Fluorinated Carbonate Electrolyte for Li-Ion Battery Stability
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Solution Overview
Problem
Lithium ion rechargeable batteries face challenges with electrochemical stability, long lifetime, high ion conductivity, low viscosity, good low-temperature discharge, safety, and cost-effectiveness, particularly in achieving high discharge voltage and reliability.
Innovation Solution
An electrolyte comprising a lithium salt, a non-aqueous organic solvent, dihalogenated ethylene carbonate, and halogenated ethylene carbonate, with specific weight percentages and ratios, is used to enhance the battery's lifetime and low-temperature discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used to achieve high discharge voltage (0-4.2V range), then electrochemical stability is required, but lifetime and low-temperature discharge characteristics deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated carbonates (fluoroethylene carbonate at 0.1-10 wt% and difluoroethylene carbonate at 0.01-2 wt%) into the conventional electrolyte system. This chemical parameter modification enables the electrolyte to maintain electrochemical stability across the 0-4.2V range while simultaneously improving battery lifetime and low-temperature discharge characteristics through enhanced film formation and reduced decomposition.
2Reliability
If conventional electrolytes are used to achieve high discharge voltage, then electrochemical stability is maintained, but low-temperature discharge performance worsens
Solution Approach 1:
The patent modifies the electrolyte composition by adding fluorinated carbonate compounds that change the physical and chemical parameters of the electrolyte system. These parameter changes include reduced viscosity and improved ionic conductivity at low temperatures, while maintaining electrochemical stability through the formation of protective SEI films on the electrodes.
3Duration of action of moving object
If electrolyte composition is optimized for lifetime, then durability improves, but low-temperature discharge characteristics may worsen
Solution Approach 1:
The patent creates a composite electrolyte system by combining conventional carbonate solvents (EC, PC, DEC, DMC, EMC) with fluorinated carbonate additives (fluoroethylene carbonate and difluoroethylene carbonate). This composite composition leverages the stability of conventional electrolytes while the fluorinated components provide improved low-temperature performance and enhanced lifetime through synergistic effects in film formation and decomposition resistance.
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 solution improves the lithium ion rechargeable battery's lifetime and low-temperature discharge performance, maintaining capacity and efficiency while optimizing cost and safety.
Implementation Method 1
During discharge of a lithium rechargeable battery, a terminal voltage may be up to about 3.7 V... an electrochemically-stable electrolyte, e.g., an electrolyte that is stable over the range of about 0-4.2V
Implementation Method 2
a non-aqueous electrolyte may be used for the lithium rechargeable battery... an electrolyte having superior durability and low temperature discharge, and a lithium ion rechargeable battery including the same
Data Source
AI summary
An electrolyte for a lithium ion rechargeable battery, including a lithium salt, a non-aqueous organic solvent, a dihalogenated ethylene carbonate, and a halogenated ethylene carbonate. The electrolyte may include about 0.01 to about 2 weight % of the dihalogenated ethylene carbonate, and the electrolyte may include about 0.1 to about 10 weight % of the halogenated ethylene carbonate.