Project title: Innovative electrodes based on graphene – carbon nitride for supercapacitor cell
Acronym: EGRAN-CELL
Programme/ Project type: PNCDI IV - Program 5.7.1 – Partnerships for Competitivity, Experimental Demonstration Project (PED)
Contract no. 3⁄ 2025 (PN-IV-P7-7.1-PED-2024-2280)
Project Duration: 08/01/2025 - 31/12/2026
Project Budget: 750.000 lei
Contractor: National Institute of Research and Development in Microtechnologies – IMT Bucharest (www.imt.ro)
Contracting Authority: Executive Agency for Higher Education, Research, Development and Innovation Funding – UEFISCDI (www.uefiscdi.gov.ro)
Project manager: Dr. Alexandru Cosmin Obreja (cosmin.obreja@imt.ro)

For optimal utilization of renewable energy, it is essential to store the generated power in a reliable energy-storage system for use when needed. One of the most effective methods for storing renewable energy is through electrochemical storage technologies. Supercapacitors are known for their high power density, while batteries excel in energy density. Because of their power-dense nature, supercapacitors are particularly useful for regulating power requirements, conditioning power during peak demands, and capturing surge power. The electrochemical performance of supercapacitors, however, is highly dependent on the properties of their electrode materials.Nickel cobalt double layered hydroxide is an attractive material for advantages including high theoretical specific capacitance, easy of manufacture and cycling stability for energy storage applications. Attempts boosting the specific capacitance include intensive research on layered double hydroxides and carbon derived material composites or to keep a specific surface area control by tuning the hierarchical morphology of this material.  The proposed project (EGRAN-CELL) consist of fabrication of a ternary nanocomposite in a well-defined architecture where graphitic carbon nitride nanoparticles act as a scaffold during the reduction of graphene oxide, preserving in this way the restacking of graphene flakes. The nickel-cobalt double layered hydroxide (LDH) formed in the presence of reduced graphene oxide-carbon nitride nanocomposite present a core-shell morphology where RGO-gCN are predominantly covered with LDH lamellar structure. The method proposed by EGRAN-CELL is the development of supercapacitor cell in one experimental model with defined characteristics from TRL2  to TRL 4  level aiming at demonstrating the feasibility of the innovative features.

• National Institute for Research and Development in Microtechnologies (IMT-Bucharest)
• Apel Laser SRL

The main scope of this project is to develop and validate innovative ternary electrodes for supercapacitor cells in the area of energy storage devices where the architecture consist of a ternary composite structure including graphitic carbon nitride (gCN), reduced graphene oxide (RGO) and nickel cobalt layered double hydroxide (NiCoLDH). The electrode material in a well-tuned hierarchical architecture will deliver high specific capacitance that significantly improve energy density, power density and cycle stability in one assembled cell. The expected performance of new ternary electrode in asymmetric cell configuration will deliver an energy density of 30 Wh/kg, power density of minimum 800 W/kg, with a specific capacitance of electrode of at least 2000 F/g, a cycling stability over 90% after 5000 cycles and a target potential window of 1.2–1.6 V.

The general objectives of this project include:

• Synthesis and characterization of reduced graphene oxide (RGO), carbon nitride(g-CN) and ternary architecture material electrode RGO/g-CN@NiCoLDH and electrochemical evaluation. The purpose is to achieve a ternary material with controlled porosity, specific surface area by monitoring the parameters of synthesis and morphology. The potential of capacitive performance will be evaluated electrochemically prior to electrodes fabrication.
• Fabrication of electrodes, development of supercapacitor cell, evaluation of laboratory model specifications and performance. With first demonstrated capacity properties, the active material will be used for fabrication of electrodes for packing in a sandwich structure using a separator and an electrolyte.

Stage 1/2025:

Phase 1/2025

In this stage, constituent materials for the synthesis of the ternary material used in active electrode were prepared and further characterized. Manufacturing flows were established for each constituent separately. The ternary material was prepared by varying the constituent materials and morphologically and structurally characterized. The ternary material was used in the composition of the active electrode and electrochemically characterized.
In a first phase, graphene oxide (GO) dispersed in aqueous solution was synthesized by the Hummers method. The obtained batches were morphologically and structurally characterized, the batch with the highest oxidation degree being selected. Reduced graphene oxide was prepared and used as a reference. Graphitic carbon nitride (g-CN) was synthesized by the pyrolysis process using amine raw materials based on urea, melamine or a mixture of cyanuric acid/melamine. Methods for exfoliating carbon nitride by sonication and combined chemical sonication were addressed. The graphene oxide and carbon nitride batches were morphologically and structurally characterized by FTIR, SEM, Raman and XRD techniques. In the next step, binary precursors in various RGO/g-CN ratios were prepared by the hydrothermal method. Then, nickel-cobalt double layer hydroxide (NiCoLDH) was synthesized in-situ using the binary precursors by the solvothermal method to obtain the ternary material (NiCoLDH@RGO/g-CN). Both the binary and ternary precursors were morphologically and structurally characterized by FTIR, SEM, EDAX, Raman and XRD techniques. The ternary material was used in the preparation of electrode inks and deposition on nickel foil. The electrodes were tested by cyclic voltammetry (CV) and charge-discharge cycling (GCD) in aqueous KOH electrolyte. Two-electrode sandwich structures were prepared in a symmetrical configuration using a cellulose separator and a KOH-based gel electrolyte. Symmetric supercapacitors were electrochemically tested by cyclic voltammetry and charge-discharge cycles. The dissemination of the results was achieved through communications presented at international conferences in the form of oral presentation and poster.

Conferences

1. A-C. Obreja, M. Stoian, V. Ţucureanu, O. Brȋncoveanu, R. Gavrilă, I. Bratoşin Investigation of carbon nitride in ternary compositions based on nickel cobalt layered double hydroxide and graphene for supercapacitor applications, 17th International Conference on Physics of Advanced Materials (ICPAM-17), November 16 - 23, 2025 Shizuoka University, Hamamatsu, Japan (Lecture).
2. A-C. Obreja, M. Stoian, V. Ţucureanu, O. Brȋncoveanu, F. Comanescu, I. Bratoşin, A. Enache, M. Udrea, B. Chiricuțǎ, “Nickel cobalt double layered hydroxide ternary nanocomposites for supercapacitor applications”,  48th International Semiconductor Conference (CAS 2025), October 7-11 2025, Sinaia, Romania (Lecture).
3. M. Stoian, A. Baracu, C. Romanitan, O. Brincoveanu, A. Radoi, “Sol-gel synthesis of cobalt oxide nanoparticles for energy storage applications”, 48th International Semiconductor Conference - CAS 2025, Sinaia, Romania, October 7-11, 2025 (Lecture).
4. M. Stoian, A. Baracu, C. Romanitan, O. Brincoveanu, A. Radoi, Synthesis of cobalt oxide and cobalt hexacyanoferrate nanoparticles for electrode development with energy storage applications, 8th Autumn School on Physics of Advanced Materials (PAMS-8), Hamamatsu, Shizuoka, Japan, November 16–23, 2025 (Poster).