Lithium Titanate Negative Electrode Charging Overpotential
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Solution Overview
Problem
Conventional lithium-ion batteries face limitations in charging speed due to the risk of lithium plating on the negative electrode, which restricts the use of high charge voltages and results in irreversible capacity loss and corrosion, especially when discharged to zero volts.
Innovation Solution
The use of a lithium titanate active material on the negative electrode allows for charging at an overpotential greater than 70 millivolts below the equilibrium potential, preventing lithium plating and enabling faster charging rates without compromising battery integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high charge voltages are used to increase charging speed, then charging rate is improved, but lithium plating occurs on the negative electrode causing corrosion and capacity loss
Solution Approach 1:
The patent changes the operating voltage parameters by applying overpotential (charging at potentials more negative than equilibrium) and controls the charging voltage profile to remain below the copper corrosion potential threshold. This parameter optimization enables faster charging while preventing lithium plating and current collector corrosion, resolving the contradiction between charging speed and battery integrity
Solution Approach 2:
The patent takes preliminary protective action by establishing and maintaining the charging voltage below the copper corrosion potential (3.5V) from the outset, preventing the harmful condition of lithium plating before it can occur. This preemptive voltage control strategy avoids the need for corrective actions and preserves battery integrity throughout the charging process
2Quantity of substance
If charging continues to zero volts discharge point, then battery capacity is maximized, but copper current collector corrosion occurs
Solution Approach 1:
The patent implements feedback control by continuously monitoring the charging voltage and comparing it against the copper corrosion potential threshold (3.5V). The charging process is adjusted in real-time to ensure the voltage remains below this critical threshold, preventing corrosion while still achieving full capacity charging. The system feedback mechanism detects approaching dangerous conditions and automatically corrects the charging profile
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 approach enables lithium-ion batteries to be charged more quickly and efficiently, reducing the risk of lithium plating and corrosion, while maintaining high energy density and power delivery, suitable for applications in implantable medical devices.
Implementation Method 1
During charging and discharging of the battery 10, lithium ions move between the positive electrode 20 and the negative electrode 30
Implementation Method 2
The use of a lithium titanate active material on the negative electrode allows for charging at an overpotential greater than 70 millivolts below the equilibrium potential, preventing lithium plating
Data Source
AI summary
A method for charging an implantable medical device includes charging a lithium-ion battery provided in a medical device, the lithium-ion battery having a negative electrode with a lithium titanate active material. For at least a portion of the charging, the potential of the negative electrode is more than approximately 70 millivolts below the equilibrium potential of the negative electrode.