Difluoro Ionic Complex Electrolyte for Low-Temperature Battery Output
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Solution Overview
Problem
Nonaqueous electrolytic solutions for lithium secondary batteries face challenges in maintaining high output characteristics at low temperatures and storage properties at high temperatures, with existing solutions often showing decreased performance after charge-discharge cycles or long-term storage.
Innovation Solution
Incorporating a difluoro ionic complex in the cis configuration and specific compounds such as carbonates with unsaturated bonds or fluorine atoms into the nonaqueous electrolytic solution to enhance ion conductivity and stability, thereby improving battery performance at extreme temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolytic solutions are used, then the battery can operate at normal temperatures, but the output characteristics deteriorate at low temperatures and storage properties deteriorate at high temperatures
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolytic solution by introducing a difluoro ionic complex with specific molecular structure (containing CF3 groups and oxalato ligands) and controlling its concentration (0.01-5 mass%). This parameter change enables the solution to maintain stable performance across extreme temperature ranges from -30°C to 60°C, resolving the contradiction between reliability and temperature adaptability.
Solution Approach 2:
The patent creates a composite electrolytic solution system combining the difluoro ionic complex (lithium salt with organic ligands) with conventional carbonate solvents (EC, DMC, DEC). This composite approach integrates the thermal stability and low-temperature conductivity of the ionic complex with the solvation ability of conventional solvents, achieving reliable battery operation across wide temperature ranges.
2Quantity of substance
If the battery is stored at high temperature for long term, then the storage capacity increases, but the output characteristics after storage deteriorate
Solution Approach 1:
The difluoro ionic complex performs preliminary protective action by forming a stable interface film on the electrode surfaces during initial cycles and storage. This pre-formed protective layer prevents harmful side reactions and solvent decomposition during high-temperature storage, ensuring that output characteristics are maintained after long-term storage at elevated temperatures.
Solution Approach 2:
The ionic complex provides beforehand cushioning against thermal degradation by its high thermal stability and low reactivity at elevated temperatures. It acts as a buffer that absorbs thermal stress and prevents chain reactions that would otherwise degrade the electrolyte and electrodes, cushioning the battery system against the harmful effects of long-term high-temperature storage.
3Duration of action of stationary object
If carbon materials are used as negative electrode, then the battery achieves good cycle characteristics, but solvent decomposition occurs on the electrode surface
Solution Approach 1:
The difluoro ionic complex acts as an intermediary substance between the carbon negative electrode and the conventional carbonate solvent. It forms a stable interfacial layer that mediates the interaction, preventing direct contact and harmful decomposition reactions between the solvent and electrode while still allowing efficient lithium ion transport, thus maintaining good cycle characteristics without solvent decomposition.
Solution Approach 2:
The ionic complex serves as a sacrificial protective layer that forms initially and stabilizes the electrode surface. This disposable-like protective film forms during initial cycles and prevents subsequent solvent decomposition, sacrificing itself to protect the main electrode-solvent interface throughout the battery's operational life.
4Quantity of substance
If metal lithium or alloys are used as negative electrode, then the initial capacity is high, but the negative electrode material pulverizes during cycles
Solution Approach 1:
The patent changes the electrochemical parameters at the electrode interface by introducing the ionic complex, which modifies the local environment around metal lithium or alloy particles. This parameter change reduces the reactivity and mechanical stress during lithium insertion/extraction cycles, preventing pulverization while maintaining high initial capacity.
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 enables high output characteristics at low temperatures and sustained performance after storage at high temperatures, ensuring the battery operates effectively in harsh environments without thermal insulation.
Implementation Method 1
Incorporating a difluoro ionic complex in the cis configuration and specific compounds such as carbonates with unsaturated bonds or fluorine atoms into the nonaqueous electrolytic solution to enhance ion conductivity
Implementation Method 2
a nonaqueous solvent in a nonaqueous electrolytic solution may be reductively decomposed on the surface of a negative electrode upon charging, resulting in generation of decomposition products or gases
Implementation Method 3
This film on the surface of the electrode which is called a Solid Electrolyte Interface (SEI) may, in nature, have significant impacts on battery performance. For example, it may reduce reductive decomposition of a solvent to prevent deterioration of battery performance
Implementation Method 4
a nonaqueous solvent in a nonaqueous electrolytic solution may partly undergo local oxidative decomposition at the interface between a positive electrode material and the nonaqueous electrolytic solution when the temperature is increased during charging
Data Source
Figure 1
AI summary
The present invention addresses the problem of providing: a nonaqueous electrolyte solution which is capable of demonstrating high output properties at a low temperature and good high-rate properties at a normal temperature, even when a cell has been used to a certain extent, and further, capable of similarly demonstrating sufficient properties at a low temperature after having been stored at a high temperature; and a nonaqueous electrolyte solution cell. Provided is a nonaqueous electrolyte solution containing a nonaqueous organic solvent and an electrolyte that dissolves in the nonaqueous electrolyte, wherein the present invention is characterized by the use of a nonaqueous electrolyte solution which contains a difluoro ionic complex (1-Cis) having a cis-type steric conformation represented by general formula (1-Cis) and at least one compound selected from the group consisting of carbonates having unsaturated bonds, carbonates having fluorine atoms, acid anhydrides, and compounds having isocyanate groups. Furthermore, the nonaqueous electrolyte solution may further comprise a difluoro ionic complex (1-Trans) or a tetrafluoro ionic complex (1-Tetra), which have a trans-type steric conformation.