Functional Electrolyte Solvent for Lithium-Ion Battery Overcharge Protection
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to overcharge conditions, which can lead to thermal runaway and explosion, as the weakest cell in a battery pack reaches full capacity before others, causing extra electricity to build up and react with the electrolyte, leading to unstable conditions.
Innovation Solution
A functional electrolyte solvent with specific compounds, such as 1-(2-methoxyethoxy)methoxy-4-methoxy-2,5-di-tert-butyl-benzene, is used in combination with an alkali metal salt and a polar aprotic solvent to provide overcharge protection by shunting extra electricity through reversible redox reactions, maintaining the cell's stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery capacity is increased to store more energy, then the energy storage capability is improved, but the system becomes more thermodynamically unstable and safety issues arise
Solution Approach 1:
A functional electrolyte solvent with redox potential of 3-5 V versus Li/Li+ is introduced as an intermediary substance between the electrodes. This mediator undergoes reversible redox reactions to shunt extra electricity during overcharge conditions, preventing direct harmful reactions between the electrolyte and electrode materials, thus maintaining system stability while enabling higher energy storage capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific functional solvents with controlled redox potentials. By adjusting the concentration of the functional electrolyte solvent (0.0005 wt% to 60 wt%) and selecting compounds with appropriate redox potentials (3-5 V versus Li/Li+), the system achieves both high energy storage capacity and enhanced safety through parameter optimization
2Use of energy by moving object
If the charging continues beyond full capacity, then more energy is forced into the cell, but extra electricity builds up on the electrode surface and triggers harmful reactions
Solution Approach 1:
The functional electrolyte solvent is pre-configured in the battery system with a redox potential higher than the operating voltage but within the electrochemical stability window. Before harmful oxidation reactions can occur, the functional solvent undergoes preliminary redox reactions to consume excess electricity, thereby preventing the electrolyte oxidation and other harmful reactions that would otherwise be triggered by overcharging
Solution Approach 2:
The patent converts the potentially harmful overcharge condition into a beneficial protective mechanism. The excess electricity that would normally cause harmful electrolyte oxidation is instead channeled through reversible redox reactions of the functional solvent. The harmful overcharge energy is transformed into a protective redox process that maintains battery safety while allowing continued energy input
3Device complexity
If the voltage monitor of the charger is used to detect full charge, then the charging control is simplified, but the weakest cell cannot be detected and overcharge protection is not activated
Solution Approach 1:
The battery system achieves self-service overcharge protection through the intrinsic redox activity of the functional electrolyte solvent. Each cell contains its own protective mechanism that automatically activates based on its individual charge state, eliminating the need for complex external monitoring systems to detect the weakest cell. The functional solvent serves itself as both the charge carrier and the protection mechanism
Solution Approach 2:
The functional electrolyte solvent acts as an intermediary between the charger's simple voltage monitoring system and the actual charge state of individual cells. While the charger monitors overall pack voltage, the functional solvent in each cell independently responds to local overcharge conditions through redox reactions, bridging the gap between simplified external control and precise individual cell protection
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 proposed solution effectively prevents overcharge-induced instability by activating redox protection, ensuring safe operation and extended cycle life of lithium-ion batteries by managing excess electrical charge, thereby preventing thermal runaway and maintaining battery health.
Implementation Method 1
provide overcharge protection by shunting extra electricity through reversible redox reactions
Data Source
AI summary
Functional electrolyte solvents include compounds having at least one aromatic ring with 2, 3, 4 or 5 substituents, at least one of which is a substituted or unsubstituted methoxy group, at least one of which is a tert-butyl group and at least one of which is a substituted or unsubstituted polyether or poly(ethylene oxide) (PEO) group bonded through oxygen to the aromatic ring, are provided.