Imide-Salt Electrolyte for Cobalt-Free Lithium Battery Cathodes
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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, increased resistance, and deteriorated cycle-life due to electrolyte decomposition and side reactions.
Innovation Solution
A rechargeable lithium battery design incorporating a cobalt-free lithium nickel manganese-based oxide positive electrode combined with an electrolyte solution containing a non-aqueous organic solvent, a first lithium salt, and an imide-based lithium salt, specifically bis sulfonyl imide-based lithium salts, to reduce transition metal elution and structural collapse, thereby 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 an imide-based lithium salt (LiFSO3) as an intermediary substance in the electrolyte that mediates between the positive electrode and electrolyte. This intermediary forms a protective interface layer that prevents direct contact and harmful reactions, thereby stabilizing the positive electrode structure without compromising the cost benefits of cobalt-free materials
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating imide-based lithium salt (LiFSO3) at specific concentrations (0.5-2.0 M). This parameter change modifies the electrolyte's chemical properties to provide enhanced structural stabilization for the cobalt-free positive electrode under high-voltage conditions
2Use of energy by moving object
If high-voltage charging is applied to increase energy density, then energy density is improved, but electrolyte decomposition occurs and transition metal elution increases
Solution Approach 1:
The patent converts the harmful high-voltage stress that causes electrolyte decomposition into a beneficial effect by using it to form a stable protective film on the positive electrode surface. The imide-based lithium salt facilitates this conversion, where the initially harmful high-voltage environment creates a protective interface layer that subsequently prevents further decomposition and metal elution
3Power
If high-temperature operation is tolerated to improve power output, then power characteristics are improved, but transition metal precipitation on negative electrode increases and cycle-life deteriorates
Solution Approach 1:
The patent performs preliminary action by forming a stable protective interface layer on the positive electrode before high-temperature operation begins. The imide-based lithium salt ensures this protective layer is established in advance, preventing transition metal elution and subsequent precipitation on the negative electrode during high-temperature power delivery, thereby preserving cycle-life
4Device complexity
If conventional electrolyte composition is used to maintain simplicity, then device complexity is reduced, but high-voltage and high-temperature characteristics deteriorate
Solution Approach 1:
The patent applies local quality by modifying only the specific local composition of the electrolyte - adding imide-based lithium salt (LiFSO3) at optimized concentrations (0.5-2.0 M). This localized compositional change provides targeted high-voltage and high-temperature stability without fundamentally redesigning the entire electrolyte system, maintaining relative simplicity while improving reliability
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 effectively suppresses gas generation, capacity deterioration, and resistance increase, improving battery stability and cycle-life characteristics by preventing structural collapse and electrolyte decomposition, while maintaining high ion conductivity and phase transition safety.
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 and thereby to suppress or reduce structural collapse
Implementation Method 2
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 and thereby to suppress or reduce structural collapse of the positive electrode
Data Source
AI summary
Provided is a rechargeable lithium battery including an electrolyte solution including a non-aqueous organic solvent, a first lithium salt, and an imide-based lithium salt; a positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material, wherein the non-aqueous organic solvent contains less than about 5 wt % of ethylene carbonate based on the total weight of the non-aqueous organic solvent, and the positive electrode active material includes a cobalt-free lithium nickel manganese-based oxide.