Silanyloxy Nitrile Electrolyte for High-Voltage Lithium Battery Swelling
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Solution Overview
Problem
High-voltage lithium secondary batteries face safety issues due to electrolyte oxidation and decomposition, leading to swelling and reduced life cycle performance, especially at high temperatures and during long-term storage.
Innovation Solution
An electrolyte composition for high-voltage lithium secondary batteries, including a lithium salt, a non-aqueous organic solvent, and a silanyloxy nitrile compound, which stabilizes the electrolyte at high voltages, reducing oxidation and decomposition, and incorporating additives like oxalatoborate and carbonate-based compounds to enhance life cycle and storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high voltage (4.4V system) is used to increase charge amount, then battery capacity increases, but electrolyte oxidation and decomposition occur leading to safety deterioration
Solution Approach 1:
The patent introduces a silanyloxy nitrile compound as an intermediary substance that mediates between the high voltage cathode and the electrolyte. This compound forms a protective interface layer that prevents direct contact and harmful reactions between the high voltage cathode material and the electrolyte, thereby enabling safe operation at 4.4V while maintaining battery capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating specific silanyloxy nitrile compounds with controlled concentrations (0.1-5 wt%). This parameter change alters the electrochemical stability window and oxidation resistance of the electrolyte system, allowing it to withstand the higher operating voltage without decomposition
2Productivity
If continuous charge is performed to increase capacity, then battery output increases, but heat generation occurs due to cathode structure collapse
Solution Approach 1:
The silanyloxy nitrile compound performs preliminary protective action by forming a stable surface film on the cathode before thermal runaway can occur. This pre-formed protective layer prevents oxygen release from the cathode structure even when subjected to high temperatures during continuous charging, thereby preventing exothermic decomposition reactions
Solution Approach 2:
The patent applies preliminary anti-action by using the silanyloxy nitrile compound to counteract the potential harmful effects of cathode structure collapse before they can occur. The compound preemptively stabilizes the cathode-electrolyte interface, preventing the conditions that would lead to thermal runaway during continuous charge operations
3Reliability
If aromatic compounds are added as redox shuttle additives to prevent thermal runaway, then safety improves, but storage characteristics deteriorate due to gradual decomposition
Solution Approach 1:
The patent changes the chemical structure parameters of the additive by using silanyloxy nitrile compounds instead of traditional aromatic compounds. This structural modification provides superior electrochemical stability and oxidation resistance, allowing the additive to maintain its protective function without decomposing during long-term storage, thus improving both safety and storage characteristics simultaneously
Solution Approach 2:
The patent creates a composite electrolyte system combining silanyloxy nitrile compounds with conventional electrolyte solvents and lithium salts. This composite formulation leverages the stability and protective properties of the silanyloxy nitrile compound while maintaining the beneficial electrochemical characteristics of the base electrolyte system, achieving both safety and long-term stability
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 significantly decreases battery swelling, maintains high-rate charge and discharge characteristics, and ensures excellent high-temperature storage and low-temperature discharge efficiency, with a thickness increase rate of 3-14% and capacity retention rate of 68% or more.
Implementation Method 1
the electrolyte is not decomposed at this voltage... stabilizes the electrolyte at high voltages, reducing oxidation and decomposition
Implementation Method 2
a cathode active material of a non-aqueous electrolyte battery is composed of lithium, a lithium containing metal oxide capable of intercalating and releasing lithium ions
Implementation Method 3
oxygen is released from the cathode active material having an unstable structure, and the released oxygen generates an exothermal decomposition reaction with an electrolyte solvent
Implementation Method 4
the released oxygen generates an exothermal decomposition reaction with an electrolyte solvent, or the like
Data Source
AI summary
Provided are an electrolyte for a high-voltage lithium secondary battery and a high-voltage lithium secondary battery containing the same, and more particularly, an electrolyte for a high-voltage lithium secondary battery which may not be oxidized and decomposed at the time of being kept at a high voltage and a high temperature to prevent swelling of a battery through suppression of gas generation, thereby having excellent high-temperature storage characteristics and excellent discharge characteristics at a low temperature while decreasing a thickness increase rate of the battery, and a high-voltage lithium secondary battery containing the same.