A Simple Synthesis of MnN0.43@C Nanocomposite:
Characterization and Application as Battery Material
Bettina Milke†, Clemens Wall‡,¤, Sarah Metzke†, Guylhaine Clavel†, Maximilian Fichtner‡,¤,
Cristina Giordano†*
† Max-Planck-Institute of Colloids and Interfaces, Department of Colloid Chemistry, Research Campus Golm, 14424 Potsdam, Germany
‡Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
¤Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081 Ulm, Germany
Supporting Information
Reactants
Manganese acetate tetrahydrate purum p.a., Sigma Aldrich; methanol with gradient grade for liquid chromatography, Merck. Urea ACS reagents, 99.0-100.5%, Sigma Aldrich.
Electrochemical characterization
Electrodes were prepared by casting a slurry of 85wt% electrode material, 10wt% carbon black (Alfa Aesar) and 5wt% poly(vinylidene difluoride) (PVDF) binder (SOLEF 21216) in N-methyl-2-pyrrolidone (NMP) solvent on stainless steel current collectors. The electrodes were dried for 5h at 60°C and subsequently for 20h at 120°C. Swagelok® type cells were assembled in an argon filled glove box using lithium foil as counter electrode, Whatman D/F glass fiber separators and 1M LiPF6 in ethylene carbonate and dimethyl carbonate as electrolyte (LP30 Merck). Galvanostatic battery tests were performed at 25°C with an Arbin battery tester between 3 and 0.01V at a current density of 10mA/g. For analysis of the discharged state by XRD, TEM and EA, MnN0,43 nanocomposite powder (without the addition of PVDF or carbon black) was discharged to 0.01V. Afterwards the electrode material was removed from the cell and washed with anhydrous DMC prior to analysis.
Techniques
Elemental Analysis
Elemental analysis was performed using a Vario EL Elementar. During the high temperature extraction, the solid samples were put into a gas phase before they are separated into their components.
ICP-OES
Inductively coupled plasma optical emission spectrometry measurements were performed at a VISTA-MPX (Varian) using an argon plasma. Sample preparation was performed using an air oven and burning the samples for 36h at 500°C in order to destroy the carbon matrix. Afterwards the samples were dissolved in aqua regia and diluted before the measurement.
Nitrogen Sorption
Nitrogen Sorption measurements were performed with a Quantachrom Quadrasorb instrument at liquid nitrogen temperature (-196°C). All samples were degassed for 20h at 150°C before the measurement. Data evaluation was done by Quantachrom QuadraWin Software (version 5.05).
SEM
SEM measurements were performed using a LEO 1550 Gemini Instrument. The samples were prepared by placing them on a carbon coated aluminum stub. The samples were measured without sputtering, since they were already conductive.
TEM/HRTEM/EELS
TEM measurements were performed at a Zeiss EM 912Ω with an acceleration voltage of 120kV. Some droplets of the sample’s dispersion in ethanol were put unto a 400 mesh carbon-coated copper grid for sample preparation. High resolution TEM/EELS were recorded on the CM200FEG (Philips) microscope, operated at 200kV and equipped with a post column electron energy loss spectrometer (GATAN Tridiem).
XRD
X-ray diffraction measurements were performed using a D8 Diffractometer by Bruker Instruments (Cu Kα-radiation, λ=0.154nm) and using a scintillation counter or Kevex detector. All reference patterns were assigned by Match! Software using the ICDD-PDF4+ database (2011 and 2012 edition).
FT-IR
Figure S1. FT-IR spectra of (a) pure manganese acetate (b) urea (c) Mn-urea complex (d) Mn-urea sample calcined at 600°C identified (by XRD) as MnNCN.
TEM and HR-TEM
Figure S2. TEM images of MnN0.43@C nanocomposites at different magnifications: (A) before and (B) after discharge.
Figure S3. HRTEM of a portion of the MnN0.43@C nanocomposite A) before and B) after discharge. In insets the fast Fourier transforms (FFT) of selected regionsare reported.
EELS
Figure S4. EELS spectra of C (285-300eV), N (400eV) and O (inset: 530eV) K edges and EELS spectra of Mn L2,L3 edges of a particle before discharge (black line taken from picture A)and after discharge (grey line and picture B).
Figure S5. EELS spectrum and TEM picture of a MnNCN particle.
Table S1. EELS signals and references
Signal / Reference / Compound285 eV / 283.7 - 284.8 eV[1] / C (graphite)
288 – 300 eV / C
399 – 402 eV / ~400 eV[1] / N (nitrides)
531 – 535eV / 531 eV[1] / O in matrix
539 – 543 eV / O
639.4 – 640.0 eV
650.6 – 652.2 eV / 641.5 eV[2]
651 eV; 639.8 eV[3] / Mn (nitride)
Battery test of MnNCN
MnNCN was prepared as reported in the text.
From a mixture of 80% MnNCN, 10% PVDF and 10% carbon black electrodes were prepared as it is described for MnN0.43-electrodes.
Figure S6. Potential versus specific capacity profile of a MnNCN electrode. The electrode was tested under the same conditions as the MnN0.43 electrodes (current density: 10mAhg-1, voltage range: 3-0.01V).
The discharge capacity of 38 in the first and ~10mAhg-1 in the consecutive cycles can be attributed to SEI (solid electrolyte-interphase) formation and Li-storage in carbon black, respectively.
[1]In NIST X-ray Photoelectron Spectroscopy Database, Vol. 4.1, National Institute of Standards and Technology, Gaithersburg, 2012.
[2]Carver, J. C.;Carlson, T. A.;Schweitz.G. K.J Chem Phys,1972, 57, 973.
[3]Lu, B.;Liu, X. D.;Nakatsuji, K.;Iimori, T.; Komori, F. Phys Rev B 2007, 76, 245433.
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