Three-dimensional (3D) printing technology is becoming a promising method for fabricating highly complex ceramics owing to the arbitrary design and the infinite combination of materials. Insufficient ...density is one of the main problems with 3D printed ceramics, but concentrated descriptions of making dense ceramics are scarce. This review specifically introduces the principles of the four 3D printing technologies and focuses on the parameters of each technology that affect the densification of 3D printed ceramics, such as the performance of raw materials and the interaction between energy and materials. The technical challenges and suggestions about how to achieve higher ceramic density are presented subsequently. The goal of the presented work is to comprehend the roles of critical parameters in the subsequent 3D printing process to prepare dense ceramics that can meet the practical applications.
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•A novel layer-by-layer in situ culture (LBLC) method was developed.•Bacterial cellulose/graphene/polyaniline nanocomposites were made by LBLC and polymerization.•The as-prepared ...nanocomposites are mechanically strong and highly flexible.•The as-prepared nanocomposites show excellent gravimetric capacitance and cycling stability.
Rational structure, mechanical robustness, high conductivity, and favorable flexibility are important requirements for superior electrodes, which should not only possess high capacitance but also have freestanding structure without collector to improve the overall performance of supercapacitors. Herein, we demonstrate the fabrication of three-dimensional (3D) porous graphene-containing nanocomposites with highly dispersed graphene (GE) nanosheets in a 3D matrix of bacterial cellulose (BC) by a novel layer-by-layer in situ culture (LBLC) method. The BC/GE nanocomposites are then deposited with polyaniline (PANI), leading to the formation of BC/GE/PANI nanocomposites. Mechanical tests demonstrate excellent robustness and flexibility of the as-prepared BC/GE/PANI nanocomposites, which are used as electrodes directly without any nickel foam or stainless steel wire. The BC/GE/PANI electrode with an optimal GE content has a specific capacitance of 645 F g−1 at a current density of 1 A g−1, which is 2.5 times higher than that of BC/PANI and superior to most previously reported PANI-based electrodes. In addition, the symmetric supercapacitor assembled with BC/GE/PANI demonstrates a high energy density of 14.2 Wh kg−1 at a power density of 200 W kg−1. The excellent electrochemical performance of this BC/GE/PANI electrode is due to its unique 3D porous structure with the uniform distribution of GE nanosheets in the BC matrix and even PANI on BC nanofibers and GE nanosheets, which makes it very promising for diverse flexible energy storage devices. The methodology presented in this work can be extended to the preparation of other BC-based nanocomposite electrodes.
The influences of CuO doping on the sintering behavior, phase formation and electrochemical properties of yttrium-doped barium zirconate were investigated in this study. Unmodified yttrium-doped ...barium zirconate was difficult to densify. 1–2
mol% CuO can markedly enhance the sinterability of yttrium-doped barium zirconate. No CuO was detected in the CuO-modified samples, which suggested that the CuO might dissolve into the perovskite lattice structure. The electrical conductivity of 1
mol% CuO-modified yttrium-doped barium zirconate was close to that of unmodified one at the testing temperatures ranging from 500
°C to 800
°C in moisture-saturated hydrogen. Electromotive force measurements under fuel cell conditions revealed that the ionic transport number of CuO-modified yttrium-doped barium zirconate was large enough to apply the material as electrolyte in solid oxide fuel cell.
FeVO
4
is considered to be a potential anode material for alkaline ion batteries due to its abundant resources, low price, and high specific capacity. To enhance the energy storage performance of ...FeVO
4
, carbon coated FeVO
4
(FeVO
4
@C) growing on carbon cloth (CC) (FeVO
4
@C/CC) was prepared by a hydrothermal method in this work. The needle-like FeVO
4
grew obliquely on CC, forming a 3D structure. This 3D structure was beneficial to shortening the Li-ion diffusion distance, buffering the strain caused by the volumetric change of FeVO
4
during phase transition process and improving the conductivity of the material. Profiting from the morphology and component, FeVO
4
@C/CC demonstrated superior electrochemical performance as an anode for alkaline ion batteries. It delivered specific capacities of 835 mAh/g, 239 mAh/g, 306 mAh/g, and 211 mAh/g after 120 cycles at the current density of 0.1 A/g for Li-ion battery, K-ion battery, Na-ion battery, and LiNi
0.8
Co
0.1
Mn
0.1
O
2
full battery, respectively.
Graphical abstract
Carbon coated FeVO
4
growing on carbon cloth is prepared by hydrothermal method. The needle-like FeVO
4
grows obliquely on carbon cloth, forming a 3D structure. This 3D structure is beneficial for shortening the Li-ion diffusion distance, buffering the strain of volume change, and improving the conductivity of the material. The prepared materials demonstrate superior electrochemical performance as the anodes for Li-ion battery, K-ion battery, Na-ion battery, and LiNi
0.8
Co
0.1
Mn
0.1
O
2
full battery.
Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC are successfully developed using a facile one‐step in situ biosynthesis by adding GO ...suspension into the culture medium of BC. During the biosynthesis process, the crystallinity index of BC decreases and GO is partially reduced. The experimental results indicate that GO nanosheets are uniformly dispersed and well‐bound to the BC matrix and that the 3D porous structure of BC is sustained. This is responsible for efficient load transfer between the GO reinforcement and BC matrix. Compared with the pure BC, the tensile strength and Young's modulus of the GO/BC nanocomposite hydrogel containing 0.48 wt% GO are significantly improved by about 38 and 120%, respectively. The GO/BC nanocomposite hydrogels are promising as a new material for tissue engineering scaffolds.
Graphene oxide–bacterial cellulose (GO/BC) nanocomposite hydrogels with well‐dispersed GO in the network of BC have been successfully developed using a facile one‐step in situ biosynthesis by adding GO suspension into the culture medium of BC. The composites show a significant increase in tensile properties at relatively low GO loadings.
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•ZnFe2O4 nanoparticles with a small diameter are uniformly anchored on RGO surface.•A strong interfacial bonding was formed between ZnFe2O4 nanoparticles and RGO.•The minimum RL of ...ZnFe2O4/RGO nanohybrids is −29.3dB at 16.7GHz and 1.6mm.•ZnFe2O4/RGO nanohybrids show great promise as a microwave absorption material.
The nanohybrids composed of ZnFe2O4 and reduced graphene oxide (RGO) have been synthesized by a facile one-step hydrothermal strategy. The morphology and structure of ZnFe2O4/RGO nanohybrids were characterized by transmission electron microscopy, X-ray diffraction and Raman spectra. RGO content was also determined by thermogravimetric analysis. The results confirm the formation of nanohybrids with a content of 20.4wt% RGO and extensive interfaces between small-diameter ZnFe2O4 nanoparticles and RGO sheets. The magnetic properties and electromagnetic parameters of ZnFe2O4/RGO nanohybrids were measured and the microwave absorption properties were investigated. ZnFe2O4/RGO nanohybrids exhibit the advantages of thin matching thickness and strong absorption at high frequency bands. It is demonstrated that ZnFe2O4/RGO nanohybrids can be a powerful candidate in the field of microwave absorption.
Zn-doped Li sub(3)V sub(2)(PO sub(4)) sub(3)/C (Li sub(3)V sub(2-x)Zn sub(x)(PO sub(4)) sub(3)/C, x = 0, 0.02, 0.04 and 0.06) cathode materials are synthesized by an improved sol-gel method of which ...pH value is controlled at 4. They are characterized by X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, linear sweep voltammetry, galvanostatic charge/discharge test, cyclic voltammetry, electrochemical impedance spectroscopy and potential step chronoamperometry. Li sub(3)V sub(1.96)Zn sub( 0.04)(PO sub(4)) sub(3) /C has the highest electrical conductivity among the four samples. Although the initial discharge capacity for the doped samples at low current rate, such as 0.2C, presents no obvious enhancement compared with that for the undoped one, the cyclability and the rate performance are improved significantly. Zn-doped samples exhibit higher initial discharge capacity than the undoped one as increasing current rates. Among the three Zn-doped samples, Li sub(3)V sub(1.96)Zn sub( 0.04)(PO sub(4)) sub(3) /C shows the highest initial discharge capacity of 105.5 mAh g super(-1) at 5C. Capacity retention for Li sub(3)V sub(1.96)Zn sub( 0.04)(PO sub(4)) sub(3) /C remains 83.6% at 0.2C after 50 cycles, higher than 62.8% for Li sub(3)V sub(2)(PO sub(4)) sub(3)/C. It is believed that Zn substitution is beneficial to the rate performance and cyclic performance due to the lower charge transfer resistance and higher diffusion coefficient of lithium ions resulted from relatively higher intrinsic conductivity and smaller particle size.
► Highly conductive La0.6Sr0.4CoO3−δ was coated on the surface of LiFePO4/C. ► Coated cathodes showed significant improved rate performance and cycle performance. ► The LiFePO4/C sample coated with ...4wt.% La0.6Sr0.4CoO3−δ delivered a maximum discharge capacity of 96mAhg−1 at 5C compared with 65mAhg−1 for the pristine LiFePO4/C sample. ► La0.6Sr0.4CoO3−δ coating increases charge transfer reaction activity and prevents LiFePO4 particles from contacting electrolyte directly.
LiFePO4/C particles were coated with highly conductive La0.6Sr0.4CoO3−δ (LSC) via a suspension mixing method followed by heat-treating. The effects of LSC coating were studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), galvanostatic charge/discharge test, electrochemical impedance spectroscopy (EIS), potential step chronoamperometry (PSCA) and cyclic voltammetry (CV). The results of HRTEM and XRD showed that the incomplete carbon network could be repaired by nanometer-sized LSC while the co-coated composite retained the structure of LiFePO4. Electrochemical test results indicated that LSC coating could significantly improve the electrochemical performances at high charge/discharge rates. The 4wt.% LSC-coated LiFePO4/C sample exhibited the best electrochemical performance with discharge capacities of 136, 125 and 96mAhg−1 at the rates of 1, 2 and 5C, respectively. These data were much higher than those of the uncoated sample. This improvement could be mainly attributed to the lower charge transfer resistance and higher diffusion coefficients of Li+ ions resulted from the higher conductivity of LSC and the faster kinetic process between the LSC/LiFePO4 interfaces.
Vanadium-based oxides are considered to be a type of promising electrode materials for Li-ion batteries due to their low cost and high theoretical capacity. However, the dissolution of vanadium (V
3+
...), low electron conductivity and volume change during charge and discharge processes hamper their application. A novel porous structure was synthesized by hydrothermal method in this study. The hierarchical porous structure is assembled with nanoflake and coated with carbon. The hierarchical porous structure provides multitudinous reaction sites, shortens the Li-ion transfer distance and buffers the volume variety. The carbon improves the conductivity of the composite. It is also found that the tetravalent and trivalence vanadium coexists in the prepared composite. V
4+
can prevent V
3+
from dissolution. The synergistic effects of hierarchical porous structure, carbon coating and the coexistence of V
3+
and V
4+
endow the composite with excellent performance as an anode material. The composite exhibits a low resistance and sizeable capacitive effects during the charge and discharge process, which are beneficial to the energy storage performance. A discharge capacity of 439.6 mAh g
−1
after 100 cycles at a current density of 0.1 A g
−1
is delivered, which is 90.0% of its initial specific capacity (488.2 mAh g
−1
). The composite processes a decent prospect in high-performance Li-ion batteries.
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