Rechargeable Lithium Battery Electrolyte for High-Voltage Fast Charging
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Solution Overview
Problem
Rechargeable lithium batteries face issues with lithium dendrite growth and deterioration due to high charging voltages and rapid charging, which can lead to internal short circuits and battery degradation, especially when using ester-based solvents with weak oxidation resistance.
Innovation Solution
An electrolyte composition for lithium batteries comprising a non-aqueous organic solvent, lithium salt, and additives such as lithium oxalato borate-based compounds and diaryl sulfate-based compounds, which stabilize lithium salts and inhibit dendrite formation, even at high charging voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high charging voltage is used to increase energy density, then charging speed and energy density are improved, but lithium dendrite growth and battery deterioration occur
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the electrode surface before dendrite formation occurs. The electrolyte composition with specific additives (lithium fluorosulfonate and/or lithium bis(fluorosulfonyl)imide) pre-treats the electrode surface to create a stable interface that prevents subsequent dendrite growth during high-voltage charging operations.
Solution Approach 2:
The patent uses intermediary substances (specific lithium salt additives) that mediate between the electrode and the bulk electrolyte. These additives act as intermediaries that form protective films on the electrode surface, preventing direct harmful interactions between the high-voltage electrode and the main electrolyte, thus suppressing dendrite formation while allowing efficient ion transport.
2Speed
If ester-based solvent is used to reduce viscosity and improve ion transport, then charging rate is improved, but oxidation resistance decreases and battery deterioration occurs
Solution Approach 1:
The patent employs composite materials by combining ester-based solvents (for low viscosity and high ion transport) with specific lithium salt additives (lithium fluorosulfonate and/or lithium bis(fluorosulfonyl)imide). This composite electrolyte system leverages the advantages of ester solvents while the additive components provide oxidation resistance and dendrite suppression, resolving the contradiction between ion transport rate and oxidation resistance.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition parameters of the electrolyte - specifically incorporating lithium salts with fluorosulfonate or bis(fluorosulfonyl)imide anions at controlled concentrations (0.1-5 wt%). This parameter modification changes the electrolyte's oxidation resistance properties while maintaining low viscosity and high ion conductivity through the ester-based solvent system.
3Loss of time
If rapid charging is implemented to increase productivity, then charging time is reduced, but lithium dendrite growth and internal short circuits increase
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable protective film on the electrode surface using specific lithium salt additives before rapid charging begins. This pre-treatment creates a barrier that prevents lithium dendrite formation even under the high current conditions of rapid charging, allowing reduced charging time without increasing dendrite-related hazards.
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 effectively suppresses lithium dendrite growth and battery deterioration, allowing for higher charging voltages and faster charging without adverse effects, thereby enhancing battery performance and cycle-life characteristics.
Implementation Method 1
a negative electrode including a negative electrode active material capable of intercalating/deintercalating lithium ions
Implementation Method 2
if lithium ions fail to intercalate into the negative electrode active material and are reduced, lithium dendrites may grow on the surface of the negative electrode
Implementation Method 3
the additive includes a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
There is provided an electrolyte for a rechargeable lithium battery. The electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive. The additive includes a first additive represented by Chemical Formula 1 and a second additive represented by Chemical Formula 2: