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 long-term durability, particularly after charge-discharge cycles and high-temperature storage, due to decomposition products and gas generation affecting battery performance.
Innovation Solution
Incorporating a difluoro ionic complex in the cis configuration and specific compounds like cyclic sulfonic acid esters into the nonaqueous electrolytic solution to enhance ion conductivity and stability, forming a protective film on electrodes that reduces oxidative decomposition and improves cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolytic solutions are used, then batteries can operate at normal temperatures, but output characteristics deteriorate at low temperatures and after extended use
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolytic solution by introducing a specific cyclic carboxylate compound (Formula 1) with controlled molar ratios relative to lithium salt (0.01-5 mol%). This parameter change optimizes the electrolyte's performance across varying temperatures and charge-discharge cycles, maintaining high output characteristics while improving cycle stability.
Solution Approach 2:
The patent creates a composite electrolytic system by combining the cyclic carboxylate compound (Formula 1) with conventional electrolyte components including lithium salt, cyclic carbonate, chain carbonate, and cyclic carboxylate. This composite approach leverages the synergistic effects of different materials to simultaneously achieve low-temperature performance and long-term durability.
2Duration of action of moving object
If charge-discharge cycles are performed repeatedly, then battery capacity is utilized, but decomposition products accumulate and gas is generated reducing performance
Solution Approach 1:
The patent converts the harmful decomposition reactions into beneficial effects by using the cyclic carboxylate compound to form a stable protective film on electrode surfaces. This film prevents further decomposition of the electrolyte and electrode materials, transforming what would be harmful continuous decomposition into a controlled initial reaction that protects the system during extended cycling.
Solution Approach 2:
The cyclic carboxylate compound acts as an intermediary substance that mediates between the electrolyte and electrode surfaces. It forms a stable interface layer that prevents direct harmful interactions between the electrolyte and electrodes during charge-discharge cycles, thereby reducing decomposition product accumulation and gas generation over time.
3Duration of action of stationary object
If batteries are stored at high temperatures, then chemical reactions proceed faster, but oxidative decomposition increases reducing low-temperature performance
Solution Approach 1:
The patent applies preliminary action by having the cyclic carboxylate compound form a stable protective film on electrode surfaces during initial cycles or storage. This pre-formed film acts as a barrier that prevents oxidative decomposition during high-temperature storage, preserving the electrolyte and electrode integrity for subsequent low-temperature operation.
4Reliability
If SEI film forms on negative electrode, then solvent decomposition is reduced, but lithium ion transport may be hindered
Solution Approach 1:
The patent optimizes the composition parameters by controlling the molar ratio of cyclic carboxylate compound to lithium salt (0.01-5 mol%) and adjusting the ratios of different carbonate solvents. These parameter changes create an SEI film with optimized properties that balances solvent protection with lithium ion transport efficiency, preventing both excessive decomposition and ion transport hindrance.
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 even after extensive use and storage at high temperatures, maintaining battery performance by minimizing decomposition and gas generation, thus improving cycle stability and high-rate discharge capabilities.
Implementation Method 1
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 2
This may form a film containing lithium oxide, lithium carbonate, and lithium alkylcarbonate as the main components on the surface of the negative electrode. This film on the surface of the electrode which is called a Solid Electrolyte Interface (SEI)
Implementation Method 3
Lithium secondary batteries mainly include a positive electrode, a nonaqueous electrolytic solution, and a negative electrode
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
AI summary
A nonaqueous electrolytic solution contains a nonaqueous solvent and an electrolyte dissolved in the solvent. The solution includes a difluoro ionic complex (1-Cis) in a cis conformation represented by the formula (1-Cis), and at least one of cyclic sulfonic acid ester, cyclic sulfonic acid ester having an unsaturated bond, cyclic sulfuric acid ester, cyclic disulfonic acid ester, chain disulfonic acid ester, cyclic disulfonic acid anhydride, nitrile group-containing compound, silyl phosphate ester derivative, and silyl borate ester derivative.