Prelithiated Carbon LIC Electrodes for High Volumetric Energy Density
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Solution Overview
Problem
The fabrication of lithium-ion capacitors is limited by the need for lithium foil as a sacrificial electrode, which requires the use of metallic lithium, and existing designs face challenges with severe mass transfer limitations and high equivalent series resistance in thick electrodes.
Innovation Solution
The development of lithium-ion capacitors that utilize prelithiated carbon materials as anodes, eliminating the need for metallic lithium and incorporating ultrathick high surface area carbon cathodes with bimodal porosity to enhance energy storage and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium foil is used as a sacrificial electrode to lithiate the graphite anode, then the lithium-ion capacitor becomes functional, but metallic lithium remains in the packaged capacitor creating safety and stability issues
Solution Approach 1:
The patent removes the harmful metallic lithium component from the capacitor system while retaining its essential function. Instead of using lithium foil as a sacrificial electrode, the invention uses prelithiated carbon materials that provide lithium ions through intercalation rather than metallic lithium, thereby extracting the harmful element while preserving functionality.
Solution Approach 2:
The patent replaces permanent metallic lithium with a disposable prelithiation layer that is consumed during initial cycles to form the solid electrolyte interphase (SEI), after which the system operates without further lithium consumption. This disposable approach eliminates the need for ongoing metallic lithium presence.
2Quantity of substance
If ultrathick high surface area carbon cathodes are used to achieve high energy density, then energy storage capacity increases, but severe mass transfer limitations and high equivalent series resistance occur
Solution Approach 1:
The patent employs carbon cathodes with engineered porous structures that provide high surface area for energy storage while maintaining efficient mass transfer. The porous architecture allows electrolyte penetration and ion transport throughout the thick electrode, resolving the contradiction between high capacity and mass transfer efficiency.
Solution Approach 2:
The patent transitions from two-dimensional surface-based energy storage to three-dimensional volumetric energy storage through thick electrodes with optimized porosity. This dimensional change enables high energy density while maintaining ion transport pathways through the electrode thickness.
3Use of energy by moving object
If carbon cathode mass loading is increased to achieve packaged energy densities >10 Wh/L, then energy density improves, but mass transfer limitations become more severe
Solution Approach 1:
The patent optimizes the porosity parameters and surface area-to-volume ratio of the carbon cathode to enable high mass loading while maintaining ion transport efficiency. By changing the structural parameters of the carbon material, the system achieves high energy density without proportionally increasing mass transfer resistance.
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 allows for higher energy density, improved cyclability, and reduced equivalent series resistance, enabling the capacitors to handle higher load currents and maintain performance in smaller form factors, suitable for applications in microelectronics and IoT devices.
Implementation Method 1
a carbon material (e.g. graphite) can be prelithiated to include lithium ions therein to form an anode for the LIC
Implementation Method 2
a balance of high surface area ultramicropores in the range of 0.8 nm-2 nm along with interconnected mesopores that can act as local reservoirs of electrolyte ions while promoting efficient ion transport through the electrode
Implementation Method 3
furfuryl alcohol can be acid polymerized in the presence of other polymers such as polyethylene glycol or polyethylene glycol diacids
Implementation Method 4
Alternately, furfuryl alcohol can be simultaneously polymerized using a co-monomer such as phloroglucinol to yield a resultant polymer during pyrolysis undergo phase separation to create micropores and mesopores
Implementation Method 5
A lithium-ion capacitor (LIC) can store more energy compared to electric double-layer capacitors (EDLC) due to the Faradaic lithium intercalation at the anode and higher voltage window (∼4V) of Li-ion electrolytes
Data Source
AI summary
A method of fabricating a capacitor can include prelithiating a carbon material to form a first layer for the capacitor. The first layer including an anode or being an anode layer. A second layer can be positioned between the first layer and a third layer. The second layer can be or include a membrane and the third layer can be or include a cathode. The third layer can include activated carbon or utilize activated carbon as a cathode. Capacitors can be formed by use of this method and devices can utilize such capacitors. Instead of relying on lithium in metallic form, a carbon material can be prelithiated to include lithium ions therein to form an anode for the LIC that avoids use of lithium foil or lithium powder in the LIC and also avoid use of lithium in a metallic form in the LIC.