abstract
This study provides detailed insights into the in-situ formation of catalytically active V-doped MgO rock salt derived from V2O5-MgH2 composite samples. X-ray diffraction studies of ball-milled (15 h) xMgH(2) + V2O5 composites (x = 0, 0.125, 0.25, 0.5, 2, 4, 6, 8, and 10) indicate that under MgH2-rich conditions V2O5 is strongly reduced. This reduction leads to the in-situ formation of a mixed Mg-V-O monoxide phase with a rock-salt structure, represented as MgxVyOx+y. This observation is supported by the identification of V2+ species through X-ray photoelectron spectroscopy. The Mg-V-O rock-salt phase was also identified as a catalytically active component for promoting the hydrogen and Li storage characteristics of MgH2. Especially, a Li-ion coin cell battery containing 5 wt% MgxVyOx+y added MgH2 on a carbon substrate as anode delivers a discharge/ recharge capacity of 1350 mAh g(-1) / 155 mAh g(-1) at 0.05 C. Though cyclic stability remains a concern in this conversion reaction (MgH2 + 2Li <-> 2LiH + Mg), it has been possible to identify the root cause issues for the reverse conversion of LiH to Li. Post-mortem analyses of the used batteries prove adequate presence of MgH2 in the anode, which rules out potential swelling issues as the reason for limited reversibility. Detailed electrochemical impedance spectroscopy analyses using the distribution function of relaxation times (DFRT) reveal that electrolyte degradation is not an issue in these batteries. On the other hand, DFRT provides crucial evidence for the presence of slow charge-transfer processes, which are found to be sensitive to the composition of the employed additive.
keywords
MAGNESIUM HYDRIDE; NEGATIVE ELECTRODE; RELAXATION-TIMES; METAL-HYDRIDES; DOPED MGO; XPS; NANOPARTICLES; BEHAVIOR; ANODE; MGXNBYOX+Y
subject category
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
authors
Pukazhselvan, D; Çaha, I; Loureiro, FJA; Deepak, FL; de Lemos, C; Shaula, AL; Mikhalev, SM; Kovalevsky, A; Fagg, DP
our authors
Andrei Kavaleuski
Principal Researcher
Sergey Mikhalev
Post-Doc FellowshipProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This article was supported by the projects 2022.09319.PTDC (https://doi.org/10.54499/2022.09319.PTDC) , 2022.02498.PTDC (htt ps://doi.org/10.54499/2022.02498.PTDC) , UIDB/00481/2020 (https://doi.org/10.54499/UIDB/00481/2020) , and UIDP/00481/2020 (htt ps://doi.org/10.54499/UIDP/00481/2020) from Fundacao para a Ciencia e a Tecnologia (FCT) , and CENTRO-01-0145-FEDER-022083 from Centro Portugal Regional Operational Programme (Centro2020) , under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) . D. P acknowledges FCT, Portugal for the financial support with reference CEECIND/04158/2017 (https://doi.org/10.54499/CEECIND/04158/2017/CP1459/CT0029) . and funding through Centro Portugal Regional Operational Programme (Centro2030) , with the reference COMPETE2030-FEDER-00770300. D. P also acknowledges funding through SMART-ER Seed Project (DHCPHV) , under the European Union's Horizon 2020 research and innovation programme, Grant Agreement#101016888. F. L acknowledges FCT, Portugal for the financial support with the reference 2020.02797.CEECIND/CP1589/CT0030 (https://doi.org/10.54499/20 20.02797.CEECIND/CP1589/CT0030) . A. S. acknowledges FCT, Portugal for the financial support with the reference 2020.01117.CEE-CIND/CP1589/CT0029 (https://doi.org/10.54499/2020.01117.CEE CIND/CP1589/CT0029) . A. K acknowledges the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.544 99/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.54499/UIDP/5 0011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) ,financed by national funds through the FCT/MCTES (PIDDAC) . F. L. D would like to acknowledge the financial support from the European Union (Grant FUNLAYERS-101079184) . This article is also a result of the Innovation Pact "NGS-New Generation Storage" (C644936001-00000045) , by "NGS" Consortium, co-financed by Next Generation EU, through the Incentive System "Agendas para a Inovacao Empresarial" ("Agendas for Business Innovation") , within the Recovery and Resilience Plan (PRR) . The authors are also grateful for the financial support granted by the Recovery and Resilience Plan (PRR) and, by the Next Generation EU European Funds to Universidade de Aveiro, through the Agenda for Business Innovation "NGS-Next Generation Storage" (Project no 02/C05-i01.01/2022 with the application C644936001-00000045) .r financed by national funds through the FCT/MCTES (PIDDAC) . F. L. D would like to acknowledge the financial support from the European Union (Grant FUNLAYERS-101079184) . This article is also a result of the Innovation Pact "NGS-New Generation Storage" (C64493 6001-00000045) , by "NGS" Consortium, co-financed by Next Generation EU, through the Incentive System "Agendas para a Inovacao Empresarial" ("Agendas for Business Innovation") , within the Recovery and Resilience Plan (PRR) . The authors are also grateful for the financial support granted by the Recovery and Resilience Plan (PRR) and, by the Next Generation EU European Funds to Universidade de Aveiro, through the Agenda for Business Innovation "NGS-Next Generation Storage" (Project no 02/C05-i01.01/2022 with the application C6449 36001-00000045) .