With aluminium being the most abundant metal in Earth’s crust, rechargeable Al batteries hold great promise as next-generation energy storage devices. However, to date it has been a challenge to...

In recent years the development of autonomous photo‐rechargeable batteries has received growing attention. Especially highly integrated photobatteries based on multifunctional materials able to harvest sunlight and store charge carriers are the holy grail amongst such devices. Recently 2‐(1‐cyclohexenyl)ethyl ammonium lead iodide (CHPI) has been reported as multifunctional photoelectrode material for the design of highly integrated Li‐ion photobatteries. CHPI is thereby believed to be able to reversibly intercalate Li‐ions from polar carbonate‐based electrolytes, typically used in Li‐ion batteries (LIBs). Herein, CHPI is examined closer to investigate its stability against dissolution, the possibility of Li‐intercalation and photo‐assisted deintercalation, and its general behavior under illumination in standard carbonate‐based electrolytes as well as in a newly developed low polarity electrolyte based on ortho‐difluorobenzene (o‐DFB). This study demonstrates that CHPI dissolves in contact with carbonate‐based electrolytes while being stable in o‐DFB‐based electrolyte and that no Li‐intercalation takes place in the latter. Furthermore, CHPI irreversibly photo‐corrodes during illumination and photo‐assisted deintercalation of lithium ions is not detected. These results lead to the conclusion, that CHPI is neither a suitable nor a stable material for the design of Li‐ion‐based photo‐rechargeable batteries and similar behavior for other organic–inorganic lead halide perovskite materials is expected.

In this work, lithium-ion battery full-cells based on sprucederived hard carbon anodes and an electrochemical prelithiation method are presented in combination with a detailed analysis of full-cell operation and the lithiation state. The physical and electrochemical properties agree well with those of previous biomass-derived hard carbon anodes. However, low initial coulombic efficiencies of 65 % represent one of the major challenges of the developed anodes with respect to full-cell operation. To counteract the initial lithium loss, in-situ electro-chemical pre-lithiation was conducted, allowing battery operation in the same cell setup without reassembly. Consequently, significantly increased capacities, cycle life, and first cycle coulombic efficiency were obtained in comparison to untreated anodes (195 mAh/g versus 150 mAh/g, state of health (SOH) 80 after 150 cycles versus 70 cycles, and 90 % versus 65 %). In summary, spruce-based hard carbon has the potential to be an environmentally friendly alternative to standard graphite.

Full utilization of the high storage capacity of conversion electrode materials as tin oxide (SnO2) in lithium‐ion batteries is hindered by the high volumetric expansion due to the high lithium storability which can lead to major cell damage and consequent safety issues. To overcome this issue, two promising approaches, nanostructures and buffer layers, are combined and evaluated. SnO2 nanowires (NWs) are coated with an aluminum oxide (Al2O3) buffer layer to investigate the combination SnO2–Al2O3. Strong differences in the crystallinity after cycling between the SnO2/Al2O3 core/shell NW‐based heterostructure and uncoated SnO2 NWs based on detailed structural analysis are shown via transmission electron microscopy (TEM) and determination of the elemental distribution of tin, oxygen, lithium, and aluminum via energy‐dispersive X‐Ray spectroscopy and energy‐filtered TEM in the as‐prepared and postmortem nanostructures. The core/shell NWs exhibit two different states after charge/discharge cycling, amorphous or crystalline, depending on the NW diameter; for the uncoated SnO2 NWs, only an amorphous postmortem structure is found. Additionally, differences in the elemental distribution for the amorphous and crystalline postmortem SnO2/Al2O3 core/shell NWs, especially for tin, are measured. Consequently, the structures and effects of the Al2O3 coating on the lithiation behavior of SnO2 NW‐based heterostructures are discussed.

Sustainable N-doped carbon aerogels were synthesized by a scalable hydrothermal approach using low-cost and abundant precursors such as glucose and ovalbumin. By adjusting the pyrolysis temperature (900-1500 °C), the surface chemistry, porosity and conductivity of these aerogels could be optimized for the design of Pt-based oxygen reduction reaction (ORR) catalysts with high Pt loading (40 wt % Pt) and improved stability. Pt nanoparticle deposition was realized by wet impregnation followed by thermal reduction and their size and distribution was found to strongly depend on the surface chemistry of the carbon aerogels. The catalysts' activities and stabilities, determined by rotating disc electrode measurements in HClO 4 , were found to strongly depend on the pyrolysis temperature of the N-doped carbon aerogel supports. While the mass activity decreased with increasing temperature, in line with a decreasing ECSA related to an increase in Pt nanoparticle size, the long-term stability of the catalysts, as revealed by accelerated stress tests for carbon support degradation (10,000 cycles), increased with increasing pyrolysis temperature, in line with increasing Pt nanoparticle sizes and increasing graphitization of the carbon aerogel supports. Most importantly, the catalyst derived from aerogels pyrolyzed at 1000 °C achieved a good compromise between activity and stability and revealed a superior ORR activity after the accelerated stress test in comparison to a commercially available Pt/C reference catalyst (40 wt % Pt).