Low-EC Electrolyte Additive for Cobalt-Free Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries using cobalt-free lithium nickel manganese-based oxide positive electrodes face structural instability and transition metal elution under high voltage and high temperature conditions, leading to capacity reduction, gas generation, and increased battery resistance.
Innovation Solution
A rechargeable lithium battery design incorporating a non-aqueous organic solvent with less than 5 wt% ethylene carbonate and an additive represented by Chemical Formula 1, which includes a compound with a substituted or unsubstituted C3 to C6 heteroaryl group, effectively reduces transition metal elution and structural collapse, enhancing high-voltage and high-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cobalt-free lithium nickel manganese-based oxide is used as positive electrode active material to reduce cost and increase energy density, then manufacturing cost is reduced and energy density is improved, but structural stability deteriorates and transition metal elution increases under high voltage conditions
Solution Approach 1:
The patent introduces a specific electrolyte additive (compound of formula 1 with heteroaryl group) as an intermediary substance that mediates between the positive electrode material and the electrolyte. This additive forms a protective interface layer that prevents direct contact and chemical reactions between the electrolyte and the unstable cobalt-free lithium nickel manganese-based oxide, thereby reducing transition metal elution while maintaining the cost advantages of the cobalt-free material
Solution Approach 2:
The patent modifies the electrolyte composition parameters by controlling the ethylene carbonate content to less than 5 wt% and incorporating specific additives with heteroaryl groups. These parameter changes in the electrolyte formulation enhance the stability of the cobalt-free lithium nickel manganese-based oxide without compromising the manufacturing cost benefits
2Use of energy by moving object
If operating voltage is increased to expand voltage region and increase energy density, then energy density is improved, but electrolyte oxidation and positive electrode deterioration occur
Solution Approach 1:
The electrolyte additive (formula 1 compound) acts as a mediator that enables high voltage operation by forming a protective interface layer. This layer prevents direct oxidation of the electrolyte by the high voltage potential while protecting the positive electrode from deterioration, thus allowing energy density improvement through voltage expansion without sacrificing reliability
3Power
If high temperature operation is performed to increase power output, then power characteristics are improved, but transition metal elution is aggravated and side reactions increase
Solution Approach 1:
The heteroaryl-containing electrolyte additive serves as a thermal protective intermediary that becomes particularly effective at high temperatures. It forms a stable protective layer that prevents thermal-induced transition metal elution and suppresses side reactions between eluted metals and the negative electrode, enabling high temperature operation with improved power characteristics without the harmful effects of metal elution
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 improves battery stability and cycle-life characteristics by suppressing structural collapse and gas generation, while reducing internal resistance and maintaining performance under high temperature and voltage conditions.
Implementation Method 1
an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive
Data Source
AI summary
A rechargeable lithium battery is provided, the rechargeable lithium battery including an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive; positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material, wherein the non-aqueous organic solvent includes less than about 5 wt % of ethylene carbonate based on a total weight of the non-aqueous organic solvent, the positive electrode active material includes lithium nickel manganese-based oxide, and the additive is represented by Chemical Formula 1.Chemical Formula 1 is as defined in the specification.