Negative Electrode Sheet Composition for Thermal Runaway Suppression
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Solution Overview
Problem
Secondary batteries, particularly those with carbon-material negative electrodes like graphite, face significant safety concerns due to unclear exothermic characteristics and thermal runaway issues.
Innovation Solution
A negative electrode sheet is developed with a current collector and a negative active material layer that includes a negative active material with controlled particle diameter and specific surface area. This configuration ensures a heat release within the range of 220 J/g to 600 J/g when the battery is fully charged or at a voltage of 3.65V, thereby enhancing high-temperature stability and preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon-material negative electrode (graphite) is used in secondary batteries, then high energy density and long service life are achieved, but thermal runaway and safety accidents (smoking, combustion, explosion) occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle diameter and specific surface area of the negative active material within defined ranges. This optimization of physical parameters reduces the heat release of the negative electrode to 220-600 J/g, thereby suppressing thermal runaway while maintaining high energy density performance
Solution Approach 2:
The patent uses composite materials by combining the negative active material with a coating layer containing lithium phosphate or lithium fluorophosphate. This composite structure reduces exothermic characteristics and improves high-temperature stability, preventing thermal runaway while preserving the high energy density benefits of carbon-based materials
2Productivity
If negative active material with high capacity is used, then battery performance is improved, but heat release increases leading to safety concerns
Solution Approach 1:
The patent optimizes the particle diameter to 7-15 μm and specific surface area to 0.003-0.008 m²/g, which balances capacity and heat release. This parameter optimization ensures high battery performance while limiting heat release to 220-600 J/g, preventing safety issues
Solution Approach 2:
The patent introduces a coating layer as an intermediary substance containing lithium phosphate or lithium fluorophosphate. This coating layer acts as a mediator between the negative active material and electrolyte, reducing direct exothermic reactions while maintaining electrochemical performance, thus achieving both high performance and low heat release
Data Source
AI summary
A negative electrode sheet, a secondary battery, and an electricity-consumption device are provided. The negative electrode sheet includes a negative active material layer. Heat release Q of the negative active material layer immersed in electrolyte satisfies 220 J/g≤Q≤600 J/g.