| This paper gives a briefing on the nature and application of Li and LiH which is categorized to hydrogens storage material and studies the microstructure mechamism of oxidizing corrosion when Li and hydrogens storage material, LiH, meets H2O. Using the theory of the transition state for the first time, this paper inquires into the reaction mechanism when Li and hydrogens storage material, LiH, meets H2O and offers the certain theoretical foundation to the further studying of Li and the compounds of Li when they are in the air. The achievement of the process which we have applied the quantum mechanics method with the help of Gaussian98 soft package and Gaussview tool soft at the full electron 6-311G(d) base sets level is the geometry configurations of the various reactant, intermediates, transition state and products, the vibration frequency, the zero point energies, the partition function and so on. To identify transition state is the real transition state of this reaction channel; we have made frequency analysis of intermediates and transition state, and then tested the convert trend of transition state. Otherwise, at the base sets level of QCISD/6-311++G**, we have calculated various compounds, single energy and intermediates, transition state, relative energy of the products after revising ZPE and referring reactant energy. Ultimately, using the formal, (1)?Hm=ΣHm(products)-ΣHm (reactants), (2)Ea=Erel(TS)-Erel(MI/ reactant),(3)k=ATβexp(-Ea/RT).We have calculated ?H reaction enthalpy change of mol, that is thermal effect ,active energy E and reaction rate constant from the comparison of among reactant, transition state, relative energy of the products. On the basis of the geometry configurations and vibration frequency of the intermediates and vibration frequency, we have inquired into the microstructure mechanisms which involves the reaction of(1)H2O+e-+Li+→LiOH+1/2H2,(2)LiOH+e-+Li+→Li2O+1/2H2,(3)1/2H2+e-+Li+→LiH according to the valence bond method and the situation of the vibration frequency of the atoms which are within the molecules. Their reaction heat are -76.881 kJ.mol-1 ,75.804 kJ.mol-1 and -173.933kJ.mol-1 respectively. The active energy of the control step of reaction are 84.685kJ.mol-1,243.531kJ.mol-1 和149.966kJ.mol-1 respectively. From the point of view of reaction thermodynamics and dynamics, the reaction of oxidizing corrosion which Li is in the atmosphere of H2O is the reaction (1) which has the minimum active energy of the control step of reaction and can be easily undertaken. As to the reaction (2),(3),it is possible to happen as long as the necessary conditions are available. Therefore, Li's surface film element is mainly LiOH. With the further reaction between the inner Li and surface LiOH, more stable Li2O and LiH have been formed which leads to the fact that Li's surface film is consist of tense endothecium's film and porosity loosen state surface film. This conclusion has remained unanimous with the current experiment and had been reported theoretically for the first time. Meaning while we have also identified theoretically the possibility that the reaction of Li and H2 can form LiH passivation film. On the basis of the study the microstructure mechanism which involves oxidizing corrosion when Li meets H2O. We have also inquired into the reaction mechanism of the oxidizing corrosion when LiH which is categorized to hydrogens storage material meets H2O according to the valence bond method and the situation of the vibration frequency of the atoms which are within the molecules. The result of the study of the microstructure reaction, microstructure shows that the potential barrier of the reaction, LiH+H2O→LiOH+H2 is minimum; it is 10.37 kJ.mol-1 whichis the main oxidizing corrosion when LiH is in the atmosphere of H2O. On the other hand, the active energy of the control step of reaction, LiH+LiOH→Li2O+H2 and Li2O +H2O→2LiOH are LiH+LiOH→Li2O+H2 and Li2O +H2O→2LiOH respectively. Therefore, the products of LiH's surface corrosion are mainly LiOH and a little Li2O. The relief of H2 can lead this corroded surface to be porosity loosen state. This finding is identical to the result of the X-ray photoelectron. Spectroscopy (XPS) which has been obtained by D.Aurbach. otherwise, these three reactions are all exothermic reaction whose reaction heat are 127.41 kJ.mol-1,49.96 kJ.mol-1 and 77.45kJ/mol respectively, and the reaction rate constant of LiH+H2O→LiOH+H2 is 13.943 cm3/mol.s, but the reaction rate constant of LiH+LiOH→Li2O+H2 Li2O+H2O→2LiOH is 3.547×10-13 cm3.mol-1.s-1 ,1.167×10-18 cm3.mol-1.s -1respectively. And this can show that LiH+H2O→LiOH+H2 is the main reaction of oxidizing corrosion when LiH is in the atmosphere of H2O, which has provided the theoretical basis with the studying of oxidizing corrosion when hydrogens storage material, LiH, is in the wet environment. It is of great significance to find the binding point between theory and practice.
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