Non-aqueous Electrolyte Reducing Gas Production in Li-Ion Batteries
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Solution Overview
Problem
Chain carbonates in non-aqueous electrolytes, such as diethyl carbonate, decompose easily at high temperatures, leading to excessive gas production and deteriorating the high-temperature storage and charge/discharge cycle characteristics of lithium ion secondary batteries.
Innovation Solution
A non-aqueous electrolyte composition is developed with reduced diethyl carbonate proportion, incorporating ethylene carbonate, propylene carbonate, and a low-viscosity additive like fluorinated aromatic compounds or fatty acid alkyl esters, optimizing weight ratios to minimize gas production while maintaining low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If DEC is used as the main component to achieve favorable low-temperature characteristics, then low-temperature performance is improved, but gas production increases during high-temperature storage and charge/discharge cycles
Solution Approach 1:
The patent changes the concentration parameters of electrolyte components, specifically reducing DEC to 10-50 wt% and introducing fluorinated aromatic compounds (5-35 wt%) and fatty acid alkyl esters (5-35 wt%) with specific molecular weight ranges (90-200 and 80-240 respectively). This parameter optimization suppresses gas production while maintaining low-temperature performance.
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple solvent types (cyclic carbonates EC and PC, chain carbonate DEC) with specific additive compounds (fluorinated aromatic compounds and fatty acid alkyl esters). This composite approach leverages the low viscosity of DEC for low-temperature performance while using the other components to suppress gas production during storage and cycling.
2Temperature
If DEC proportion is increased to ensure favorable low-temperature characteristics, then low-temperature performance is improved, but high-temperature storage characteristics deteriorate
Solution Approach 1:
The patent optimizes the concentration parameters by limiting DEC to 10-50 wt% and introducing fluorinated aromatic compounds (5-35 wt%) and fatty acid alkyl esters (5-35 wt%) with specific molecular weight ranges. This parameter configuration maintains low-temperature fluidity while suppressing decomposition reactions at high temperatures.
Solution Approach 2:
The patent develops a composite electrolyte formulation combining cyclic carbonates (EC, PC), chain carbonate (DEC), fluorinated aromatic compounds, and fatty acid alkyl esters. This composite system balances the low-temperature performance provided by DEC with the high-temperature stability provided by the fluorinated and ester components.
3Temperature
If DEC proportion is increased to ensure favorable low-temperature characteristics, then low-temperature performance is improved, but charge and discharge cycle characteristics deteriorate
Solution Approach 1:
The patent optimizes concentration parameters by setting DEC at 10-50 wt% and introducing fluorinated aromatic compounds (5-35 wt%) and fatty acid alkyl esters (5-35 wt%) with specific molecular weight ranges (90-200 and 80-240). This configuration maintains low-temperature operability while suppressing gas production that degrades cycle life.
Solution Approach 2:
The patent creates a composite electrolyte system integrating cyclic carbonates (EC, PC), chain carbonate (DEC), fluorinated aromatic compounds, and fatty acid alkyl esters. The synergistic combination maintains low-temperature performance while the fluorinated and ester components suppress decomposition during charge/discharge cycling.
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 effectively suppresses gas production during high-temperature storage and charge/discharge cycles, enhancing the safety and low-temperature characteristics of lithium ion secondary batteries.
Implementation Method 1
a non-aqueous electrolyte including a non-aqueous solvent and a solute dissolved in the non-aqueous solvent
Implementation Method 2
a non-aqueous electrolyte in which proportion of DEC is reduced... ensuring favorable low-temperature characteristics
Data Source
AI summary
A non-aqueous electrolyte in which the proportion of diethyl carbonate is reduced, and a nonaqueous electrolyte secondary battery using the same that has high safety are provided. The non-aqueous electrolyte of the invention for use in secondary batteries includes ethylene carbonate, propylene carbonate, diethyl carbonate, and an additive, as a non-aqueous solvent. The additive is at least one of a fluorinated aromatic compound having a molecular weight of 90 to 200 and a fatty acid alkyl ester having a molecular weight of 80 to 240. A weight ratio WEC ethylene carbonate, a weight ratio WPC of propylene carbonate, a weight ratio W DEC of diethyl carbonate, and a weight ratio WLV of the additive are 5 to 30 wt %, 15 to 60 wt %, 10 to 50 wt %, and 5 to 35 wt %, respectively, to the total of the non-aqueous electrolyte.