control deteriorates leading to thermal runaway
Solution Approach 1:
The patent applies segmentation by dividing the heat release process into three distinct exothermic peaks at different temperature ranges. Instead of a single uncontrolled exothermic reaction, the negative active material layer exhibits segmented thermal behavior: first peak (120-150°C), second peak (220-260°C), and third peak (260-310°C). This segmentation allows for controlled energy release and prevents catastrophic thermal runaway.
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 negative electrode sheet with the controlled heat release profile significantly enhances the high-temperature stability of the negative electrode, preventing excessive heat buildup and thereby avoiding thermal runaway. This ensures the battery maintains low heat release across various temperature ranges, preventing spontaneous combustion or explosion.
Implementation Method 1
a differential scanning calorimeter (DSC) curve of the negative active material layer includes: a first exothermic peak from 120° C. to 150° C., in which the negative active material layer has heat release A1 satisfying 2 J/g≤A1≤50 J/g; a second exothermic peak from 220° C. to 260° C., in which the negative active material layer has heat release A2 satisfying 20 J/g≤A2≤100 J/g; and a third exothermic peak from 260° C. to 310° C., in which the negative active material layer has heat release A3 satisfying 200 J/g≤A3≤600 J/g
Implementation Method 2
When a state of charge (SOC) of a battery with the negative electrode sheet is 100% or a voltage of the battery is 3.65V, a differential scanning calorimeter (DSC) curve of the negative active material layer includes
Data Source
AI summary
A negative electrode sheet, a battery, and an electricity-consumption device are disclosed. The negative electrode sheet includes a current collector and a negative active material layer. When a state of charge of a battery is 100% or a voltage of the battery is 3.65 V, a differential scanning calorimeter curve of the negative active material layer includes: a first exothermic peak from 120° C. to 150° C., in which the negative active material layer has heat release A1 satisfying 2J/gSA1≤50 J/g; a second exothermic peak from 220° C. to 260° C., in which the negative active material layer has heat release A2 satisfying 20J/g≤A2≤100 J/g; and a third exothermic peak from 260° C. to 310° C., in which the negative active material layer has heat release A3 satisfying 200J/g≤A3≤600J/g.