A Pore-Forming Strategy Toward Porous Carbon-Based Substrates for High Performance Flexible Lithium Metal Full Batteries

Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.

Construction of MnO2 Nanowire for a High-Performance Lithium Ion Supercapacitor

Developing lithium ion capacitors possessing both brilliant energy and power density is still significant for numerous re-searchers.In this paper,we synthesized MnO2 nanowires via a simple hydrothermal process.The nanostructure MnO2 can expose more electrochemical sites and thus optimize the kinetics of Li+.Moreover,we used MnO2 nanowires(MnO2 NWs)as anode and a N-doped porous carbon(NPC)as cathode to assemble lithium ion capacitors(MnO2 NWs//NPC LIC).Compared to the traditional supercapacitor with aqueous electrolyte,the MnO2 NWs//NPC LIC exhibits a wider voltage of 0-4.2 V,which is helpful to enhance its energy and power density.Furthermore,MnO2 NWs//NPC LIC can deliver an excellent capacity of 150 mAh g-1 with an excellent energy density of 82.7 Wh kg-1 and power density of 1.05 kW kg-1.Meanwhile,a good cyclic stability of LICs with a 20%retention after 1000 times charge and discharge process proves its practical potential,indicating a good promising for the application in storage devices.

B, N-Co-doped Carbon Tubes with P Encapsulated in 3D Graphene Aerogel for High-stable Lithium-ion Batteries

Li-related anodes with stable ability and excellent rate performance are urgently being pursued to overcome the slow kinetic of current lithium ion storage devices.In this work,an annealing-hydrothermal method is developed to fabricate the anode of a three-dimension nano-construction with robust charge transfer networks,which is composed of elements B,N co-doped carbon tube(BN-CT)as the carrier of red phosphorous to(3D BN-CT@P).Then,3D BN-CT@P is embedded in the graphene aerogel network to obtain (3D BN-CT@P@GA).Impressively,the 3D BN-CT@P@GA shows high capacity and good cycle stability in the potential rage of 0.01-2.5V.Especially,the discharge capacity is~800 mAh g^(-1) at 500 mA g^(-1) after 500 cycles when evaluated as anode materials for lithium-ion batteries(LIBs).The improved electrochemical performances result from the unique structure of the 3D BN-CT@P@GA.With the hetero atoms doping,the active P can load up to the BN-CT,which can realize the high capacity as well as the low potential for the anode.At the same time,the graphene aerogel network provides the protection for the BN-CT@P species and good conductivity to enhance ion diffusion.This work fundamentally presents an effective structural engineering way for improving the performance of P-based anodes for advanced LIBs.

An Effective Method to Prepare Polymer/Nanocrystal Composites with Tunable Emission over the Whole Visible Light Range

Materials with emission over the whole visible range(400-800 nm)have been obtained through incorporating single-colored CdTe nanocrystals(NCs)into a poly(p-phenylene vinylene)(PPV)precursor[the sulfonium polyelectrolyte precursor of PPV].Firstly,the quantum yield(QY)of the PPV precursor was improved to~50%via heat treatment of a mixed solution of the PPV precursor and poly(vinyl alcohol)(PVA)at 100°C for 3 min.Then,single-colored CdTe NCs were incorporated into the mixed solution.The introduction of the PVA was necessary to reduce the electrostatic interaction between the PPV precursor and CdTe NCs,which improved their compatibility.The reduced electrostatic interaction eliminated Förster resonance energy transfer(FRET)processes between NCs,as well as between NCs and the PPV precursor,which allowed the functional integration of the polymer and NCs.Consequently,polymer/NC composites with almost any Commission Internationale de L’Eclairage(CIE)coordinates can be achieved by simply changing the size and amount of the NCs.In particular,when the emission wavelength of the CdTe NCs was 559 nm,a pure white-light emitting material with CIE coordinates(0.337,0.332)was obtained.

Aqueous-processed insulating polymer/nanocrystal solar cells with effective suppression of the leakage current and carrier recombination

As one of the most environmentally friendly photovoltaic(PV)conversion equipments,aqueousprocessed CdTe nanocrystal solar cells(NC SCs)have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption.However,two issues including interfacial recombination and leakage current seriously restrict their performance.In this paper,insulating polymer poly(vinyl pyrrolidone)(PVP)is introduced into CdTe NC SCs to solve the problems.The experimental results of transmission electron microscopy(TEM),atomic force micro scopy(AFM)and dark current measurements,etc.,demonstrate the leakage current is effectively suppressed by introducing PVP.Through further designing device structure,the reduction of interfacial recombination after introducing PVP is confirmed.By strategically taking the advantages of PVP properties(e.g.,water solubility and thermostability),the power conversion efficiency of the devices with PVP is enhanced by almost 37%compared to pure CdTe devices.This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route.Moreover,it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.