TY - GEN

T1 - Tailoring of metal borohydrides for hydrogen storage applications

AU - Nakamori, Yuko

AU - Miwa, Kazutoshi

AU - Li, Hai Wen

AU - Ohba, Nobuko

AU - Towata, Shin Ichi

AU - Orimo, Shin Ichi

PY - 2006

Y1 - 2006

N2 - Recent investigations on thermodynamical stabilities of metal borohydrides were reviewed. The first-principles calculations indicated that the heat of formation normalized by the number of BH4 complexs, ΔHboro, show a good correlation with the Pauling electronegativitiese of M, χP, which is represented by the liner relation, Delta;H boro = 252.8;χP - 396.4 in the unit of kJ/mol BH 4. In order to clarify the correlation between the stability of borohydrides and the electronegativity χP of M, M(BH 4)n (M= Mg, Ca, Sc, Ti, V, Cr, Mn, Zn, Zr and Al; n = 2-4) were systematically synthesized by mechanical milling. The thermal desorption analyses indicated that Td correlate with χP of M; Td decrease with increasing the values of χP, in M(BH4)n. Furthermore, the correlation can be reasonably extended to double cation ones, ZrLin-4(BH4)n. For single cation, M(BH4)n (M = Mn, Zn and Al; χP ≧ 1.5) desorb borane besides hydrogen, and M(BH 4)n (M = Ti, V and Cr; χP ≧ 1.5) desorb small amount of hydrogen provably due to desorption reaction during milling. Therefore χP is an indicator to approximately estimate the stability of M(BH4)n, and appropriate χP in M(BH4)n is expected to be smaller than 1.5. The enthalpy change for the desorption reaction, Δdes, is estimated using our predicted ΔHboro and the reported data for decomposition product, ΔHhyd/boride, which shows a good correlation with the observed Td. These results are useful for exploring M(BH 4)n with appropriate stability for hydrogen storage applications

AB - Recent investigations on thermodynamical stabilities of metal borohydrides were reviewed. The first-principles calculations indicated that the heat of formation normalized by the number of BH4 complexs, ΔHboro, show a good correlation with the Pauling electronegativitiese of M, χP, which is represented by the liner relation, Delta;H boro = 252.8;χP - 396.4 in the unit of kJ/mol BH 4. In order to clarify the correlation between the stability of borohydrides and the electronegativity χP of M, M(BH 4)n (M= Mg, Ca, Sc, Ti, V, Cr, Mn, Zn, Zr and Al; n = 2-4) were systematically synthesized by mechanical milling. The thermal desorption analyses indicated that Td correlate with χP of M; Td decrease with increasing the values of χP, in M(BH4)n. Furthermore, the correlation can be reasonably extended to double cation ones, ZrLin-4(BH4)n. For single cation, M(BH4)n (M = Mn, Zn and Al; χP ≧ 1.5) desorb borane besides hydrogen, and M(BH 4)n (M = Ti, V and Cr; χP ≧ 1.5) desorb small amount of hydrogen provably due to desorption reaction during milling. Therefore χP is an indicator to approximately estimate the stability of M(BH4)n, and appropriate χP in M(BH4)n is expected to be smaller than 1.5. The enthalpy change for the desorption reaction, Δdes, is estimated using our predicted ΔHboro and the reported data for decomposition product, ΔHhyd/boride, which shows a good correlation with the observed Td. These results are useful for exploring M(BH 4)n with appropriate stability for hydrogen storage applications

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U2 - 10.1557/proc-0971-z02-01

DO - 10.1557/proc-0971-z02-01

M3 - Conference contribution

AN - SCOPUS:40949134635

SN - 9781604234206

T3 - Materials Research Society Symposium Proceedings

SP - 76

EP - 86

BT - Hydrogen Storage Technologies

PB - Materials Research Society

T2 - 2006 MRS Fall Meeting

Y2 - 27 November 2006 through 1 December 2006

ER -