Hybrid Capacitor Pre-Lithiation for Energy Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current energy storage devices, such as lithium ion capacitors and electric double layer capacitors, face limitations in capacitance and power density due to the formation of a solid electrolyte interface (SEI) film, which reduces initial charging and discharging efficiency and stability, and the complexity of their structures hinders miniaturization.
Innovation Solution
A hybrid capacitor design incorporating a cathode with activated carbon and an anode with lithium metal layers and lithium nitride, along with a mixture of lithium and non-lithium salts as an electrolyte solution, to enhance capacitance and output characteristics by leveraging both lithium ion capacitor and electric double layer capacitor mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte interface (SEI) film is formed on the graphite anode surface, then lithium ion passage is enabled and graphite layer peeling is suppressed, but initial charging and discharging efficiency is reduced and irreversible capacitance increases
Solution Approach 1:
The anode is pre-lithiated before battery assembly by immersing it in an ethylene carbonate-based electrolyte solution containing lithium salts, allowing controlled formation of SEI film and lithium deposition in advance. This preliminary action enables the anode to have a potential of 0.1V or less and provides lithium reserves that compensate for irreversible capacitance, thereby improving initial charging efficiency while maintaining anode stability
Solution Approach 2:
The anode potential is changed to 0.1V or less through pre-lithiation, and the electrolyte composition is modified by using ethylene carbonate-based solutions with specific lithium salts. These parameter changes enable optimal SEI film formation that balances stability with reduced irreversible capacitance, improving both reliability and productivity
2Quantity of substance
If lithium pre-doping is performed to increase energy density, then energy density increases by three to four times, but device structure becomes more complex and manufacturing难度 increases
Solution Approach 1:
The pre-lithiation process is merged with the battery assembly process itself. The anode is prepared by immersing it in the electrolyte solution with lithium salts, and then the same electrolyte solution is used as the final battery electrolyte. This merging eliminates the need for separate pre-lithiation equipment and complex additional structures, achieving high energy density while simplifying manufacturing
Solution Approach 2:
The ethylene carbonate-based electrolyte solution serves multiple functions: it acts as the medium for pre-lithiation, provides the lithium source for doping, and becomes the final battery electrolyte. This multi-functionality reduces the number of components and simplifies the overall device structure while achieving three to four times energy density increase
3Adaptability or versatility
If graphite is used as anode material to enable lithium ion insertion, then lithium ion passage is achieved, but irreversible capacitance occurs and initial efficiency is reduced
Solution Approach 1:
Lithium is deposited on the graphite anode surface in advance during the pre-lithiation process, creating lithium reserves that compensate for the irreversible capacitance that will occur during initial charging. This preliminary action ensures that even though graphite causes irreversible capacitance, the initial charging efficiency is maintained at high levels
Solution Approach 2:
The graphite anode itself serves dual purposes: it provides the structure for lithium ion insertion and simultaneously accepts pre-deposited lithium that compensates for its irreversible capacitance. The anode structure is designed to accommodate both functions, allowing it to serve itself in compensating for its own deficiency
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 hybrid capacitor achieves increased energy density and improved power output while addressing issues of short circuits and process inefficiencies, offering a more stable and reliable energy storage solution with reduced resistance and simplified manufacturing.
Implementation Method 1
The supercapacitor is driven based on an electrochemical reaction mechanism that carrier ions in the electrolyte solution are selectively adsorbed to the electrode by applying power to the electrode structure
Implementation Method 2
This SEI film passes lithium ions therethrough and is cointercalated with solvent molecules
Implementation Method 3
uses an ethylene carbonate (EC) based electrolyte solution containing lithium salts
Data Source
AI summary
Disclosed herein is a hybrid capacitor including: a first structure including a cathode containing activated carbon and an anode containing lithium; and a second structure including activated carbon layers formed on both surfaces of a current collector. With the hybrid capacitor, characteristics of an LIC and characteristics of an EDLC are implemented in a single cell, thereby making it possible to increase energy density and improve output characteristics.