Periodic Reporting for period 1 - SEINE (2-Dimensional Graphene/MoS2 HeteroStructures as AnodE Compartment of SodIum IoN BattEries)
Reporting period: 2023-05-01 to 2025-04-30
The global shift toward renewable energy has made energy storage a key technological challenge. Since solar and wind power are intermittent, storing electricity reliably and affordably is vital for a stable and sustainable energy supply. Lithium-ion batteries (LIBs) currently dominate storage in electric vehicles and electronics, but the rising cost, limited supply, and uneven distribution of lithium highlight the need for alternatives.
Sodium-ion batteries (SIBs) offer a promising solution. Sodium is abundant, widely available, and shares many characteristics with lithium, making SIBs attractive for large-scale storage. However, finding efficient and durable anode materials remains a major hurdle.
The SEINE project addresses this challenge by developing advanced two-dimensional (2D) materials made from graphene and molybdenum disulfide (MoS2). These materials are assembled into heterostructures—ultra-thin layered systems—that combine the best properties of each component. The project explores how different combinations and modifications, such as doping with nitrogen atoms, affect the electrochemical behavior and stability of the anodes. By understanding these effects in detail, SEINE aims to design anodes that are more efficient, stable, and cost-effective.
The project brings together expertise from top European research institutions to investigate these advanced materials using state-of-the-art synthesis techniques, high-resolution microscopy, and electrochemical testing. Its long-term goal is to contribute to the development of next-generation batteries that are not only cheaper and safer but also made from earth-abundant elements—helping Europe lead the way in green energy technologies and support the transition to a low-carbon economy.
Sodium-ion batteries (SIBs) offer a promising solution. Sodium is abundant, widely available, and shares many characteristics with lithium, making SIBs attractive for large-scale storage. However, finding efficient and durable anode materials remains a major hurdle.
The SEINE project addresses this challenge by developing advanced two-dimensional (2D) materials made from graphene and molybdenum disulfide (MoS2). These materials are assembled into heterostructures—ultra-thin layered systems—that combine the best properties of each component. The project explores how different combinations and modifications, such as doping with nitrogen atoms, affect the electrochemical behavior and stability of the anodes. By understanding these effects in detail, SEINE aims to design anodes that are more efficient, stable, and cost-effective.
The project brings together expertise from top European research institutions to investigate these advanced materials using state-of-the-art synthesis techniques, high-resolution microscopy, and electrochemical testing. Its long-term goal is to contribute to the development of next-generation batteries that are not only cheaper and safer but also made from earth-abundant elements—helping Europe lead the way in green energy technologies and support the transition to a low-carbon economy.
The SEINE project focused on developing and investigating two-dimensional (2D) heterostructures composed of graphene (Gr) and molybdenum disulfide (MoS2) as advanced anode materials for sodium-ion batteries (SIBs). Over the course of the project, significant technical and scientific progress was made across all key research objectives.
In the first phase of the project (RO1), single-layer graphene and MoS2 were successfully synthesized using chemical vapor deposition (CVD). These ultrathin films were then transferred to appropriate substrates and thoroughly characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm their quality, thickness, and chemical composition. These experiments established reliable protocols for producing high-quality 2D films with atomic-scale precision.
In the second phase (RO2), nitrogen-doped graphene (NGr) was prepared through plasma-based doping methods. Structural and compositional analyses confirmed successful incorporation of nitrogen in controlled configurations. While the original project plan also included nitrogen doping of MoS2 (NMoS2), further evaluation, supported by the fellow’s previous research, indicated that N-doped MoS2 suffers from instability under electrochemical operating conditions. In order to maintain experimental clarity, avoid introducing uncontrolled variables, and focus on the most scientifically robust systems, the decision was made to exclude NMoS2 from further development. This adjustment allowed for a more systematic and reproducible investigation of the role of doping in the performance of 2D heterostructures.
In the third phase (RO3), nine distinct three-layered 2D heterostructures were fabricated using combinations of pristine and nitrogen-doped graphene with MoS2. The stacking order and interface quality of these heterostructures were carefully controlled, and their physical properties were characterized using Raman spectroscopy, XPS, and transmission electron microscopy (TEM). This resulted in a unique dataset describing the structure-property relationships of engineered 2D materials at the atomic scale.
To evaluate their electrochemical behavior (RO4), coin-type sodium half-cells were assembled using the 2D heterostructures as anodes and metallic sodium as the counter/reference electrode. A combination of cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were performed to study their rate capabilities, reversibility, and stability. The experimental results revealed unique CV features and peak shapes not typically observed in bulk analogues of these materials. These findings suggest the possibility of alternative intercalation and co-intercalation mechanisms that are likely suppressed or masked in thicker-layered structures. The reproducibility and distinctiveness of these results mark a key scientific achievement of the project.
Finally, in-situ Raman spectroscopy was employed to monitor the structural evolution of the heterostructures during electrochemical cycling (RO5). Clear correlations were observed between Raman intensity/peak shifts and specific electrochemical potentials, providing new insights into the redox behavior and ion interactions within the layered structures. Complementary operando optical microscopy and in-situ TEM investigations are ongoing to further elucidate dynamic changes at the nanoscale.
Overall, SEINE has successfully demonstrated the synthesis, integration, and electrochemical evaluation of tailored 2D heterostructures for sodium-ion storage. It has produced fundamental knowledge about structure-function relationships, highlighted the limitations of doping in certain 2D systems, and revealed novel electrochemical phenomena with implications for future battery technologies.
In the first phase of the project (RO1), single-layer graphene and MoS2 were successfully synthesized using chemical vapor deposition (CVD). These ultrathin films were then transferred to appropriate substrates and thoroughly characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to confirm their quality, thickness, and chemical composition. These experiments established reliable protocols for producing high-quality 2D films with atomic-scale precision.
In the second phase (RO2), nitrogen-doped graphene (NGr) was prepared through plasma-based doping methods. Structural and compositional analyses confirmed successful incorporation of nitrogen in controlled configurations. While the original project plan also included nitrogen doping of MoS2 (NMoS2), further evaluation, supported by the fellow’s previous research, indicated that N-doped MoS2 suffers from instability under electrochemical operating conditions. In order to maintain experimental clarity, avoid introducing uncontrolled variables, and focus on the most scientifically robust systems, the decision was made to exclude NMoS2 from further development. This adjustment allowed for a more systematic and reproducible investigation of the role of doping in the performance of 2D heterostructures.
In the third phase (RO3), nine distinct three-layered 2D heterostructures were fabricated using combinations of pristine and nitrogen-doped graphene with MoS2. The stacking order and interface quality of these heterostructures were carefully controlled, and their physical properties were characterized using Raman spectroscopy, XPS, and transmission electron microscopy (TEM). This resulted in a unique dataset describing the structure-property relationships of engineered 2D materials at the atomic scale.
To evaluate their electrochemical behavior (RO4), coin-type sodium half-cells were assembled using the 2D heterostructures as anodes and metallic sodium as the counter/reference electrode. A combination of cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were performed to study their rate capabilities, reversibility, and stability. The experimental results revealed unique CV features and peak shapes not typically observed in bulk analogues of these materials. These findings suggest the possibility of alternative intercalation and co-intercalation mechanisms that are likely suppressed or masked in thicker-layered structures. The reproducibility and distinctiveness of these results mark a key scientific achievement of the project.
Finally, in-situ Raman spectroscopy was employed to monitor the structural evolution of the heterostructures during electrochemical cycling (RO5). Clear correlations were observed between Raman intensity/peak shifts and specific electrochemical potentials, providing new insights into the redox behavior and ion interactions within the layered structures. Complementary operando optical microscopy and in-situ TEM investigations are ongoing to further elucidate dynamic changes at the nanoscale.
Overall, SEINE has successfully demonstrated the synthesis, integration, and electrochemical evaluation of tailored 2D heterostructures for sodium-ion storage. It has produced fundamental knowledge about structure-function relationships, highlighted the limitations of doping in certain 2D systems, and revealed novel electrochemical phenomena with implications for future battery technologies.
The SEINE project has delivered several results that extend well beyond the current state of the art in sodium-ion battery research and the study of 2D materials for energy storage.
First, the project successfully demonstrated the controlled synthesis and assembly of nine novel three-layered heterostructures using combinations of graphene, nitrogen-doped graphene (NGr), and molybdenum disulfide (MoS2). While bulk heterostructures based on these materials have been studied previously, this is one of the first systematic efforts to explore their combinations with well-defined structural arrangements and doping profiles at the atomic thickness level.
Second, electrochemical analysis of these heterostructures revealed unique features in cyclic voltammetry that differ significantly from those observed in bulk analogues. These findings suggest the presence of alternative sodium intercalation and co-intercalation mechanisms that have been largely overlooked in conventional studies. The ability to observe and analyze such phenomena opens new avenues for the design of more efficient, high-capacity battery materials based on finely engineered 2D architectures.
Third, in-situ Raman spectroscopy demonstrated, for the first time, clear correlations between potentials associated to the electrochemical reactions and vibrational signatures of the materials. This insight provides a powerful new tool to monitor the dynamic evolution of electrode materials during operation and to study charge storage mechanisms. The methodology established in SEINE can be extended to other 2D systems and electrochemical processes, offering a platform for future real-time diagnostics.
By producing a better fundamental understanding of 2D materials in sodium-ion batteries, SEINE contributes to the broader effort to develop low-cost, sustainable, and high-performance energy storage solutions aligned with EU energy policy and industrial strategy. The scientific results of SEINE lay a strong foundation for further applied research and technology development. To move toward demonstration and application, the following steps are foreseen:
- Extended cycling and scalability tests to validate long-term stability and manufacturability of the best-performing heterostructures.
- Integration of the most promising materials into full-cell configurations to assess real-world performance.
- Exploration of intellectual property protection pathways for distinctive synthesis protocols or electrode designs.
- Strengthening of academic-industry collaborations, particularly within the European battery ecosystem, to explore technology transfer opportunities.
First, the project successfully demonstrated the controlled synthesis and assembly of nine novel three-layered heterostructures using combinations of graphene, nitrogen-doped graphene (NGr), and molybdenum disulfide (MoS2). While bulk heterostructures based on these materials have been studied previously, this is one of the first systematic efforts to explore their combinations with well-defined structural arrangements and doping profiles at the atomic thickness level.
Second, electrochemical analysis of these heterostructures revealed unique features in cyclic voltammetry that differ significantly from those observed in bulk analogues. These findings suggest the presence of alternative sodium intercalation and co-intercalation mechanisms that have been largely overlooked in conventional studies. The ability to observe and analyze such phenomena opens new avenues for the design of more efficient, high-capacity battery materials based on finely engineered 2D architectures.
Third, in-situ Raman spectroscopy demonstrated, for the first time, clear correlations between potentials associated to the electrochemical reactions and vibrational signatures of the materials. This insight provides a powerful new tool to monitor the dynamic evolution of electrode materials during operation and to study charge storage mechanisms. The methodology established in SEINE can be extended to other 2D systems and electrochemical processes, offering a platform for future real-time diagnostics.
By producing a better fundamental understanding of 2D materials in sodium-ion batteries, SEINE contributes to the broader effort to develop low-cost, sustainable, and high-performance energy storage solutions aligned with EU energy policy and industrial strategy. The scientific results of SEINE lay a strong foundation for further applied research and technology development. To move toward demonstration and application, the following steps are foreseen:
- Extended cycling and scalability tests to validate long-term stability and manufacturability of the best-performing heterostructures.
- Integration of the most promising materials into full-cell configurations to assess real-world performance.
- Exploration of intellectual property protection pathways for distinctive synthesis protocols or electrode designs.
- Strengthening of academic-industry collaborations, particularly within the European battery ecosystem, to explore technology transfer opportunities.