Battery Electrolyte Salt Additive for Stable High-Temperature Interfaces
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Solution Overview
Problem
Secondary batteries, such as lithium-ion batteries, face challenges in high-temperature cycling performance due to enhanced activity of positive and negative electrodes reacting with the electrolyte, leading to gas production and stability issues at elevated temperatures.
Innovation Solution
An electrolyte comprising a non-aqueous organic solvent and an additive A, where the additive A is a salt with specific anions and cations, is used. This additive is preferentially reduced during charging, forming an alloy phase with the negative electrode and an inert fluorine-containing compound at the positive electrode interface, enhancing stability and reducing gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in secondary batteries at high temperatures, then the electrodes exhibit enhanced activity and react with the electrolyte, but this leads to gas production and instability of electrode interfaces, deteriorating high-temperature cycling performance
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the electrode interfaces and the conventional electrolyte. This compound preferentially decomposes to form protective interface layers (CEI and SEI films) that act as barriers, preventing direct harmful reactions between the electrodes and the main electrolyte, thereby reducing gas production and stabilizing the interfaces at high temperatures
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonate compounds with specific molecular structures and fluorine content ratios. By changing the chemical parameters of the electrolyte components (introducing fluorine atoms at specific positions), the decomposition behavior and interface layer properties are altered to achieve better high-temperature stability and reduced gas evolution
2Reliability
If the concentration of additive A is increased to enhance interface stability and reduce gas production, then the high-temperature cycling performance improves, but excessive salt concentration prevents dissociation of ions, increasing electrolyte viscosity and hindering ion migration
Solution Approach 1:
The patent optimizes the concentration parameter of additive A within a specific range (0.01-60 mass%) to achieve the best balance between interface stability and ion conductivity. This parameter optimization ensures sufficient additive to form protective layers while maintaining adequate free-migrating ions for good kinetic performance
Solution Approach 2:
The patent creates a composite electrolyte system combining additive A with conventional electrolyte components. This composite formulation allows the additive to form protective interface layers while the bulk electrolyte maintains good ionic conductivity, achieving both interface stability and fast ion transport
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 solution improves high-temperature cycling and storage performance by stabilizing the electrode interfaces and enhancing ionic conductivity, leading to better kinetic performance of the secondary batteries.
Implementation Method 1
the additive A has a relatively high reduction potential and is preferentially reduced in the first charging process of a secondary battery to obtain a group IIIA element
Implementation Method 2
anions in the additive A, under the action of electric field force, migrate to the positive electrode interface
Implementation Method 3
are oxidatively decomposed into an inert fluorine-containing compound
Implementation Method 4
due to the high ionic conductivity of the fluorine-containing compound formed by the additive A in the interface layer, the kinetic performance of the secondary battery can also be improved
Data Source
AI summary
An electrolyte includes a non-aqueous organic solvent and an additive A, where the additive A includes a salt composed of anions and cations represented by formula (I); M1 is selected from group IIIA elements, and cations include any one of Li+, Na+, K+, Mg2+, Ca2+, and Zn2+; and based on a mass of the electrolyte, a mass percentage of the additive A is x %, with 0.01≤x≤60. The electrolyte with the additive A included and its mass percentage controlled within the range defined in this application can enhance the stability of the negative electrode interface and the positive electrode interface, reducing the high-temperature gas production of the electrolyte and thereby improving the high-temperature cycling performance and high-temperature storage performance of the secondary battery.