CO - National Institute of Research and Development in Materials Physics, Magurele

P1 - National Institute of Research and Development for Cryogenic and Isotopic Technologies, Râmnicu Vâlcea

Summary of Stage I/2020:

The first stage of the 472PED/2020 project was primarily focused on (i) a preliminary study concerning the synthesis of vanadium oxide-based (VO_x) materials and (ii) the setting up of a benchtop equipment dedicated to electrochemical measurements (i.e., a Potensiostat/Galvanostat system, purchased in the framework of 472PED). Furthermore, new working electrode holders have been fabricated and were found adequate for performing electrochemical measurements on metallic current collectors. Supplemental, a V₂O₅ target has been fabricated by spark plasma sintering, and used to synthesize the first series of vanadium oxide-based thin films by the pulsed laser deposition (PLD) technology, which were subsequently converted by thermal annealing (with the help of a lab-made rapid thermal annealing system) to the V₂O₅ phase.

Results delivered at the end of Stage I/2020:

• 1 preliminary scientific study on the synthesis and characterization of the VO_x-based materials;
• 1 physical object: a preliminarily-defined material based on VO_x;
• 1 experimental set for electrochemical measurements.

Summary of Stage II/2021:

The second stage of execution targeted the synthesis and characterization of undoped and doped vanadium oxide directly on the current collector, as well as the investigation of their integration with others materials such as graphene. Based on the physical-chemical analyses and the in-situ electrochemical characterization, a selection of the most promising materials was accomplished, which, in the final stage of the project (2022), will be integrated and tested in delineated prototypes. We have demonstrated the possibility to reduce VO_x by thermal annealing in nitrogen at low pressure to form either a predominant VO₂(B) phase on aluminum foil or rhombohedral V₂O₃ phase on graphene foil. Furthermore, we have also shown the possibility to functionalize VO_x thin films deposited on graphene with ZnO micro-sheets and nano-rods after electrodeposition. Both partner institutions (i.e., INCDFM and ICSI) adopted its own measures to perform electrochemical tests on the electrodes. Samples have been self-assembled in coin cells. The testing was performed at the same temperature and humidity conditions for all samples. The results indicated that VO₂(B) samples show the best electrochemical performance. The C/20 capacity obtained for the first cycle in the case of this type of sample, compared to the theoretical capacity, was 57%, which is mainly explained by the intercalation/deintercalation of Li⁺ during discharge/charge cycles.

Results delivered at the end of Stage II/2021:

• 1 scientific study on the influence of doping, morphology, defects and crystal order and interfaces on the functional response and electrochemical properties of materials of interest;
• 2 physical objects: 1 functional material and 1 working electrode;
• 1 optimized synthesis method;
• 3 scientific communications at international conferences;
• 1 article published in a Web of Science® indexed journal with impact factor, situated in the Q2 quartile.

The scientific report cannot be yet divulged on the project website, as the results are in the process of being published, but it can be accessed upon request at UEFISCDI.

2020-2021: THE joint SYNTHETIC SCIENTIFIC REPORT corresponding to Stages I+II, in .pdf format, is available at UEFISCDI, and can be accessed by request.

Summary of Stage III/2022:

In the 3^rd Stage of the project, vanadium oxide (VO_x) thin films and compounds have been prepared by various deposition methods (e.g., pulsed laser ablation (PLD); magnetron sputtering; electrochemistry), in full agreement with the implementation plan. Their applicability as energy storage devices, such as lithium ion battery (LiBs), has been investigated. The physico-chemical properties of the samples have been unveiled by using an array of advanced characterization methods.

In continuation of the progresses achieved in the 2^nd Stage of the project (2021), new batches of undoped and doped vanadium oxide films have been synthesized by PLD and deposited either on aluminium (Al) or on graphene/aluminium foil (G/Al). The results have confirmed the possibility to reproducibly obtain the VO₂(B) polymorph phase on Al and the V₂O₃ phase on G/Al; these two phases being the most promising for LiBs, amongst all vanadium oxide phases, possessing theoretical capacities as cathodes of 322 mAhg^-1 and 356 mAhg^-1, respectively. Selected samples have been tested as CR 2032-type coin cells prototypes for LiBs. Unfortunately, despite the efforts and a clear observation of Li intercalation/desintercalation, the capacity of VO₂(B) on Al foil from ALL FOILS company (thickness 38 mm) was found to be quite mitigated with a first capacity of only 62 mAhg^‑1; those results contrasted to those obtained on the Al foil from MTI corporation (i.e., 161 mAhg^-1), and suggest an electrochemical dependence of the Al foil used. Furthermore, important capacity fading was also observed after 200 cycles, with the capacity declining to 2 mAhg^-1. The electrochemical performance of batches of V₂O₃ deposited on G/Al was found better with an initial capacity of 300 mAhg^-1. Furthermore, we observed that a 5 mol% Sn-doping in V₂O₃ can improve the electrochemical performance (i.e., loss of only 0.128% per cycle during a long cycle stability test of 200 cycles), notably concerning the cycling stability. This can be owned to Sn, causing an expansion of V₂O₃ lattice which reduces the electrochemical reaction resistance, improving the reversibility of electrochemical processes. The innovative methodology to obtain VO₂(B) directly on Al foil has been included into a patent application submitted to OSIM, while the results obtained on G/Al will be disseminated through a scientific article (in this respect a manuscript has been submitted to Electrochimica Acta, a Q1 Web of Science®-indexed journal). In the same direction, we have also explored the possibility to obtain the VO₂(B) phase on another current collector (i.e., nickel). By using a different annealing protocol, we have obtained the desired phase in both undoped and Sn-doped phases form. However, non-reproducibility occurrences were also met, even if striving to apply identical preparation and post-processing conditions.

In the framework of this 3^rd Stage of the project, further significant efforts have been devoted to delineate deposition protocols for larger area applications. One drawback of the PLD method is that the size of the sample is limited to less than 20 mm, which hampers its large-scale applicability to ESDs (pouch cells included). Also, the mass of the active materials generally does not exceed few hundreds of micrograms, which could limit the energy density as battery devices. For this purpose, in accordance to the tasks defined in the 3^rd Stage of the project, other deposition techniques have been explored, such as radio-frequency magnetron sputtering (RF-MS). Batches of thin films have been synthesized by RF-MS in inert (pure argon (Ar)) and in reactive (5 vol% O₂ + 95 vol% Ar) working atmosphere by using a target made of V₂O₅ powder. By designed RTA treatments was made possible to obtain the VO₂(B) phase at 480 °C for the samples without oxygen, but the results were rather dependent on the film thickness. Importantly, we found that it is also possible to obtain by RF-MS directly a crystalline V₂O₅ phase for as-deposited film prepared under a reactive (oxygen containing) working gas ambient. Thereby, we have decided to use this advantage to the benefit of pouch cells fabrication. Furthermore, other alternative deposition methods have been explored, in the pursuit to obtain either VO₂(B) or V₂O₃ phase son larger surface area substrates. In this respect, the (i) electrochemical; (ii) hydrothermal approach; and (iii) spray coating methods have been approached. Several innovative aspects emerged during our researches, as it will be described hereafter. Briefly, we have been able to obtain: a V₂O₃ phase on Ni foam; a VO₂(B) phase in a controlled way by hydrothermal treatment; and established an extremely cheap V₂O₅ spray-coating-based deposition solution without evidences of precipitation. Some samples prepared by spray coating have been used to fabricate pouch cells in the framework of this project.

Results delivered at the end of Stage III/2022:

• 1 scientific study on the electrochemical properties of the PVD-deposited films;
• 1 scientific study on the reversibility, charge-discharge and cycling of devices;
• Physical objects: 1 material with reproducible electrochemical response, 1 working-electrode; 1 energy storage device (pouch cell);

• 1 manuscript submitted to a Web of Science®-indexed journal with impact factor, situated in the Q1 quartile;
• 1 OSIM patent request;
• 3 communications to conferences with international participation.

The scientific report cannot be yet divulged on the project website, as the results are in the process of being published, but it can be accessed upon request at UEFISCDI.

2022: THE SYNTHETIC SCIENTIFIC REPORT corresponding to Stage III, in .pdf format, is available at UEFISCDI, and can be accessed by request.

2021: Hajar GHANNAM, ABDELMALEK ESSAADI UNIVERSITY, MOROCCO, performed in the period September – December 2021, a scientific work stage in the field of synthesis, characterization, and integration of oxide materials in battery devices, under the coordination of Dr. Teddy TITE (Project director of 472 PED/2020).

Web of Science® articles - published or submitted:

• 01. A. Gaddam*, A.A. Allu, S. Ganisetti, H.R. Fernandes, G.E. Stan^, C.C. Negrila^, A.P. Jamale, F. Mear, L. Montagne, J.M.F. Ferreira*; Effect of vanadium oxide on the structure and Li-Ion conductivity of lithium silicate glasses; J PHYS CHEM C 125 (2021) 16843. https://doi.org/10.1021/acs.jpcc.1c05059.
• 02. C. Ungureanu^, T. Tite^^,*, M. Buga^^,*, I. Stavarache, E. Matei^, C.C. Negrila^, A.C. Galca, A.A. Zaulet^, L. Trupina; Pulsed laser deposited vanadium sesquioxide thin films on graphene/aluminium foil for battery applications; submitted to ELECTROCHIM ACTA (2022).

OSIM Patent request:

• 01. T. Tite^, I. Stavarache, A. Galatanu, M. Lazar, C. Negrila^, M. Buga^, C.G. Ungureanu^, A.A. Spinu-Zaulet^; Binder-free vanadium dioxide VO2(B) thin films obtained directly on aluminium foil by pulsed laser deposition as battery cathode and method of preparation thereof; OSIM patent request no. A/00665/2022.

International conferences:

• 01. T. Tite^^,*, M. Buga^, C. Ungureanu^, A.A. Zaulet^, I. Stavarache, E. Matei^, G.E. Stan^, C.C. Negrila^, A.C. Galca, M.C. Bartha^, M. Baibarac^; Synthesis of vanadium oxide/graphene thin films by physical vapor deposition method for high performance batteries, E-MRS 2021 Fall Meeting, Symposium B: “Battery and Energy Storage Devices: From Materials to Eco-Design”, 20^th–23^rd September 2021, online (poster presentation).
• 02. T. Tite^^,*, H. Ghannam, M. Buga^, C. Ungureanu^, A.A. Zaulet^, I. Stavarache, E. Matei^, G.E. Stan^, C.C. Negrila^, A.C. Galca, M.C. Bartha^, M. Baibarac^; Doped vanadium oxide films by physical vapour deposition method for energy storage application, 23^rd International Conference “New Cryogenic and Isotope Technologies for Energy and Environment” EnergEn 2021, Băile Govora, Romania, 26^th–29^th October 2021, online (oral presentation).
• 03. H. Ghannam*, T. Tite^^,*, A. Chahboun, M. Buga^, C. Ungureanu^, A.A. Zaulet^, A.C. Galca, M.Y. Zaki,  E. Matei^, I. Stavarache, C.C. Negrila^, G.E. Stan^, M.C. Bartha^, M. Baibarac^; Advanced electrode based on zinc oxide-graphene for sodium-ion battery: Influence of morphology and doping, 23^rd International Conference “New Cryogenic and Isotope Technologies for Energy and Environment” EnergEn 2021, Băile Govora, Romania, 26^th–29^th October 2021, online (poster presentation).
• 04. T. Tite^^,*, H. Ghannam, C. Ungureanu^, M. Buga^, A.A. Zaulet^, I. Stavarache, O. El Khouja, E. Matei^, G.E. Stan^, M.Y. Zaki, C.C. Negrila^, A. Galatanu, A.C. Galca, M.C. Bartha^, M. Baibarac^, A. Chahboun; Vanadium oxides/zinc oxide thin films for energy storage applications: Study of their combination and synergy with graphene; E-MRS 2022 Spring Meeting, Symposium J: “Future electrochemical energy storage materials: From nanoscience to device integration and real environment application”, March 30^th–June 3^rd 2022, online (oral presentation).
• 05. H. Ghannam*, O. El Khouja, C. Ungureanu^, T. Tite^, M. Buga^, A.A. Zaulet^, E. Matei^, C.C. Negrila^, G.E. Stan^, A.C. Galca, A. Chahboun; Porous cobalt oxides nanostructures electrodeposited on graphene electrode for energy storage applications; E-MRS 2022 Spring Meeting, Symposium J: “Future electrochemical energy storage materials: From nanoscience to device integration and real environment application”, March 30^th–June 3^rd 2022, online (poster presentation).
• 06. T. Tite^^,*, C.G. Ungureanu^, M. Buga^ , H. Ghannam, O. El Khouja, A.A. Zaulet^, I. Stavarache, E. Matei^, G.E. Stan^, C. C. Negrila^, M.C. Bartha^, A.C. Galca, A. Galatanu, M.Y. Zaki, M. Baibarac^; Vanadium oxides thin films by physical vapor deposition and electrodeposition for energy storage applications, 20^th International Balkan Workshop on Applied Physics and Materials Science, July 12^th–15^th 2022, Constanta, Romania (poster presentation).

*corresponding/presenting author

^project team member

Teddy TITE, PhD in Materials Science
Senior Researcher II
Telephone: +40-(0)21-2418 131
Department: Laboratory of Multifunctional Materials and Structures