Nanohollow Carbon for Rechargeable Batteries:Ongoing Progresses and Challenges

Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.

Identification of Lablab Semen Album by DNA Barcode Technology

[Objectives] To identify ITS2 barcode of Lablab Semen Album and its adulterants,and provide a new method for the identification of Lablab Semen Album. [Methods] The ITS2 sequence was amplified by PCR and sequenced bi-directionally. After splicing by Codon Code Aligner,the data were processed with the aid MEGA software to construct the cluster dendrogram( neighbor-joining,NJ tree). [Results]The ITS2 sequence of Lablab Semen Album had length of 218 bp; the constructed cluster dendrogram indicated that all species were monophyletic and could be distinguished from other species. [Conclusions] The ITS2 barcode can be used for rapid identification of Lablab Semen Album and its adulterants and this experiment further verified that DNA barcode technology is effective in identification of traditional Chinese medicines.

Porous current collector enables carbon superior electrochemical performance for K-ion capacitors

The current collector is an indispensable component in potassium-ion hybrid capacitors,which not only provides mechanical support to load electrode materials,but also collects and outputs the current generated.Herein,we investigate the effect of three different current collectors on the electrochemical properties of potassium ion capacitors using carbon black anode as a demonstration.Because of better adhesion and lower charge transfer resistance,the specific capacity of half-cells assembled using three-dimensional(3D)porous copper foil(PCu)and copper as current collector is better than that of Al foil,which stabilizes at 138.2 and 132.8 mAh·g^(-1)after 100 cycles at 0.05 A·g^(-1).The potassium-ion capacitor assembled using PCu exhibits an excellent energy/power density of 86.1 Wh·kg^(-1)and 4000 W·kg^(-1),respectively.This work will boost the rational design and provide an effective strategy to improve the performance of potassium-ion capacitors.

Electrochemical activation of oxygen atom of SnO2 to expedite efficient conversion reaction for alkaline-ion(Li+/Na+/K+)storages

SnO2-based anode materials have attracted much attention due to high capacity and relatively mild voltage platforms.However,limited by low initial Coulombic efficiency(ICE)and poor stability,its practical application is still challenging.Recently,it has been found that compositing carbon or metal particles with SnO2 is an effective strategy to achieve high alkaline-ion storages.Although this strategy may improve the kinetics and ICE of the electrochemical reaction,the specific mechanism has not been clearly elucidated.In this work,we found that the invalidation SnO2 may go through two steps:1)the conversion process from SnO2 to Sn and Li2O;2)the collapse of the electrode material resulted from huge volume changes during the alloyed Sn with alkaline ions.To address these issues,a unique robust Co-NC shell derived from ZIF-67 is introduced,in which the transited metallic Co nanoparticles could accelerate the decomposition of Sn-O and Li-O bonds,thus expedite the kinetics of conversion reaction.As a result,the SnO2@Co-NC electrode achieves a more complete and efficient transfer between SnO2 and Sn phases,possessing a potential to achieve high alkaline-ion(Li+/Na+/K+)storages.

SbPS_(4):A novel anode for high-performance sodium-ion batteries

With the in-depth research of sodium-ion batteries(SIBs),the development of novel sodium-ion anode material has become a top priority.In this work,tube cluster-shaped SbPS_(4)was synthesized by a high-temperature solid phase reaction.Then the typical short tubular ternary thiophosphate SbPS_(4)compounded with graphene oxide(SbPS_(4)/GO)was successfully synthesized after ultrasonication and freeze-drying.SbPS_(4)shows a high theoretical specific capacity(1335 mAh/g)according to the conversion-alloying dual mechanisms.The unique short tube inserted in the spongy graphene structure of SbPS_(4)/GO results in boosting the Na ions transport and alleviating the huge volume change in the charging and discharging processes,improving the sodium storage performance.Consequently,the tubular SbPS_(4)compounded with 10%GO provides an outstanding capacity of 359.58 mAh/g at 500 mA/g.The result indicates that SbPS_(4)/GO anode has a promising application potential for SIBs.

Boron and nitrogen dual-doped carbon as a novel cathode for high performance hybrid ion capacitors

Hybrid ion capacitors have been considered as a very attractive energy source with high energy density and power density since it combines both merits of lithium ion batteries and supercapacitors. However,their commercial application has been limited by the mismatch of charge-storage capacity and electrode kinetics between the capacitor-type cathode and battery-type anode. Herein, B and N dual-doped 3D superstructure carbon cathode is prepared through a facile template method. It delivers a high specific capacity, excellent rate capability and good cycling stability due to the B, N dual-doping, which has a profound effect in control the porosity, functional groups, and electronic conductivity for the carbon cathode. The hybrid ion capacitors using B, N dual-doping carbon cathode and prelithiated graphite anode show a high energy density of 115.5 Wh/kg at 250 W/kg and remain about 53.6 Wh/kg even at a high power density of 10 kW/kg. Additionally, the novel hybrid device achieves 76.3% capacity retention after 2000 cycles tested at 1250 W/kg power density. Significantly, the simultaneous manipulation of heteroatoms in carbon materials provides new opportunities to boost the energy and power density for hybrid ion capacitors.