The First Alkaline-Earth Azidoaurate(III), Ba[Au(N3 )4 ]2 ⋠4 H2 O.

Transparent, dark orange Ba[Au(N3 )4 ]2 ⋅ 4 H2 O was synthesized by reaction of Ba(N3 )2 and AuCl3 or HAuCl4 in aqueous solution. The novel barium tetraazidoaurate(III) tetrahydrate crystallizes in the monoclinic space group Cc (no. 9) with a=1813.68(17) pm, b=1737.95(11) pm, c=682.04(8) pm and ß=108.849(4)°. The predominant structural features of Ba[Au(N3 )4 ]2 ⋅ 4 H2 O are two crystallographically independent discrete anions [Au(N3 )4 ]- with gold in a tetragonal planar coordination by nitrogen. Vibrational spectra show good agreement with those of other azidoaurates(III). Upon drying, this salt was shown to be a highly explosive material.

LiMg0.1Co0.9BO3 as a positive electrode material for Li-ion batteries.

LiCoBO3 could be a promising cathode material given the electronic and ionic conductivity problems are addressed. Here, Mg substitution in LiCoBO3 is employed to stabilise the structure and improve the electrochemical performance. LiMg0.1Co0.9BO3 is synthesised for the first time via sol-gel method and Mg substitution in the structure is verified by X-ray powder diffraction and energy dispersive X-ray analyses. The electrochemical properties are investigated by galvanostatic cycling and cyclic voltammetry tests. The composite electrode with conductive carbon (reduced graphite oxide and carbon black) delivers a first discharge capacity of 32 mA h g-1 within a 4.7-1.7 voltage window at a rate of 10 mA g-1. The cycling is relatively stable compared to the unsubstituted LiCoBO3. Mg substitution may enhance the electrochemical performance of borate-based electrode materials when combined with suitable electrode design techniques.

Investigating the all-solid-state batteries based on lithium garnets and a high potential cathode - LiMn1.5Ni0.5O4.

All-solid-state Li-ion batteries based on lithium garnets give new prospects for safer battery operations avoiding liquids, and could enable the integration of high energy density electrode materials. Herein, we critically investigate the structural and chemical stability of the high voltage cathode material, LiMn1.5Ni0.5O4, based on the solid lithium garnet electrolyte LLZO (c-Li6.4Ga0.2La3Zr2O12) for all-solid Li-ion batteries. We manufacture battery cells based on nano-grained synthesized LLZO and composite cathodes (LiMn1.5Ni0.5O4/LLZO/C) fabricated via direct slurry casting of the cathode material and additives on sintered LLZO pellets against metallic Li anodes. The galvanostatic tests of such all-solid-state batteries up to 4.9 V at 95 °C reveal the incompatibility of the solid electrolyte and the cathode material under given conditions. Post-mortem analyses of the all-solid-state batteries demonstrate the formation of new inactive phases at the LLZO/LiMn1.5Ni0.5O4 interfacial region through an irreversible reaction starting at ∼3.8 V during charging. The discovered limited chemical stability under the investigated conditions raises the question if LLZO could be a promising solid-electrolyte for future all-solid-state Li-ion batteries especially at higher operation potentials and demanding operation conditions.

New high capacity cathode materials for rechargeable Li-ion batteries: vanadate-borate glasses.

V2O5 based materials are attractive cathode alternatives due to the many oxidation state switches of vanadium bringing about a high theoretical specific capacity. However, significant capacity losses are eminent for crystalline V2O5 phases related to the irreversible phase transformations and/or vanadium dissolution starting from the first discharge cycle. These problems can be circumvented if amorphous or glassy vanadium oxide phases are employed. Here, we demonstrate vanadate-borate glasses as high capacity cathode materials for rechargeable Li-ion batteries for the first time. The composite electrodes of V2O5 - LiBO(2) glass with reduced graphite oxide (RGO) deliver specific energies around 1000 Wh/kg and retain high specific capacities in the range of ~ 300 mAh/g for the first 100 cycles. V2O5 - LiBO(2) glasses are considered as promising cathode materials for rechargeable Li-ion batteries fabricated through rather simple and cost-efficient methods.