Fluorinated Electrolyte Additives for High-Temperature Li-Ion Batteries
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Solution Overview
Problem
Current lithium ion batteries face issues with high-temperature performance degradation due to electrolyte decomposition and intensified side reactions at high voltages, leading to battery swelling, capacity decay, and poor cycle performance.
Innovation Solution
An electrolyte composed of a fluorinated solvent with a specific content of tetravinylsilane (TVSI) and optionally 1-propene-1,3-sultone, forming a silicon-rich CEI film on the positive electrode side, which enhances oxidation stability and thermal stability, reducing side reactions and gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery voltage is increased to improve energy density, then the energy density is improved, but the oxidation activity of the positive electrode material increases and the electrolyte is susceptible to decomposition
Solution Approach 1:
The patent introduces fluorinated solvents (FEMC and FEC) to replace traditional carbonate solvents, changing the chemical composition parameters of the electrolyte. The fluorinated solvents have higher oxidation stability and can withstand high voltage conditions while maintaining good ionic conductivity, thus resolving the contradiction between energy density improvement and electrolyte stability
Solution Approach 2:
The patent uses a composite electrolyte system combining fluorinated solvents (FEMC+FEC) with specific additives (TVSI and 1-propene-1,3-sultone). This composite formulation creates synergistic effects where the fluorinated solvents provide high voltage stability while the additives form protective interface films, enabling both high energy density and electrolyte reliability
2Productivity
If the battery operates at high temperature, then the reaction rate is improved, but the side reactions of the electrolyte are intensified causing rapid battery swelling and capacity decay
Solution Approach 1:
The patent employs TVSI and 1-propene-1,3-sultone additives that react in advance to form stable protective films (CEI and SEI) on the electrode surfaces before high-temperature operation begins. These pre-formed films act as barriers that prevent subsequent decomposition reactions and gas generation, allowing the battery to maintain good cycle performance even at high temperatures
Solution Approach 2:
The patent converts the potentially harmful side reactions into beneficial effects by using controlled decomposition of TVSI and 1-propene-1,3-sultone to form stable protective films. The initial controlled reaction products create a stable interface that prevents further harmful decomposition, thus converting what would be harmful side reactions into protective mechanisms
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 improves high-voltage resistance and high-temperature storage and cycle performance by inhibiting electrolyte decomposition and reducing direct current resistance (DCR) in lithium ion batteries.
Implementation Method 1
The strong electron-withdrawing ability of fluorine atoms is beneficial for the electrolyte to have high oxidation stability
Implementation Method 2
the specific content of the TVSI forms a CEI film rich in silicon element on the positive electrode side
Implementation Method 3
The CEI film has good thermal stability and is not easily swollen, which may reduce side reactions between the electrolyte and the positive electrode material at high temperatures
Data Source
AI summary
Disclosed are an electrolyte and a battery including the same. The electrolyte includes a solvent, a lithium salt, and an additive. The solvent is composed of a fluorinated solvent. The additive includes tetravinylsilane (TVSI). Based on a total mass of the electrolyte, a content of the TVSI is 0.01% to 1%. The fluorinated solvent in combination with a specific content of the TVSI is used in the electrolyte, so that the battery has excellent high-temperature storage capacity performance and high-temperature cycle performance when showing good performance of high-voltage resistance.