High Energy Density Supercapacitors

Project Overview

Energy storage devices typically excel in one of two key metrics: energy density or power density. Energy density, a measure of how much energy a device can store, is traditionally the domain of batteries and fuel cells that depend on energy-dense (but relatively slow) chemical reactions. Power density, a measure of how fast a device can be charged or discharged, is typically dominated by capacitors because they are based on charge separation, an extremely fast but surface area-limited process. Pseudocapacitors, which rely on fairly fast redox reactions, could provide a path to energy storage devices with good power and energy density. However, good performance with many pseudocapacitve materials, like manganese oxide (MnO2), is difficult to achieve in practical devices due to low electron conductivity and sluggish ion diffusion. Specifically, excellent capacitance performance is observed with extremely low loadings of active material (MnO2). But when active material content is increased, performance deteriorates. Therefore, this project aimed to realize an order of magnitude increase in the volumetric energy density of a supercapacitor device by taking advantage of performance enhancements afforded by additive manufacturing. The approach this project used to achieve this goal is two-fold. First, the most efficient use of the electrode volume was pursued by optimizing the active material (e.g. MnO2) loading and pore architecture. Recent work has shown that 3D-printed symmetric supercapacitor devices (0.8V) can sustain extremely high active material loading (>300 mg cm-2) without the typical decay of capacitance performance observed due to sluggish ion diffusion. To realize the goals of this project, the high MnO2 loading was coupled with a 3D-printed electrode that was designed to maximize the energy density of the device. It is expected that a more intelligent design of the electrode architecture alone should almost double the energy density of the storage device. Secondly, the operating voltage of the device was expanded from 0.8 V to over 3.6 V. To increase the voltage window, we moved from a symmetric supercapacitor device to an asymmetric supercapacitor. This involves finding a matching electrode material that complements the MnO2/carbon aerogel electrode, which in this case was vanadium oxide. We also moved to a non-aqueous electrolyte which further increased the operating voltage of our device. By optimizing the active material loading and moving to asymmetric supercapacitors and non-aqueous electrolytes (>2V), a more than 10x improvement in energy density was realized (>20 Wh/l).

Mission Impact

With targeted applications for supercapacitors in energy storage and capacitive desalination, this work is directly related to the Energy and Climate Security Mission Focus Area. In addition, with a focus on material feedstock and transport modeling we will leverage and advance Core Competencies in Advanced Materials and Manufacturing and Computational Science and Engineering. Finally, this work address DOE's energy and environmental security missions by developing science and technology tools and capabilities to meet future national security challenges.

Publications, Presentations, and Patents

Yao, B. et al., 2021. "Printing Porous Carbon Aerogels for Low Temperature Supercapacitors," Nano Letters 21: 3731 (2021). https://doi.org/10.1021/acs.nanolett.Oc04780.

Chandrasekaran, S. et al., 2021. "Carbon Aerogels with Integrated Engineered Macroporous Architecture for Improved Mass Transport." Carbon 179: 125 (2021). https://doi.org/10.1016/j.carbon.2021.04.017.

Roy, T., et al., 2022. "Topology Optimization for the Design of Porous Electrodes." Structural and Multidisciplinary Optimization 65, 171 (2022).

Reale Batista, M. D. et al. 2022. "3D Printing of Graphene/Acrylate Electrodes for Supercapacitor Applications." International Conference on Materials Science, Engineering & Technology, Singapore. Virtual. September 2022.

Worsley, M..A. 2022. "Innovations in Pore Architecture: Lessons from Additive Manufacturing & Computational Design of Electrodes for Membranes." Membranes: Materials and Processes, Gordon Research Conference, New London, New Hampshire. July 2022.

Worsley, M. A. et al. 2022. "3D Printing of 2D Materials for Optimized Electrochemical Performance." ECS Meeting Abstracts MA2022-01. 2460-2460. https://doi.org/10.1149/MA2022-01122460mtgabs.

Beck, V. A. et al. 2022. "Elucidating the Mass Transport Properties of Additively Manufactured Electrodes Using Spatially Resolved Simulation." 241st ECS Meeting, Vancouver, Canada, May 2022. ECS Meeting Abstracts MA2020-02: 2141-2141. https://doi.org/10.1149/MA2020-02332141mtgabs.

Roy, T. et al. 2022. "Maximizing Energy Efficiency of Porous Electrodes Via Topology Optimization." 241st ECS Meeting, Vancouver, Canada. May 2022.

Beck, V. A. et al. 2021. "Additive Manufacturing of Graphene Aerogel Electrodes," 2021 Spring ECS Meeting. June 2021.

Beck, V. A. et al. 2020. "Optimizing 2D Materials-based Electrodes for Electrochemical Energy Storage and Conversion Devices." Bay Area Battery Summit. Virtual. November 2020.

Worsley, M. A. 2020. "Aerogels for Energy and Environmental Applications." Fall 2020 NNSA, MSIPP, STEAM, CHRES Seminar. October 2020.

Beck, V. A. et al., 2020. "3D Printing Aerogels." MRS Fall Meeting 2019, Boston, Massachusetts. December 2019.