Pre-doped Anodes for Lithium Ion Capacitors
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Solution Overview
Problem
Lithium ion capacitors face significant irreversible capacity loss and poor electrochemical performance due to lithium metal plating and gassing issues, which can lead to cell failure and thermal runaway, especially when the anode voltage exceeds critical values during cycling.
Innovation Solution
The implementation of pre-doped anodes with a controlled level of intercalated lithium ions, achieved through methods such as printing lithium powder or electrochemical incorporation, to limit lithium metal plating and gassing by maintaining the anode voltage between 0.05 to 0.3 V compared to the Li/Li+ reference voltage, thereby preventing critical voltage thresholds during cell cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the anode voltage exceeds critical values during cycling, then the energy storage device can operate at higher power, but lithium metal plating and gassing occur leading to cell failure
Solution Approach 1:
The anode is pre-doped with lithium ions before the energy storage device operates. This preliminary action ensures that the anode has sufficient lithium ions available from the start, preventing lithium metal plating during high-power operation when the anode voltage might otherwise drop to critical levels. The pre-doping is performed by contacting the anode with a lithium source at controlled conditions.
Solution Approach 2:
The invention controls the concentration of intercalated lithium ions in the anode by adjusting the pre-doping conditions (lithium source contact time, temperature, and lithium-to-anode mass ratio). By optimizing these parameters, the anode achieves an optimal lithium ion concentration that prevents plating and gassing while enabling high-power operation.
2Reliability
If the anode is pre-doped with lithium ions to prevent plating and gassing, then reliability improves, but the manufacturing process becomes more complex
Solution Approach 1:
The pre-doping process uses simple contact between the anode and a lithium source (such as lithium powder or lithium foil) without requiring complex electrochemical equipment. The lithium ions transfer spontaneously under controlled conditions, making the process self-service and avoiding the need for additional doping apparatus or complex manufacturing steps.
Solution Approach 2:
The invention extracts the complex electrochemical doping step and replaces it with a simpler physical contact process. By removing the need for external power supplies, electrolytes, and complex control systems, the manufacturing process becomes less complex while still achieving reliable pre-doping.
3Object-affected harmful factors
If lithium ions are intercalated into the anode to a high level, then lithium metal plating is limited, but the anode voltage drops to critical levels
Solution Approach 1:
The invention optimizes the lithium ion concentration in the anode by controlling pre-doping parameters (contact time, temperature, lithium-to-anode mass ratio). This parameter optimization achieves the right balance: sufficient lithium ions to prevent plating, but not so many that the anode voltage drops to critical levels during operation.
Solution Approach 2:
The pre-doping process monitors the anode voltage and adjusts the lithium source contact conditions accordingly. By using feedback from voltage measurements, the process achieves optimal lithium ion intercalation that prevents plating while maintaining safe operating voltage levels during device operation.
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 reduces equivalent series resistance, improves cycling performance, and enhances capacitance stability, preventing lithium plating and gassing, thus extending the lifespan and reliability of lithium ion capacitors.
Implementation Method 1
Lithium ions can be incorporated into the anode of a lithium ion capacitor and/or a lithium ion battery through a pre-doping process
Implementation Method 2
a first electrode comprising lithium ions adsorbed to a first electrode surface
Data Source
AI summary
An energy storage device can include a cathode, an anode, and a separator between the cathode and the anode, where the anode can have a desired lithium pre-doping level to facilitate desired capacitor performance. Controlled anode pre-doping can include printing lithium powder or a mixture including lithium powder onto a surface of the anode. Controlled anode pre-doping can include electrochemically incorporating lithium ions into the anode. A duration of the pre-doping process can be selected such that desired anode pre- doping is achieved.