image: The supercapacitor memristor, derived from pseudocapacitors, integrates the programmable resistance and memory functions of ionic memristors, showcasing significant potential for extending traditional energy storage applications into emerging fields like biomimetic nanofluidics and neuromorphic computing.
Credit: ©Science China Press
In a groundbreaking development, Professor Xingbin Yan and his team have successfully merged two seemingly disparate research areas: supercapacitors, traditionally used in energy storage, and memristors, integral to neuromorphic computing. Their study introduces a novel phenomenon—the memristive effect in supercapacitors.
“Scientifically, we combine two seemingly disparate research areas: supercapacitors, traditionally used in energy storage, and memristors, integral to neuromorphic computing.” Prof. Xingbin Yan said, “the introduction of memristive behavior in supercapacitors not only enriches the fundamental physics underlying capacitive and memristive components but also extends supercapacitor technology into the realm of artificial synapses. This advancement opens new avenues for developing neuromorphic devices with advanced functionalities, offering a fresh research paradigm for the field.”
In 1971, Chua et al. at UC Berkeley introduced the memristor, proposing it as the fourth fundamental circuit element. Memristors have variable resistance that retains its value after current stops, mimicking neuron behavior, and are considered key for future memory and AI devices. In 2008, HP Labs developed nanoscale memristors based on TiO2. However, solid-state devices struggle with simulating chemical synapses. Fluidic memristors are promising due to their biocompatibility and ability to perform various neuromorphic functions. Confining ions in nanoscale channels allows for functionalities like ion diodes and switches, with some systems exhibiting memristive effects.
In 2021, Bocquet et al. predicted that two-dimensional nanoscopic channels could achieve ionic memory functions. Their simulations showed strong nonlinear transport effects in these channels. They confined electrolytes to a monolayer and observed that salts could form tightly bound pairs. Following this, Bocquet's team created nanoscale fluidic devices with salt solutions, showing hysteresis effects and variable memory times. Similarly, Mao et al. found comparable results with polymer electrolyte brushes, demonstrating hysteresis and frequency-dependent I-V curves. Both studies highlight advancements in controlling ions in nanofluidic devices, mimicking biological systems.
Supercapacitors are known for their higher power density, rapid response, and long lifespan, making them essential for applications in electronics, aerospace, transportation, and smart grids. Recently, a novel type of capacitive ionic device, called supercapacitor-diodes (CAPodes), has been introduced. These devices enable controlled and selective unidirectional ion transport, enhancing the functionality of supercapacitors.
In supercapacitors, charge storage occurs through ion adsorption or rapid redox reactions at the electrode surface, a principle similar to that in fluidic memristors. Inspired by CAPodes, the innovative idea is to explore whether a supercapacitor can be designed with nano-ion channels within the electrode material to achieve memory performance similar to that of fluidic memristors. If feasible, this would not only enhance traditional energy storage but also enable hysteresis in the transport and redistribution of electrolyte ions under varying electric fields.
In this design, the nanochannels of the ZIF-7 electrode in an aqueous supercapacitor allow for the enrichment and dissipation of anionic species (OH−) under varying voltage regimes. This results in a hysteresis effect in ion conductivity, which imparts memristive behavior to the supercapacitor. Consequently, the CAPistor combines the programmable resistance and memory functions of an ionic memristor with the energy storage capabilities of a supercapacitor. This integration opens up new possibilities for extending supercapacitors' traditional applications into advanced fields such as biomimetic nanofluidic ionics and neuromorphic computing.
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See the article:
Constructing a supercapacitor-memristor through nonlinear ion transport in MOF nanochannels
https://doi.org/10.1093/nsr/nwae322
Journal
National Science Review