Plant-derived hard carbon as anode for sodium-ion batteries: A comprehensive review to guide interdisciplinary research

Sodium-ion batteries (SIBs) are one of the most promising candidates to replace lithium-ion batteries (LIBs) in grid-scale energy storage applications. SIBs technology is still in an early development stage and new feasible and low-cost active materials are required. The design of high-performance anodes and the fully understanding of the sodium storage mechanisms are the main bottleneck to overcome. Hard carbons (HCs) are extensively studied as anode material since sodium ions can be intercalated in pseudographitic domains and reversibly adsorbed in surface edges, defects and nanopores. This review aims at providing a comprehensive overview of the current state of knowledge of plant-derived HC anodes in SIBs, which can be helpful for researchers from different backgrounds working in the field. Working principles of SIBs are summarized, together with a detailed description of the Na-ion storage mechanisms in hard carbon anodes proposed to date. Finally, an exhaustive literature review on the performance of plant-derived HCs in SIBs is presented, with special focus on the synthesis pathways (including activation and/or doping treatments)

Ultra-microporous adsorbents prepared from vine shoots-derived biochar with high CO2 uptake and CO2/N2 selectivity

There is a growing interest in developing renewable biomass-based adsorbents to be used in numerous applications, including CO2 capture in postcombustion conditions. In the present study, several activated carbons (ACs) were produced from vine shoots-derived biochar through both physical and chemical activation using CO2 and KOH, respectively. The performance of these ACs was tested in terms of CO2 uptake capacity at an absolute pressure of 15 kPa and at different temperatures (0, 25, and 75 °C), apparent selectivity towards CO2 over N2, and isosteric heat of adsorption. At 25 °C, the chemically ACs with KOH impregnation exhibited the highest CO2 adsorption capacity, which was similar or even higher than those recently reported for a number of carbon-based adsorbents. However, the AC prepared through physical activation with CO2 at 800 °C and a soaking time of 1 h appears as the most promising adsorbent analyzed here, due to its higher CO2 uptake capacity and adsorption rate at relatively high temperature (75 °C), its relatively high selectivity at this temperature, and its apparently low energy demand for regeneration. Given that physical activation with CO2 is more feasible at industrial scale than chemical activation using corrosive alkalis, the results reported here are encouraging for further development of vine shoots-derived adsorbents

Pyrolysis and char reactivity of a poor-quality refuse-derived fuel (RDF) from municipal solid waste

The present study focuses on analyzing the pyrolysis and combustion behaviors of a refuse-derived fuel (RDF), which is generated in a MSW treatment plant located in Zaragoza (Spain). Pyrolysis experiments were carried out in a TGA apparatus and a fixed-bed reactor at different peak temperatures (400 and 600 °C) and heating rates (5 and 40 °C min- 1). The reactivity towards oxygen of produced chars was also measured in the same TGA device at a heating rate of 10 °C min- 1 and a final temperature of 800 °C. Pyrolysis results were significantly affected by peak temperature and heating rate. The found effect of peak temperature on char and fixed-carbon yields as well as on measured properties (H:C and O:C ratios, BET surface area and average pore diameter) was in agreement with previous studies. However, the effect of heating rate, especially on the release rate of volatiles, could be explained by a change in the pyrolysis reaction scheme. The RDF-derived chars obtained at the highest heating rate showed a higher reactivity in air. In addition, an increase in peak temperature also led to a higher reactivity. This result can indicate that the carbon present in the RDF-derived char is dispersed within an ash matrix containing a high number of active sites, the distribution of which could be improved when heating rate (and, to a lesser extent, peak temperature) is increased. The addition of 10 wt.% RDF to two-phase olive mill waste prior to slow pyrolysis led to an apparent increase in the carbonization efficiency as well as to an enhancement of the resultant char''s reactivity in air