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Nanocrystalline LiTi2(PO4)3/C has been synthesized by employing a solvothermal process in which oxalic acid was used as a solubilizer for the titanium source, a surfactant, and a carbon source. Additionally, Pechini's sol–gel‐based method was also used as the synthesis method for comparison. LiTi2(PO4)3/C prepared by using a solvothermal route showed a homogenous particle size with spindle‐like microstructures formed from self‐assembled nanosized‐platelets, whereas preparation by the sol–gel process resulted in agglomerated powders with irregular morphology and particle size. The different morphologies of LiTi2(PO4)3/C prepared in the two synthesis methods tend to form different electrode layer structures, which results in remarkable differences in their electrochemical properties. In particular, the solvothermally synthesized LiTi2(PO4)3/C composite exhibits superior high‐rate‐discharge capability and cycling stability. A capacity of approximately 97.7 % of the initial capacity was maintained for the solvothermal sample after 500 cycles at 5 C.

Intermediate term discharge experiments were performed for Si-air full cells using As-, Sb-and B-doped Si-wafer anodes, with 100 and 111 orientations for each type. Discharge characteristics were analyzed in the range of 0.05 to 0.5 mA/cm 2 during 20 h runs, corrosion rates were determined via the mass-change method and surface morphologies after discharge were observed by laser scanning microscopy and atomic force microscopy. Corresponding to these experiments, potentiodynamic polarization curves were recorded and analyzed with respect to current-potential characteristics and corrosion rates. Both, discharge and potentiodynamic experiments, confirmed that the most pronounced influence of potentials -and thus on performance -results from the dopant type. Most important, the corrosion rates calculated from the potentiodynamic experiments severely underestimate the fraction of anode material consumed in reactions that do not contribute to the conversion of anode mass to electrical energy. With respect to materials selection, the estimates of performance from intermediate term discharge and polarization experiments lead to the same conclusions, favoring 100 and 111 As-doped Si-wafer anodes. However, the losses in the 111 As-doped Si-anodes are by 20% lower, so considering the mass conversion efficiency this type of anode is most suitable for application in non-aqueous Si-air batteries. One line of development in technologies for electrical energy storage is metal-air batteries, which provide high specific energies and -when referring to Zn, Al, Fe, or Si -are at the same time resource effective with respect to the availability and price of the anode materials. The theoretical specific energy of a Si-air cell, related to the anode mass only, is 8470 Wh/kg. Using Si material in aqueous alkaline solutions, however, results in a severe corrosion reaction which is accompanied by intense hydrogen evolution.1-3 Despite the corrosion reaction, it is still feasible to build an alkaline Si-air cell at a discharge potential around 1.1 V, however, with sacrifice of huge amount of Si anode to corrosion. [4][5][6] Therefore, new approaches to establish batteries on silicon materials have been put forward using ionic liquid electrolytes. One of the possible approaches is the usage of EMIm(HF) 2.3 F electrolyte which possesses high conductivity, low viscosity and chemical stability in air.7-10 The proof of concept, that substantial discharge was possible when using EMIm(HF) 2.3 F electrolyte, was proposed in 2010 according to the following reactions: Additionally, a screening of several anode materials -As-, Sband B-doped Si wafers -was performed, in which the cell potential at intermediate current densities as determined from potentiodynamic polarization measurements, was set as major criterion. The corrosion current densities as obtained by the Tafel fits from the polarization experiments for the different wafer types were also considered for the material selection. However, owing to the low corrosion rates, it played a minor ro...