High-Voltage Electrolyte Additives for Cobalt-Free Lithium Batteries
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Solution Overview
Problem
Cobalt-free lithium nickel manganese-based oxide positive electrodes in rechargeable lithium batteries face structural collapse and transition metal elution at high voltage and temperature conditions, leading to capacity reduction, increased battery resistance, and deteriorated cycle-life characteristics.
Innovation Solution
A rechargeable lithium battery design incorporating a positive electrode with cobalt-free lithium nickel manganese-based oxide and an electrolyte solution containing specific additives and solvents, forming a protective layer to mitigate structural collapse and transition metal elution, thereby enhancing high-voltage and high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
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 collapse and transition metal elution occur at high voltage causing capacity reduction and performance deterioration
Solution Approach 1:
The patent applies composite materials by combining cobalt-free lithium nickel manganese-based oxide with a specifically designed electrolyte solution containing multiple additives (compounds of formulas 1A and 1B). This composite system creates a protective interface layer that stabilizes the positive electrode structure at high voltage while maintaining high energy density, resolving the contradiction between using cost-effective cobalt-free materials and preventing their structural collapse.
2Quantity of substance
If charging voltage is increased to expand voltage range for higher capacity, then energy density is improved, but electrolyte oxidization occurs causing positive electrode performance deterioration
Solution Approach 1:
The patent uses the electrolyte solution containing compounds of formulas 1A and 1B as an intermediary substance that mediates between the high-voltage positive electrode and the bulk electrolyte. This intermediary layer prevents direct contact and oxidization reactions between the electrolyte and positive electrode at high voltage (4.4-4.7V), enabling high capacity operation without electrolyte degradation.
3Power
If high temperature operation is tolerated for improved performance, then power output is improved, but transition metal precipitation on negative electrode increases causing side reactions and resistance increase
Solution Approach 1:
The patent applies beforehand cushioning by pre-forming a stable protective interface layer on the positive electrode using the electrolyte additives before high-temperature operation begins. This pre-formed protective layer acts as a barrier that prevents transition metal elution and subsequent precipitation on the negative electrode during high-temperature power output operation, cushioning against the harmful effects before they occur.
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 forming a protective layer that reduces gas generation and internal resistance, maintaining performance across high-temperature and high-voltage conditions.
Implementation Method 1
an electrolyte solution capable of effectively protecting the positive electrode including cobalt-free lithium nickel manganese-based oxide to reduce elution of transition metals under high-voltage and high-temperature conditions
Data Source
AI summary
Provided is a rechargeable lithium battery including an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive; a positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material, wherein the additive includes one or more of a compound represented by Chemical Formula 1A and a compound represented by Chemical Formula 1B, the positive electrode active material includes a lithium nickel manganese-based oxide represented by Chemical Formula 2, and a charging upper limit voltage is about 4.4 V to about 4.7 V. Chemical Formula 1A and Chemical Formula 1B are as defined in the specification.