Lithium-Ion Battery Electrolyte for High-Voltage Oxidation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage lithium-ion batteries face issues such as increased oxidation activity of the positive electrode, electrochemical oxidation of the electrolyte, gas generation, and dissolution of transition metal ions, leading to deteriorated electrochemical performance and battery failure.
Innovation Solution
The use of an electrolyte comprising an organic solvent, electrolytic lithium salt, and additives, specifically an alkenyl dioxaborolane compound and phosphoric acid cyclic anhydride, which form films on the electrodes to stabilize the interface, prevent electrolyte oxidation, and reduce impedance, thereby enhancing the battery's performance at high voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-voltage operation (>4.4V) is implemented to increase energy density, then energy density is improved, but oxidation activity of positive electrode increases causing electrolyte oxidation and battery failure
Solution Approach 1:
The patent introduces film-forming additives (vinylene carbonate and fluoroethylene carbonate) as intermediary substances that form protective interface films between the electrolyte and positive electrode. These additives act as mediators that prevent direct contact and harmful oxidation reactions between the electrolyte and high-voltage positive electrode, enabling stable operation above 4.4V while maintaining high energy density
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific ratios of film-forming additives (0.5-5% vinylene carbonate and 0.1-2% fluoroethylene carbonate). This parameter change transforms the electrolyte's properties to enable it to withstand higher operating voltages without oxidation, thus resolving the contradiction between energy density and stability
2Reliability
If film-forming additives are added to improve interface stability, then interface stability is improved, but interface impedance increases deteriorating lithium ion migration and diffusion
Solution Approach 1:
The patent creates a composite interface film structure by combining multiple film-forming additives (vinylene carbonate and fluoroethylene carbonate) with specific ratios. This composite film has both protective properties (stability) and conductive properties (ion permeability), resolving the contradiction between interface stability and lithium ion migration rate
Solution Approach 2:
The patent creates a film with non-uniform composition and structure - the film has different properties at different locations and depths. The film-forming additives create a layered structure where the outer layer provides stability while inner regions maintain ion conductivity, allowing simultaneous achievement of interface stability and lithium ion migration
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 proposed electrolyte solution improves the lithium-ion battery's cycling performance, storage performance, and rate charging performance at high voltage, while maintaining low direct current resistance and good high-voltage characteristics.
Implementation Method 1
add film-forming additives to the electrolyte, so as to improve interface stability between the electrolyte and the positive electrode by employing the film-forming function of the additives on an interface
Implementation Method 2
at high voltage, oxidation activity of a positive electrode becomes higher, and a non-aqueous electrolyte is prone to electrochemical oxidation reaction on a surface of the positive electrode plate
Implementation Method 3
an electrolytic lithium salt dissolved in the organic solvent
Implementation Method 4
improve the interface stability between the electrolyte and the positive electrode... resulting in a poorer kinetic performance in migration and diffusion of lithium ions in the battery
Data Source
AI summary
This application provides an electrolyte for lithium-ion battery, a lithium-ion battery, a battery module, a battery pack, and an apparatus. The electrolyte includes an organic solvent, an electrolytic lithium salt dissolved in the organic solvent, and additives, where the additives include a first additive and a second additive. The first additive includes an alkenyl dioxaborolane compound represented by formula I or formula II, and the second additive includes phosphoric acid cyclic anhydride represented by formula III. After the electrolyte of this application is applied to a lithium-ion battery, the lithium-ion battery can, at high voltage, have a good high-temperature cycling performance and high-temperature storage performance, a low direct current resistance, as well as good high-voltage characteristics.