Electrochemical Evaluation of La-Ni-Sn Metal Hydride Alloys
A detailed electrochemical evaluaiton of Sn-modified LaNi 5 was performed to evaluate its applicability as negative electrode in alkaline rechargeable cells.
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A detailed electrochemical evaluaiton of Sn-modified LaNi 5 was performed to evaluate its applicability as negative electrode in alkaline rechargeable cells.
LaNiSn is Titanium Disilicide-derived structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. La is bonded in a 1-coordinate geometry to four equivalent Ni and six equivalent Sn atoms. There are a spread of La–Ni bond distances ranging from 2.97–3.27 Å. There are a spread of La–Sn bond distances ranging from 3.24–3.46 Å. Ni is bonded in a 10-coordinate geometry to four equivalent La and four equivalent Sn atoms. There are a spread of Ni–Sn bond distances ranging from 2.63–2.76 Å. Sn is bonded in a 10-coordinate geometry to six equivalent La and four equivalent Ni atoms.
La3Ni2Sn7 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent La sites. In the first La site, La is bonded in a 10-coordinate geometry to four equivalent Ni and ten Sn atoms. All La–Ni bond lengths are 3.65 Å. There are a spread of La–Sn bond distances ranging from 3.43–3.57 Å. In the second La site, La is bonded to two equivalent Ni and twelve Sn atoms to form a mixture of distorted corner and face-sharing LaNi2Sn12 cuboctahedra. Both La–Ni bond lengths are 3.56 Å. There are four shorter (3.29 Å) and eight longer (3.40 Å) La–Sn bond lengths. Ni is bonded in a 5-coordinate geometry to five La and five Sn atoms. There are one shorter (2.52 Å) and four longer (2.56 Å) Ni–Sn bond lengths. There are four inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to four La and two equivalent Ni atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six equivalent La, one Ni, and two equivalent Sn atoms. Both Sn–Sn bond lengths are 2.91 Å. In the third Sn site, Sn is bonded in a square co-planar geometry to four equivalent La atoms. In the fourth Sn site, Sn is bonded in a 12-coordinate geometry to four La and two equivalent Ni atoms.
LaNi2Sn2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. La is bonded in a 8-coordinate geometry to eight equivalent Ni and eight equivalent Sn atoms. All La–Ni bond lengths are 3.45 Å. All La–Sn bond lengths are 3.48 Å. Ni is bonded in a 4-coordinate geometry to four equivalent La and four equivalent Sn atoms. All Ni–Sn bond lengths are 2.53 Å. Sn is bonded in a 9-coordinate geometry to four equivalent La, four equivalent Ni, and one Sn atom. The Sn–Sn bond length is 2.90 Å.
LaNi2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. La is bonded in a 12-coordinate geometry to eight Ni and eight Sn atoms. There are four shorter (3.34 Å) and four longer (3.44 Å) La–Ni bond lengths. There are four shorter (3.40 Å) and four longer (3.46 Å) La–Sn bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 8-coordinate geometry to four equivalent La and four equivalent Sn atoms. All Ni–Sn bond lengths are 2.58 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to four equivalent La and five Sn atoms. There are one shorter (2.54 Å) and four longer (2.60 Å) Ni–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to four equivalent La and four equivalent Ni atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent La and five Ni atoms.