More Like this

1. Machine-learning-assisted material discovery of oxygen-rich highly porous carbon active materials for aqueous supercapacitors

   https://doi.org/10.1038/s41467-023-40282-1  

   Wang, Tao; Pan, Runtong; Martins, Murillo L.; Cui, Jinlei; Huang, Zhennan; Thapaliya, Bishnu P.; Do-Thanh, Chi-Linh; Zhou, Musen; Fan, Juntian; Yang, Zhenzhen; et al (December 2023, Nature Communications)

   Abstract Porous carbons are the active materials of choice for supercapacitor applications because of their power capability, long-term cycle stability, and wide operating temperatures. However, the development of carbon active materials with improved physicochemical and electrochemical properties is generally carried out via time-consuming and cost-ineffective experimental processes. In this regard, machine-learning technology provides a data-driven approach to examine previously reported research works to find the critical features for developing ideal carbon materials for supercapacitors. Here, we report the design of a machine-learning-derived activation strategy that uses sodium amide and cross-linked polymer precursors to synthesize highly porous carbons (i.e., with specific surface areas > 4000 m²/g). Tuning the pore size and oxygen content of the carbonaceous materials, we report a highly porous carbon-base electrode with 0.7 mg/cm²of electrode mass loading that exhibits a high specific capacitance of 610 F/g in 1 M H₂SO₄. This result approaches the specific capacitance of a porous carbon electrode predicted by the machine learning approach. We also investigate the charge storage mechanism and electrolyte transport properties via step potential electrochemical spectroscopy and quasielastic neutron scattering measurements. 

   more » « less
2. Advancements in 2D MXene-based supercapacitor electrodes: synthesis, mechanisms, electronic structure engineering, flexible wearable energy storage for real-world applications, and future prospects

   https://doi.org/10.1039/D4TA00328D  

   Kadam, Sujit Anil; Kadam, Komal Prakash; Pradhan, Nihar R (January 2024, Journal of Materials Chemistry A)

   Hagfeldt, Anders (Ed.)

   Supercapacitors are widely recognized as a favorable option for energy storage due to their higher power density compared to batteries, despite their lower energy density. However, to meet the growing demand for increased energy capacity, it is crucial to explore innovative materials that can enhance energy storage efficiency. Recent research has focused on investigating various electrode materials for use in supercapacitors, with particular attention given to MXenes. MXenes exhibit immense potential for energy storage due to their unique characteristics, including a 2D van der Waals layered structure, small band gaps, hydrophilic surface, excellent electrical conductivity, high specific surface area, and active redox sites on the surface facilitated by transition metals. These attributes collectively contribute to their promising stability, energy and power density, and overall lifespan. This comprehensive review explores a diverse array of topics pertaining to the latest 2D MXene-based supercapacitor electrodes. It encompasses discussions on different synthesis methods, electrode structures, the underlying working mechanisms, and the impact of electrolytes on supercapacitor performance. Additionally, a concise overview of various types of MXene materials is presented, ranging from titanium-based MXenes to niobium-based MXenes, vanadium-based MXenes, molybdenum-based MXenes, and tantalum-based MXenes. Furthermore, this review focuses on electronic structure engineering strategies such as heterostructures based on MXenes, heteroatom-doping based on MXenes, polymer based MXenes, and ternary composites based on MXenes, all of which contribute to improving the electrochemical performance of supercapacitors. The review thoroughly examines the advantages and disadvantages of MXene-based supercapacitor electrodes, offering a comprehensive understanding of their strengths and limitations. Additionally, it discusses the structural stability of MXene-based electrodes after electrochemical testing, as well as their applications in daily human life, particularly focusing on the uses of MXene-based flexible wearable energy storage for real-world applications. In the end, the challenges and prospects of MXenes in supercapacitors are discussed. 

   more » « less
3. Interfacial Engineering of Conformal Titanium Oxide Nanofilms on Porous Carbon Supercapacitor Electrodes Via Atomic Layer Deposition

   https://doi.org/10.2139/ssrn.5224571  

   Vitto, Remuel Isaac; Pourkheirollah, Hamed; Keskinen, Jari; Vindt, Steffen Thrane; Cook, Andrew; Grīnberga, Līga; Ignatane, Liga; Kučinskis, Gints; Tewari, Amit; Lupo, Donald; et al (January 2025, Materials Research Society)

   Atomic layer deposition (ALD) has been gaining in popularity as a powerful deposition technique and have been shown to be a promising interfacial engineering method to boost the electrochemical performance of supercapacitors, bridging the gap in energy density. In that regard, we developed an ALD technique to deposit titanium dioxide (TiO2) nanofilms onto porous activated carbon (AC) electrodes. This study focused on the critical aspects of the ALD process that were still unexplored by previous relevant works, including the effects of precursor pulse duration and film thickness on the complex porous structures of AC. In particular, these comprehensive investigations pave the way towards uniform distribution and excellent conformity of the TiO2 nanofilms across the AC surface. Moreover, the deposited films were found to be amorphous and resulted in increased amounts of oxygen-containing surface functional groups. The enhanced electrochemical behavior from the TiO2 nanofilms were found to be optimal at 60 ALD cycles with an estimated film thickness of 2.3 nm. The assembled supercapacitor device coated with this ALD technique exhibited higher specific capacitance compared to the bare AC. The key findings of this work provide the foundation of an effective strategy using ALD for fabricating new electrode materials for high-performance supercapacitors. 

   more » « less
4. Tuning the water interlayer spacer of microwave-synthesized holey graphene films towards high performance supercapacitor application

   https://doi.org/10.1088/2053-1583/ad42ae  

   Bi, Kun; Jiang, Xinyu; Sun, Haofan; Dou, Yan; Nile, Richard; wang, dini; Rubbi, Fazlay; Zhang, Xing; Wang, Yan; Liao, Yiliang; et al (April 2024, 2D Materials)

   Abstract Graphene-based electrodes have been extensively investigated for supercapacitor applications. However, their ion diffusion efficiency is often hindered by the graphene restacking phenomenon. Even though holey graphene is fabricated to address this issue by providing ion transport channels, those channels could still be blocked by densely stacked graphene nanosheets. To tackle this challenge, this research aims at improving the ion diffusion efficiency of microwave-synthesized holey graphene films by tuning the water interlayer spacer towards the improved supercapacitor performance. By controlling the vacuum filtration during graphene-based electrode fabrication, we obtain dry films with dense packing and wet films with sparse packing. The SEM images reveal that 20 times larger interlayer distance is constructed in the wet film compared to that in the dry counterpart. The holey graphene wet film delivers a specific capacitance of 239 F/g, ~82% enhancement over the dry film (131 F/g). By an integrated experimental and computational study, we quantitatively show that the interlayer spacing in combination with the nanoholes in the basal plane dominates the ion diffusion rate in holey graphene-based electrodes. Our study concludes that novel hierarchical structures should be further considered even in holey graphene thin films to fully exploit the superior advantages of graphene-based supercapacitors. 

   more » « less
5. Ion transport in hydroxide conducting block copolymers

   https://doi.org/10.1039/C9ME00022D  

   Elabd, Yossef A. (June 2019, Molecular Systems Design & Engineering)

   Hydroxide ion conducting block copolymers have the potential to possess the multiple properties required for anion exchange membranes to enable long-lasting alkaline fuel cell performance, and therefore can accelerate the advancement of the alkaline fuel cell, a low-cost alternative to the well-adopted commercial proton exchange membrane fuel cell. In this paper, an overview of hydroxide ion transport (a property that is proportional to fuel cell performance) in block copolymers will be presented and the subsequent impact of block copolymer morphology on ion transport (conductivity), where the careful design of block copolymer chemistry and chain architecture can accelerate hydroxide ion transport. 

   more » « less