Lithium-Ion Battery Electrolyte Stabilizing High-Nickel Interface
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Solution Overview
Problem
High nickel ternary materials and increased charging voltage in lithium-ion batteries lead to instability at the positive electrode/electrolyte interface, causing oxidation and decomposition of the electrolyte, which results in poor cycle performance and power degradation due to gas generation and interface impedance issues.
Innovation Solution
An electrolyte solution comprising a primary lithium salt with a fluorine-containing sulfonimide structure and an additive that decomposes into sulfur-containing compounds, reducing reactive activity at the positive electrode and forming a protective film to inhibit decomposition and corrosion, thereby stabilizing the interface and improving power and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel ternary materials are used to improve energy density, then battery energy density is improved, but the positive electrode/electrolyte interface stability deteriorates causing electrolyte oxidation and decomposition
Solution Approach 1:
A lithium salt comprising a fluorine-containing sulfonimide compound is introduced as an intermediary substance in the electrolyte. This lithium salt acts as a mediator that forms a stable protective film at the positive electrode/electrolyte interface, preventing direct contact and harmful reactions between the high nickel ternary material and the electrolyte, thus resolving the contradiction between achieving high energy density and maintaining interface stability
Solution Approach 2:
The chemical composition parameters of the electrolyte are changed by incorporating a specific lithium salt with fluorine-containing sulfonimide structure. This parameter change modifies the interface properties and forms a stable protective layer, enabling the system to maintain stability while operating with high nickel content electrodes for improved energy density
2Quantity of substance
If charging voltage is increased to improve energy density, then battery energy density is improved, but electrolyte oxidation and decomposition are accelerated
Solution Approach 1:
The fluorine-containing sulfonimide lithium salt performs preliminary protective action by forming a stable interface film before the electrolyte can undergo oxidation and decomposition at high voltages. This pre-formed protective layer prevents the harmful effects of high voltage charging, allowing energy density improvement without accelerating electrolyte decomposition
Solution Approach 2:
The lithium salt with fluorine-containing sulfonimide serves as an intermediary that buffers the direct interaction between the high voltage electric field and the electrolyte. This mediator protects the electrolyte from oxidation and decomposition even when charging voltage is increased to improve energy density
3Ease of manufacture
If conventional lithium salts are used, then cost is reduced, but high-temperature storage performance and power performance deteriorate
Solution Approach 1:
The chemical structure parameters of the lithium salt are changed from conventional options to a fluorine-containing sulfonimide compound. This parameter change enhances thermal stability and high-temperature storage performance while maintaining reasonable manufacturing feasibility, resolving the contradiction between cost and 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 enhances the power performance and high-temperature storage gas production of lithium-ion batteries, particularly those with high nickel systems operating at high charging voltages, by stabilizing the electrolyte and reducing gas generation and interface impedance.
Implementation Method 1
the by-products produced by oxidation and decomposition of electrolytic solution will cover the electrode/electrolytic solution interface, causing the solid electrolytic solution interface (SEI) film to continue to thicken
Implementation Method 2
the positive electrode/electrolytic solution interface is unstable, resulting in continuous oxidation and decomposition of the electrolytic solution on the positive electrode
Implementation Method 3
the additive includes a second compound represented by the following formula II... which decomposes into sulfur-containing compounds
Implementation Method 4
stabilizing the interface and improving power and high-temperature storage performance
Data Source
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Figure 3~4
AI summary
The present application relates to an electrolytic solution including an organic solvent, a lithium salt and an additive, wherein the lithium salt comprises a primary lithium salt, the primary lithium salt is a first compound in an amount of 30% or more relative to the total molar amount of the lithium salt, and the first compound has a structure represented by the following formula I, and wherein the additive comprises a second compound represented by the following formula II. The present application further relates to a lithium ion battery comprising the electrolytic solution, especially those especially in the form of a high-nickel system.