Fluorinated Carbonate Electrolyte for High-Voltage Lithium Battery Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with high-voltage stability and cycle life characteristics due to electrolyte decomposition and dendrite growth, particularly when charged above 4.2 V, and existing electrolytes with fluorine-containing carbonates suffer from low solubility and inadequate SEI formation.
Innovation Solution
An electrolyte composition comprising a fluorine-containing cyclic carbonate and a fluorine-containing linear asymmetric carbonate in a specific volume ratio, forming a stable SEI layer to suppress decomposition and dendrite growth, with a high fluorine content for improved oxidation stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a common non-aqueous carbonate solvent is used as an electrolyte and charging voltage is increased above 4.2 V, then energy capacity is improved, but electrolyte decomposition occurs resulting in deteriorated cycle life characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorine-containing cyclic carbonate and fluorine-containing linear asymmetric carbonate with specific molecular structures and ratios, enabling the electrolyte to withstand higher charging voltages (4.2-4.5 V) without decomposition, thus simultaneously achieving high energy capacity and maintained cycle life
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorine-containing cyclic carbonate (providing high-voltage stability) and fluorine-containing linear asymmetric carbonate (providing good solubility and SEI formation), where each component compensates for the limitations of the other, enabling stable operation at elevated voltages while maintaining cycle life
2Reliability
If fluorine-containing linear symmetric carbonate and fluorine-containing cyclic carbonate are used as electrolyte, then high-voltage stability is improved, but solubility is low causing salt precipitation during long-term storage
Solution Approach 1:
The patent combines fluorine-containing cyclic carbonate (providing high-voltage stability) with fluorine-containing linear asymmetric carbonate (providing excellent solubility properties), creating a composite electrolyte where the linear asymmetric component acts as a solubility-enhancing carrier that prevents salt precipitation while the cyclic component maintains voltage stability
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 enhances high-voltage stability and cycle life characteristics by forming a stable SEI layer, suppressing electrolyte decomposition and dendrite formation, thereby improving capacity retention rates.
Implementation Method 1
a stable solid electrolyte interphase (SEI) may not be formed on the anode surface
Implementation Method 2
charging the battery at a voltage higher than 4.2 V may cause a decomposition reaction of the electrolyte
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
An electrolyte for a lithium secondary battery of the embodiments of the present disclosure includes a fluorine-containing cyclic carbonate and a fluorine-containing linear asymmetric carbonate in a volume ratio of 1:9 to 8:2. Accordingly, the cycle life characteristics and high-voltage stability of a lithium secondary battery including the electrolyte may be improved.