Unravelling ultraslow lithium-ion diffusion in γ-LiAlO2 : experiments with tracers, neutrons, and charge carriers

Lithium aluminum oxide (γ-LiAlO2) has been discussed and used for various applications, e.g., as electrode coating, membrane, or tritium breeder material. Although lithium-ion diffusion in this solid is essential for these purposes, it is still not sufficiently understood on the microscopic scale. Herein, we not only summarize and assess the available studies on diffusion in different crystalline forms of γ-LiAlO2, but also complement them with tracer-diffusion experiments on (001)- and conductivity spectroscopy on (100)-oriented single crystals, yielding activation energies of 1.20(5) and 1.12(1) eV, respectively. Scrutinous crystal-chemical considerations, Voronoi–Dirichlet partitioning, and Hirshfeld surface analysis are employed to identify possible diffusion pathways. The one-particle potential, as derived from high-temperature powder neutron diffraction data presented as well, reveals the major path to be strongly curved and to run between adjacent lithium positions with a migration barrier of 0.72(5) eV. This finding is substantiated by comparison with recently published computational results. For the first time, a complete model for lithium-ion diffusion in γ-LiAlO2, consistent with all available data, is presented.DFG, FOR 1277, Mobilität von Lithiumionen in Festkörpern (molife

Design of a Rapid Vacuum Pressure Swing Adsorption (RVPSA) Process for Post-combustion CO2 Capture from a Biomass-fuelled CHP Plant

It was aimed to design a novel RVPSA (Rapid Vacuum Pressure Swing Adsorption) unit for CO2 concentration and recovery in order to achieve the aggressive CO2 capture target, i.e. 95+% CO2 purity and 90+% CO2 recovery at the same time, applied to an existing 10 MWth biomass-fuelled CHP plant. Biomass-fuelled CHP plants are deemed carbon-neutral on the grounds of the net CO2 addition to the atmosphere as a result of its operation being practically zero, ignoring the CO2 emissions involved in the ancillary processes, such as soil enhancement, biomass transport and processing, etc. Furthermore, integrating the biomass-fuelled CHP plant with carbon capture, transport and storage enables carbon-negative energy generation, as its net effect is to recover some CO2 in the air and then store it underground through this plant operation. By the way, a RVPSA process features more efficient utilisation of the adsorbents in the column, leading to much higher bed productivity than a conventional adsorption process. Such a high bed productivity makes it easier to scale up this adsorption process for its application to industrial post-combustion capture. A two-stage, two-bed RVPSA unit was designed and simulated to capture CO2 from the biomass-fuelled CHP plant flue gas containing 13.3% CO2 mole fraction. Effects of operating conditions such as the Purge-to-Feed ratio (P/F) and desorption pressure on the specific power consumption were investigated in detail. It was found that the integrated two-stage RVPSA unit was capable of achieving the following overall performances: CO2 recovery of 90.9%, CO2 purity of 95.0%, bed productivity of 21.2 molCO2/kg/h and power consumption of 822.9 kJ/kgCO2. The productivity of the RVPSA unit designed in this study was 20-30 times higher than those of the conventional CO2 capture VPSA processes.</p