Sodium-Ion Battery Electrolyte for Stable Anode Interface Films
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Solution Overview
Problem
The negative electrode interface film of sodium-ion secondary batteries is unstable, leading to side reactions with the electrolyte, increased interface impedance, and sodium precipitation, which severely reduces the cycle performance and safety of the battery.
Innovation Solution
An electrolyte containing a sulfur-containing compound with a boiling point not exceeding 70°C is used, forming a stable negative electrode interface film that inhibits side reactions, reduces interface impedance, and improves the cycle and safety performance of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte is used in sodium-ion secondary battery, then the battery can operate, but the negative electrode interface film is unstable and side reactions occur, leading to increased interface impedance and sodium precipitation
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the electrolyte and the negative electrode. This additive preferentially reacts with the negative electrode to form a stable interface film, preventing direct contact and harmful reactions between the electrolyte and electrode, thus resolving the contradiction between battery operation and interface stability
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding fluorinated cyclic carbonate compounds with specific molecular structures and fluorine content ratios. This parameter change transforms the electrolyte's interaction characteristics with the negative electrode, enabling formation of a stable interface film that prevents sodium precipitation while maintaining ionic conductivity
2Reliability
If additive is added to electrolyte to improve interface film stability, then side reactions are reduced, but the additive may form by-products that increase interface impedance
Solution Approach 1:
The patent applies local quality by designing the additive to specifically target and modify only the interface region between the electrolyte and negative electrode. The fluorinated cyclic carbonate concentrates at the electrode surface to form a protective film, leaving the bulk electrolyte composition and properties unchanged, thus improving interface stability without significantly increasing overall impedance
Solution Approach 2:
The patent creates a composite interface structure consisting of the base electrolyte and fluorinated cyclic carbonate additive working together. The additive forms a composite interface film that combines the benefits of low impedance with high stability, resolving the contradiction between film stability and impedance by creating a multi-component protective layer
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 use of the sulfur-containing compound in the electrolyte results in a stable negative electrode interface film, reducing sodium precipitation and interface impedance, thereby enhancing the cycle and safety performance of sodium-ion secondary batteries.
Implementation Method 1
the first additive is a sulfur-containing compound with a boiling point not exceeding 70° C. under a standard atmospheric pressure... the electrolyte of the present application can form a stable negative electrode interface film on the surface of the negative electrode plate
Implementation Method 2
The viscosity of the electrolyte of the present application is low, the first additive diffuses quickly in the electrolyte, and can quickly form a film on the surface of the negative electrode
Implementation Method 3
The selected first additive has a low viscosity and a fast diffusion speed after being dissolved in a solvent, and is superior to a solvent and can react quickly on the surface of the negative electrode to form a sulfur-containing inorganic salt
Data Source
AI summary
Provided are an electrolyte, a secondary battery, a battery module, a battery pack and a power consuming device. The electrolyte of the present application comprises a first additive, wherein the first additive is a sulfur-containing compound with a boiling point not exceeding 70° C. under a standard atmospheric pressure, and the mass content of the first additive in the electrolyte is 0.05%-6%. The electrolyte of the present application can form a stable interface film on the surface of the negative electrode plate, which inhibits side reactions between the electrolyte and the negative electrode plate, thereby reducing the interface impedance of the negative electrode, reducing the precipitation of sodium, and improving the cycle performance and safety performance of the secondary battery.