Lithium-Ion Battery Electrolyte Additives for Extreme Temperature Performance
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining performance under extreme temperature conditions, as conventional electrolytes either deteriorate high-temperature performance or low-temperature performance, and existing additives either improve high-temperature performance at the expense of low-temperature performance or vice versa.
Innovation Solution
An electrolyte composition comprising an organic solvent, an electrolyte lithium salt, a first additive selected from specific sulfur-containing compounds, and a second additive such as silylphosphite or silylborate compounds, which synergistically enhance both high-temperature and low-temperature performance by forming stable interface films and reducing impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional film-forming additives are introduced to passivate the positive electrode, then high-temperature performance is improved, but low-temperature power performance deteriorates due to increased impedance
Solution Approach 1:
The patent changes the chemical structure parameters of the film-forming additive by introducing specific sulfur-containing groups (such as -S(=O)2-, -O-S(=O)2-O-, etc.) and controlling the carbon chain length (1-10 atoms), which modifies the film formation characteristics to achieve better high-temperature stability without excessive impedance increase at low temperatures
Solution Approach 2:
The patent uses a composite additive system combining sulfur-containing compounds with specific molecular structures (Formula I compounds) that create a composite protective film on the positive electrode, achieving synergistic effects that simultaneously improve high-temperature performance and maintain acceptable low-temperature power delivery
2Reliability
If electrolyte solvent composition is optimized to reduce viscosity, then low-temperature performance is improved, but high-temperature gas production increases
Solution Approach 1:
The patent adjusts the electrolyte composition parameters by selecting specific organic solvents and controlling their ratios, along with adding small amounts of the specialized additives (0.1-5 wt%), which modifies the electrolyte's physical and chemical properties to reduce viscosity at low temperatures while suppressing gas generation at high temperatures through stable film formation
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 composition improves high-temperature cycle performance, high-temperature storage performance, and low-temperature DC impedance, ensuring better overall performance across a range of temperatures.
Implementation Method 1
passivation of the positive electrode by introducing film-forming additives
Implementation Method 2
The second additive can undergo complex exchange reactions with the main components in the interface film formed at the negative electrode interface
Implementation Method 3
optimizing the electrolyte solvent composition ratio reduces the viscosity of the electrolyte at low temperatures
Implementation Method 4
the interface film formed on the positive electrode can effectively inhibit the electrolyte from being oxidatively decomposed on the surface of the positive electrode
Data Source
AI summary
In the embodiments of the present application, an electrolyte, a lithium-ion battery comprising the electrolyte, a battery module, a battery pack, and a device are provided. The electrolyte in the embodiments of the present application comprises an organic solvent, an electrolyte lithium salt dissolved in the organic solvent, and an additive comprising a first additive and a second additive. The first additive is selected from one or more of the compounds represented by formula I, and the second additive is selected from one or more of the compounds represented by formula II. After applying the electrolyte of the present application to a lithium-ion battery, the lithium ion battery has a better cycle performance and storage performance at a high temperature, and lower direct-current impedance at a low temperature, such that the lithium ion battery has both a better high-temperature performance and a better low-temperature performance.