Nitrogen and fluorine co-doped TiO_(2)/carbon microspheres for advanced anodes in sodium-ion batteries: High volumetric capacity, superior power density and large areal capacity

Fast charging and high volumetric capacity are two of the critical demands for sodium-ion batteries(SIBs).Although nanostructured materials achieve outstanding rate performance,they suffer from low tap density and small volumetric capacity.Therefore,how to realize large volumetric capacity and high tap density simultaneously is very challenging.Here,N/F co-doped TiO_(2)/carbon microspheres(NF- TiO_(2)/C)are synthesized to achieve both of them.Theoretical calculations reveal that N and F co-doping increases the contents of oxygen vacancies and narrows the bandgaps of TiO_(2) and C,improving the electronic conductivity of NF- TiO_(2)/C.Furthermore,NF- TiO_(2)/C exhibits the high binding energy and low diffusion energy barrier of Na+,significantly facilitating Na+storage and Na+diffusion.Therefore,NF- TiO_(2)/C offers a high tap density(1.51 g cm^(-3)),an outstanding rate performance(125.9 mAh g^(-1) at 100 C),a large volumetric capacity(190 mAh cm^(-3) at 100 C),a high areal capacity(4.8 mAh cm^(-2))and an ultra-long cycling performance(80.2%after 10,000 cycles at 10 C)simultaneously.In addition,NF- TiO_(2)/C||Na_(3)V_(2)(PO_(4))_(3) full cells achieve an ultrahigh power density of 25.2 kW kg^(-1).These results indicate the great promise of NF- TiO_(2)/C as a high-volumetric-capacity and high-power-density anode material of SIBs.

A thin Si nanowire network anode for high volumetric capacity and long-life lithium-ion batteries

Silicon nanowires(Si NWs)have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries(LIBs)owing to their high capacity and low discharge potential.However,growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors(CCs),and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+inactive silicide phases.Here,the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide(CS)network in situ grown on a Cu-foil,allowing for a thin active NW layer(<10μm thick)and high areal loading(≈1.04 mg/cm^(2))binder-free electrode architecture.The electrode exhibits an average Coulombic efficiency(CE)of>99.6%and stable performance for>900 cycles with≈88.7%capacity retention.More significantly,it delivers a volumetric capacity of≈1086.1 m A h/cm^(3)at 5C.The full-cell versus lithium manganese oxide(LMO)cathode delivers a capacity of≈1177.1 m A h/g at 1C with a stable rate capability.This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.

Congener-derived template to construct lithiophilic organic-inorganic layer/interphase for high volumetric capacity dendrite-free Li metal batteries

The development of lithium-metal batteries(LMBs)is seriously restricted by the out-of-control dendrites growth and infinite volume expansion.Herein,a pervasive organic-inorganic layer construction strategy is reported for the composite lithium metal anode with congener-derived organic-inorganic solid electrolyte interphase(SEI).In this strategy,the organic-inorganic Ag@polydopamine(Ag@PDA)layer is coated on the arbitrary substrates by a simple two-step method.The thin and stable congener-derived SEI is insitu formed with fewer inorganic components and more organic components during charging/discharging.The polydopamine with sufficient adhesion groups and lithiophilic Ag layer realize near-zero nucleation overpotential during lithium deposition.The low interface resistance and stable lithium deposition are achieved.Moreover,the practical areal and volumetric capacities of the composite anode with three-dimensional copper(3DCu)as the substrate are 10 mAh/cm^(2)and 1538 mAh/cm^3(vs.the mass of anode).The symmetrical cell shows very low polarization voltage(10 mV)and more than 2500 h cycles life at 1 mA/cm^(2)(1 mAh/cm^(2)).The LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)-based full cells show improved capacity retention(82%)after 100 cycles at 0.5 C.The modified lithiophilic anode with congener-derived interphase provides a promising strategy to realize the next-generation dendrite-free LMBs.

Sulfur/nickel ferrite composite as cathode with high-volumetric-capacity for lithium-sulfur battery

Low volumetric energy density is a bottleneck for the application of lithium-sulfur (Li-S)battery.The low- density sulfur cooperated with the light-weight carbon sub- strate realizes electrochemical cycle stability,but leads to worse volumetric energy density.Here,nickel ferrite (NiFe2O4)nanofibers as novel substrate for sulfur not only anchor lithium polysulfides to enhance the cycle stability of sulfur cathode,but also contribute to the high volumetric capacity of the S/nickel ferrite composite.Specifically,the S/ nickel ferrite composite presents an initial volumetric capacity of 1,281.7mA h cm^-3-composite at 0.1C rate,1.9times higher than that of S/carbon nanotubes,due to the high tap density of the S/nickel ferrite composite.

High-volumetric-capacity WSe2 Anode for Potassium-ion Batteries

Exploring high-capacity electrode materials is critical for the development of K-ion batteries.In this work,we report a layered-structured tungsten selenide(WSe2)anode,which not only delivers an ultrahigh volumetric capacity of 1772.8 Ah/L(or 188.4 mAh/g)at a current density of 5 mA/g but also exhibits good rate capability(72 mAh/g at 200 mA/g)and cycling stability(83.14%capacity retention over 100 cycles at 100 mA/g).We have also revealed the underlying reaction mechanism through ex situ X-ray powder diffraction.Furthermore,proof-of-concept full-cell batteries comprising of WSe2 anodes and Prussian Blue cathodes are capable of delivering an energy density of 135.2 Wh/kgcathode+anode.This work highlights the potential of WSe2 as a promising high-volumetric-capacity anode material for rechargeable potassium-ion batteries.

Synthesis of SiOx Nano-Powders Using a Microwave Plasma Torch at Atmospheric Pressure

The silicon oxide nano-powders (SiOx-NPs) were obtained in an atmospheric microwave plasma torch using a gas-phase silicon tetrachloride (SiCl4) with N2 and H2. The gas-phase SiCl4 was injected with H2 gas into the microwave plasma torch generated by N2 and air swirl gas, and then the dark brown powders were deposited on the inner wall of a quartz tube. The sample was analyzed by an X-ray photoelectron spectroscopy (XPS), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and an X-ray diffraction (XRD). The average size and oxidation x values of synthesized SiOx-NPs were approximately 230 nm and 0.91, respectively. Furthermore, the volumetric charge capacity is 1127 mAh/g and has 89.2% retention after 100 cycles.

Ultra-thick,dense dual-encapsulated Sb anode architecture with conductively elastic networks promises potassium-ion batteries with high areal and volumetric capacities

Ultra-thick,dense alloy-type anodes are promising for achieving large areal and volumetric performance in potassium-ion batteries(PIBs),but severe volume expansion as well as sluggish ion and electron diffusion kinetics heavily impede their widespread application.Herein,we design highly dense(3.1 g cm^(-3))Ti_(3)C_(2)T_(x) MXene and graphene dual-encapsulated nano-Sb monolith architectures(HD-Sb@Ti_(3)C_(2)T_(x)-G)with high-conductivity elastic networks(1560 S m^(-1))and compact dually encapsulated structures,which exhibit a large volumetric capacity of 1780.2 mAh cm^(-3)(gravimetric capacity:565.0 mAh g^(-1)),a long-term stable lifespan of 500 cycles with 82%retention,and a large areal capacity of 8.6 mAh cm^(-2)(loading:31 mg cm^(-2))in PIBs.Using ex-situ SEM,in-situ TEM,kinetic investigations,and theoretical calculations,we reveal that the excellent areal and volumetric performance mechanism stems from the three dimensional(3D)high-conductivity elastic networks and the dualencapsulated Sb architecture of Ti_(3)C_(2)T_(x) and graphene;these effectively mitigate against volume expansion and the pulverization of Sb,offering good electrolyte penetration and rapid ionic/electronic transmission.Ti_(3)C_(2)T_(x) also decreases the Kþdiffusion energy barrier,and the ultra-thick compact electrode ensures volumetric and areal performance.These findings provide a feasible strategy for fabricating ultra-thick,dense alloy-type electrodes to achieve high areal and volumetric capacity energy storage via highly-dense,dual-encapsulated architectures with conductive elastic networks.

Compacted mesoporous titania nanosheets anode for pseudocapacitance-dominated,high-rate,and high-volumetric sodium-ion storage

Surface-redox pseudocapacitive nanomaterials show promise for fast-charging energy storage.However,their high surface area usually leads to low density,which is not conducive to achieving both high volumetric capacity and high-rate capability.Herein,we demonstrate that TiO_(2)nanosheets(meso-TiO_(2)-NSs)with densely packed mesoporous are capable of fast pseudocapacitance-dominated sodium-ion storage,as well as high volumetric and gravimetric capacities.Through compressing treatment,the compaction density of meso-TiO_(2)-NSs is up to~1.6g/cm^(2),combined with high surface area and high porosity with mesopore channels for rapid Na+diffusion.The compacted meso-TiO_(2)-NSs electrodes achieve high pseudocapacitance(93.6%of total charge at 1mV/s),high-rate capability(up to 10 A/g),and long-term cycling stability(10,000 cycles).More importantly,the space-efficiently packed structure enables high volumetric capacity.The thick-film meso-TiO_(2)-NSs anode with the mass loading of 10mg/cm^(2)delivers a gravimetric capacity of 165 mAh/g and a volumetric capacity of 223 mAh/cm^(3)at 5 mA/cm^(2),much higher than those of commercial hard carbon anode(80mAh/g and 86mAh/cm^(3)).This work highlights a pathway for designing a dense nanostructure that enables fast charge kinetics for high-density sodium-ion storage.

Nanosized-bismuth-embedded 1D carbon nanofibers as high-performance anodes for lithium-ion and sodium-ion batteries

Bi is a promising candidate for energy storage materials because of its high volumetric capacity, stability in moisture/air, and facile preparation. In this study, the electrochemical performance of nanosized-Bi-embedded one-dimensional （1D） carbon nanofibers （Bi/C nanofibers） as anodes for Li-ion batteries （LIBs） and Na-ion batteries （NIBs） was systematically investigated. The Bi/C nanofibers were prepared using a single-nozzle electrospinning method with a specified Bi source followed by carbothermal reduction. Abundant Bi nanoparticles with diameters of approximately 20 nm were homogeneously dispersed and embedded in the 1D carbon nanofibers, as confirmed by structural and morphological characterization. Electrochemical measurements indicate that the Bi/C nanofiber anodes could deliver a long cycle life for LIBs and a preferable rate performance for NIBs. The superior electrochemical performances of the Bi/C nanofiber anodes are attributed to the 1D carbon nanofiber structure and uniform distribution of Bi nanoparticles embedded in the carbon matrix. This unique embedded structure provides a favorable electron carrier and buffering matrix for the effective release of mechanical stress caused by volume change and prevents the aggregation of Bi nanoparticles.