Cyclic Sulfone Electrolyte Additives for High-Temperature Capacity Retention
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Solution Overview
Problem
There is a need to improve the high-temperature characteristics of power storage devices by maintaining high capacity and minimizing gas generation in non-aqueous electrolyte secondary batteries.
Innovation Solution
Incorporating a cyclic sulfone compound represented by Formula (1) into the non-aqueous electrolytic solution, which forms a stable Solid Electrolyte Interface (SEI) on the electrode surface during initial charging and discharging, enhancing the SEI's ability to minimize solvent decomposition and gas generation at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional additives are used to form SEI, then battery capacity is maintained during normal operation, but gas generation increases and capacity retention deteriorates at high temperatures
Solution Approach 1:
The invention modifies the chemical structure of cyclic sulfone compounds by introducing fluorine atoms at specific positions (α-position and/or β-position relative to the sulfonyl group). This parameter change in molecular structure alters the electrochemical behavior of the additive, enabling it to form an SEI layer with higher stability and lower gas-generating tendency at high temperatures compared to conventional non-fluorinated cyclic sulfone additives.
Solution Approach 2:
The invention uses composite molecular structures combining cyclic sulfone core with fluorinated substituent groups. The synergistic effect of the cyclic sulfone framework (which forms protective SEI) and the fluorinated groups (which enhance thermal stability and reduce gas generation) creates an additive with superior high-temperature performance compared to either component alone.
2Duration of action of moving object
If existing cyclic sulfone additives are used, then initial capacity is achieved, but capacity decreases rapidly with repeated charging and discharging at high temperature
Solution Approach 1:
By changing the molecular parameters of the cyclic sulfone additive through fluorine substitution, the invention creates an SEI layer with improved electrochemical stability. The fluorinated groups modify the SEI composition and structure, reducing its reactivity and decomposition at high temperatures, thereby maintaining capacity over repeated charge-discharge cycles.
Solution Approach 2:
The fluorinated cyclic sulfone additive performs preliminary action by forming a stable, protective SEI layer during initial charging cycles. This pre-formed SEI acts as a stable interface that prevents further solvent decomposition and electrode degradation during subsequent high-temperature cycling, thereby extending cycle life and maintaining capacity retention.
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 cyclic sulfone compound maintains high capacity and reduces gas generation in power storage devices exposed to high temperatures by forming a stable SEI with a high density of polar groups, thereby improving capacity retention and stability.
Implementation Method 1
some additives electrochemically decompose on the electrode surface during initial charging and discharging, forming a coating called a Solid Electrolyte interphace (SEI) on the electrode surface
Implementation Method 2
The SEI is considered to minimize the decomposition of solvent molecules on the electrode surface, thereby minimizing the consumption of electricity associated with the decomposition of solvent molecules
Data Source
AI summary
An additive for a non-aqueous electrolytic solution includes a cyclic sulfone compound represented by Formula (1):X1 represents a sulfonyl group and Z represents a monovalent group represented by Formula (21), (22), (23), or (24):