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Thrust 1: Single-particle electrochemistry in Battery Materials
Thrust 1: Single-particle electrochemistry in Battery Materials
Li-ion batteries are a crucial technology in our transition to a clean energy future. The batteries are comprised of micron-sized particles that are able to store and release energy through electrochemical reactions. Most research is conducted using a porous electrode containing an ensemble (>1 million) of particles, which makes it difficult to deconvolute the intrinsic particle-level behavior with electrode-level transport. Our goal is to understand the intrinsic properties of batteries by studying them on the single-particle level.
Our primary tool is the microelectrode array (left). Widely used to probe the action potential of individual neurons, we have adopted them to charge and discharge individual battery particles. Using the Lurie Nanofabrication Facility (LNF), we pattern metallic microelectrodes that are about the same size as the battery particles.
Afterward, we can assemble a single battery particle on the microelectrode. This ensures that the measured electrochemical signals can only come from that single battery particle, without the influence of other particles or of the porous electrode.
Using the microelectrode array, we are able to charge and discharge a single battery particle, which shows a similar charge and discharge profile as that of an electrode. We can also take an electron microscopy image of that particle before and after cycling to understand how the size and microstructure affect the charge and discharge properties.
Please see the video below for a presentation of our research.
While we started with NMC cathodes, we have since expanded to lithium-manganese rich, lithium iron phosphate, silicon-carbon anodes, organic cathodes, and Zn electrodeposition.
Publication:
Direct measurements of size-independent lithium diffusion and reaction times in individual polycrystalline battery particles. Energy and Environmental Sciences, 16, 3847-3859 (2023)
Direct measurements of size-independent lithium diffusion and reaction times in individual polycrystalline battery particles. Energy and Environmental Sciences, 16, 3847-3859 (2023)
Single-Particle Electrochemical Cycling Single-Crystal and Polycrystalline NMC Particles, Advanced Functional Materials, 34, 2410241 (2024)
Microelectrodes for Battery Materials, ACS Nano, 18, 35119-35129 (2024)
Microelectrode Arrays for Electrochemical Cycling of Individual Battery Particles, Chemistry of Materials, 37, 1788-1797 (2025)
Current-Controlled Zinc Electrodeposition Morphology in Ionic Liquid Electrolytes Using Microelectrode Arrays. ACS Nano, 20, 18, 13560–13571 (2026)
Intergranular degradation of secondary NMC particles in liquid and solid-state environments. EES Batteries (2026)
Activation of Hydroxylated Organic Cathodes Enables High-Rate Sodium Batteries. Preprint (2026)
Thrust 2: Oxide Electronics for Energy-Efficient Computing
Thrust 2: Oxide Electronics for Energy-Efficient Computing
Moore's Law and the continued downscaling and improvement of transistors has yielded the fastest pace of technological transformation in human history. Today, as Moore's Law is nearing its physical atomic limits, computing demands are rapidly increasing, especially for data-intensive operations like artificial intelligence (see left). Indeed, over 10% of global electricity is consumed for computing, including processing, storing, and processing data. Alternative technological approaches are needed to satiate the increasing global demand for computing.
[Graphic from Mehonic & Kenyon, Nature, 604, 255 (2022)]
We believe that the next frontier of microelectronics will come from utilizing device chemistry. While synthetic chemical approaches like atomic layer deposition are presently used to synthesize and fabricate semiconductors, semiconducting devices today operate primarily through physical processes such as gating, ferroelectricity, and light emission and generation. By leveraging electrochemistry, which enables the reversible control of chemistry using current and voltage, we enable microelectronic devices to change chemical bonds and electron valence, and therefore embed new functionality. Importantly, we also aim to understand how chemical processes affects the operations of existing electronic devices. We are motivated by the human brain, which also utilize chemical and electrochemical processes, and which are many orders of magnitude more energy efficient than the best digital computers today.
Towards this goal, we leverage fundamental understanding of ionic materials, especially motivated by the development of energy transformation technologies like the Li-ion battery. We follow a rich legacy of cross-pollination between solid-state chemistry and microelectronics. For example, the Nobel Laureates credited for the development of the Li-ion battery all first worked on electronic materials and devices: Stan Whittingham was studying superconductivity in transition metal dichalcogenides; Akira Yoshino was investigating conductive polymers; John Goodenough was already a world-renowned leader in magnetic materials.
Project 1: Oxygen Transport in Memristive Devices
Project 1: Oxygen Transport in Memristive Devices
The memristor is a promising next-generation nonvolatile memory and computing device that uses electric fields and joule heating to move point defects like oxygen vacancies. This movement of point defects allow for changes in the resistance state. In recent years, there have been substantial research in using memristors not just for high-density information storage, but also for highly-efficient memory-based computing. As shown below, memristive device switch between low and high resistance states with the formation and dissolution of conducting filmaent.
Memristive devices witch between the low and high resistance state upon applying a voltage.
In the low resistance state, or 1, oxygen vacancies form a conducting filament.
In the high-resistance state, or 0, the filament is broken due to the electric field, resulting in much higher resistance.
Our research in this area is more fundamental: instead of aiming to build the best memristive devices, architectures, and systems, we want to understand how such devices work. We are currently asking one of the most fundamental questions: why are memristors nonvolatile? In general, it is believed that memristors are nonvolatile because oxygen vacancies are too slow to diffuse at room temperatures. However, if we compute the diffusion time based on experimental parameters, we expect retention time of about 1 hour. Instead, many researchers have built memristors that retain state for 10 years.
We hypothesize that the existing model that memristors are nonvolatile due to slow oxygen diffusion may not be correct. This model was modified from the drift-diffusion equation in semiconductor device physics. We believe that oxygen transport in memristors have very different properties than electron and holes in silicon. Instead, other interactions like phase separation become much more important.
Publication:
Oxygen tracer diffusion in amorphous hafnia films for resistive memory Materials Horizons, 11, 2372-2381 (2024)
Oxygen tracer diffusion in amorphous hafnia films for resistive memory Materials Horizons, 11, 2372-2381 (2024)
Project 2: Electrochemical Random-Access Memory
Electrochemical random-access memory is a three-terminal memory technology that utilizes the electrochemical motion of ions to store information states. By combining two mixed ionic and electronic conductors and a solid electrolyte, the ECRAM cell is able to precisely tune the oxygen vacancy concentration in the "switching layer," or channel. This yields the opportunity to store analog information states in a nonvolatile fashion. In addition to oxygen vacancies, we can also use protons and copper ions.
Electrochemical random-access memory is a three-terminal memory technology that utilizes the electrochemical motion of ions to store information states. By combining two mixed ionic and electronic conductors and a solid electrolyte, the ECRAM cell is able to precisely tune the oxygen vacancy concentration in the "switching layer," or channel. This yields the opportunity to store analog information states in a nonvolatile fashion. In addition to oxygen vacancies, we can also use protons and copper ions.
While we envisioned ECRAM as an analog "synapse" for in-memory computing or neuromorphic computing, our recent developments show that this cell is highly promising as logic and memory architectures in extreme environments including high temperatures (600C) and radiation (10+ MRad) environments.
ECRAM cells switch analog resistance states through the electrochemical modulation of oxygen vacancies.
Experimental demonstration of analog resistance states enabled by ECRAM
Publications:
Nonvolatile Electrochemical Random-Access Memory Under Short Circuit. Advanced Electronic Materials 9, 2200958 (2023)
Nonvolatile Electrochemical Random-Access Memory Under Short Circuit. Advanced Electronic Materials 9, 2200958 (2023)
Nonvolatile electrochemical memory at 600°C enabled by composition phase separation, Device, 3, 100623 (2025)
Electrochemical Random-Access Memory: Progress, Perspectives, and Opportunities Chemical Reviews, 125, 1962-2008 (2025)
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