Lithium Battery Electrolyte Additives for Dendrite-Safe Fast Charging
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Solution Overview
Problem
Rechargeable lithium batteries face issues with lithium dendrite generation, reduced cycle-life, and safety concerns under high voltage and high-speed charging conditions due to undesired reactions between electrodes and electrolytes, with existing surface treatments failing to provide sufficient protection.
Innovation Solution
An electrolyte composition comprising a non-aqueous organic solvent, lithium salt, and additives such as a fluoroalkyl compound (Chemical Formula 1), Ag salt, and fluorinated ketone, which form a protective film on electrodes to improve lithium ion conduction and suppress dendrite formation, enhancing safety and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high voltage (4.5 V or greater) and high-speed charging are implemented to increase energy density, then charging performance and energy density are improved, but electrode deterioration and lithium dendrite growth accelerate causing safety issues and reduced cycle life
Solution Approach 1:
A coating layer comprising a fluorinated compound and a silver salt is formed on the positive electrode surface to act as an intermediary barrier. This coating layer suppresses direct contact and undesired reactions between the high-voltage positive electrode and the electrolyte, thereby maintaining cycle life while enabling high-voltage operation and high-speed charging
Solution Approach 2:
The invention changes the chemical composition parameters of the electrode surface by introducing specific fluorinated compounds (with fluorine content of 10-40 wt%) and silver salts. This parameter change creates a protective interface that enables stable operation at high voltages (4.5 V or greater) without accelerating deterioration
2Reliability
If surface treatment of the positive electrode is applied to suppress undesired reactions, then electrode protection is improved, but sufficient protection effect under high voltage conditions is not achieved
Solution Approach 1:
The coating layer uses a composite material system combining fluorinated compounds (such as fluorinated carbonates, carboxylic acids, or sulfonic acids) with silver salts. This composite provides synergistic effects where the fluorinated compound forms a stable protective matrix and the silver salt enhances suppression of undesired reactions, achieving sufficient protection under high voltage conditions
Solution Approach 2:
The invention specifies precise compositional parameters for the coating layer: fluorinated compounds with 10-40 wt% fluorine content, and silver salt content of 1-20 wt% based on total coating weight. These parameter optimizations ensure the coating maintains stability and protective function at high voltages up to 4.5 V and above
3Reliability
If surface treatment of the negative electrode is applied, then electrode protection is improved, but battery capacity deteriorates
Solution Approach 1:
The invention segments the protection strategy by applying surface treatment only to the positive electrode rather than both electrodes. The coating layer on the positive electrode suppresses undesired reactions that would otherwise occur during high-voltage operation, while leaving the negative electrode untreated to maintain its original capacity and performance characteristics
4Reliability
If ester-based solvent is used in the electrolyte to suppress lithium dendrites and improve impregnability, then dendrite growth is reduced, but oxidation resistance decreases and flammability increases compromising safety
Solution Approach 1:
The coating layer on the positive electrode acts as an intermediary that suppresses undesired reactions between the electrolyte and electrodes. This allows the use of ester-based solvents with low viscosity for improved impregnability and dendrite suppression, while the coating prevents oxidation reactions and reduces flammability risks by blocking direct contact between the reactive electrolyte and electrode surfaces
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 composition improves lithium ion impregnability, reduces dendrite generation, and enhances high-speed charging performance and high-temperature cycle-life characteristics, ensuring improved safety and stability of rechargeable lithium batteries.
Implementation Method 1
the Ag salt improves conduction of lithium ions in the negative electrode
Implementation Method 2
a coating layer comprising a fluorinated compound and a silver salt is formed on a positive electrode
Implementation Method 3
a positive electrode active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative electrode active material capable of intercalating/deintercalating lithium ions
Data Source
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AI summary
An electrolyte for a rechargeable lithium battery, and a rechargeable lithium battery including the same. The electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a first compound selected from among a compound represented by Chemical Formula 1, CsPF6, and a combination thereof, and an Ag salt.