Electrolyte Composition Stabilizing Cathode at High Voltage
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Solution Overview
Problem
Conventional lithium-ion batteries face performance deterioration at high working voltages due to electrolyte oxidation and increased impedance, leading to reduced energy density and cycling efficiency.
Innovation Solution
An electrolyte composition including an organic solvent, a cyclic borate, a nitrile compound, and a fluorosulfonate is used, with specific structures and concentration ranges to stabilize the cathode surface, improve ion transfer, and enhance the battery's floating charge and dynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the working voltage of lithium-ion battery is increased to 4.35 V or higher to improve energy density, then the energy density is improved, but the electrolyte is easily oxidized and decomposed resulting in increased impedance and rapid electrolyte consumption
Solution Approach 1:
The patent introduces a mediator substance (specifically a sulfone compound with nitrogen-containing group) into the electrolyte system to protect the cathode-electrolyte interface from direct oxidation. This intermediary forms a stable protective film that prevents the electrolyte from decomposing at high voltages, thereby enabling high energy density operation without sacrificing electrolyte stability
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific ratios of cyclic carbonate (15-30%), chain carbonate (70-85%), and sulfone compound with nitrogen-containing group (0.1-5%). This parameter optimization allows the electrolyte to maintain stability at high working voltages while supporting high energy density requirements
2Use of energy by moving object
If conventional electrolyte is used at high working voltage, then the battery can operate at higher energy density, but the impedance of cathode increases and cycling performance deteriorates
Solution Approach 1:
The sulfone compound with nitrogen-containing group acts as an intermediary that forms a stable protective interface layer between the cathode and electrolyte. This intermediary layer prevents harmful side reactions during cycling while maintaining ionic conductivity, thus preserving cycling performance even at high working voltages required for high energy density
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components (cyclic carbonate, chain carbonate, and sulfone compound with nitrogen-containing group) that work synergistically. The composite structure provides both the high voltage stability needed for energy density and the interfacial protection required for sustained cycling performance
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 achieves a rate performance of 80% or greater, improving energy density, storage, and floating charge performance while reducing impedance and electrolyte consumption.
Implementation Method 1
the additive includes a cyclic borate and a nitrile compound... the cyclic borate has the following structure... the nitrile compound has the following structure
Implementation Method 2
improve ion transfer... achieving a rate performance of 80% or greater
Implementation Method 3
When the conventional lithium-ion battery is at a high working voltage of 4.35 V or higher, the electrolyte is easily oxidized and decomposed... the electrolyte composition achieves... improving energy density, storage, and floating charge performance while reducing impedance and electrolyte consumption
Data Source
AI summary
The present application relates to an electrolyte and an electrochemical device. The electrolyte includes an organic solvent, an additive and a lithium salt, the additive including a cyclic borate and a nitrile compound. The electrolyte of the present application has good stability at a high working voltage. In another embodiment of the present application, the combination of the electrolyte and an anode having a high compacted density provides a high energy density for the electrochemical device, and improves the storage, floating charge and dynamicperformance of the electrochemical device.