Nonaqueous Electrolyte Additives for Battery Capacity and Reliability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in suppressing gas generation, high-temperature storage characteristics, and cycle characteristics due to issues with active material distribution and electrolyte decomposition, leading to performance limitations and potential battery failure.
Innovation Solution
Incorporating specific compounds such as those represented by Formulas (1) and (2)/(3) into the electrolytic solution, along with cyclic carbonate compounds having carbon-carbon unsaturated bonds and difluorophosphates, to reduce gas generation and enhance storage and cycle characteristics by forming protective films on electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is pressurized to increase density or the amount of electrolytic solution is decreased to increase capacity, then the battery capacity increases, but the active material cannot be uniformly used and degradation is accelerated by uneven reaction
Solution Approach 1:
The patent introduces specific compounds (Formula 1: phosphonate ester with specific structural parameters; Formula 2: cyclic carbonate with unsaturated bonds) and controls their concentration ranges to modify the electrochemical reaction parameters. This enables uniform lithium ion insertion/extraction at high density, resolving the contradiction between high capacity and uniform active material utilization.
Solution Approach 2:
The patent uses compounds of Formula 1 and Formula 2 as intermediary substances that mediate between the electrolytic solution and the active material. These intermediaries form protective films on electrode surfaces, ensuring uniform reaction distribution even when the active material layer is highly pressurized, thus maintaining reliability while increasing capacity.
2Quantity of substance
If the amount of gas generated by decomposition of the electrolytic solution is small, then the battery can maintain high capacity, but the internal pressure increases significantly when the battery is in continuous charging state at high temperature
Solution Approach 1:
The patent converts the potentially harmful gas decomposition products into beneficial protective films on the electrode surfaces. The compounds of Formula 1 and Formula 2 promote decomposition reactions that form stable solid electrolyte interphase (SEI) layers, which prevent further decomposition and gas generation, thus converting harm into benefit by protecting the battery while maintaining high capacity.
Solution Approach 2:
The patent applies preliminary protective action by having the compounds of Formula 1 and Formula 2 form stable protective films on the electrodes before significant gas generation occurs. This preliminary film formation prevents subsequent decomposition reactions that would generate gas and increase internal pressure, especially under continuous charging at high temperature.
3Quantity of substance
If the battery is designed with reduced volume of non-active materials to increase capacity, then the battery size is reduced, but the space inside the battery decreases causing significant internal pressure increase
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by introducing compounds of Formula 1 and Formula 2 in specific concentrations. This chemical parameter change enables the system to achieve high capacity with minimal gas generation, allowing reduced volume of non-active materials without causing internal pressure problems.
4Ease of operation
If the battery supplies extremely weak current for compensating self-discharge in continuous charging state, then the battery can maintain operation, but heat generated accelerates capacity decrease and electrolytic solution decomposition
Solution Approach 1:
The patent converts the heat generated during continuous charging from a harmful factor into a beneficial one by designing the compounds of Formula 1 and Formula 2 to form more stable protective films at elevated temperatures. The heat accelerates the formation of stable SEI layers that prevent further decomposition, thus converting thermal energy that would normally degrade the battery into a protective mechanism.
Solution Approach 2:
The patent provides beforehand cushioning against thermal degradation by having the compounds of Formula 1 and Formula 2 form stable protective films before significant capacity loss occurs. These films act as a cushion that prevents heat from accelerating decomposition reactions, protecting the battery during continuous charging operation.
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 proposed solution significantly reduces gas generation, improves high-temperature storage, and maintains cycle performance, leading to a nonaqueous electrolyte battery with enhanced capacity and reduced size, while minimizing the risk of battery failure.
Implementation Method 1
the cyclic carbonate having a double bond preferentially reacts with a negative electrode to form a high-quality film on the surface of the negative electrode
Implementation Method 2
heat generated by the equipment accelerates a decrease in the capacity of the battery or decomposition of the electrolytic solution to tend to generate gas
Data Source
AI summary
A nonaqueous electrolyte battery comprising a nonaqueous electrolytic solution selected from the following nonaqueous electrolytic solutions (i), (ii) and (iii), and negative and positive electrodes that can absorb and desorb lithium ions: (i) a nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent dissolving the electrolyte, containing 0.001 vol% or more and less than 1 vol% of a compound represented by the following Formula (1) in the nonaqueous solvent: (ii) a nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent dissolving the electrolyte, containing 0.001 vol% or more and less than 5 vol% of a compound represented by Formula (1) as defined above in the nonaqueous solvent and further containing at least one compound selected from the group consisting of cyclic carbonate compounds having carbon-carbon unsaturated bonds, cyclic carbonate compounds having fluorine atoms, monofluorophosphates, and difluorophosphates; or (iii) a nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent dissolving the electrolyte, containing a compound represented by the following Formula (2): and/or a compound represented by the following Formula (3) :