Electrolyte Additive Composition for Stable Li-Ion Electrode Interfaces
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Solution Overview
Problem
Current electrochemical devices, such as lithium-ion batteries, face challenges in maintaining cycle performance and high-temperature storage performance due to the oxidative decomposition of electrolyte solutions by high-valent transition metals, leading to gas production and impaired performance.
Innovation Solution
An electrolyte solution containing a compound with multiple cyano groups, a sulfur-oxygen double bond-containing compound, and other additives is introduced to stabilize the positive electrode interface, suppress electrolyte decomposition, and enhance the stability of both electrode interfaces, thereby improving cycle and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mass percentage of the compound represented by Formula I is increased to improve cycle performance and high-temperature storage performance, then the stability of electrode interfaces is improved, but the viscosity of the electrolyte solution becomes overly high which impairs performance
Solution Approach 1:
The patent optimizes the mass percentage of the compound represented by Formula I to a specific range (0.01% to 5%, preferably 0.1% to 3%) based on the mass of the electrolyte solution. This parameter optimization ensures that the compound provides sufficient protection to the electrode interfaces and stabilizes high-valent transition metals without causing the electrolyte solution viscosity to become excessively high, thereby resolving the contradiction between improving reliability and maintaining compositional stability.
2Reliability
If the mass percentage of the sulfur-oxygen double bond-containing compound is increased to improve interface stability, then the protection effect is enhanced, but the viscosity and impedance increase excessively which impairs kinetics
Solution Approach 1:
The patent specifies that the mass percentage of the sulfur-oxygen double bond-containing compound in the electrolyte solution should be controlled within the range of 0.01% to 10%, preferably 0.1% to 5%. This parameter control ensures that the compound provides adequate protection to both positive and negative electrode interfaces while preventing excessive increase in viscosity and impedance, thus maintaining good kinetic performance and resolving the contradiction between interface stability and compositional stability.
3Device complexity
If conventional electrolyte solutions are used, then the device structure is simple, but the electrolyte decomposes oxidatively leading to gas production and poor cycle performance
Solution Approach 1:
The patent creates a composite electrolyte solution by combining conventional electrolyte components with specific additives: a compound represented by Formula I containing cyano groups for stabilizing high-valent transition metals, and a sulfur-oxygen double bond-containing compound for protecting electrode interfaces. This composite formulation suppresses oxidative decomposition of the electrolyte, reduces gas production, and improves cycle performance while maintaining relatively simple device structure.
Solution Approach 2:
The compound represented by Formula I and the sulfur-oxygen double bond-containing compound act as intermediary substances that mediate between the electrode interfaces and the bulk electrolyte. These intermediaries form protective films on the electrode surfaces and stabilize high-valent transition metals, preventing direct contact and oxidative decomposition between the electrolyte and electrodes, thereby improving reliability without significantly complicating the overall device structure.
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 electrolyte solution significantly enhances the cycle performance and high-temperature storage performance of electrochemical devices by stabilizing the high-valent transition metal and reducing gas production, while maintaining optimal viscosity and kinetic performance.
Implementation Method 1
A plurality of cyano groups (—CN) in the compound represented by Formula I can stabilize the high-valent transition metal in a positive electrode
Implementation Method 2
The compound represented by Formula I can also be reduced at a negative electrode to protect a negative electrode interface and play a role in suppressing continuous decomposition of the electrolyte solution and suppressing gas production
Implementation Method 3
The sulfur-oxygen double bond-containing compound is strongly resistant to oxidation and can improve the stability of the positive electrode interface
Implementation Method 4
the sulfur-oxygen double bond-containing compound can be reduced on the surface of the negative electrode to form a protection film to suppress the decomposition of the electrolyte solution
Data Source
AI summary
An electrolyte solution includes a compound represented by Formula I:where m, n, k, and x are each independently selected from 1, 2, or 3; R11 and R12 are each independently selected from hydrogen, halogen, substituted or unsubstituted C1 to C3 alkyl, substituted or unsubstituted C2 to C4 alkenyl, substituted or unsubstituted C2 to C4 alkynyl, or substituted or unsubstituted C6 to C10 aryl, wherein when substituted, a substituent is independently selected from halogen. The multi-cyano (—CN) compound represented by Formula I is introduced into the electrolyte solution, so that the multi-cyano group can stabilize a transition metal in a positive active material and protect a positive electrode interface. The compound represented by Formula I can also be reduced at a negative electrode to protect a negative electrode interface and play a role in suppressing continuous decomposition of the electrolyte solution and suppressing gas production.