First Principles Study of H-insertion in MnO2

We present an extensive First Principles study on proton intercalation in the pyrolusite and ramsdellite forms of MnO2 .I t is shown that protons are always covalently bonded to an oxygen atom in MnO2. In ramsdellite, the proton prefers the pyramidal oxygen to the planar coordinated oxygen as that site is farther away from the Mn cations. In both pyrolusite and manganite, the octahedral sites are unstable, but the two local minima on each side of the octahedron are connected by a barrier of only about 25 meV, so that protons may rapidly exchange between these sites. Proton di4usion in pyrolusite occurs by hopping along the 1 1 open tunnels with an activation barrier that increases from about 575 meV at the beginning of discharge to about 1 eV at high H concentration. Di4usion in ramsdellite takes place along the 2 1 open tunnels and occurs with much lower activation energy (respectively, 200 and 400 meV, at low and high H concentrations). Introduction of twinning defects has a large adverse e4ect on the proton di4usivity. Results indicate that direct H+H interactions are not that signi5cant compared to oxygen-mediated-interactions. Experimental and calculated ramsdellite discharge curves deviate signi5cantly at early stages of the reduction process. The calculations on defected structures indicate that a signi5cant source of this discrepancy may be due to presence of proton-compensated Mn vacancies in real MnO2, which create local sites with higher discharge potential. The calculations suggest that the ordered phase, observed in experiments at mid-reduction (groutellite, MnOOH0.5), is due to the lattice remaining coherent during intercalation. 2002 Elsevier Science (USA)

[1]  Anton Van der Ven,et al.  Phase diagrams of lithium transition metal oxides: investigations from first principles , 1999 .

[2]  Gerbrand Ceder,et al.  Structural stability of lithium manganese oxides , 1999 .

[3]  Anton Van der Ven,et al.  Lithium Diffusion in Layered Li x CoO2 , 1999 .

[4]  T. Armbruster,et al.  Hydrogen Bonding and Jahn–Teller Distortion in Groutite,α-MnOOH, and Manganite,γ-MnOOH, and Their Relations to the Manganese Dioxides Ramsdellite and Pyrolusite☆ , 1997 .

[5]  Gerbrand Ceder,et al.  Ab initio study of lithium intercalation in metal oxides and metal dichalcogenides , 1997 .

[6]  F. L. Tye,et al.  The manganese dioxide electrode: Part XIII: An FTIR study of H-insertion into EMD , 1997 .

[7]  V. J. Emery,et al.  Spin-Gap Proximity Effect Mechanism of High Temperature Superconductivity , 1996, cond-mat/9610094.

[8]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[9]  H. Jónsson,et al.  Reversible work transition state theory: application to dissociative adsorption of hydrogen , 1994, chem-ph/9411012.

[10]  J. Pannetier,et al.  Structural and electrochemical properties of the proton / γ-MnO2 system , 1995 .

[11]  Hafner,et al.  Ab initio molecular-dynamics simulation of the liquid-metal-amorphous-semiconductor transition in germanium. , 1994, Physical review. B, Condensed matter.

[12]  D. Fontaine.  Cluster Approach to Order-Disorder Transformations in Alloys , 1994 .

[13]  M. Elcombe,et al.  A powder neutron diffraction study of λ and γ manganese dioxide and of LiMn2O4 , 1994 .

[14]  L. Yu,et al.  Inelastic Neutron Scattering Study of the Proton Dynamics in Manganese Oxides I . and Manganite , 1993 .

[15]  C. Howard,et al.  Powder Neutron Diffraction Study of Pyrolusite, β-MnO2 , 1993 .

[16]  D. Vanderbilt,et al.  Soft self-consistent pseudopotentials in a generalized eigenvalue formalism. , 1990, Physical review. B, Condensed matter.

[17]  J. Kendrick,et al.  Theoretical studies of protons in sodium hydroxide , 1985 .

[18]  P. Rüetschi.  Cation‐Vacancy Model for MnO2 , 1984 .

[19]  J. Connolly,et al.  Density-functional theory applied to phase transformations in transition-metal alloys , 1983 .

[20]  W. C. Maskell,et al.  Manganese dioxide electrode—IV. Chemical and electrochemical reduction of an electrolytic γ-MnO2 , 1981 .

[21]  F. L. Tye,et al.  States of water associated with electrodeposited manganese dioxide as revealed by pyknometric density measurements , 1981 .

[22]  E. Preisler.  Semiconductor properties of manganese dioxide , 1976 .

[23]  A. Kozawa,et al.  The Cathodic Reduction Mechanism of Electrolytic Manganese Dioxide in Alkaline Electrolyte , 1965 .

[24]  P. Hohenberg,et al.  Inhomogeneous Electron Gas , 1964 .

[25]  G. S. Bell,et al.  On the Cathodic Reduction of Manganese Dioxide in Alkaline Electrolyte , 1964 .

[26]  A. Kozawa.  The Potential of the Manganese Dioxide Electrode and the Surface Composition of the Oxide , 1959 .