Pyridine Nitrile Electrolyte Additive for High-Voltage Battery Swelling
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Solution Overview
Problem
Lithium secondary batteries face safety issues such as ignition and explosion due to heat generation and gas formation at high temperatures, especially in high-voltage conditions, and conventional additives like biphenyl decompose rapidly, leading to reduced battery life and storage characteristics.
Innovation Solution
Incorporating a pyridine-based additive containing two nitrile groups into the non-aqueous electrolyte solution to form a film on the positive electrode surface, inhibiting side reactions and reducing gas generation and transition metal leaching, thereby improving swelling characteristics and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional non-aqueous electrolytes are used in high-voltage lithium secondary batteries, then energy density and operating voltage are improved, but electrolyte decomposition and safety issues occur
Solution Approach 1:
The patent introduces a pyridine-based additive with two nitrile groups as an intermediary substance between the electrolyte and electrode. This additive forms a protective film that mediates the interaction between the electrolyte and electrode at high voltage, preventing direct decomposition reactions while allowing ionic conduction to continue
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific pyridine-based compounds with nitrile groups. This parameter change transforms the electrolyte system from one that decomposes at high voltage to one that maintains stability through the formation of protective surface films on electrodes
2Object-affected harmful factors
If aromatic compounds such as biphenyl are added as redox shuttle additives, then thermal runaway prevention is improved, but internal resistance increases and safety cannot be guaranteed after prolonged high-temperature discharge
Solution Approach 1:
The patent changes the chemical structure parameters of the additive by using pyridine-based compounds with two nitrile groups instead of conventional aromatic compounds. This structural modification enables the additive to form stable protective films that do not decompose during prolonged high-temperature operation, maintaining both safety and performance
Solution Approach 2:
The patent creates a composite protective film on the electrode surface consisting of the pyridine-based additive and electrolyte components. This composite structure provides both thermal protection and long-term stability, combining the benefits of redox shuttle mechanisms with enhanced chemical resistance
3Quantity of substance
If the battery operates at high voltage to increase charging amount, then capacity is improved, but electrolyte decomposition and electrode potential increase causing safety problems
Solution Approach 1:
The pyridine-based additive acts as an intermediary that forms a protective interface between the electrolyte and electrode at high voltage. This intermediary layer prevents direct contact and decomposition reactions while maintaining ionic conductivity, enabling safe operation at elevated voltages for increased capacity
4Use of energy by moving object
If overcharging occurs causing large amounts of lithium release, then positive electrode structure becomes thermally unstable, but oxygen release and exothermic decomposition reactions cause thermal runaway
Solution Approach 1:
The patent applies preliminary action by having the pyridine-based additive form a protective film on the electrode surface before overcharging occurs. This pre-formed protective layer prevents the structural degradation and oxygen release that would otherwise occur during overcharging, blocking the initiation of thermal runaway
Solution Approach 2:
The patent converts the potentially harmful high-voltage and overcharge conditions into beneficial effects by using the pyridine-based additive to form stable protective films. These films transform the harmful thermal and chemical energy that would cause runaway into stable surface structures that enhance safety
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 pyridine-based additive significantly reduces gas generation and transition metal leaching, enhancing battery performance by maintaining high-rate charging/discharging characteristics and improving storage stability at high temperatures.
Implementation Method 1
The pyridine-based additive containing two nitrile groups forms a protective film on the positive electrode, suppressing the leaching of transition metals and reducing the amount of gas generated at high temperatures
Implementation Method 2
U.S. Pat. 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 3
a positive electrode active material for a battery using a non-aqueous electrolyte solution consists of lithium-containing metal oxides that can intercalate and deintercalate lithium and/or lithium ions
Implementation Method 4
the released oxygen causes an exothermic decomposition reaction with the solvent of the electrolyte solution
Data Source
AI summary
Provided are a non-aqueous electrolyte solution for a lithium secondary battery comprising a lithium salt, an organic solvent, and a dialkylenenitrile-containing pyridine additive, and a lithium secondary battery comprising the same, where such non-aqueous electrolyte solution reduces the resistance and swelling phenomenon of the lithium secondary battery under high voltage.