behavior explored by in situ neutron powder diffraction during electrochemical oxygen

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1 (Nd/Pr)2NiO4+δ: reaction intermediates and redox behavior explored by in situ neutron powder diffraction during electrochemical oxygen intercalation Monica Ceretti a,*, Olivia Wayudi a,b, Gilles André c, Martin Meven d, Antoine Villesuzanne b and Werner Paulus a a. Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM-ENSCM, Université de Montpellier, Place Eugène Bataillon, Montpellier Cedex 5, France. b. CNRS, Université de Bordeaux, ICMCB, 87 Av. Dr. A. Schweitzer, PESSAC, F c. Laboratoire Léon Brillouin, UMR12, CEA-CNRS, CEA Saclay, Gif Sur Yvette, France d. Institute of Crystallography, RWTH Aachen University and Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany S1

2 Figure S1: X-ray diffraction patterns of Pr 2NiO 4.23 electrode, showing the (220) monoclinic splitting (in the inset). XRD measurements were performed with a Bruker D8 DISCOVER VARIO powder diffractometer, equipped with a Johansson Monochromator (Quartz, Cu K α1) and LYNXEYE XE-T detector Data were refined in the F112/m SG (a = (4) Å, b = (4) Å, c = (10) Å, γ = 90.07(1) ) Figure S2: X-ray diffraction patterns of Nd 2NiO 4.23 electrode, showing the (220) monoclinic splitting (in the inset). XRD measurements were performed with a PANalytical X'Pert powder diffractometer (Cu K α1, α2). Excluded regions (39.5 2θ 40 and θ 46.5 ) are due to the presence of reflections of the samples holder (Pt).Data were refined in the F112/m SG (a = (4) Å, b = (4)Å, c = (10)Å, γ = 90.07(1) ) S2

3 Figure S3: Neutron powder diffraction pattern of the starting Nd 2NiO 4.23 phase obtained on (λ=2.42å), in the quartz cell and with KOD electrolyte. Refinement was done in the SG Fmmm. Lattice parameters: a = (6) Å; b= (6) Å; c = (9) Å. (R p = 17 %, R wp = 12 %, R bragg = 6.4 %, χ 2 = 3.5). Refinements have been done assuming the model reported in Ceretti, M et al., J. Mater. Chem. A 2015, 3 (42), ). Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. Peak at 44 in 2θ (marked with *) is caused by the carbon glue. In the region 60 2θ 70 the incommensurate peaks are evident. It is worth to underline that these are the original data collected on G41, before background subtraction. Figure S4: Neutron powder diffraction pattern of the stoichiometric Nd 2NiO 4.00 phase obtained on G41@LLB (λ=2.42å), in the quartz cell and electrolyte. Refinement has been done in the SG Bmab. Lattice parameters: a = (4) Å; b= (5) Å; c = (7) Å. (R p = 17 %, R wp = 9.90 %, R bragg = 2.4 %, χ 2 = 2.5). Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. Peak at 28 in 2theta is magnetic (011) reflection, while peak (*) comes from the carbon glue. It is worth to underline that these are the original data collected on G41, before background subtraction. S3

4 Figure S5: Neutron powder diffraction pattern of the intermediate phase Nd 2NiO 4.10 phase obtained on (λ=2.42å), in the quartz cell and electrolyte. Refinement was done in the SG P4 2/ncm, using structural model reported in Table 1 (of the main article): lattice parameters a = b = (2) Å, c= (7) Å. Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. In the inset shows a zoom of the region in 2θ, illustrating clearly the presence of the (104) superstructure reflection. It is worth to underline that these are the original data collected on G41, before background subtraction. Figure S6: Neutron powder diffraction pattern of the stoichiometric Pr 2NiO 4.00 phase obtained on G41@LLB (λ=2.42å), in the quartz cell and electrolyte. Refinement was done in the SG Bmab. Lattice parameters: a = (7) Å; b= (7) Å; c = (9) Å (R p = 17 %, R wp = 10 %, R bragg = 2 %, χ 2 = 1.73). Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. Peak at 28 in 2theta is the magnetic (011) reflection. It is worth to underline that these are the original data collected on G41, before background subtraction. S4

5 Figure S7: Neutron powder diffraction pattern of the stoichiometric Pr 2NiO 4.09 phase obtained on (λ=2.42å), in the quartz cell and electrolyte. Refinement was done in the SG P4 2/ncm. Refinement was done using structural model reported in Table 1 (main article): lattice parameters a = b = (7) Å, c = (9) Å. Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. It is worth to underline that these are the original data collected on G41, before background subtraction. Figure S8: X-ray diffraction patterns of Pr 2NO 4.16 after re-oxidation. It shows an orthorhombic symmetry (Fmmm space group). XRD measurements were performed with a PANalytical X'Pert powder diffractometer (Cu K α1, α2). The (220) reflection appears as non-splitted, confirming the absence of a monoclinic distortion. S5

6 Figure S9: Neutron powder diffraction pattern of the final re-oxidized Nd2NiO4.09 intermediate phase obtained on (λ=1.225 Å). Figure shows observed (black scattered points), calculated (red solid line) and the difference (blue solid line) diffraction profiles. Inset shows a zoom of the region in 2θ, illustrating clearly the presence of a (104) superstructure reflection. Table S1: Refined structural data Nd 2NiO 4.10, assuming interstitial atom at 4e site (3T2 data, λ=1.225 Å) Nd 2NiO 4.10 Lattice parameters: a = b = (5) ; c = (1) Å Structure refined in P4 2/ncm space group (R p = 14.8%, R wp = 11.5%, R bragg = 2.15%, χ 2 = 2.09) Atom x y z Occ U 11 U 22 U 33 Nd (4) (4) (1) 2.00 U iso = (4) Ni U iso = (4) O eq1 ¼ ¼ (6) 1.01(3) (6) (6) (6) O ap (4) (4) (3) 2.00(2) (3) (3) (3) O eq2 ¾ ¼ (3) (6) (6) (9) O int ¼ ¼ 0.250(4) (9) U iso = Table S2: Refined structural data Nd 2NiO 4.10, assuming interstitial atom at 4b site (3T2 data, λ=1.225 Å) Nd 2NiO 4.10 Lattice parameters : a = b = (5) ; c = (1) Å Structure refined in P4 2/ncm space group (R p = 14.9%, R wp = 11.5%, R bragg = 2.16%, χ 2 = 2.1). Atom x y z Occ U 11 U 22 U 33 Nd (4) (4) (1) 2.00 U iso = (4) Ni U iso = (4) O eq1 ¼ ¼ (6) 1.01(4) (6) (6) (6) O ap (4) (4) (3) 2.00(2) (3) (3) (3) O eq2 ¾ ¼ (4) (6) (6) (9) O int ¾ ¼ ¼ 0.092(9) U iso = S6