High-Nickel Lithium Secondary Battery Electrolyte for Wetting and Cycle Life
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in securing sufficient capacity and cycle characteristics due to the dissolution of transition metals in high-nickel-based positive electrode active materials, exacerbated by insufficient electrolyte solution wetting and potential imbalances.
Innovation Solution
A lithium secondary battery design incorporating a non-aqueous electrolyte solution with a specific ratio of carbonate-based and fluorine-based organic solvents, along with a high-nickel-based transition metal oxide, to improve electrolyte wetting and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in the positive electrode active material is increased to improve capacity characteristics, then the energy density and capacity are improved, but the structural stability and chemical stability are reduced leading to transition metal dissolution
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by substituting nickel with manganese and aluminum, and by controlling the oxidation state of nickel to +3, thereby improving stability while maintaining capacity. The electrolyte composition is also adjusted by selecting specific carbonate solvents to resolve the contradiction between capacity and stability.
Solution Approach 2:
The patent uses composite positive electrode active materials containing multiple elements (nickel, manganese, aluminum, oxygen) in specific ratios. This composite structure combines the high capacity of nickel with the stability of manganese and aluminum, preventing transition metal dissolution while maintaining high capacity characteristics.
2Quantity of substance
If the nickel content in the positive electrode active material is increased to improve capacity characteristics, then the energy density is improved, but the dissolution of transition metal due to side reactions with the electrolyte solution occurs
Solution Approach 1:
The patent changes the chemical parameters of the positive electrode material by controlling nickel oxidation state to +3 and adjusting the Ni:Mn:Al ratio, which reduces the reactivity with electrolyte and prevents transition metal dissolution. The electrolyte composition is also optimized to minimize side reactions.
Solution Approach 2:
The patent converts the potential harm of high-nickel content (prone to dissolution) into a benefit by carefully controlling the oxidation state and combining with stabilizing elements. The high nickel content provides high capacity, while the controlled composition prevents dissolution, turning a problematic feature into an advantageous one.
3Quantity of substance
If high-nickel-based transition metal oxide is used to improve capacity characteristics, then the energy density is improved, but the cycle characteristics at room temperature deteriorate due to insufficient electrolyte solution wetting
Solution Approach 1:
The patent changes the electrolyte parameters by selecting specific carbonate-based solvents and adjusting their proportions to achieve optimal wetting of the high-nickel positive electrode. This improves ion transport and ensures uniform electrolyte distribution, thereby improving cycle characteristics at room temperature while maintaining high capacity.
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 improved electrolyte solution and positive electrode composition enhance the battery's room-temperature cycle characteristics and capacity, minimizing structural collapse and transition metal dissolution.
Implementation Method 1
improve electrolyte wetting and stability
Implementation Method 2
a non-aqueous electrolyte solution containing a lithium salt
Implementation Method 3
a positive electrode including a lithium transition metal oxide
Data Source
AI summary
A lithium secondary battery is disclosed herein. In some embodiments, a lithium secondary battery includes a positive electrode including a lithium transition metal oxide represented by Formula 1, a negative electrode, a non-aqueous electrolyte solution containing a lithium salt, a first non-aqueous solvent, and a second non-aqueous solvent, and a separator, wherein the first non-aqueous solvent is a carbonate-based organic solvent, the second non-aqueous solvent is a fluorine-based organic solvent, and a volume ratio of the first non-aqueous solvent to the second non-aqueous solvent is in a range of 5:5 to 9:1.