Non-Aqueous Battery Electrolyte with Pyridine Additive for High-Voltage Safety
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Solution Overview
Problem
Conventional lithium secondary batteries face safety issues such as ignition and explosion due to heat generation and gas generation at high temperatures, especially in high-voltage conditions, leading to rapid deterioration of performance and reduced lifetime.
Innovation Solution
Incorporating a pyridine-based additive with two nitrile groups into the non-aqueous electrolyte solution to form a protective film on the positive electrode, reducing gas generation and leaching of transition metals, thereby improving safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aromatic compounds (biphenyl) are used as redox shuttle additives to control thermal runaway, then safety is improved, but the additive decomposes during charging/discharging and at high temperature, reducing effectiveness after 300 cycles
Solution Approach 1:
The patent changes the chemical structure parameters of the additive by introducing fluorine atoms at specific positions (2 and 6) of the pyridine ring, and replacing hydrogen with fluorine in the acetonitrile groups. This structural modification enhances the additive's stability against decomposition during charging/discharging and at high temperatures, while maintaining its redox shuttle functionality for safety protection.
Solution Approach 2:
The patent creates a composite electrolyte system by combining the fluorinated pyridine-based additive with specific lithium salts (LiPF6, LiBF4) and carbonate solvents (EC, DEC, DMC). This composite formulation synergistically improves both the stability and safety performance of the battery, with the fluorinated additive providing enhanced thermal stability and the lithium salts/solvents providing ionic conductivity and electrochemical stability.
2Quantity of substance
If high voltage (4.2V or higher) is applied to increase charging amount and capacity, then energy density is improved, but electrolyte solution decomposes and safety problems occur
Solution Approach 1:
The patent changes the electrochemical stability window parameters of the electrolyte system by introducing the fluorinated pyridine additive. The electron-withdrawing fluorine atoms increase the oxidation resistance of the pyridine ring, allowing the electrolyte to remain stable at high voltages (4.2V or higher) where conventional electrolytes would decompose. This enables higher charging amounts without sacrificing electrolyte stability.
3Quantity of substance
If positive electrode structure collapses during overcharging to release lithium, then capacity is improved, but thermal instability increases causing oxygen release and exothermic reactions
Solution Approach 1:
The fluorinated pyridine additive performs preliminary protective action by forming a stable surface film on the positive electrode before overcharging occurs. This pre-formed protective layer prevents direct contact between the electrolyte and the electrode surface during overcharging, inhibiting the exothermic decomposition reactions that would otherwise occur when the electrode structure collapses and releases oxygen. The additive essentially prepares a protective barrier in advance to prevent thermal runaway.
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 additive significantly reduces battery swelling and gas generation at high temperatures, maintaining excellent discharging characteristics and extending the battery's lifetime.
Implementation Method 1
U.S. Patent No. 5,879,834 also describes a method for improving the safety of the battery, by adding a small amount of aromatic compounds such as biphenyl and 3-chlorothiophene and thus increasing the internal resistance by electrochemical polymerization in an abnormal overvoltage condition.
Implementation Method 2
Incorporating a pyridine-based additive with two nitrile groups into the non-aqueous electrolyte solution to form a protective film on the positive electrode
Implementation Method 3
The additive significantly reduces battery swelling and gas generation at high temperatures, maintaining excellent discharging characteristics and extending the battery's lifetime.
Implementation Method 4
U.S. Patent No. 5,879,834 also describes a method for improving the safety of the battery, by adding a small amount of aromatic compounds such as biphenyl and 3-chlorothiophene and thus increasing the internal resistance by electrochemical polymerization in an abnormal overvoltage condition.
Data Source
AI summary
The present invention provides a non-aqueous electrolyte solution for a lithium secondary battery comprising a lithium salt, an organic solvent, and a pyridine-based additive containing two nitrile groups.