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1. Rapid 3D Printing of Nanoporous Microsupercapacitor Electrodes Using Projection Two‐Photon Lithography

   https://doi.org/10.1002/eng2.70364  

   Chance, Henry R; Kim, Harnjoo; Brown, Billyde; Saha, Sourabh K (August 2025, Engineering Reports)

   ABSTRACT Despite their high power density, microsupercapacitors (MSCs) are impractical for many energy storage applications due to their limited energy density. Their energy density can be increased by shaping the electrodes into 3D structures with high specific surface area (SSA). Direct printing of nanoporous 3D electrodes is a promising approach for achieving high SSA. However, conventional nanoscale 3D printing is too slow due to point‐by‐point processing. Here, we have employed the projection two‐photon lithography technique to fabricate nanoporous 3D electrodes via a rapid layer‐by‐layer mechanism. The 3D MSC electrodes are engineered as an array of nanoporous polymeric micropillars that are printed with customizable spacing and count over a 0.25 cm²area. After printing, these micropillars are conformally coated with titanium nitride to form conductive 3D electrodes, which exhibit a specific capacitance of 361 μF/cm². This is two orders of magnitude higher than the capacitance of the flat surface and exceeds the capacitance of both traditional bare electrodes, such as single‐wall carbon nanotubes (< 100 μF/cm²), and electrodes produced by photo‐polymerization 3D printing (˜200 μF/cm²). As our work demonstrates that high energy density 3D electrodes can be rapidly fabricated, it significantly expands the utility of MSCs as miniaturized energy storage devices. 

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2. StableTi ₃ C ₂ T _x MXene Ink Formulation and High‐Resolution Aerosol Jet Printing for High‐Performance MXene Supercapacitors

   https://doi.org/10.1002/smtd.202500499  

   Kouchi, Fereshteh Rajabi; Varghese, Tony Valayil; Burgoyne, Hailey; Mansoor, Naqsh E; Seol, Myeong‐Lok; McKibben, Nicholas; Nirantar, Shruti; Chinnathambi, Karthik; Eixenberger, Josh; Maryon, Olivia; et al (May 2025, Small Methods)

   Abstract Lightweight energy storage devices are essential for developing compact wearable and distributed electronics, and additive manufacturing offers a scalable, low‐cost approach to fabricating such devices with complex geometries. However, additive manufacturing of high‐performance, on‐demand energy storage devices remains challenging due to the need for stable, multifunctional nanomaterial inks. Herein, the development of 2‐dimensional (2D) titanium carbide (Ti₃C₂T_xMXene) ink that is compatible with aerosol jet printing for energy storage applications is demonstrated. The developed MXene ink demonstrates long‐term chemical and physical stability, ensuring consistent printability and achieving high‐resolution prints (≈45 µm width lines) with minimal overspray. The high‐resolution aerosol‐jet printed MXene supercapacitor achieves an areal capacitance of 122 mF cm⁻²and a volumetric capacitance of 611 F cm⁻³, placing them among the highest‐performing printed supercapacitors reported to date. These findings highlight the potential of aerosol jet printing with MXene inks for on‐demand, scalable, and cost‐effective fabrication of printed electronic and electrochemical devices. 

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3. Transforming scalable synthesis of graphene aerosol gel material toward highly flexible and wide-temperature tolerant printed micro-supercapacitors

   https://doi.org/10.1063/5.0186302  

   Raihan, Kh_MAsif; Sahoo, Surjit; Nagaraja, Thiba; Sigdel, Shusil; LaCroix, Brice; Sorensen, Christopher M; Das, Suprem R (March 2024, APL Energy)

   Lira-Cantu, Monica (Ed.)

   The ever-growing demand for portable, bendable, twistable, and wearable microelectronics operating in a wide temperature range has stimulated an immense interest in the development of solid-state flexible energy storage devices using scalable fabrication technology. Herein, we developed additively manufactured graphene aerosol gel-based all-solid-state micro-supercapacitors (MSCs) via inkjet printing with functioning temperature in the range from −15 to +70 °C and exhibiting a super-stable and reliable electrochemical performance using interdigitated finger electrodes and PVA/H3PO4 solid-state electrolyte. The graphene aerosol gel was obtained using a scalable single step synthesis method from a gas phase precursor using a detonation process, producing a nanoscale shell type structure. The fabricated graphene aerosol gel-based solid-state MSC achieved a volumetric capacitance of 376.63 mF cm−3 (areal capacitance of 76.23 μF cm−2) at a constant current of 0.25 μA and demonstrated exceptional cyclic stability (∼99.6% of capacitance retention) over 10 000 cycles. To exploit the mechanical strength of the as-fabricated graphene aerosol gel-based solid-state MSC, its supercapacitive performance was scrutinized under various bending and twisting angles and the results showed excellent mechanical flexibility. Furthermore, to study the electrochemical performance of the as-fabricated graphene aerosol gel solid-state MSC in stringent surroundings, a broad temperature dependent supercapacitive analysis was performed as stated above. The electrochemical results of the as-fabricated graphene aerosol gel based all-solid-state MSC exhibit a highly potential route to develop scalable and authentic future miniaturized energy storage devices for IoT based smart electronic appliances. 

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4. Carbon Nanostructures Derived from In Situ Grown ZIF Nanocages within Bacterial Cellulose for AC‐Filtering Electrochemical Capacitors

   https://doi.org/10.1002/smll.202409110  

   Baranwal, Rishav; Lin, Xueyan; Qiao, Yinxuan; Tan, Haiyan; Goryll, Michael; Fan, Zhaoyang (December 2024, Small)

   Abstract Electrochemical capacitors (ECs) offer superior specific capacitance for energy storage compared to traditional electrolytic capacitors but face limitations in alternating current (AC) filtering due to the need for balancing fast response and high capacitance. This study addresses these challenges by developing a freestanding nanostructured carbon electrode, derived from the rapid carbonization of bacterial cellulose (BC) embedded with zeolitic imidazolate framework 8 (ZIF‐8) and in situ formed carbon nanotubes (CNTs). The electrode exhibits an exceptionally low area resistance of 9.8 mΩ cm²and a high specific capacitance of 2.1 mF cm⁻²at 120 Hz, maintaining performance even at high frequencies. Stacking these electrodes enhances the capacitance to 5.3 mF cm⁻², with the phase angle degrading to −74.4° at 120 Hz; however, they retain a phase angle below −45° up to ≈50 kHz, demonstrating excellent high‐frequency performance. Furthermore, connecting three aqueous units in series as an integrated cell or utilizing organic electrolytes extends the voltage window to 2.4 V, enhancing their suitability for high‐voltage applications. Ripple voltage analysis under various loads and frequencies indicates effective filtering capabilities, highlighting the potential of these nanostructured ECs for next‐generation electronic applications. 

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5. Germanium‐Functionalized 3D Microporous, Nanostructured Nickel–Nickel Oxides for Application in Asymmetric Supercapacitors

   https://doi.org/10.1002/ente.202300360  

   Kr_Singh, Balwant; Das, Debabrata; Gonzalez, Cristina; Ramana, C V (October 2023, Energy Technology)

   Supercapacitors and batteries are essential for sustainable energy development. However, the bottleneck is the associated high cost, which limits bulk use of batteries and supercapacitors. In this context, realizing that the cost of energy‐storage device mainly depends on materials, synthesis processes/procedures, and device fabrication, an effort is made to rationally design and develop novel low‐cost electrode materials with enhanced electrochemical performance in asymmetric supercapacitors. Herein, surface functionalization approach is adopted to design low‐cost 3D mesoporous and nanostructured nickel–nickel oxide electrode materials using facile synthesis for application in supercapacitors. It is demonstrated that the 3D mesoporous Ni provides the high surface area and enhanced ionic conductivity, while germanium functionalization improves the electrical conductivity and reduces the charge‐transfer resistance of NiO. Surface functionalization with Ge demonstrates the significant improvement in specific capacitance of NiO. The asymmetric supercapacitor using these Ge‐functionalized NiO–Ni electrodes provides a specific capacitance of 304 Fg⁻¹(94 mF cm⁻²), energy density of 23.8 Wh kg⁻¹(7.35 μWh cm⁻²), and power density of 6.8 kW kg⁻¹(2.1 mW cm⁻²) with excellent cyclic stability of 92% after 10 000 cycles. To validate their practical applications, powering the digital watch using the asymmetric supercapacitors in laboratory conditions is demonstrated. 

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