• Energy Research

Biochar, a carbon-rich material derived from lignocellulose biomass through pyrolysis, is being considered for lithium-ion battery (LIB) applications due to its sustainable sourcing, manufacturing, and favourable electrochemical properties. A biochar-based anode is a greener alternative to conventional materials, potentially reducing the environmental and financial costs of LIB production. Minimizing cost and simplifying the manufacturing process for LIBs drive the development of new scalable production of plant-based products to create greener anodes for lithium batteries. In this work, bamboo-based biochar (BCs) was prepared through an optimized slow pyrolysis route with two thermal treatments at 800 °C (B800) and 1000 °C (B1000), and used as a LIB anode. Compared to B1000, B800 presented higher d-spacing (d002 = 0.3657 nm) and graphitic crystallite size (La = 13.8 nm), smaller pore sizes (38 Å) with higher surface area (310 m2/g), and a higher concentration of permanent free radicals (PFRs) centered on the carbon (1.85 × 1018 spin/g). Although B1000 is slightly more conductive than B800, the physicochemical properties of B800 could enhance the lithiation of the pseudographitic structures and facilitate the reduction of Li+ ions due to the presence of PFRs. The half-cell LIB using B800 presented a reversible capacity of about 250 mA h/g at C/5 and long-term stability up to 450 cycles. This study highlights the potential of bamboo-based biochar as a viable and environmentally friendly anode material for the next generation of high-performance LIBs.

The initial stages of oxide nucleation and surface oxide formation are hot topics at the moment due to the possible application of these materials in many fields of science and technology. The understanding of the parameters controlling these processes is therefore pivotal not only for the fundamental knowledge of the physical phenomenon but also for enabling the growth of better quality oxide phases, with a higher degree of order and/or a lower density of contaminants. Here I will summarize the main results obtained by a collaboration between experimental groups in Genova and Osaka and between the experimentalists in Genova and theoretical groups in Trieste and Ljubljana, on the initial oxidation of the noble metals Ag and Cu. I will show that the local morphology of surface defects and/or the dosing conditions are essential elements to determine the nature of the oxide form which starts to nucleate upon exposure to O2. On stepped Ag we find that, under vacuum conditions, the stoichiometry of the initial oxide nuclei is tuned by the atomic geometry at the low coordination site, while on Cu(410) the oxidation efficiency comes out to be highly enhanced both by the presence of steps and by exposure to hyperthermal oxygen. The relative amount of cuprous and cupric oxide formed depends on oxidation temperature.