Life cycle assessment of an efficient biomass power plant supported by semi-closed supercritical CO2 cycle and chemical looping air separation.

Biomass power plant with carbon capture facility has great carbon emission reduction potential due to biomass's carbon neutrality characteristic, but it has been long-time suffered from undesirable system efficiency. This paper explored the life cycle carbon emission of a high-efficient biomass power generation system, which was comprised by the semi-closed supercritical CO2 cycle and chemical looping air separation sub-units. This system was proved to be environmentally superior with the life cycle warming impact value at 97.69 kg CO2 eq./MWh, the life cycle carbon emission reduction rate was 49.61 % and 45.46 % compared with traditional biomass gasification combined cycle system and biomass chemical looping gasification combined cycle system, respectively. The fuel and materials preparation stage should receive improvement attention due to its largest emission share of 76 %. In addition, the effects of key parameters, such as CO2 to biomass ratio (CO2/C), biomass gasification temperature, oxygen carrier and biomass types on environmental performance were investigated to further reveal this system's carbon emission reduction potential. The biomass/coal co-fired system showed net zero carbon emission was achieved when biomass share exceeded only around 10 %.

Sulfur-doped carbon nanotubes with hierarchical micro/mesopores for high performance pseudocapacitive supercapacitors.

Increasing the specific surface area and the amount of doping heteroatoms is an effective means to improve the electrochemical properties of carbon nanotubes (CNTs). The usual activation method makes it difficult for the retention of the heteroatoms while enlarging the specific surface area, and it can be found from literatures that specific surface area and S-content of carbon-based electrode materials are mutually exclusive. Here, CNTs with high specific surface area and sulfur content are constructed by simple activation of sulfonated polymer nanotubes with KHCO3, and the excellent electrochemical performance can be explained by the following points: first, KHCO3can be decomposed into K2CO3, CO2and H2O during the activation process. The synergistic action of physical activation (CO2and H2O) and chemical activation (K2CO3) equips the electrode material with high specific surface area of 1840 m2g-1and hierarchical micro/mesopores, which is beneficial to its double-layer capacitance. Second, compared with reported porous CNTs prepared by chemical activation (KOH) or physical activation (CO2or H2O), the mild activator KHCO3makes the sulfur content at a high level of 4.6 at%, which is very advantageous for high pseudocapacitance performance.

Restraining polysulfide shuttling by designing a dual adsorption structure of bismuth encapsulated into carbon nanotube cavity.

The shuttle effect derived from the dissolution of lithium polysulfides (LIPs) seriously hinders commercialization of lithium-sulfur (Li-S) batteries. Hence, we skillfully designed 1D cowpea-like CNTs@Bi composites with a double adsorption structure, where the bismuth nanoparticles/nanorods are encapsulated in the cavities of CNTs, avoiding the aggregation of bismuth nanoparticles during cycling and improving the conductivity of the electrode. Meanwhile, the sulfur was evenly distributed on the surface of bismuth nanoparticles/nanorods, ensuring effective catalytic activity and displaying high sulfur loading. Under the synergetic effects of the physical detention of abundant pores and chemical adsorption of bismuth, LIPs can be minimised, effectively curbing the shuttle effect. Benefiting from the above advantages, the CNTs@Bi/S cathodes exhibit a high capacity of 1352 mA h g-1, long cycling lifespan (708 mA h g-1 after 200 cycles at 1 C) and excellent coulombic efficiency. As the anodes of lithium-ion batteries (LIBs), the CNTs@Bi composites also show excellent performance due to the encapsulated structure to accommodate the serious volume change. This work offers an innovative strategy for improving the performances of the Li-S batteries and LIBs.

Rational design of FeTiO3/C hybrid nanotubes: promising lithium ion anode with enhanced capacity and cycling performance.

Ilmenite FeTiO3 has the advantage of high theoretical capacity and abundant sources as an anode material for lithium-ion batteries (LIBs). However, it suffers inferior rate capability caused by the aggregation of particles. To solve this problem, FeTiO3 nanoparticles embedded in porous CNTs were developed by the sol-gel route and subsequent calcination. The unique hybrids have a uniform distribution of FeTiO3 nanoparticles (5-20 nm) in the carbon matrix. Electrochemical tests prove that the porous FeTiO3/C hybrid nanotubes deliver a high capacity of 612.5 mA h g-1 at 0.2 A g-1 after 300 cycles. Moreover, they present remarkable rate capability and exceptional cycling stability, possessing 163.8 mA h g-1 at 5 A g-1 for 1000 cycles. The enhanced electrochemical performance of the FeTiO3/C hybrid is derived from the shortened Li+ transport length, good structure stability and conductive carbon matrix, which simultaneously solves the major problems of pulverization and agglomeration of FeTiO3 nanoparticles during cycling.

Construction of the NaTi2(PO4)3/C electrode with a one-dimensional porous hybrid structure as an advanced anode for sodium-ion batteries.

The inferior electronic conductivity of NASICON materials leads to poor cyclability and rate capability, which severely inhibits their extensive development. Therefore, we have developed a one-dimensional (1D) hybrid electrode material that combines small NaTi2(PO4)3 nanoparticles (5-50 nm) with a porous carbon matrix using a controllable sol-gel strategy. This unique design enables the electrode to possess good structural stability, superior charge transfer kinetics, and low polarization. The intimate combination between the nanoparticles and the porous carbon matrix can effectively facilitate Na+/e- transfer and accommodate volume variation during cycling. The construction of the new structure presented in this work will extend the applications of the NaTi2(PO4)3 system. Furthermore, the formed hybrid structure has potential to be a universal model for various electrode materials.

Physical Forces Inducing Thin Amorphous Carbon Nanotubes Derived from Polymer Nanotube/SiO2 Hybrids with Superior Rate Capability for Lithium-Ion Batteries.

Different from the traditional template method, a thin amorphous carbon nanotube was prepared by constructing a polymer/SiO2 composite, utilizing the shrinking action of sulfonated polymer nanotubes (SPNTs) and the physical squeezing action of SiO2 on it during the pyrolysis of SPNT/SiO2. Remarkably, the heat treatment atmosphere (N2, N2-H2, or O2) has an important effect on the surface properties, pore structure, crystallinity, and especially the defect sites, leading to different lithium storage performances. Particularly, the sample calcined in N2-H2 (NHCNTs) exhibits outstanding reversible capacity (400.6 mA h g-1 at 2 A g-1 after 200 cycles) and rate capability (268.4 mA h g-1 at 5 A g-1 and 212.1 mA h g-1 at 10 A g-1 after 400 cycles), which are attributed to the thin-walled tubular structure and abundant defect sites. NOCNTs can be obtained by the thermal treatment of NCNTs (the sample of polymer pyrolysis in N2) in air, and the oxygen content was increased. However, the destruction of the tubular structure led to poor electrochemical properties. These results proved the importance of the thin-walled tubular structure to the electrochemical properties. Surely, this strategy for preparing thin-walled carbon nanotubes can be widely extended to the preparation of other nanomaterials with thin-walled structures.