Fluorinated Cyclic Carbonate Electrolyte Additives for High Voltage Li-Ion Stability
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Solution Overview
Problem
Current electrolytes, primarily organic carbonates, decompose at potentials below 4.5 V on high voltage cathode surfaces, limiting the use of high voltage cathode materials and resulting in capacity fading and increased cell impedance in lithium-ion batteries and other electrochemical devices.
Innovation Solution
Incorporation of novel compounds as electrolyte co-solvents, additives, or solutes that form a passivation film upon initial charging, stabilizing the cathode surface and enabling reversible Li ion intercalation/de-intercalation at potentials above 4.5 V without degrading the electrolyte, thereby supporting high voltage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic carbonate electrolytes are used, then the electrolyte is compatible with standard Li ion chemistry, but the electrolyte decomposes at potentials below 4.5 V on high voltage cathode surfaces causing capacity fading and increased cell impedance
Solution Approach 1:
A fluorinated cyclic carbonate compound acts as an intermediary substance that mediates between the high voltage cathode surface and the conventional organic carbonate electrolyte. This compound decomposes sacrificially to form a passivation film that protects the cathode surface, preventing direct contact and harmful interactions between the electrolyte and cathode, thereby enabling stable operation at potentials above 4.5 V
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate compounds with specific molecular structures (containing F, C, O, and H atoms in defined ratios). This parameter change modifies the electrolyte's electrochemical stability window and its interaction characteristics with high voltage cathode surfaces, enabling operation at higher potentials
2Use of energy by moving object
If high voltage cathode materials are used, then energy density and electricity quality are improved, but the conventional electrolyte decomposes causing capacity fading
Solution Approach 1:
The fluorinated cyclic carbonate compound performs a preliminary action by decomposing during initial charging cycles to form a protective passivation film on the cathode surface before the conventional electrolyte can decompose. This pre-formed film prevents subsequent electrolyte decomposition and capacity fading, enabling long-term stable operation of high voltage cathode materials
Solution Approach 2:
The invention converts the potentially harmful decomposition of the fluorinated cyclic carbonate compound into a beneficial protective mechanism. The sacrificial decomposition of this compound forms a stable passivation film that prevents the more harmful sustaining decomposition of the main electrolyte, thereby converting a short-term loss into long-term stability and extended battery life
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 novel compounds extend the electrochemical stability window, allowing for higher energy density and quality electricity delivery in batteries and other devices, preventing decomposition and maintaining performance without increasing manufacturing costs or impedance.
Implementation Method 1
the compounds that can be incorporated into the electrolyte as electrolyte co-solvents, electrolyte additives, or electrolyte solutes, which, upon the initial charging of cathode, decompose sacrificially to form a passivation film
Implementation Method 2
This passivation film prevents sustaining decomposition of electrolyte components
Implementation Method 3
reversible Li ion intercalation/de-intercalation chemistry at potentials above 4.5 V
Implementation Method 4
Li ion chemistry is established upon reversible intercalation/de-intercalation of Li ion into/from host compounds
Implementation Method 5
The presence of the novel compounds in the electrolyte can stabilize the highly oxidizing surface of the positive electrode
Implementation Method 6
stabilizing the cathode surface and enabling reversible Li ion intercalation/de-intercalation at potentials above 4.5 V
Data Source
AI summary
This invention described the preparation of a series of compounds that can be used as co-solvents, solutes or additives in non-aqueous electrolytes and their test results in various electrochemical devices. The inclusion of these novel compounds in electrolyte systems can enable rechargeable chemistries at high voltages that are otherwise impossible with state-of-the-art electrolyte technologies. These compounds are so chosen because of their beneficial effect on the interphasial chemistries formed at high potentials, such as 5.0 V class cathodes for new Li ion chemistries. The potential application of these compounds goes beyond Li ion battery technology and covers any electrochemical device that employs non-aqueous electrolytes for the benefit of high energy density resultant from high operating voltages.