Supporting information. Alkali Metal Ion Templated Transition Metal Formate. Framework Materials: Synthesis, Crystal Structures,

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1 Supporting information Alkali Metal Ion Templated Transition Metal Formate Framework Materials: Synthesis, Crystal Structures, Ion Migration and Magnetism Espen Eikeland, 1 Nina Lock, 2 Mette Filsø, 1 Marian Stingaciu, 1 Yanbin Shen, 1,2 Jacob Overgaard, 1 Bo Brummerstedt Iversen 1 * 1 Center for Materials Crystallography, Department of Chemistry and inano, Aarhus University, DK-8000 Aarhus C, Denmark 2 Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark Corresponding author: bo@chem.au.dk 1

2 Powder X-Ray Diffractograms Figure S1. (a) Rietveld refinement of PXRD data (100 K) for Na[Mn(HCOO) 3] obtained at the BL44-B2 beamline at the synchrotron facility SPring8 in Japan using a wavelength of 0.49 Å. Figure S2. (b) Rietveld refinement of K[Mn(HCOO)3] at 295 K. Data obtained from in-house Rigaku SmartLab powder diffractometer. 2

3 Figure S3. (c) Rietveld refinement of Na 2[Cu 3(HCOO) 8] at 295 K. Data obtained from in-house Rigaku SmartLab powder diffractometer. Figure S4. (d) Rietveld refinement of Na 2[Cu 3(HCOO) 8] at 295 K. Data obtained from in-house Rigaku SmartLab powder diffractometer. 3

4 Figure S5. Changes in Cu2-X bond lengths from 100 K to 300 K for Na-Cu formate. 4

5 Figure S6. Isotropic ADPs for the metal atoms in (a) Na[Mn(HCOO)3], (b) K[Mn(HCOO)3], (c) Na2[Cu3(HCOO)8], and (d) K2[Cu5(HCOO)12]. 5

6 K ion-migration Figure S7. Prussian blue K 2Fe[Fe(CN) 6]. 3D K + ion migration pathway at an isosurface of au. Fe (gray), C (black) and N (blue). Na ion-migration Figure S8. Na 3V 2O 2(PO 4) 2F. left) an isosurface of au showing circular migration pathways for Na + ions. Right) an isosurface of au. The circular migration pathways are now connected, resulting in a 2D ion migration pathway. This corresponds remarkably well with the suggested migration paths in the original article, with Ea,path1 = 30 mev corresponds to the left figure and E a,path2 = mev corresponds to the right figure. Fe (gray), O (red), Cu (orange), F (yellow) isosurface (blue). 6

7 Figure S9. Na 3/4[Fe 2/3Mn 1/3]O 2.Isovalue of au, Layered structure of alternating Na and Fe/Mn, with Fe and Mn randomly distributed. To correct for the disorder Isovalues of structures with only Fe and only Mn atoms have been found, resulting in and au respectively. The last value is shown in the figure. O (red), Mn (gray). Electrochemical measurements: The electrochemical performances of K-Mn and Na-Mn formate were investigated in sodium ion battery (SIB) and Lithium ion battery (LIB) as cathode electrode. The studied materials were thoroughly mixed with acetylene black and polyvinylidene difluoride (PVdF) binder (8:1:1 in mass) in N-methyl-2-pyrrolidone (NMP). The obtained mixture was coated onto an aluminum foil with a coating bar and dried overnight under pre-vacuum at 100 C. The electrodes were punched in the shapes of 12 mm diameter disks. The loading of the electrode is around 3 mg/cm 2. For the LIB cells, metallic lithium foil was used as anode, and the cathode and anode were separated by two polypropylene membranes wetted in a commercially available standard electrolyte (1 M LiPF6 in ethylene carbonate (EC) : dimethyl carbonate (DMC) : diethyl carbonate (DEC) 4:3:3 in volume; 7

8 MTI corporation). For the SIB cell, metallic sodium foil was used as anode. The used electrolyte was 1 M NaClO4 mixed with propylene carbonate (PC) with 2 V% of fluorinated ethylene carbonate (FEC) as additive. The separator was porous glass fiber (Whatman, GF/D). The electrochemical cell was assembled in an Ar filled glove box as described above. An argon atmosphere was maintained in the cell by sealing the cell using a graphite dome. The galvanostatic charge and discharge tests were conducted in the range of 1.0 (1.5) V to 4.80 V with a current density of ~0.03 mah/cm 2 in a constant current (CC) constant voltage (CV) mode. Cyclic voltammetry was performed at a scan rate of 0.05 mv/s between 1.0 and 5.0 V vs. Li/Li +. As shown at Figure S10, after assembling the K-MOF in with a lithium counter electrode, the coin cell had an open-circuit voltage around 2.75 V. The cell voltage jumped to around 4 V quickly after applied a small current density (~0.03 mah/cm 2 ) on it indicating very high cell impedance. It seemed that K + could be extracted from the structure at higher potential. A platform can be found at around 4.6 V. However, a reversible platform at similar potential cannot be found on the followed discharge. As shown at the discharge curve at Figure S10, Li + /K + seems to be inserted back into the structure at potential lower than 1.5 V. This result indicates low conductivity of the material or instability of the structure upon K + extraction. When applied the as-prepared K-MOF in a SIB, similar electrochemical behavior can be obtained expect with lower extraction/insertion potential (vs Na/Na + ), as shown in Figure S11. At the second cycle, the platform for K + /Li + at around 4.4 V was decreased significantly, but a new platform can be found at around 2.25V. The cyclic voltammetry result at Figure S12 showed exactly the same behavior as that shown at Figure S11, which means that the electrochemical performance is reproducible. The Na-Mn material showed quite similar result as the K-Mn material, Figure S13. As conclusion, it is possible to extract and insert the K + or Na + from the as-prepared materials, but the reversibility is very poor. This could 8

9 due to low ionic/electronic conductivity or structural instability upon charge/discharge at the material. Figure S10. Voltage profile from the first charge and discharge of K-MOF in a LIB cell 9

10 Figure S11. Voltage profile from the first two cycle of K-MOF in a SIB cell Figure S12. Cyclic voltammetry from the first charge and discharge of K-MOF in a SIB cell 10

11 Figure S13. Voltage profile from the first charge and discharge of N-MOF in a SIB cell 11

12 Magnetic Measurements Figure S14. Curie Weiss plot for (a) Na-Mn formate at 100 Oe, (b) K-Mn formate at 100 Oe, (c) Na-Cu formate at 500 Oe, (d) K-Cu formate at 1000 Oe. The Curie/Néel temperatures (θ) for the four compounds were determined using the Curie-Weiss law, x mol = C/(T - 8) (Figure S14). The Curie constants (C) were used to calculate effective magnetic moments using, ll eff = (3Ck B /ZN A ) 1/2 μ B, where k B is the Boltzmann s constant, N A the Avogadro s constant, ll B the Bohr magneton and Z is the number of magnetic ions (e.g. Cu 2+ and Mn 2+ ) per formula unit. 39 The manganese containing compounds, Na-Mn and K-Mn, have similar effective magnetic moments (ll eff,namn = 5.444(8)μ B, ll eff,kmn,zfc = 5.404(1)μ B, ll eff,kmn,fc = 5.419(1)μ B ) and Néel temperatures close to zero (θ NaMn = -0,91(6) K, θ KMn,ZFC = -2.34(4) K, 12

13 θkmn,fc = -1.06(6) K). An effective magnetic moment of ~ 5.4 μ B is lower than what is expected for uncoupled (high spin) Mn 2+ ions (~ 5.9 μ B ). A more detailed magnetic study is needed to fully explain this ll eff lowering, but such investigations are outside the scope of this paper. To get a magnetic signal from the Na-Cu and K-Cu formates the field had to be increased from 100 Oe to 500 Oe and 1000 Oe, respectively. The data collected on Na2[Cu3(HCOO)8] did not follow the Curie-Weiss law above 150 K. Whether this is due to slight impurities, or the actual sample behavior is unclear, but no impurities were observed in the PXRD data prior to the magnetic measurements. The measurements on the K 2[Cu 5(HCOO) 12 sample resulted in a Néel temperature of -14.2(1) K and an effective magnetic moment of 1.810(1) µb, which is in agreement with high spin Cu 2+ ions (1.7 µb 2.2 µb). 40 Thermal stabilities The thermal decomposition pathways of Na[Mn(HCOO)3] and K[Mn(HCOO)3] are very similar according to TGA and DTA measurements, and they are displayed in Figure S15. The decomposition starts at 341 C for Na-Mn formate and at 327 C for K-Mn formate and results in significant mass losses of 39 % and 32 % for Na-Mn and K-Mn formate, respectively. The decomposition consists in both cases of multiple steps with the first step being endothermic followed by several smaller mass losses with undetermined thermodynamics. PXRD analysis of the materials obtained after thermal analysis reveals MnO in both cases, while the phase(s) containing the alkali metals could not be identified. 13

14 Figure S15. (a) TGA (solid lines) and DTA (dashed lines) results for Na[Mn(HCOO) 3] (black) and K[Mn(HCOO) 3] (red). (b) TGA (solid lines) and DTA (dashed lines) results for Na 2[Cu 3(HCOO) 8] (black) and K2[Cu5(HCOO)12] (red). The thermal decomposition pathways of Na2[Cu3(HCOO)8] and K2[Cu5(HCOO)12] are displayed in Figure S15. Large weight losses of 48 % for Na-Cu formate and 44 % for K-Cu formate are observed over a small temperature interval with onset temperatures of 147 C and 144 C, respectively. The decomposition is endothermic for both compounds. In addition both compounds show small weight losses of 1-2 % at higher temperatures before remaining constant. PXRD data from both end products reveal formation of elemental copper during the decomposition. This 14

15 indicates that K 2[Cu 5(HCOO) 12] and Na 2[Cu 3(HCOO) 8] undergoes internal redox reactions where copper is reduced, and this may be the origin of the small weight loss at higher temperatures. The phase(s) containing the alkali metals could not be identified. 15