Electrolytic solution, electrochemical device, secondary cell, and module
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Solution Overview
Problem
Conventional electrolyte solutions for lithium-ion secondary batteries experience increased resistance when stored at high temperatures, leading to degraded performance.
Innovation Solution
The use of a specific combination of tris(trimethylsilyl) phosphite and fluorinated saturated cyclic carbonates, along with a solvent system that includes non-fluorinated and fluorinated cyclic and acyclic carbonates and esters, to maintain low resistance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional electrolyte solutions are used in lithium-ion secondary batteries, then the batteries can operate at high voltage (4.5V or higher), but the resistance increases when stored at high temperature
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific fluorinated cyclic carbonate compound with particular molecular structure (formula 1) and controlling its concentration range (0.01-5% by mass). This parameter change enables the electrolyte to maintain stability at high voltage while preventing resistance increase during high-temperature storage
Solution Approach 2:
The patent creates a composite electrolyte system by combining the fluorinated cyclic carbonate compound (formula 1) with conventional electrolyte components including other fluorinated cyclic carbonates (formula 2), chain carbonates, and lithium salts. This composite approach leverages the synergistic effects of different materials to achieve both high voltage stability and resistance prevention
2Use of energy by moving object
If high voltage operation (4.5V or higher) is implemented, then energy density improves, but battery characteristics degrade due to resistance increase
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating the fluorinated cyclic carbonate compound (formula 1) at optimized concentrations (0.01-5% by mass), which changes the electrochemical parameters of the system. This enables high voltage operation for improved energy density while maintaining stable battery characteristics through reduced resistance
Solution Approach 2:
The fluorinated cyclic carbonate compound (formula 1) acts as an intermediary substance that mediates between the high voltage electrode reactions and the electrolyte stability. It forms protective interfaces that enable high voltage operation for energy density improvement while preventing the resistance increase that would otherwise degrade battery characteristics
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
This combination effectively reduces resistance in lithium-ion secondary batteries even after high-temperature storage, ensuring stable charge and discharge characteristics.
Implementation Method 1
a non-aqueous electrolyte solution containing tris(trimethylsilyl) phosphite and at least one fluorinated saturated cyclic carbonate
Implementation Method 2
electrochemical stability in a high voltage battery at voltages above about 4.2 V
Implementation Method 3
a positive electrode, a negative electrode, and a non-aqueous electrolyte solution
Implementation Method 4
ensuring stable charge and discharge characteristics
Data Source
AI summary
The invention provides an electrolyte solution that can hardly increase the resistance of an electrochemical device such as a lithium ion secondary battery even after the electrochemical device is stored at high temperature in comparison with that before the storage. The electrolyte solution contains tris(trimethylsilyl) phosphite and at least one fluorinated saturated cyclic carbonate (1) selected from the group consisting of pentafluoropropylethylene carbonate and heptafluoroisobutylethylene carbonate.