Lithium Battery Electrolyte Additives for High-Temperature Stability
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Solution Overview
Problem
Rechargeable lithium batteries using transition metal oxides as positive electrodes experience deterioration in cycle-life and storage characteristics, especially at high temperatures, when employing electrolyte solutions containing hydrofluoroether.
Innovation Solution
Incorporating specific additives, such as disilane compounds, unsaturated phosphoric acid esters, and other electrolyte components into the electrolyte solution, including hydrofluoroether, to enhance the oxidation resistance and stability of the battery, thereby forming a dense passivation film that reduces contact between the positive active material and the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydrofluoroether is used in the electrolyte solution for a rechargeable lithium battery with transition metal oxide positive electrode, then the battery can operate at high voltage, but the cycle-life and storage characteristics deteriorate especially at high temperatures
Solution Approach 1:
The patent introduces specific additives (sulfone compounds and carboxylate compounds) as intermediaries between the hydrofluoroether electrolyte and the transition metal oxide positive electrode. These additives form protective films that mediate the interaction, preventing direct harmful reactions while allowing ionic conduction, thus resolving the contradiction between maintaining high voltage operation and improving cycle-life/storage characteristics
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding specific sulfone compounds (0.01-5 wt%) and carboxylate compounds (0.01-5 wt%) to the hydrofluoroether base. This parameter modification transforms the electrolyte's properties, enabling it to form stable protective films that improve reliability without sacrificing the high voltage capability provided by hydrofluoroether
2Power
If conventional transition metal oxide is used as positive electrode material to realize high voltage battery, then the battery achieves high power, but the cost is lower compared to solid solution oxide, while cycle-life and high-temperature storage characteristics deteriorate
Solution Approach 1:
The patent uses sulfone compounds and carboxylate compounds as intermediary substances that form protective interfacial films between the conventional transition metal oxide positive electrode and the hydrofluoroether electrolyte. This intermediary layer prevents direct degradation reactions, enabling conventional materials to achieve reliability comparable to or exceeding solid solution oxides while maintaining high voltage and lower cost
3Power
If hydrofluoroether is used in the electrolyte solution, then the battery can achieve high voltage operation, but high-resistance passivation films form and gas generation increases, reducing capacity retention
Solution Approach 1:
The patent introduces sulfone compounds and carboxylate compounds as intermediary substances that preferentially react with hydrofluoroether to form stable, low-resistance protective films. This intermediary action prevents the formation of high-resistance passivation films and reduces gas generation, thereby maintaining capacity retention while preserving high voltage operation capability
Solution Approach 2:
The patent converts the potentially harmful decomposition of hydrofluoroether into a beneficial process by controlling it through additive-mediated reactions. The controlled decomposition forms protective films rather than harmful passivation layers, and gas generation is redirected into useful film formation, thus transforming the harmful effects of hydrofluoroether into benefits for capacity retention
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 significantly improves the cycle-life and storage characteristics of rechargeable lithium batteries at high temperatures by reducing the formation of high-resistance passivation films and gas generation, leading to increased capacity retention and reduced volume changes.
Implementation Method 1
forming a dense passivation film that reduces contact between the positive active material and the electrolyte
Implementation Method 2
Incorporating specific additives, such as disilane compounds, unsaturated phosphoric acid esters, and other electrolyte components into the electrolyte solution, including hydrofluoroether, to enhance the oxidation resistance and stability of the battery
Data Source
AI summary
A rechargeable lithium battery includes: a positive electrode including a positive active material; and an electrolyte solution including a solvent and an additive, wherein the positive active material includes a lithium-containing transition metal oxide, the solvent includes a hydrofluoroether, and the additive includes a first additive represented by Chemical Formula 1 and at least one selected from a second additive represented by Chemical Formula 2, a third additive represented by Chemical Formula 3, and a fourth additive represented by Chemical Formula 4.