Cyclic Sulfate Electrolyte for Lithium Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to the volatility and flammability of organic electrolytes, leading to potential ignition during overcharge or over-discharge, and existing additives like biphenyl degrade over time, compromising safety and storage characteristics.
Innovation Solution
An electrolyte composition for lithium secondary batteries incorporating a lithium salt, non-aqueous organic solvent, and a cyclic sulfate compound, along with optional cyclic sulfite and specific additives, which enhances high-temperature storage and low-temperature discharge performance by stabilizing the electrolyte and reducing swelling, while maintaining charge and discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic electrolyte is used in lithium secondary battery, then basic battery function is achieved, but safety problems occur due to volatility and flammability at high temperature
Solution Approach 1:
The patent introduces a solid electrolyte interface (SEI) film as an intermediary layer between the organic electrolyte and the electrode. This SEI film acts as a protective barrier that prevents direct contact between the flammable organic electrolyte and the electrode, thereby eliminating the safety hazards of volatility and flammability while maintaining the basic battery function. The SEI film is formed through electrochemical reactions and serves as a solid protective interface.
2Reliability
If aromatic compound additive like biphenyl is used to prevent over-charge current and thermal runaway, then safety is improved, but the additive decomposes over time and safety is compromised after 300 charge-discharge cycles
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte additive system. Instead of using single aromatic compounds like biphenyl that decompose over time, the invention uses a combination of cyclic carbonate compounds and chain carbonate compounds in specific proportions. This parameter change in additive composition results in the formation of a more stable SEI film that maintains protective function throughout the battery's service life, solving the decomposition problem after 300 cycles.
3Productivity
If electrolyte is kept at high temperature in high voltage state, then battery operation is maintained, but swelling phenomenon occurs due to oxidation/decomposition of electrolyte
Solution Approach 1:
The patent uses the SEI film as an intermediary protective layer that prevents direct oxidation and decomposition reactions between the electrolyte and the electrode at high temperatures. This SEI film barrier maintains electrolyte stability even when the battery operates at high voltage and temperature conditions, preventing swelling phenomenon while allowing continuous battery operation.
4Ease of operation
If conventional organic electrolyte is used, then battery can be charged and discharged, but high-rate charge and discharge characteristics deteriorate
Solution Approach 1:
The patent optimizes the physical and chemical parameters of the electrolyte system by using specific ratios of cyclic carbonate to chain carbonate compounds. This parameter optimization creates an electrolyte with improved ionic conductivity and lower viscosity, enabling faster lithium ion transport between electrodes. The result is enhanced high-rate charge and discharge characteristics while maintaining basic charge-discharge functionality.
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 achieves excellent high-temperature storage and low-temperature discharge efficiency, with a significant reduction in battery thickness increase and improved capacity retention, ensuring enhanced safety and performance over long cycles.
Implementation Method 1
a surface of carbon particles, which is an anode active material, and an electrolyte react with each other, a coating film referred to as a solid electrolyte interface (SEI) film is formed on a surface of the anode
Implementation Method 2
lithium ions intercalated into and deintercalated from a cathode and an anode
Implementation Method 3
the lithium secondary battery, which generates electrical energy by oxidation-reduction reactions when lithium ions are intercalated into and deintercalated from a cathode and an anode
Data Source
AI summary
Provided are an electrolyte for a lithium secondary battery and a lithium secondary battery containing the same. The electrolyte for a secondary battery according to the present invention has excellent high-temperature stability, excellent low-temperature discharge capacity, and excellent life cycle characteristics.