La-Mg-Ni
2 H 2 O e - e - H OH - H + e - H H 2 O OH - H + e - O H O Ni Ni O H O H
3 La, Pr, Nd, etc. Ni, Co, Mn, Al, etc. 0 0.2 0.4 0.6 0.8 1 H/M Equilibrium Hydrogen Pressure MPa (MPa) 10 1 0.1 0.01 0.001 La Ni Ni + Ni H x + xoh - + xh 2 O + x e-
4 AA Energy density (Wh/l) 600 500 400 300 200 100 0 1996 1998 2000 2002 2004 2006 Year 2008
La-Mg-Ni Kadir, Sakai 1997 : AB 3.0 -AB 4.0 (A:La, Mg, B:Ni) 1-2 wt.% (CaCu 5 -) La La, Mg Ni Ni + Ni c c c c A 2 B 4 (Laves ) 2:7H (AB 3.5 ) 5:19R (AB 3.8 ) 5 5:19H (AB 3.8 ) 1:4R (AB 4.0 )
La-Mg-Ni Voltage (V) 1.6 1.4 1.2 1.0 0.8 1.2 La-Mg-Ni La-Pr-Mg-Ni-based alloy MmNi -based alloy (conventional) 1.2 0 100 200 300 400 Discharge capacity (mah/g) M. Kanemoto et al., ECS 208th Meeting, Abstract number 852, Los Angeles (2005). T. Ozaki, M. Kanemoto,T. Kakeya, Y. Kitano, M. Kuzuhara, M. Watada, S. Tanase, and T. Sakai, J. Alloys Compds., 446-447, 620 (2007). 6 Discharge capacity (mah/g) 360 340 320 300 280 La-Mg-Ni-based La-Mg-Ni alloy Conventional AB5 alloy 0 20 40 60 Cycle number
7 La-Mg-Ni LaNi La 1-x Mg x Ni y (x = 0.150.2, y = 3.6-3.8) Ce, Pr, Nd Co, Mn, Al X
8 (900-1000 C) X (SPring8 BL19B2 ) XRD : 0.7Å 0.75Å) XAFS ) Rietveld : RIETAN-2000) EPMA
Mn,Al La-Mg-Ni La 0.8 Mg 0.2 Ni 3.4-x Co 0.3 (MnAl) x Mass fraction 0% 20% 40% 60% 80% 100% x = 0 x = 0.1 x = 0.15 2:7H 5:19R 5:19H x = 0.2 1:4R x = 0.25 x = 0.4 AB 2 x = 0.15, 0.2 5:19H, 1:4R 9
10 Mn,Al La-Mg-Ni La 0.8 Mg 0.2 Ni 3.4-x Co 0.3 (MnAl) x Discharge capacity (mah/g) 380 360 340 320 300 280 260 0 1 2 3 4 5 6 7 8 9 10 Cycle number x=0 x=0.15 x=0.25 x=0.4 5:19H x = 0.15
11 Mn,La,Ni,Co La 0.8 Mg 0.2 Ni 3.25 Co 0.3 (MnAl) 0.15 Co K Mn K FT Ni K La K R Mn La NiCo Mn NiCo
12 La La 0.8 Mg 0.2 Ni 3.25 Co 0.3 (MnAl) 0.15 FT R
Ni La 0.8 Mg 0.2 Ni 3.25 Co 0.3 (MnAl) 0.15 FT R 13
XAFS LaNiCo La La-Mg-Ni LaNi 5 Ni La LaNi5 La Ni Ni La 14
15 La La 0.64 RE 0.2 Mg 0.16 Ni 3.45 Co 0.2 Al 0.15 Potential / V (Hg/HgO) -1-0.9-0.8-0.7, : 0.2 I t A RE': La RE': Ce RE': Nd RE': Pr -0.6 0 100 200 300 400 Capacity / mah
16 La Discharge capacity (mah/g) 360 340 320 300 280 La 0.64 RE 0.2 Mg 0.16 Ni 3.45 Co 0.2 Al 0.15 RE':La RE':Ce RE':Nd 0 20 40 60 Cycle number RE':Pr 0.1 I t A, 15h 0.2 I t A cut off voltage -0.6V vs. Hg/HgO Pr, Nd- : 50 96% Ce- :
17 La La 0.64 RE 0.2 Mg 0.16 Ni 3.45 Co 0.2 Al 0.15 Phase abundancemass% 0% 20% 40% 60% 80% 100% RE': La 2:7H AB2 RE': Ce RE': Pr 5:19R 1:4R 2:7H 5:19R 5:19H 1:4R AB5 RE': Nd 5:19H Pr, Nd :, 2:7H. 5:19H, 5:19R
Pr, Nd Al 5:19R phase A 2 B 4 A 2 B 4 A 2 B 4 RE RE, Mg Ni,Co,Mn,Al 18h1 site M / Al = 0.89 / 0.11 18h2 site M / Al = 0.95 / 0.05 RE = (La, Pr) M=(Ni,Co,Mn) Ni La Ni Ni Ni Al Ni Ni Nd Ni La: 1.877 Nd: 1.821 Ni: 1.246 Al: 1.432 La Pr Nd c Al Ni 18
19 Pr, Nd Pr, Nd Al-poor Al-rich Al Al
20 Pr, Nd La-Mg-Ni Particle size after cycle test (µm) (um) 40 35 30 25 20 15 10 5 0-10 0 10 20 30 40 50 60 70 80 Abundance of of ABAB5 5 phase (%) Pr, Nd
Ce Ce-LIII XANES Normalized absorption La 0.64 Ce 0.2 Mg 0.16 Ni 3.45 Co 0.2 Al 0.15 1 Before hydriding Ce metal 0.8 CeCl 3 0.6 CeO 2 0.4 After hydriding 0.2 0 5700 5720 5740 5760 Energy (ev) : CeO 2 CeCl 3 : Ce 4+ Ce 3+ 21
22 La 0.64 RE 0.2 Mg 0.16 Ni 3.45 Co 0.2 Al 0.15 Intensity (a.u.) RE : Nd RE : Ce SPring8 BL19B2 :0.75Å 10 20 30 2θ (degree) RE' Phases Volume increase V /V (%) Ce 14.4 1:4R 16.5 5:19H 18.2 5:19R 19.5 2:7H 21.6 20.0 Pr 5:19H 20.3 5:19R 20.3 17.5 Nd 5:19H 21.0 5:19R 20.9
23 La-Mg-Ni HRTEM 3 c A 2 B 4 3 A 2 B 4 3 A 2 B 4 4 A 2 B 4 4 5:19 1:4 c
24 Ce Ce 4+ - Ce 3+ - 2:7H 2:7H 2:7H 2:7H 5:19H 5:19H Ce5:19R 1:4R 1:4R 1:4R 1:4R
25 La-Mg-Ni Ni Mn,Al 5:19H 350 mah/g La Ni Ni La La Pr,Nd Ce Ce Ce(III) Ce(IV) XRD XAFS
26 XRD XAFS SPring8 TEM