Negative Electrode Sheet Heat Release Window for Thermal Runaway
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Solution Overview
Problem
Existing secondary batteries, particularly those with carbon-based negative electrodes, face significant challenges in managing thermal runaway due to unclear exothermic characteristics, leading to safety concerns such as combustion and explosion.
Innovation Solution
A negative electrode sheet with a negative active material layer designed to have controlled heat release (220-600 J/g) and particle diameter (6.5-10 µm) to enhance high-temperature stability, using materials like graphite, soft carbon, or hard carbon, and incorporating a binder and conductive agent to form a slurry coated on a current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon-based negative electrode materials are used to achieve high energy density, then battery capacity is improved, but thermal runaway risk increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the heat release characteristics of the negative active material layer, specifying that the heat release Q must satisfy 220 J/g ≤ Q ≤ 600 J/g. This quantitative parameter control transforms the thermal behavior of carbon-based materials from dangerous to safe, resolving the contradiction between high energy density and thermal safety.
Solution Approach 2:
The patent applies local quality by focusing the safety improvement specifically on the negative electrode's active material layer rather than the entire battery system. By controlling the heat release properties of this specific component, the patent achieves localized thermal management that prevents system-wide thermal runaway while maintaining high energy density.
2Object-affected harmful factors
If the heat release of negative active material is reduced to prevent thermal runaway, then safety is improved, but electrical performance may deteriorate
Solution Approach 1:
The patent resolves this contradiction through precise parameter optimization within the range 220 J/g ≤ Q ≤ 600 J/g. This parameter window is carefully selected to simultaneously achieve thermal safety (by limiting heat release) and maintain electrical performance (by ensuring sufficient reactivity and ion transfer). The lower bound ensures safety while the upper bound preserves electrical functionality.
Solution Approach 2:
The patent employs composite materials by combining negative active material with binder and conductive agent to form a slurry-based active material layer. This composite structure allows the material to exhibit both safe thermal characteristics and good electrical performance, as the composite formulation can be optimized to balance thermal stability with electrochemical activity.
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 solution effectively reduces the risk of thermal runaway by maintaining heat release within safe limits, ensuring high-temperature stability and safety, while preserving electrical performance and cycle life of the battery.
Implementation Method 1
the negative active material layer has a preset exothermic characteristic under preset conditions... when the state of charge of the secondary battery is 100% or a voltage of the secondary battery is 3.65 V, heat release Q of the negative active material layer immersed in electrolyte satisfies 220 J/g≤Q≤600 J/g
Data Source
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AI summary
A negative electrode sheet (100), a secondary battery (1000), and an electricity-consumption device (2000) are provided. The negative electrode sheet (100) includes a negative active material layer (10). Heat release Q of the negative active material layer (10) immersed in electrolyte (400) satisfies 220 J/g≤Q≤600 J/g.