Fluorinated Organic Electrolyte for High-Voltage Battery Stability
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Solution Overview
Problem
Existing organic electrolytes decompose at high voltages or cause side reactions, leading to instability and increased overvoltage during charging and discharging in secondary batteries.
Innovation Solution
An organic electrolyte composition including a lithium salt, a non-aqueous solvent comprising a fluorinated cyclic carbonate, a fluorinated chain carbonate, and a nitrile-based compound, which stabilizes the positive electrode film at high voltages and suppresses side reactions, maintaining low overvoltage during discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional organic electrolytes are used for high-voltage charging, then charging capacity is improved, but electrolyte decomposition occurs and stability deteriorates
Solution Approach 1:
The patent introduces a mediator substance (fluorinated cyclic carbonate compound with specific molecular structure) that forms a protective interface layer between the electrolyte and electrode. This intermediary layer prevents direct contact and harmful reactions while allowing ion transport, thus enabling high-voltage charging without electrolyte decomposition.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific fluorine substitution patterns. This parameter change (adding fluorinated groups) fundamentally alters the electrolyte's electrochemical stability window, raising the decomposition voltage from conventional levels to above 5V, thereby enabling stable high-voltage operation.
2Quantity of substance
If high-voltage charging is performed, then battery capacity is increased, but overvoltage increases during discharging
Solution Approach 1:
The patent applies preliminary action by forming a stable protective film on the electrode surface during initial high-voltage charging cycles. This pre-formed film prevents subsequent side reactions and voltage drift, maintaining consistent discharge voltage and low overvoltage throughout the battery's operational life after the initial conditioning.
3Quantity of substance
If conventional electrolytes are used at low discharge voltage, then discharge capacity is maintained, but side reactions occur
Solution Approach 1:
The fluorinated cyclic carbonate compound acts as an intermediary that forms a selective barrier layer at the electrode-electrolyte interface. This layer allows beneficial ion transport for discharge capacity while blocking harmful side reactions, even at low discharge voltages where conventional electrolytes would undergo parasitic reactions.
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 ensures high voltage charge stability and low voltage discharge stability, effectively preventing overvoltage increases and maintaining battery capacity, allowing for stable battery operation across a wide electrochemical window.
Implementation Method 1
a nitrile-based compound which stabilizes the positive electrode film at high voltages
Implementation Method 2
suppresses side reactions, maintaining low overvoltage during discharge
Data Source
AI summary
An organic electrolyte includes: a lithium salt, a non-aqueous solvent; and a nitrile-based compound represented by a certain formula, wherein the non-aqueous solvent includes a fluorinated cyclic carbonate compound and a fluorinated chain carbonate compound. A secondary battery including such an organic electrolyte is also disclosed.