Nitrile Benzoquinone Electrolyte for High-Voltage Cathode Stability
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Solution Overview
Problem
Lithium ion batteries face challenges with increased voltage, leading to side reactions between the cathode and electrolyte, particle surface layer deactivation, increased impedance, and rapid capacity fading due to electrolyte oxidation and by-product formation.
Innovation Solution
The development of an electrolyte containing nitrile benzoquinone compounds, which inhibit oxidation reactions at the cathode interface, forming a stable protective film and improving battery capacity retention and reducing gas generation during high temperature cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the voltage platform of lithium ion batteries is increased to meet high energy density demands, then energy density is improved, but side reactions between the cathode and electrolyte become more serious, leading to increased impedance and capacity fading
Solution Approach 1:
The patent introduces a coating layer comprising a metal oxide or metal oxyfluoride on the cathode surface as an intermediary substance. This coating layer acts as a mediator between the cathode and electrolyte, preventing direct harmful interactions while allowing beneficial electrochemical reactions to proceed, thereby resolving the contradiction between high voltage operation and battery reliability
Solution Approach 2:
The patent modifies the surface properties of the cathode by changing its chemical composition through the coating layer. This parameter change in the cathode surface chemistry enables it to withstand higher voltages without undergoing detrimental phase changes or reacting with the electrolyte, thus maintaining capacity retention at elevated voltage platforms
2Use of energy by moving object
If the voltage platform is increased to improve energy density, then energy density is improved, but the particle surface layer of the cathode undergoes phase change and is deactivated, resulting in increased impedance
Solution Approach 1:
The metal oxide or metal oxyfluoride coating layer serves as a protective intermediary that prevents the cathode surface from undergoing phase changes at high voltages. This coating stabilizes the surface structure and prevents deactivation, allowing the cathode to operate at higher voltages without suffering from surface layer degradation
Solution Approach 2:
The patent creates a composite structure by combining the cathode material with a metal oxide or metal oxyfluoride coating layer. This composite material approach allows the cathode to benefit from the high voltage stability of the coating while maintaining the high capacity characteristics of the underlying cathode material
3Use of energy by moving object
If the voltage platform is increased to improve energy density, then energy density is improved, but the electrolyte oxidizes on the cathode surface to form by-products, resulting in increased impedance and rapid capacity fading
Solution Approach 1:
The metal oxide or metal oxyfluoride coating layer acts as a physical and chemical barrier that prevents the electrolyte from contacting and oxidizing at the cathode surface. This intermediary layer suppresses electrolyte decomposition reactions and prevents the formation of harmful by-products, thereby eliminating the source of impedance increase and capacity fading
Solution Approach 2:
The patent converts the potentially harmful high voltage conditions that cause electrolyte oxidation into a beneficial situation by using the coating layer to suppress these side reactions. The coating transforms the high voltage environment from a source of harm into an operational condition that can be sustained without degradation
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 proposed electrolyte effectively enhances battery capacity retention and reduces impedance, improving both cycle and storage performance of lithium ion batteries, especially under high temperature conditions.
Implementation Method 1
the nitrile benzoquinone compound is not easily oxidized and can also undergo a complexation reaction with active ions, so that the electrolyte can form an SEI film having lower impedance and higher stability on the cathode and the anode
Implementation Method 2
the nitrile benzoquinone compound is not easily oxidized and can also undergo a complexation reaction with active ions, so that the electrolyte can form an SEI film having lower impedance and higher stability on the cathode and the anode
Data Source
AI summary
An electrolyte including one or more nitrile benzoquinone compounds, and the nitrile benzoquinone compound is selected from the group consisting of the compounds represented by formula I, formula II, and formula III:The substituents R1 to R9 are each independently selected from the group consisting of hydrogen, a C2 to C12 ether group, a C1 to C12 alkoxy group, halogen, a C1 to C12 alkyl group, a C2 to C12 alkenyl group, a C2 to C12 alkynyl group, and a C6 to C26 aryl group. The electrolyte can form a stable protective film on a cathode, thereby increasing the cycle capacity retention rate and high temperature storage performance of an electrochemical device.