Lithium Battery Electrolyte Composition for High-Temperature Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with battery expansion at high voltages and temperatures, leading to decreased cycle-life and high-rate charge/discharge characteristics.
Innovation Solution
An electrolyte composition comprising lithium salt and a non-aqueous organic solvent mixture of ethylene carbonate, ethyl propionate, and propylene carbonate, with specific volume ratios and optional additives, which enhances ion mobility and conductivity, thereby improving high temperature cycle-life and high-rate charge/discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolytes are used in rechargeable lithium batteries, then the batteries can operate at high voltage, but battery expansion occurs at high temperatures leading to decreased cycle-life
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific mixture of cyclic carbonate (15-40 vol%), chain carbonate (10-50 vol%), and ester (10-50 vol%). This parameter change in electrolyte composition prevents battery expansion at high temperatures while maintaining good cycle-life characteristics, resolving the contradiction between high temperature operation and reliability.
2Speed
If conventional electrolytes are used in rechargeable lithium batteries, then the batteries can operate at high voltage, but high-rate charge/discharge characteristics deteriorate
Solution Approach 1:
The patent optimizes the electrolyte composition parameters with a specific ratio of cyclic carbonate, chain carbonate, and ester components. This parameter optimization improves ion mobility and conductivity, enabling better high-rate charge/discharge characteristics while maintaining high voltage operation capability.
3Reliability
If the electrolyte composition is optimized for high temperature stability, then cycle-life improves, but manufacturing complexity increases
Solution Approach 1:
The patent uses a composite electrolyte formulation combining three types of solvents (cyclic carbonate, chain carbonate, and ester) in specific proportions. This composite approach achieves high temperature stability and improved cycle-life while using commercially available components that can be mixed directly, maintaining ease of manufacture.
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 composition effectively prevents battery expansion at high voltages and temperatures, enhancing cycle-life and high-rate discharge performance of rechargeable lithium batteries.
Implementation Method 1
Lithium rechargeable batteries use an organic electrolyte and thereby have twice or more the discharge voltage than a conventional battery using an alkali aqueous solution
Implementation Method 2
The electrolyte composition effectively prevents battery expansion at high voltages and temperatures, enhancing cycle-life and high-rate discharge performance
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes a lithium salt and a non-aqueous organic solvent. The non-aqueous organic solvent includes about 1 volume % to about 40 volume % of ethylene carbonate, about 1 volume % to about 50 volume % of ethyl propionate, about 1 volume % to about 50 volume % of diethyl carbonate, and about 1 volume % to about 40 volume % of propylene carbonate.