The new phosphidosilicates Li SiP and LiSi P were synthesized by heating the elements at 1123 K and characterized by single-crystal X-ray diffraction. Li SiP (I4 /acd, Z=32, a=12.111(1) Å, c=18.658(2) Å) contains two interpenetrating diamond-like tetrahedral networks consisting of corner-sharing T2 supertetrahedra [(SiP ) ]. Sphalerite-like interpenetrating networks of uniquely bridged T4 and T5 supertetrahedra make up the complex structure of LiSi P (I4 /a, Z=100, a=18.4757(3) Å, c=35.0982(6) Å). The lithium ions are located in the open spaces between the supertetrahedra and coordinated by four to six phosphorus atoms. Temperature-dependent Li solid-state MAS NMR spectroscopic data indicate high mobility of the Li ions with low activation energies of 0.10 eV in Li SiP and 0.07 eV in LiSi P .

Fast sodium-ion conductors are key components of Na-based all-solid-state batteries which hold promise for large-scale storage of electrical power. We report the synthesis, crystal-structure determination, and Na -ion conductivities of six new Na-ion conductors, the phosphidosilicates Na Si P , Na Si P , Na Si P , Na Si P , LT-NaSi P and HT-NaSi P , based entirely on earth-abundant elements. They have SiP tetrahedra assembled interpenetrating networks of T3 to T5 supertetrahedral clusters and can be hierarchically assigned to sphalerite- or diamond-type structures. Na solid-state NMR spectra and geometrical pathway analysis show Na -ion mobility between the supertetrahedral cluster networks. Electrochemical impedance spectroscopy shows Na -ion conductivities up to σ (Na )=4×10 S cm . The conductivities increase with the size of the supertetrahedral clusters through dilution of Na -ions as the charge density of the anionic networks decreases.

The all-solid-state battery (ASSB) is a promising

Abstract. Ba 2 SiP 4 was synthesized by heating of the elements at 1173 K and the crystal structure was determined from single-crystal X-ray diffraction [I42d, a = 990.57(3) pm, c = 731.80(3) pm; Z = 4]. The novel structure is homeotypic to hp-Zn 2 SiO 4 but the SiP 4 tetrahedra are exclusively bridged by P-P bonds [d(P-P) = 222 pm] which is

Die neuen Phosphidosilicate Li2SiP2 und LiSi2P3 wurden aus den Elementen bei 1123 K synthetisiert und durch Einkristallstrukturanalyse charakterisiert. Li2SiP2 (I41/acd, Z=32, a=12.111(1) Å, c=18.658(2) Å) enthält zwei sich durchdringende Diamant‐analoge Tetraedernetzwerke aus eckenverknüpften T2‐Supertetraedern [(SiP4/2)4]. In der komplexen Struktur von LiSi2P3 (I41/a, Z=100, a=18.4757(3) Å, c=35.0982(6) Å) liegen Sphalerit‐analoge sich durchdringende Netzwerke aus T4‐ und T5‐Supertetraedern mit je einer gemeinsamen SiP4‐Gruppe vor. Lithium ist in den Zwischenräumen der Supertetraeder durch vier bis sechs Phosphoratome koordiniert. Temperaturabhängige 7Li‐MAS‐NMR‐Spektren deuten auf eine hohe Beweglichkeit der Li+‐Ionen mit geringen Aktivierungsenergien von 0.1 eV für Li2SiP2 und 0.07 eV für LiSi2P3.

Ion conductors of light alkaline metals based on earth‐abundant elements are important components for all‐solid‐state batteries. The new sodium‐rich phosphidosilicate Na2SiP2 was synthesized by solid state reaction of stoichiometric amounts of the elements at 973 K and characterized by single‐crystal X‐ray diffraction (space group Pccn (no. 56), a = 12.7929(5) Å, b = 22.3109(9) Å, c = 6.0522(2) Å and Z = 16) and solid‐state NMR under MAS conditions. The compound forms dark‐red twinned crystals, and its crystal structure contains edge‐sharing SiP4 tetrahedra connected to infinite ∞1[SiP4/2] chains. The sodium ions between the chains are fairly mobile. Electrochemical impedance spectroscopy shows a total ionic conductivity of σ(Na+, 373 K) = 2.3 ? 10–6 Scm–1 with an activation energy of Ea = 0.43 eV, and the galvanostatic polarization reveals mixed conduction behavior with a transference number of 0.8.

Fast sodium‐ion conductors are key components of Na‐based all‐solid‐state batteries which hold promise for large‐scale storage of electrical power. We report the synthesis, crystal‐structure determination, and Na+‐ion conductivities of six new Na‐ion conductors, the phosphidosilicates Na19Si13P25, Na23Si19P33, Na23Si28P45, Na23Si37P57, LT‐NaSi2P3 and HT‐NaSi2P3, based entirely on earth‐abundant elements. They have SiP4 tetrahedra assembled interpenetrating networks of T3 to T5 supertetrahedral clusters and can be hierarchically assigned to sphalerite‐ or diamond‐type structures. 23Na solid‐state NMR spectra and geometrical pathway analysis show Na+‐ion mobility between the supertetrahedral cluster networks. Electrochemical impedance spectroscopy shows Na+‐ion conductivities up to σ (Na+)=4×10−4 S cm−1. The conductivities increase with the size of the supertetrahedral clusters through dilution of Na+‐ions as the charge density of the anionic networks decreases.

The three‐dimensional SiP4 network in the known phosphidosilicate Ba2SiP4‐tI28 is analogous to β‐Cristobalite if oxygen is formally replaced by P–P dimers. Here we report a second polymorph Ba2SiP4‐oP56 [Pnma, a = 12.3710(4) Å, b = 14.6296(7) Å, c = 7.9783(3) Å; Z = 8] with chains of SiP4 tetrahedra connected by P–P bonds, reminiscent to the elusive fibrous SiO2. Ba2SiP4 is enantiotropic. The high temperature polymorph Ba2SiP4‐oP56 transforms to the low‐temperature phase Ba2SiP4‐tI28 at 650 °C and reconstructs to the high‐temperature modification at 1100 °C. DFT calculations predict an indirect optical bandgap of about 1.7 eV.