High-Voltage Lithium-Ion Cell Electrolyte for Capacity Stability
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Solution Overview
Problem
Lithium-ion battery cells with cathodes exceeding 4.3 volts face instability due to oxidative reactions with cyclic and linear carbonates in the electrolyte, leading to irreversible capacity fading and reduced performance.
Innovation Solution
The use of an electrolyte comprising carbonic esters and lithium salts with high voltage stability, combined with lithium metal-based oxide or sulfide materials in the electrodes, enables the electrochemical cell to operate at higher voltages while maintaining stability, reducing the number of cells needed and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium-ion battery cells use cathodes with voltages over 4.3 volts, then the nominal voltage and power density are improved, but the stability of the electrolyte deteriorates due to oxidative reactions with cyclic and linear carbonates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing traditional cyclic and linear carbonate solvents with fluorinated carbonate solvents and specific ester solvents. This parameter change allows the electrolyte to maintain stability at higher voltages (4.3V and above) by resisting oxidative decomposition, thus resolving the contradiction between achieving high power density and maintaining electrolyte stability
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorinated carbonate solvents (FMAn, FEMn, FDMn) with specific ester solvents (GBL, GVL, HM). This composite material approach synergistically combines the high voltage stability of fluorinated carbonates with the solvation capabilities of esters, enabling both high power density and electrolyte stability simultaneously
2Quantity of substance
If more battery cells are included in a battery module to increase capacity, then the energy storage is improved, but the size and cost of the battery module increase
Solution Approach 1:
The patent changes the voltage parameter of individual battery cells from traditional 3.7V to 4.3V or higher through the use of stabilized cathode materials and compatible electrolytes. This parameter change allows achieving the same total battery capacity with fewer cells, thereby reducing battery module size while maintaining required energy storage
3Use of energy by moving object
If traditional carbonate electrolytes are used in high voltage lithium-ion cells, then the solvation capability is maintained, but irreversible capacity fading occurs due to oxidative reactions
Solution Approach 1:
The patent introduces fluorinated carbonate solvents and ester solvents as intermediary substances that mediate between the high voltage cathode and traditional electrolyte components. These intermediary solvents provide both solvation capability for lithium ions and protection against oxidative reactions, preventing capacity fading while maintaining ionic conductivity
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
This configuration enhances the stability of lithium-ion battery cells at high temperatures, maintaining a stable electrochemical window and reducing costs by allowing fewer cells in a battery module, while improving discharge capacity and high-rate characteristics.
Implementation Method 1
The electrolyte is formed from ingredients that include a solvent and a lithium salt. The solvent includes at least one carbonic ester
Implementation Method 2
The electrochemical cell includes a positive electrode that includes a first lithium metal-based material including one or more transition metal ions, and a negative electrode that includes a second lithium metal-based material including one or more transition metal ions
Data Source
AI summary
An electrochemical cell is provided. The electrochemical cell includes a positive electrode including a first lithium metal-based material, the first lithium metal-based material including one or more transition metal ions, and wherein the positive electrode has an operating voltage of 4.5 volts versus lithium metal potential or greater. The electrochemical cell also includes an electrolyte formed from ingredients comprising a solvent and lithium salt. The solvent includes at least one carbonic ester. The electrochemical cell further includes a negative electrode including a second lithium metal-based material, the second lithium metal-based material including one or more transition metal ions.