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 29 November 2006
ER -