Lithium Battery Electrolyte Additive for High-Voltage Gas Suppression
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Solution Overview
Problem
Current lithium batteries face issues with gas generation and performance deterioration at high voltages, leading to safety concerns and reduced cycling capacity, especially at high and low temperatures, due to the oxidative decomposition of electrolytes.
Innovation Solution
An electrolyte additive, represented by a specific sulfone or sulfoxide compound, forms a passivation layer on the cathode and anode surfaces, inhibiting gas generation and enhancing cycling stability at high voltages and temperatures, while maintaining lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating voltage of the battery is increased to increase energy density, then the energy density is improved, but the electrolyte undergoes oxidative decomposition and generates gas, resulting in performance deterioration
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the high-voltage cathode and the electrolyte. This compound preferentially reacts with the cathode material to form a stable interfacial film that acts as a protective barrier, preventing direct contact and oxidative decomposition between the electrolyte and cathode at high voltages, thus enabling safe operation at elevated voltages while maintaining high energy density
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds (such as fluoroethylene carbonate or difluorocyclopropene) at specific concentrations (0.1-5 wt%). This parameter change alters the electrochemical window and stability characteristics of the electrolyte system, enabling it to withstand higher operating voltages without decomposition, thereby resolving the contradiction between energy density and electrolyte stability
2Reliability
If sulphone compounds are added as additives to improve high voltage performance, then the electrolyte stability is improved, but no suitable sulphone additive has been found to achieve sufficiently satisfactory effect
Solution Approach 1:
The patent transitions from using conventional sulphone additives to fluorinated cyclic carbonate compounds by changing the chemical structure parameters (introducing fluorine atoms and cyclic carbonate groups). This parameter change fundamentally alters the additive's reactivity, film-forming capability, and electrochemical stability, achieving superior high-voltage performance that sulphone compounds could not attain
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorinated cyclic carbonate compounds with traditional lithium salts and solvents. This composite approach leverages the unique properties of the fluorinated additive (high electrochemical stability, low reactivity) complemented by conventional electrolyte components, achieving synergistic effects that improve overall high-voltage performance beyond what single-component systems can provide
3Productivity
If the electrolyte is oxidatively decomposed at high voltage, then gas is generated, but the cycling stability and safety performance deteriorate
Solution Approach 1:
The fluorinated cyclic carbonate compound performs preliminary action by preferentially reacting with the cathode surface during initial cycles to form a stable protective film before the electrolyte can undergo oxidative decomposition. This preliminary film formation prevents subsequent gas-generating decomposition reactions, maintaining cycling stability and preventing harmful gas generation throughout battery operation
Solution Approach 2:
The patent converts the potentially harmful oxidative decomposition reaction into a beneficial process by using the fluorinated additive to control and direct the reaction. The additive sacrifices itself in controlled, minimal decomposition reactions that form protective films, thereby preventing the much more harmful uncontrolled decomposition of the main electrolyte that would generate gas and degrade performance
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 additive maintains high cycling capacity retention rates and improves safety by preventing gas generation and oxidative decomposition, even at high temperatures and voltages, thus ensuring stable battery performance over hundreds of charge-discharge cycles.
Implementation Method 1
forms a passivation layer on the cathode and anode surfaces, inhibiting gas generation and enhancing cycling stability
Implementation Method 2
the operation of the lithium battery mainly depends on the movement of lithium ions (Li+) between a cathode and an anode thereof through an electrolyte
Data Source
AI summary
The present disclosure provides an additive for an electrolyte for a lithium battery, an electrolyte, and an electrochemical device. The additive includes a compound represented by the following formula I, wherein R1, R2, R3, and R4 are identical to or different from each other, and are independently selected from a group consisting of hydrogen, halogen, substituted or unsubstituted C1-C20 alkyl, and substituted or unsubstituted C6-C18 aryl, and a substituent of the substituted or unsubstituted C1-C20 alkyl or the substituted or unsubstituted C6-C18 aryl can be halogen, C1-C20 alkyl, or C6-C18 aryl; wherein denotes a single bond or a double bond; and wherein n is 1 or 2.