Carbonate-Nitrile Electrolyte for Safe Li-Ion Batteries
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Solution Overview
Problem
Current lithium-ion battery technologies face limitations due to the limited supply of cobalt, high flammability of carbonate solvents, and low chemical stability of LiPF6 electrolyte salt, which restricts operating temperature range and poses safety risks.
Innovation Solution
A carbonate:nitrile type solvent mixture-based electrolyte with lithium-difluoro(oxalato)borate (LiDFOB) salt and polymer additives, such as poly(methyl vinyl ether - alt - maleic anhydride), is used to enhance ionic conductivity, stability, and safety, allowing for extended temperature range and stable cycling of advanced battery electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 electrolyte salt is used in carbonate solvents, then ionic conductivity is achieved, but chemical stability deteriorates and operating temperature range is restricted
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by replacing LiPF6 with LiTFSI salt and transitioning from pure carbonate solvents to a hybrid solvent system containing cyclic carbonate, chain carbonate, and nitrile components. This parameter change achieves both high ionic conductivity and extended operating temperature range from -30°C to 60°C with stable capacity retention
Solution Approach 2:
The patent employs a composite electrolyte formulation combining multiple solvent types (cyclic carbonate EC, chain carbonate DMC, and nitrile SCN) with LiTFSI salt. This composite approach synergistically combines the high dielectric constant of cyclic carbonate, low viscosity of chain carbonate, and low freezing point of nitrile, achieving both chemical stability and wide temperature operation
2Reliability
If carbonate solvents are used, then ionic conductivity is maintained, but flammability increases and safety deteriorates
Solution Approach 1:
The patent introduces nitrile solvent (SCN) as an intermediary component that modifies the electrolyte's fire safety properties. The nitrile acts as a mediator between the carbonate solvents and the electrode interfaces, forming a protective SEI layer that reduces flammability while maintaining ionic conductivity and electrochemical performance
3Productivity
If conventional electrolyte formulations are used, then manufacturing simplicity is maintained, but cobalt supply bottleneck limits production volume increase
Solution Approach 1:
The patent extracts cobalt from the cathode material formulation by developing high-voltage Li-ion batteries (4.3V) using cobalt-free or low-cobalt cathodes paired with the new LiTFSI-based electrolyte. This extraction eliminates the cobalt supply bottleneck while maintaining high energy density and enabling scaled production
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 provides higher operating temperature, stable cycling of advanced cathodes and anodes, improved safety by reducing volatility and dendrite growth, and maintains high ionic conductivity, addressing the limitations of existing lithium-ion battery technologies.
Implementation Method 1
The electrolyte may comprise a carbonate : nitrile type solvent mixture based electrolyte... allows stable cycling of advanced Li-ion battery electrodes... maintains high ionic conductivity
Implementation Method 2
The electrolyte may comprise one or more ionic salts dissolved in the dinitrile such that the melting point of the dinitrile is depressed to below the operating temperature
Data Source
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AI summary
An electrochemical cell is disclosed comprising a carbonate : nitrile type solvent mixture based electrolyte. The electrolyte may comprise an alkali salt and/or at least one polymer additive. The alkali salt cation may be a lithium cation and/or the alkali salt anion may comprise an oxalato-borate group. The electrolyte may further comprise one or more electrolyte additives, which may be an SEI improving additive. The anode may comprise carbon. The anode may be an alkali metal anode.The operating voltage and energy density performance of the disclosed invention is at the same level as the performance of presently market- leading battery cells, thereby these disclosed improvements do not come at the expense of battery performance. The utility of the herein disclosed battery electrolyte allows stable cycling of advanced Li-ion battery electrodes, an extended operating temperature range and improves battery safety by making the electrolyte less reactive and volatile than conventional LiPF6 electrolyte salt in carbonate solvents.