Difluorophosphite Electrolyte for High-Nickel Cathode Gas Suppression
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Solution Overview
Problem
High-voltage lithium secondary batteries face challenges with rapid phase transformation, chemical resistance deterioration, and excessive gas generation, leading to reduced lifespan and stability, especially at high temperatures, due to the use of nickel-based cathode active materials.
Innovation Solution
An electrolytic solution containing a difluorophosphite compound, specifically A-OPF2, is used in conjunction with a nickel-containing transition metal compound cathode active material, along with additional additives like 1,3-propane sultone, lithium bis(oxalato)borate, and ethylene sulfate, to stabilize the cathode structure and suppress side reactions, thereby enhancing high-temperature stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nickel-based cathode active material is used to increase capacity, then energy density is improved, but chemical resistance deteriorates and lifespan is reduced
Solution Approach 1:
A coating layer comprising metal fluoride, metal oxide, or metal oxyfluoride is formed on the surface of the nickel-based cathode active material particles. This coating layer acts as an intermediary barrier between the nickel-based material and the electrolyte, preventing direct contact and chemical reactions that would otherwise deteriorate the material's chemical resistance and reduce lifespan, while allowing the high capacity and energy density of the nickel-based material to be maintained
2Use of energy by moving object
If high voltage charging is applied to increase energy density, then capacity is improved, but internal resistance increases and lifespan is reduced
Solution Approach 1:
The coating layer of metal fluoride, metal oxide, or metal oxyfluoride serves as a protective intermediary on the cathode material surface, enabling the battery to withstand high voltage charging conditions. This coating prevents harmful side reactions at high potentials while maintaining ionic conductivity, thus allowing high energy density to be achieved through high voltage charging without sacrificing lifespan
3Use of energy by moving object
If nickel content is increased to improve capacity, then energy density is improved, but gas generation increases causing swelling
Solution Approach 1:
The coating layer comprising metal fluoride, metal oxide, or metal oxyfluoride acts as a protective barrier that suppresses gas-generating side reactions between the high-nickel cathode material and the electrolyte. This intermediary layer prevents decomposition reactions that会产生 gas, thereby eliminating battery swelling while maintaining the high capacity and energy density benefits of high-nickel content materials
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 solution significantly reduces thickness increase and internal resistance, improves high-temperature storage stability, and maintains excellent charge and discharge characteristics, ensuring the battery's performance is preserved even at high voltages and temperatures.
Implementation Method 1
a difluorophosphite compound, specifically A-OPF2, is used in conjunction with a nickel-containing transition metal compound cathode active material, along with additional additives like 1,3-propane sultone, lithium bis(oxalato)borate, and ethylene sulfate, to stabilize the cathode structure
Implementation Method 2
stabilize the cathode structure and suppress side reactions, thereby enhancing high-temperature stability and lifespan
Data Source
AI summary
The present invention relates to an electrolytic solution for a lithium secondary battery, and a lithium secondary battery comprising the same. The lithium secondary battery according to the present invention employs the electrolytic solution for a lithium secondary battery, containing a difluorophosphite compound, according to the present invention, and thus has improved characteristics.