Lithium Battery Negative Electrode Functional Layer Safety
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Solution Overview
Problem
Rechargeable lithium batteries face safety risks due to internal short circuits, overcharge, and over-discharge, which can lead to thermal runaway and explosions, compromising user safety and stability.
Innovation Solution
A rechargeable lithium battery design incorporating a negative electrode with a flake-shaped polyethylene particle functional layer, a specific electrolyte solution composition of propionate-based and carbonate-based solvents, and a balanced mixture of active materials in the electrodes to enhance electrolyte impregnation and stability, including a negative electrode functional layer with flake-shaped polyethylene particles and inorganic particles, and a positive active material layer with a composite oxide and LiFePO4, to improve safety and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions and electrode structures are used, then basic battery operation is achieved, but safety risks arise due to internal short circuits and thermal runaway
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a negative electrode functional layer containing flake-shaped polyethylene particles and inorganic particles before any thermal runaway can occur. This functional layer acts as a preventive safety mechanism that will activate (melt and close pores) when temperature rises, blocking ion transport and preventing thermal runaway before it can develop into a harmful event.
Solution Approach 2:
The patent implements beforehand cushioning by creating a protective functional layer on the negative electrode that serves as a safety cushion. This layer absorbs thermal energy and provides a buffer against thermal runaway through its heat-resistant inorganic particles and melt-closing polyethylene particles, cushioning the system against catastrophic failure.
2Reliability
If standard electrode and electrolyte configurations are used, then battery assembly is simplified, but electrolyte impregnation is insufficient leading to poor cycle-life characteristics
Solution Approach 1:
The patent applies local quality by creating a specialized functional layer with specific local properties on the negative electrode. This functional layer has distinct characteristics (flake-shaped polyethylene particles for melting, inorganic particles for thermal stability) that are localized to where they are most needed - at the negative electrode interface where electrolyte impregnation and initial thermal protection occur.
Solution Approach 2:
The patent uses composite materials by combining flake-shaped polyethylene particles with inorganic particles in the negative electrode functional layer. This composite structure provides synergistic effects: the polyethylene provides melt-closing action for pore closure, while the inorganic particles provide thermal stability and heat resistance, together achieving both improved electrolyte impregnation and enhanced safety.
3Use of energy by moving object
If high energy density materials are used in electrodes, then battery capacity increases, but stability decreases making the battery more prone to exothermic reactions
Solution Approach 1:
The patent introduces an intermediary element - the negative electrode functional layer - that mediates between the high-energy-density electrode materials and the electrolyte. This functional layer with its inorganic particles and controlled pore structure acts as a buffer that allows high capacity operation while providing thermal management and stability control, preventing direct harmful interactions between active materials.
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 design effectively suppresses exothermic reactions, enhances physical and thermal stability, and improves room temperature and high-temperature cycle-life characteristics, ensuring early shut-down functionality and maintaining excellent battery performance and safety.
Implementation Method 1
the negative electrode functional layer includes flake-shaped polyethylene particles
Implementation Method 2
improves electrolyte impregnation
Implementation Method 3
a rechargeable lithium battery includes a negative electrode including a negative active material layer
Implementation Method 4
The flake-shaped polyethylene particles and the inorganic particles may be included in a weight ratio of 95:5 to 10:90
Data Source
AI summary
Rechargeable lithium battery includes a negative electrode including a negative active material layer and a negative electrode functional layer disposed on the negative active material layer; a positive electrode including a positive active material; an electrolyte solution, wherein the negative electrode functional layer includes flake-shaped polyethylene particles, the electrolyte solution includes a lithium salt and a non-aqueous organic solvent, and the non-aqueous organic solvent includes about 60 volume % to about 80 volume % of a propionate-based solvent and about 20 volume % to about 40 volume % of a carbonate-based solvent.