Battery Electrolyte Composition for Low-Impedance Negative Electrodes
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to the instability of positive electrode active materials at high temperatures, leading to metal ion dissolution, solid electrolyte interface (SEI) film destruction, increased negative electrode impedance, and potential safety accidents.
Innovation Solution
A battery electrolyte solution comprising an organic solvent with an ethyl group, an additive of fluoroethylene carbonate, and a lithium salt, with specific percentage configurations to enhance peeling strength and reduce negative electrode impedance, thereby forming a robust SEI film and improving safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame retardant is added to the electrolyte solution to improve safety performance at high temperature, then safety performance is improved, but other performance of the battery deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by introducing a specific compound (cyclic carboxylate) with defined molecular structure and concentration range (0.1-5 wt%), which modifies the electrolyte's chemical properties to achieve both safety improvement and performance maintenance without using conventional flame retardants
Solution Approach 2:
The patent creates a composite electrolyte system by combining cyclic carboxylate with traditional electrolyte components (lithium salt, carbonate solvents), forming a multi-component system where each component contributes specific functions: cyclic carboxylate provides safety enhancement through SEI film modification, while lithium salts and carbonate solvents maintain ionic conductivity and electrochemical performance
2Temperature
If the positive electrode active material structure is unstable at high temperature, then metal ions are dissolved and deposited on the negative electrode plate, but this destroys the SEI film structure and causes continuous increase in negative electrode impedance
Solution Approach 1:
The cyclic carboxylate in the electrolyte solution performs preliminary action by preferentially reacting with metal ions during the initial stages of battery operation or at early high temperature exposure, forming a protective interface layer that prevents subsequent metal ion deposition and SEI film destruction before they can occur
Solution Approach 2:
The cyclic carboxylate acts as an intermediary substance between the positive electrode active material and the negative electrode plate, intercepting dissolved metal ions and preventing them from reaching and damaging the SEI film on the negative electrode, thus mediating the harmful interaction between unstable positive electrode material and the SEI film
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 effectively increases the peeling strength of the negative electrode plate, reduces negative electrode impedance and internal resistance, and enhances safety performance by preventing self-heating and self-ignition, while maintaining other battery performance.
Implementation Method 1
This destroys a structure of a solid electrolyte interface (Solid Electrolyte Interface, SEI) film on the surface of the negative electrode plate... forming a robust SEI film
Implementation Method 2
A battery electrolyte solution includes an organic solvent, an additive, and an electrolyte salt... the electrolyte solution is in contact with a negative electrode plate
Data Source
AI summary
Disclosed are a battery electrolyte solution and a battery. The battery electrolyte solution includes an organic solvent, an additive, and an electrolyte salt, and the electrolyte solution is in contact with a negative electrode plate; the organic solvent includes an ethyl group solvent, the additive includes fluoroethylene carbonate, the electrolyte salt includes a lithium salt, and percentages of the ethyl group solvent, the fluoroethylene carbonate, and the lithium salt in a total mass of the electrolyte solution are configured as follows: 0.4−N3≤A+B2+C2≤5.2−N3, where N denotes a peeling strength value of the negative electrode plate, A, B, and C respectively denote a percentage of the mass of the ethyl group solvent, the fluoroethylene carbonate and the lithium salt in the total mass of the electrolyte solution.