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Doped PbPdO2 materials have attracted much attention as a spin gapless semiconductor (SGS) with the important properties of colossal electroresistance (CER) and giant magnetoresistance (GMR). In this study, the PbPdO2 thin films with (002) preferred orientation were prepared by pulsed laser deposition (PLD), and the temperature dependences of resistance and resistivity, R (T) and ρI (T), were measured under different applied DC currents. Remarkably, a positive CER effect induced by the current was firstly observed in the PbPdO2 films. In particular, it is novelty found that the positive CER value of PbPdO2 with I = 10 μA and T = 10 K reached about 300%. Moreover, the cyclic ρI (T) curves were also measured for I = 0.01 and 10 μA going back and forth between 10 K and 400 K. The time dependences of ρt/ρ0 ratio with T = 100 K, 300 K, 400 K and I = 0.01 and 0.1 μA were also obtained. A critical temperature Tc with about T = 260 K for all applied currents was found. As T > Tc，the band gap of the film is enhanced by the combined effect of the temperature and current. At the same time, Pb and O vacancies, and the evolution of oxygen valence states in the PbPdO2 film were observed by energy dispersive spectrometer (EDS), electron paramagnetic resonance (EPR) and in-situ x-ray photoelectron spectroscopy (XPS). Especially, the charge transport between O1− and O2− was confirmed by in-situ XPS. Finally, based on first-principles calculation, an internal electric field model and its induced potential barrier were established, which well explains the positive CER effect and the critical temperature Tc.

The oxygen vacancies and micro-nano structure can optimize the electron/Li+ migration kinetics in anode materials for lithium batteries (LIBs). Here, porous micro-nano structured VNb9O25 composites with rich oxygen vacancies were reasonably prepared via a facile solvothermal method combined with annealing treatment at 800℃ for 30 h (VNb9O25-30 h). This micro-nano structure can enhance the contact of active material/electrolyte, and shorten the Li+ diffusion distance. The introduction of oxygen vacancies can further boosts the intrinsic conductivity of VNb9O25-30 h for achieving excellent LIB performance. The as-prepared VNb9O25-30 h anode showed advanced rate capability with reversible capacity of 122.2 mA h g−1 at 4 A g−1, and delivered excellent capacity retention of ∼100 % after 2000 cycles. Meanwhile, VNb9O25-30 h provides unexpected long-cycle life (i.e., reversible capacity of 165.7 mA h g−1 at 1 A g−1 with a high capacity retention of 85.6 % even after 8000 cycles). Additionally, coupled with the LiFePO4 cathode, the LiFePO4//VNb9O25-30 h full cell delivers superior LIB properties with high reversible capacities of 91.6 mA h g−1 at 5C for 1000 cycles. Thus, such reasonable construction method can assist in other high-performance niobium-based oxides in LIBs.

Antimony chalcogenide Sb2(S, Se)3 is attracting a lot of attention as photovoltaic absorber owing to its rewarding photoelectric properties, low toxicity, and earth abundance. However, its device efficiency is still limited by the absorber material quality and device interface recombination. In this work, a fluorine-doped tin oxide (FTO) substrate with ultra-thin SnO2 layer and a low-cost stabilized carbon paste are introduced as a front and back contact layer respectively in Sb2(S, Se)3 based planar solar cells. Over 5.2 % efficiency is demonstrated in the structure of FTO/SnO2/CdS/Sb2(S, Se)3/Carbon/Ag, where the Sb2(S, Se)3 is prepared by hydrothermal technique. The complementary device physics characterizations reveal that the interfacial recombination between TCO and CdS is significantly suppressed by the introduction of ultra-thin SnO2 layer, which is profited from the leakage protection and bandgap offset engineering by its high resistivity and suitable conduction band minimum. Meanwhile, the successful adoption of the low-cost stabilized carbon as a back contact here shows an enormous potential to replace the conventional organic hole transport materials and noble metal. We hope this work can provide positive guidance to optimize Sb2(S, Se)3 based planar solar cells in the future.

Building stable SEI film is highly desirable for high-performance Si-based anode materials used in high energy-density lithium ion batteries (LIBs), which is strongly related with the generated-heat distribution in the electrode. Herein, Si/graphene@carbon embedding with TiN nanoparticles (Si/G@C/TiN) are prepared via a facile ultrasonic spraying method. The Si/G@C/TiN delivers a reversible discharge capacity of 660 ​mAh▪g−1 ​at 10 A▪g−1 and 776.5 ​mAh▪g−1 ​at 5 A▪g−1 after 400 cycles. High electronical conductivity of TiN embedding in the porous carbon framework can not only facilitate electrons transfer in the electrode, but also improve Li-ion kenetic diffusion. High thermal conductivity of TiN would be helpful to faster heat-dissipation and uniform heat-distribution in the electrode during the charging/discharging process, resulting in balanced growth of stable SEI film and excellent cycling stability especially at elevated temperature. Moreover, Si/G@C/TiN pouch cells using LiNi0.5Co0.2Mn0.3O2 as cathode, deliver impressive energy density of ~476 ​Wh▪kg-1 based on the total weight of active materials, suggesting its promising application in the high energy-density LIBs.

One-dimensional semiconductor nanostructures, which are different from those of bulk materials, have attracted considerable interest in either scientific research or practical application. Herein, ...

To understand Li (de)intercalation and related processes on the LiFePO4 (010) surface is of great importance for formulating effective approaches to further improve the rate performance of LiFePO4 cathode. In this article, we propose a new method that surface work function can be used to insight into the delithiation process on the LiFePO4 (010) surface. Density functional theory (DFT) calculations indicate that the extraction of Li from surface layer has a significant effect on the work function of LiFePO4 (010) surface, which in turn provides evidence for whether Li atoms are present in the outermost layer of LiFePO4 (010) surface or not. Moreover, the redox potentials and formation energies for Li extraction from various Li layers in the LiFePO4 (010) surface are also investigated. The calculated results indicate that Li extraction from surface-layer has the lowest redox potential and formation energy, indicating that it is energetically favorable to extract Li first from the surface layer. However, the large difference between the Li vacancy formation energy in the surface layer and the deeper subsurface layer creates a high surface barrier for Li diffusion along the [010] channel. Additionally, we evaluate two simple delithiation models for the LiFePO4 (010) surface, and finding that the work functions are also sensitive to the different delithiation processes. Our results suggest the surface work function as a promising method of identifying the delithiation process on the LiFePO4 (010) surface.

PbPdO2 and M-doped PbPdO2 (M = Cu, Co, Fe) films were prepared using pulsed laser deposition (PLD) method. The structures, electrical and magnetic properties were systematically investigated by XRD, Raman, SEM, XPS, AFM and VSM. Our results indicate that PbPdO2 and PbPd0.9M0.1O2 (M = Cu, Co, Fe) film with (0 0 2) preferred orientation can be well fabricated. The valence states of magnetic atoms in M-doped PbPdO2 (M = Cu, Co, Fe) thin films are identified to be Cu1+, Co2+,3+ and Fe3+, respectively. All Pb(Pd,M)O2 (M = Cu, Co, Fe) films exhibit ferromagnetism with high metal-insulator transition temperatures at around 330–370 K. Moreover, the resistivity of Fe doped PbPdO2 film is higher than that of the pristine PbPdO2 film, while the resistivities of Co and Cu doped PbPdO2 films are lower. At the same time, Fe, Co and Cu dopants do enhance the ferromagnetism of PbPdO2 film, while the enhancement of magnetic moment for Fe dopant is most evident. Lastly, based on Pb vacancy and O−1 observed experimentally, the band gaps and magnetic moments of Pb(Pd,M)O2 films were calculated by first-principles, and the results explain well the experimental facts.

The three-dimensional hierarchical nanocomposites of NiSnO3/graphene encapsulated in a thin carbon shell were synthesized via a facile solvothermal approach followed by thermal treatment. The obtained C/NiSnO3/RGO shows a much improved lithium storage properties than that of NiSnO3/RGO when used as lithium battery (LIB) anode material. The reversible capacities of C/NiSnO3/RGO composites are up to 899 mAh g−1 after 300 cycles at 200 mA g−1, and even undergoing high rate cycling at 10000 mA g−1, the charge capacity maintains 680 mAh g−1 at 200 mA g−1 after 650 cycles. The excellent LIB performance could be attributed that the carbon-coating of C/NiSnO3/RGO composites are found to prevent the restack of graphene effectively, and the aggregation of metal oxide nanoparticles (NPs) is efficiently suppressed under the double protection of coated carbon layer and graphene in the long-life cycling process.

Lithium ion battery (LIB) anode of Fe3C modified SnO2@void@C has been rationally prepared via wet chemical method coupled with vapor-phase treatment. In this architecture, the Fe3C modification and carbon protective shell can both improve the electrical conductance, the inner void space can tolerate the volume expansion/shrinkage of SnO2, and the outer carbon protective shell can hamper aggregation of active materials. These composites have been used as LIB anodes, delivering good LIB performance with a capacity of ∼580 mAh g−1 cycling after 350 cycles at 800 mA g−1, good rate performance with a capacity retention of over 728 mAh g−1 for 65 cycles. Kinetic analysis reveals that the improved LIB performance of Fe3C modified composites could be also associated with the contribution of capacitive charge. In addition, the related redox mechanism has been investigated in detail. Thus, this work supplied a promising route to prepare the high-performance LIB anodes with improved coulombic efficiency, large reversible electrochemical capacity and long cycling life.

As high capacity cathodes, O3-type Na-based oxides always suffer from a series of monoclinic transitions upon sodiation/desodiation, mainly caused by Na+/vacancy ordering and Jahn–Teller (J−T) dist...

Wreath-like Co3O4 particles consisting of microplates are synthesized by a facile solvothermal method and subsequently surface-modified with TiO2 ultrathin layer using a low-temperature hydrolysis process. Comparing with pure Co3O4, Co3O4@TiO2 exhibits superior electrochemical performances in terms of reversible capacity, rate capability and cycling stability. Co3O4@TiO2 exhibits high reversible capacity of 813.0 mAhg−1 at 500 mAg−1 after 180 cycles while the pristine Co3O4 only has a discharge capacity of 512.5 mAhg−1. The filling of TiO2 nanoparticles in porous Co3O4 sheets and the TiO2-coating on Co3O4 surface, could effectively suppress large volume expansion of Co3O4 and consequently enhance structural stability during the Li-ion insertion/extraction processes. Analysis from the electrochemical measurements reveals that the improved performances should be attributed to reduced the charge-transfer resistance and enhanced Li-ion diffusion kinetics because of TiO2-coating. In addition, the reduced work function induced by TiO2-coating is helpful to facilitate electron transfer in composites. Moreover, the built-in electric field resulting from the difference in work function between Co3O4 and TiO2, would facilitate electron-transfer and Li-ion migration across heterojunction interfaces.

Base on the Monte Carlo simulation and fast Fourier transformation micromagnetism (FFTM) method, the magnetic dynamic properties of defective Cobalt (Co) nanorings are studied. The simulated results indicate that the hysteresis loops of Co nanorings with small defect are similar to those of the symmetric nanorings. However, when the area of defect increases, the magnetization process of the defective Co nanorings is different from that of symmetric Co nanorings. It is found that the remanence (Mr) of the system increases at first and then decreases with the increase of defect location. Nevertheless, there is a relative stable region in which Mr almost do not change with the defect location varying when the defect is small. The simulated results are well analyzed through the evolution of spin-configurations (SCs) of the defective Co nanorings. The investigation about magnetic dynamic properties of the defective Co nanorings may provide reference for their application in high-density data storage.

Solid-state thermo-stamping of fabric reinforced composites has attracted extensive attention for its efficiency and potential energy saving in recent years. In this paper, a hybrid lamination model is proposed to describe the forming behavior of woven fabric reinforced thermoplastic composites (WFRTP) during solid-state thermo-stamping process. The woven carbon fiber (CF)/ Polyetheretherketone (PEEK) sheet/prepreg is modelled as laminate structure with woven reinforcement layers (shell elements) embedded in thermoplastic resin layer (solid elements). More specifically, a hypoelastic constitutive model is used to represent the anisotropic mechanical behavior of fabric reinforcement under large deformation, while the fabric model is calibrated and validated by uniaxial bias extension (UBE) test and tensile test of woven fabric. A phenomenological model is adopted to describe the viscoelastic-plastic deformation behavior of thermoplastic resin, while the resin model is calibrated by tensile tests of PEEK. The applicability of the hybrid model is demonstrated through comparing numerical results of UBE tests and Erichsen tests with their corresponding experiment results. The hybrid lamination model provides a theoretical foundation for numerical simulation of WFRTP solid-state thermo-stamping.

Up to now, the silicon-graphite anode materials with commercial prospect for lithium batteries (LIBs) still face three dilemmas of the huge volume effect, the poor interface compatibility, and the high resistance. To address the above challenges, micro-nano structured composites of graphite coating by ZnO-incorporated and carbon-coated silicon (marked as Gr@ZnO-Si-C) are reasonably synthesized via an efficient and convenient method of liquid phase self-assembly synthesis combined with annealing treatment. The designed composites of Gr@ZnO-Si-C deliver excellent lithium battery performance with good rate performance and stable long-cycling life of 1000 cycles with reversible capacities of 1150 and 780 mAh g-1 tested at 600 and 1200 mA g-1 , respectively. The obtained results reveal that the incorporated ZnO effectively improve the interface compatibility between electrolyte and active materials, and boost the formation of compact and stable surface solid electrolyte interphase layer for electrodes. Furthermore, the pyrolytic carbon layer formed from polyacrylamide can directly improve electrical conductivity, decrease polarization, and thus promote their electrochemical performance. Finally, based on the scalable preparation of Gr@ZnO-Si-C composites, the pouch full cells of Gr@ZnO-Si-C||NCM523 are assembled and used to evaluate the commercial prospects of Si-graphite composites, offering highly useful information for researchers working in the battery industry.

Surface properties of cathode materials play important roles in the transport of lithium-ions/electrons and the formation of surface passivation layer. Optimizing the exposed crystal facets of cathode materials can promote the diffusion of lithium-ions and enhance cathode surface stability, which may ultimately dominate cathode’s performance and stability in lithium-ion batteries. Here, polycrystalline LiCoO2 (LCO) thin films with (0003) and {10 1 - 1} preferred orientations were prepared as the well-defined model electrodes. In situ Current-Sensing Atomic Force Microscopy (CSAFM) was employed to investigate the lithium de-intercalation and electronic conductivity evolution of the (0003) and {10 1 - 1} facts in organic electrolyte at the nanoscale. It was found that the lithium deintercalation following a “Li-rich core model” in the LCO grains, and the LCO grains with (0003) crystal face show less conductivity than those with {10 1 - 1} faces. Moreover, X-ray Photoelectron Spectroscopy characterization of the charged electrode surface indicates that a denser surface passivation layer is formed on {10 1 - 1} than that on (0003) crystal faces. This is caused by the lower adsorption energy of decomposition molecule on {10 1 - 1} crystal faces and higher work function (due to the surface atomic structure) for {10 1 - 1} crystal faces, as confirmed by Density Functional Theory (DFT) and Kelvin probe force microscopy (KPFM) results. In addition, electrochemical measurements confirm that the thin film electrodes with {10 1 - 1} preferred orientation not only show smaller electrode polarization, but also more readily form a stable surface passivation layer compared with the (0003) preferred orientation. This work highlights the importance of cathode conductivity, and suggests that the LCO {10 1 - 1} facet atomic structure may thermodynamically promote the physical/chemical adsorption and decomposition of electrolyte.

Germanium selenide (GeSe), a IV-VI chalcogenide containing earth-abundant and low-toxic elements, has attracted increasing interest as a potential absorber material for photovoltaics due to its excellent optical and electrical properties. In this work, a simple and effective magnetron sputtering method was proposed to deposite GeSe precursor thin films using GeSe alloy target. Subsequently, the as-deposited samples were post-annealed in vacuum atmosphere. The effects of different annealing temperatures on crystallinity, morphology and phase transformation of the as-prepared films were systematically investigated. It has been revealed that phase-pure and uniform GeSe thin films were obtained through the self-decomposition of slight GeSe2 impurity at 400 °C. Finally, a prototypical FTO/CdS/GeSe/C-Ag solar cell with 220 mV open circuit voltage and 0.05% power conversion efficiency was fabricated, which suggests the potential of sputtering processed GeSe thin film for low cost solar cell.

A big challenge in the high-performance transition metal oxide anode for lithium-ion batteries (LIBs) is relieving the volume changes during the lithiation/delithiation. In this work, CuO nanorod array was produced via glancing angle deposition and directly used as anode materials for thin film electrodes of LIBs. The obtained CuO nanorod array anodes show good LIB performance with a capacity of 220 μAh/cm2/μm tested at 100 μA/cm2 after 80 cycles and excellent rate performance. The obtained properties for CuO nanorod array anodes were much better than thin film anodes without nanorod array structure. In addition, the in situ electrochemical atom force microscopy (EC-AFM) characterization has been used to reveal the enhanced mechanism of CuO nanorod array anodes. On the one hand, CuO nanorods within the electrodes may serve as the hosts for Li+, and ease intercalation by shortening Li+ ion diffusion pathways, resulting in the remarkable cycling stability and rate performance. On the other hand, the “breathing” of CuO nanorod array electrode clearly observed by in situ EC-AFM with the appearance and disappearance of cracks, demonstrated that the nanorod array may act as a buffering to alleviate the giant volume variations during the cycling. As a result, the remarkable stability of the CuO nanorod array electrode allowed its use in a full lithium-ion cell with a pervasive LiCoO2 thin film cathode. Additionally, we also observed the SEI formed on the surface of electrode during cycling, which may benefit the further studies on transition metal oxide as anodes for LIBs.

Sb2(S,Se)3 are considered as a promising absorber material for solar cells owing to its earth-abundant, nontoxic constituent, simple phase and long-term durability. In this work, a facile chemical bath deposition followed by post-selenization was introduced to prepare Sb2(S,Se)3 thin film, which leads to a graded band gap structure. The sulfoselenide Sb2(S,Se)3 thin films with smooth morphology were obtained through optimizing the selenization process. Meanwhile, a low cost and substitutable carbon electrode was used as hole selection material. Sequentially, the full-inorganic Sb2(S,Se)3 device with efficiency of 2.64% was also fabricated according to structure of FTO/CdS/Sb2(S,Se)3/Carbon, which is the highest value in CBD processed FTO/CdS/Sb2(S, Se)3/Carbon solar cells.

In this work, Cu2ZnSnS4 (CZTS) thin film was successfully prepared from four types of mixed binary sulfides nanoparticles under inert Ar atmosphere. A comparison study was conducted to explore the effect of binary sulfides with different value states on the CZTS thin films. Through X-ray diffraction (XRD), Raman and scanning electron microscopy (SEM), the pure CZTS phase can be obtained independent of the value states. However, distinguished crystallinity and morphology of CZTS were observed by using binary precursor with different value states. The grain size up to 1 µm was achieved by annealing (Cu2S+ZnS+SnS2) precursor without additional sulfur atmosphere, suggesting that value state of binary sulfides precursor play an important role in CZTS growth. This result also agrees well with our theoretical prediction. Finally, appropriate ratio of Cu/Zn/Sn was evidenced to yield an enhancement in power conversion efficiency from 0.09% (stoichiometric ratio) to 0.55% (Cu-poor, Zn-rich).

Traditional 3D printing craft's limit in fabricating micro/nanostructures and thermosetting materials makes it hard to be directly applied to the fabrication of triboelectric nanogenerator (TENG), whose performance strongly relies on structures and properties of the used materials. To meet these challenges, polymer tubes (tubular polyethylene (PE) and nylon (PA)) are used as carrier boats of directly printing polydimethylsiloxane (PDMS) and polyethylene glycol (PEG) without templates for the purpose of gaining a device with the highest output performance, which in turn can be obtained by adding a more electronegative material and removing PEG out of the film after printing to fabricate a sponge-like structure. Under these conditions, a best performance of 306 V output voltage, 6.14 mA instantaneous current, 74.4% energy conversion efficiency and 236.67 W/m3 power density could be achieved, which are higher than the values with traditional 3D printing method. Most importantly, this device can be applied to light a processed LED bulb (85 V, 3 W) directly. This innovative method based on fused deposition modeling (FDM) exhibits outstanding properties of short fabrication cycle, low cost, possibility of large-area modeling and wider selection of materials, which can stimulate the industrialization of TENG and make it more accessible to practical applications.

Triboelectric nanogenerator (TENG) is one of the most attractive candidates for providing a green energy source capable of satisfying the world's energy consumption. 3D printing is a promising route to satisfy the demands of various self-powered devices with individualized design in practical applications such as signal processing, precisely tuning circuits, active sensor networks, remote controls, and flexible electronics. This work reports an approach of fused deposition modeling (FDM), one of 3D printing methods, which enables the creation of optimized digital designs for TENG devices for the purpose of efficiently harvesting ambient vibration energy. To obtain satisfying output power and high mechanical energy conversion efficiency, various positive and negative polymers were chosen as friction layers, such as polylactic acid (PLA), nylon (PA), a mixture of polypropylene and polyethylene (PP/PE), and poly(ethylene terephthalateco-1,4-cylclohexylenedimethylene terephthalate) (PETG). By increasing the vibrational frequency from 5 Hz to 20 Hz, the output voltage of the TENG device increased from 50 V to 241 V in a TENG device using nylon (PA) and a mixture of polypropylene and polyethylene (PP/PE). The TENG device had a 0° contact angle between the two films, which also had some macroscopic patterns on their surfaces. Simultaneously, a decrease in the filling rate (from 100% to 20%) and thickness (from 0.4 to 0.2 mm) resulted in an increase in the output voltage from 57 V to 176 V and from 50 V to 241 V, respectively. To better understand the effects of the printing parameters on the output performance, we studied the factors of the filling rate, thickness, contact angle and the width of the zigzag pattern. From these results, we conclude that 3D printing based on the FDM strategy to fabricate TENG outstandingly improves the output performance by decreasing the effective Young's modulus. Additionally, the peak of the current reaches 1.52 mA in ultrashort time. The triboelectrification efficiency in this vertical contact-separation mode reaches 63.9%. Our concept of 3D printing based on FDM will stimulate further fundamental work in fabricating approaches to harvesting environmental energy.

To synthesize nonmetallic magnets containing exclusively s-p orbitals with high magnetic moments and magnetic ordering is a great challenge in physics and material science. In this study, we report increased localized spin magnetic moments and observation of ferromagnetic ordering by annealing of fluorographene. It is found that the magnetic properties is sensitive to fluorine (F) distribution. The samples annealed at ca. 400–450 °C exhibits an interesting ferromagnetic state, attributing to the fragmentizing of big F clusters into many small F domains after thermo defluorination. There are high-intensity magnetic moments in the annealed samples because of the enhanced edge effect of small F clusters, which contribute to the magnetic ordering in fluorographene for a shrunken average spacing between localized moments. The increasing structure defects after annealing can be as new centers of small F domains, and greatly stabilize magnetically ordered state.

Ternary Cu2SnS3 (CTS) thin films have attracted lots of attention due to its low cost, nontoxic element for solar cell. However, Tin losses always happen during sulfurization, which will affect the phase purity and morphology of CTS thin films and relevant solar cell. In this work, a low cost oxides route was used to prepare CTS thin films. The influences of sulfurizaton temperature on the crystal structure, morphology and composition were studied carefully. From the XRD, SEM and EDX results, it was found that the stable oxides were conducive to alleviate the Sn loss even at the higher sulfurization temperature (580 °C). Meanwhile, the crystal structure evolution along annealing temperature was also observed from mixed phase (Monoclinic and Tetragonal) to single phase Monoclinic. The Monoclinic CTS thin films sulfurized at 580 °C were used to fabricate CTS solar cell with Mo/CTS/CdS/ZnO/AZO/Ag structure, exhibiting efficiency of 0.16%. The comparable Voc of 300 mV was achieved by benefiting from the precise composition control. Besides, the photoelectric properties of the device were carefully studied as well. This study provides a low-cost and facile strategy for the fabrication of Sn-loss free CTS solar cells.

In this work, Cu2MSnS4 (M: Zn, Mn, Cd) thin films were successfully prepared by a low-cost and facile oxide-based route. After sulfurization of oxides precursor, the Cu2MSnS4 thin films with composition control exhibit good morphology, analogous crystal structure and suitable bandgaps. Finally the preliminary solar cells based on these films show proper power conversion efficiencies, which demonstrate a high potential application in low cost thin film solar cells.

Initial coulombic efficiency (ICE) is an important evaluation index to weigh the applicability of electrode materials, but it is not acknowledged by many researchers. Herein, S-doped TiO2 nanosheets with porous and layered structures are utilized as anodes to fabricate hybrid sodium-ion capacitors in an ether electrolyte with high performance, especially through dramatically improved ICE. For Na-ion half cell tests in a DME electrolyte, S-doped TiO2 nanosheets display record high ICE of 88.6%, excellent rate capability and good cycling performance. We also find that TiO2 material with a large surface area is helpful for reducing the first irreversible capacity in an ether electrolyte, which is different from that observed using a traditional ester-based electrolyte. This could be due to excellent electronic conductivity with charge resistance of ∼1 Ω through the construction of an ultrathin solid electrolyte interphase (SEI) layer. Coupling with an Na3V2(PO4)3 cathode, we verify a successful Na-ion hybrid capacitor, delivering high energy and power density values of 158 W h kg−1 and 1075 W kg−1, respectively, at room temperature. Moreover, it also exhibits satisfactory performance of 82 W h kg−1 at −20 °C and outstanding cycling performance with over 95% retention after 800 cycles even at 1 A g−1 charge and discharge rate.

The inhibition and removal of the SnS2 impurity phase in the kesterite Cu2ZnSnS4 (CZTS) layer is a major challenge for the improvement of CZTS solar cells; this impurity phase can critically damage device performance by forming a diode and a barrier for carrier collection. However, the formation and growth mechanism of SnS2 is incomplete and the common etching treatment with (NH4)2S is problematic because of its toxic characteristics. In this study, the formation and growth of large-size SnS2 sheets were observed to occur on the surface of the CZTS thin film via condensation during the cooling process. Sequently, a novel and benign peeling process was carried out using a sticky tape to effectively remove the SnS2 formed on the surface, resulting in a uniform CZTS thin film. A maximum efficiency of 4.3% of the oxides-derived CZTS device was obtained after this mechanical exfoliation, which is nearly eleven times that of the device without stripping. It was confirmed that this surface treatment is an effective and green way to remove the SnS2 impurity, which largely improved the performance of the CZTS device and may guide the preparation of pure phase CZTS thin films.

Three-dimensional hierarchical flower-like TiO2@graphdiyne is prepared via a solvothermal process, and the structural properties and electrochemical performances are systematically investigated. The obtained results show that TiO2@graphdiyne delivers a high reversible capacity of 432.4 mA h g−1 after 300 cycles at a current density of 1 A g−1, about 3 times that (139.7 mA h g−1) of pristine TiO2. The high reversible capacities, excellent rate capability and cycle stability of TiO2@graphdiyne might be attributed to the hierarchical mesoporosity of graphdiyne with butadiyne linkages, which could not only provide innumerable interconnected active sites for lithium storage but also facilitate fast Li-ion diffusion. The built-in electric field derived from the difference in work function between TiO2 and graphdiyne could facilitate electron-transfer and Li-ion migration across heterojunction interfaces. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the TiO2 matrix could also enhance the kinetics of Li-ion insertion/deinsertion.

3D plum candy-like NiCoMnO4 microspheres have been prepared via ultrasonic spraying and subsequently wrapped by graphene through electrostatic self-assembly. The as-prepared NiCoMnO4 powders show hollow structures and NiCoMnO4@graphene exhibits excellent electrochemical performances in terms of rate performance and cycling stability, achieving a high reversible capacity of 844.6 mA h g−1 at a current density of 2000 mA g−1. After 50 cycles at 1000 mA g−1, NiCoMnO4@graphene delivers a reversible capacity of 1045.1 mA h g−1 while the pristine NiCoMnO4 only has a capacity of 143.4 mA h g−1. The hierarchical porous structure helps to facilitate electron transfer and Li-ion kinetic diffusion by shortening the Li-ion diffusion length, accommodating the mechanical stress and volume change during the Li-ion insertion/extraction processes. Analysis from the electrochemical performances reveals that the enhanced performances could be also attributed to the reduced charge-transfer resistance and enhanced Li-ion diffusion kinetics because of the graphene-coating. Moreover, Schottky electric field, due to the difference in work function between graphene and NiCoMnO4, might be favorable for the redox activity of the NiCoMnO4. In light of the excellent electrochemical performance and simple preparation, we believe that 3D plum candy-like NiCoMnO4@graphene composites are expected to be applied as a promising anode materials for high-performance lithium ion batteries.

In this work, CuO ( 1 ¯ 1 1 ) preferred orientation thin films with nano wheatear array have been prepared by using reactive magnetron sputtering. Their structures, physical properties were measured, and the surface energies of CuO films were calculated by first-principle calculations. Especially, single nanowire electronic measuring method based on conductive atomic force microscopy (C-AFM) and Kelvin probe force microscopy (KPFM) were developed. The prepared CuO films with nano wheatear array have good crystallinity. Here, wheatear is an ear of wheat, and the morphology of nanowire is similar to that of the wheatear. It is found that the band gaps of CuO films can be modulated from 1.54 to 1.25 eV by changing length of nano wheatear. Moreover, the measured results by KPFM show the existence of the p-type carrier, the decrease of the band gap with increasing length of nano wheatear. At the same time, the applied electric field (E) dependence of the current density (J) for single nano CuO wheatear was measured by C-AFM. The experimental results in the injection and direct tunnel regimes indicate that, with increasing length of nano CuO wheatear, the work function is enhanced and the band gap is decreased. The measured results on work function and band gap by C-AFM are consistent with those by KPFM. At last, it is suggested that KPFM and C-AFM can provide both effective methods in measuring the band gap of the semiconductor.

There is an urgent demand for flexible multifunctional sensitive electronic devices in several potential applications, including personalized health monitoring, human motion detection, human–machine interfaces, soft robotics, and so on. Although exciting progress has been witnessed in recent decades, the excessive dependence on inorganic sensors and flexible substrates makes it difficult to attain multi-function sensing and excellent flexibility simultaneously, as well as their complicated fabrication, technical barriers and high cost. Herein, we report on a family of flexible multi-functional sensitive nanocomposites consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a high elastic form-stable phase change polymer (HEPCP) that exhibit dramatic response to infrared light (IR), temperature and tensile stress in air, together with outstanding flexibility and stretchability. Optimum sensitivity to on/off IR, temperature and tensile stress is demonstrated with electrical conductivity ratios of 103.7, 11.8 and 1084.0 times at room temperature, respectively. The excellent performance of the MWCNT/HEPCP nanocomposites was largely attributed to the cyclic and reversible changes of their MWCNTs conductive network owing to the reversible form-stable phase transitions and high elasticity of the HEPCP substrate, which subsequently affected the thickness of the interfacial HEPCP between adjacent conductive MWCNTs, and thereby the electron tunneling efficiency between the MWCNTs. The novel MWCNT/HEPCP nanocomposites open a new window for multi-function sensing of electronic skin.

PbPdO2, PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 thin films with body-centered orthorhombic structure were prepared by PLD technique, respectively. Their structures, magnetic and electrical properties were measured by XRD, SEM, AFM, EDS, XPS and VSM, respectively. The experimental results indicate that the three samples all have the preferred orientation of (002), and room temperature ferromagnetism. From EDS and XPS results, we can deduce that there exist Pb vacancies in the three samples. Meanwhile, the valence states for Pb, Pd, O, Gd and V ions were found to be 2+, 2+, 2−, 3+ and mixed 4+ and 5+, respectively. It was also found that the magnetic moments of PbPdO2 and PbPd0.9Gd0.1O2 are least and largest, respectively. Moreover, the electrical characteristics analysis indicates that the electrical resistivity is enhanced by V ion substitution, but reduced by Gd ion substitution. In addition, the significant insulator–metal transition temperatures of PbPdO2, PbPd0.9V0.1O2 and PbPd0.9Gd0.1O2 were found to be about 385 K, 390 K and 430 K, respectively. Finally, according to the experimental facts of Pb vacancies in the three samples, the first-principles calculated models containing Pb vacancies were established. The calculated results explain well the magnetic origin of PbPdO2, and V and Gd doping roles on its electrical and magnetic properties.

Flower-like Li4Ti5O12 hollow microspheres consisting of nanosheets are prepared via a hydrothermal process, and subsequently wrapped by graphene through electrostatic interactions. In comparison with pristine Li4Ti5O12, Li4Ti5O12@graphene exhibited higher capacities and improved rate capability in the 0.01–3.0 V or 1.0–3.0 V potential range. Li4Ti5O12@graphene composite shows specific capacity of 272.7 mAh g−1 at 750 mA g−1 after 200 cycles in the potential range from 0.01 to 3.0 V, while the pristine Li4Ti5O12 only delivered a discharge capacity of 235.6 mAh g−1. The improved electrochemical performances of Li4Ti5O12@graphene should be attributed to lower charge-transfer resistances, larger lithium-ion diffusion coefficient and lower activation energy. The electrons transfer at Li4Ti5O12/graphene heterojunction interface, originating from difference in the work function of two composites, reduces the localized work function of the composites, decreases energy required for electrons to escape and consequently results in the improved electrochemical performances.

The objective of this paper is to accurately predict the rate/temperature-dependent deformation of a polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blend at low, moderate, and high strain rates for various temperatures. Four constitutive models have been employed to predict stress–strain responses of PC/ABS under these conditions, including the DSGZ model, the original Mulliken–Boyce (M–B) model, the modified M–B model, and an adiabatic model named the Wang model. To more accurately capture the large deformation of PC/ABS under the high strain rate loading, the original M–B model is modified by allowing for the evolution of the internal shear strength. All of the four constitutive models above have been implemented in the finite element software ABAQUS/Explicit. A comparison of prediction accuracies of the four constitutive models over a wide range of strain rates and temperatures has been presented. The modified M–B model is observed to be more accurate in predicting the deformation of PC/ABS at high strain rates for various temperatures than the original M–B model, and the Wang model is demonstrated to be the most accurate in simulating the deformation of PC/ABS at low, moderate, and high strain rates for various temperatures.

Selenization is a key process to prepare Cu 2 ZnSnS x Se 4-x (CZTSSe) thin films from sulfide for high efficient solar cell. To explore the effect of annealing atmosphere on the substitution of S by Se in Cu 2 ZnSnS 4 (CZTS) thin films, different selenization atmosphere (Vacuum or Ar) are used. By examining the annealed sample, it is found that selenization under Ar atmosphere replaces S with Se more efficiently, resulting large grain and small band-gap. The reaction kinetics has been studied to explore such phenomena. It demonstrates that the substitution reaction is enhanced when the flowing Ar carries off S gas. Finally, the effect of annealing atmosphere on oxide-based CZTSSe devices has also been studied. The Vacuum selenized CZTSSe device shows a higher efficiency of 4.4%, due to the more appropriate band-gap. To the best of our knowledge, this is the best device performance in oxides nanoparticles-derived CZTSSe solar cell.

The present study investigates the deformation behavior of Poly-Ether-Ether-Ketone (PEEK) at elevated temperatures and low strain rates through a combination of experiments and simulations. Uniaxial tension tests at elevated temperatures (293–543 K) and strain rates (8.3 × 10−3 to 3.3 × 10−1 s−1) were performed, and the temperature- and rate-dependencies of the deformation behavior and mechanism of PEEK were discussed in detail. The Erichsen test was performed at temperatures varying from 473 to 533 K and a fixed speed of 1 mm/s. Based on an investigation of numerous constitutive models, a phenomenological model called DSGZ was employed in ABAQUS/Explicit to characterize the deformation behavior of PEEK at elevated temperatures, and the deviation between experimental and simulation data was less than 10% at large deformations. Moreover, the simulation results accurately predicted the necking and cold drawing phenomena in the tension test as well as the deformation in the Erichsen test.

TiO2 is a most promising anode candidate for rechargeable Na-ion batteries (NIBs) because of its appropriate working voltage, low cost, and superior structural stability during chage/discharge process. Nevertheless, it suffers from intrinsically low electrical conductivity. Herein, we report an in situ synthesis of Co2+-doped TiO2 through the thermal treatment of metal organic frameworks precursors of MIL-125(Ti)-Co as a superior anode material for NIBs. The Co2+-doped TiO2 possesses uniform nanodisk morphology, a large surface area and mesoporous structure with narrow pore distribution. The reversible capacity, Coulombic efficiency (CE) and rate capability can be improved by Co2+ doping in mesoporous TiO2 anode. Co2+-doped mesoporous TiO2 nanodisks exhibited a high reversible capacity of 232 mAhg–1 at 0.1 Ag1–, good rate capability and cycling stability with a stable capacity of about 140 mAhg–1 at 0.5 Ag1– after 500 cycles. The enhanced Na-ion storage performance could be due to the increased electrical...

We have fabricated PbPdO 2 nano-particles and PbPdO 2 films with (211) preferred orientation (sample A) and with (002) preferred orientation (sample B), respectively. The structures and physical properties were measured by XRD, Raman, SEM, XPS and AFM. The experimental results indicate that the PbPdO 2 films have granular structure with the grain size of about 200 nm and some Pb vacancies exist in both samples. It is found that PbPdO 2 with (002) preferred orientation has near zero-gap, while PbPdO 2 with (211) preferred orientation has larger band gap. This surface anisotropy band gap is also proved by our first principles band structure calculations. Moreover, one notices that the sample B possesses lower resistivity than sample A, and both samples possess a wide insulator-metal transition temperature ( T MI ) with around 370 K.

The substitution of Sn with Ge is one of the promising approaches to fabricate high-efficiency Cu 2 ZnSn 1-x Ge x S(e) 4 (CZTGS(e)) thin-film solar cells, especially for the multijunction or bandgap-graded solar cells. However the evolution of structure and optical properties of CZTGS(e) in a wide composition range (0 ≤ x ≤ 1) hasn't been researched and elucidated systematically. In this paper, CZTGS(e) films were synthesized by selenizing or sulphidising oxide precursors, and their optical, componential and structural property were investigated by absorption spectroscopy, scanning electron microscopy and X-ray diffraction (XRD)/Raman, respectively. The insertion of germanium into the lattice of Cu 2 ZnSnS(e) 4 (CZTS(e)) is verified by relevant XRD peaks and Raman vibrational modes, as both of them shift towards higher diffraction angles and wave-numbers respectively. Besides, the spectrum of absorption revealed that the bandgap of CZTGS(e) can be widely adjusted between 0.96 and 2.0 eV. The preliminary solar cells show that the Voc increases with the increase of bandgap, while the Jsc exhibits opposite tendency. This can be expected to be applied in full solar spectrum absorption.

Layered LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials were prepared using a sol-gel method and subsequently surface-modified with YF 3 layer by a wet chemical process. In comparison with pristine LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 @YF 3 exhibited higher rate capability, better cyclability and better thermal stability. After 100 cycles at 5 C and 25 °C, LiNi 1/3 Co 1/3 Mn 1/3 O 2 @YF 3 showed 93% capacity retention compared with 74% for pristine LiNi 1/3 Co 1/3 Mn 1/3 O 2 . Electrochemical measurements demonstrated that the improved electrochemical performances of YF 3 -coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 might be attributed to smaller charge-transfer resistance, higher lithium diffusion rate, more stable electrolyte/electrode interfacial structure, and lower activation energy. Kelvin probe force microscopy measurements revealed that the LiNi 1/3 Co 1/3 Mn 1/3 O 2 @YF 3 cathode possessed a lower surface potential and work function than those of the pristine one, which help to facilitate electron transport and suppress reactions between the electrolyte and cathode during the charge/discharge processes. In a certain way, the reported results clarified the possible mechanism of the enhanced performances of cathode materials with surface modification in terms of interfacial effect.

High-performance actuators have been studied for many years, as they can be used in the fields of artificial muscles, optical switches and biomimetic applications. However, previous actuators mostly had single colors. Actuators with switchable optical properties are still rare. Here, we propose a transparency-switchable actuator based on single-layer superaligned carbon nanotube sheet and paraffin-polydimethylsiloxane composite. When a voltage is applied, the transmittance of the actuator changes from 0.7% to 67% (at the wavelength of 550 nm). At the same time, it bends obviously with a displacement up to 8.4 mm. The actuator is also durable, demonstrating both reversible actuation phenomenon and repeatable switchable transparency for 100 cycles. In addition, since this new type of actuator demonstrates optical property changing together with actuation process, which is smarter compared to previous conventional actuators, a smart window is fabricated, indicating its application in personal privacy protection and intelligent household devices. In a word, this work opens new perspectives on smart windows, optical switches and so on.

The sulfurization is an essential process during the preparation of high quality Cu2ZnSnS4 (CZTS) absorber layers, which is controlled by the parameters such as annealing time, temperature and atmosphere, etc. The heat under different temperature not only provides energy for the samples, but also determines the sulfur vapor pressure, which affects the CZTS growth. To distinguish the effect of energy supply and sulfur vapor pressure on CZTS films, a two-temperature zone tube furnace was used, which permits independent control of the sulfur source and substrate temperature. Keeping the substrate temperature constant, the morphology and crystalline of CZTS thin films were investigated under various sulfur vapor pressure by changing sulfur temperature. Finally, the device performances have also been studied, which depended significantly on the sulfur vapor pressure. A champion PCE (2.59%) of oxide-derived CZTS device was obtained under high sulfur vapor pressure.

Most metal oxides with high theoretical specific capacities including Fe 3 O 4 are promising lithium battery (LIB) anode materials, which capacities are larger than that of current commercial graphite. However, most of these anodes suffer from the defects of poor electronic conductivity, large volumetric expansion upon lithiation and low coulombic efficiency. Here, as a typical work, we develop and fabricate a novel composite of yolk-shell structured Fe 3 O 4 @C mixed with Fe 3 C catalysts directly used as LIB anodes. The anode of Fe 3 O 4 nanospheres protected by the carbon shell and added with the Fe 3 C catalysts, can deliver obviously enhanced LIB performance. Especially, tested at 1000 mA g −1 , the electrodes afforded high capacity of ∼600 mAh g −1 after 300 cycles at room temperature and high reversible capacity of ∼380 mAh g −1 even after 700 cycles at a relatively low temperature of 0 o C. The enhanced LIB performance could be associated with the contribution of carbon shell and Fe 3 C adding. These results revealed the potential applications of Fe 3 C/Fe 3 O 4 @C nanostructure materials as anodes for LIBs.

Hierarchical Fe 3 O 4 hollow nanostructures are synthesized from the phase transition of Fe 2 O 3 hollow nanostructures, which are prepared through a dissolution-recrystallization process. The hierarchical Fe 3 O 4 hollow nanostructures, applied as an anode material for Na-ion batteries, display good rate capability and cycling stability. The reversible capacity of 150 mAh/g at 100 mA/g after 50 cycles can be maintained for Fe 3 O 4 anode. The superior Na-ion storage properties of hierarchical Fe 3 O 4 could be largely ascribed to the stable electrode structure during Na-ion insertion and extraction process. On the contrary, Fe 2 O 3 anode exhibits a high initial discharge capacity (686 mAh/g), but it suffers from poor cycling stability due to the remarkable pulverization of the electrode.

The Cu2O/AZO heterojunction solar cells were successfully constructed by synthesising p-Cu2O layer upon AZO using the electrochemical deposition method. The p-Cu2O nanostructures with different grain shape and preferred crystal orientation, including (100), (110) and (111) indicated by SEM and XRD, were obtained by controlling electrodeposition bath pH. The J–V characteristic shows that the performance of the Cu2O/AZO heterojunction solar cells is found to be dependent on the crystal orientation of p-Cu2O. Only the solar cell with Cu2O (111) exhibits well-defined rectifying behaviour and good photoelectric conversion efficiency, which may due to the optimised energy band structure of Cu2O (111)/AZO heterojunction solar cells . Furthermore, VOC and JSC were sharply increased by further optimising energy band structure through inserting the intrinsic ZnO layer between the Cu2O (111) and AZO. Therefore, the results illustrated above may offer a helpful guidance to design and construct the high perfor...

In this study, a simple and novel oxide-nanoparticles-based process was applied to prepare Cu2FeSnS4 (CITS) thin films. Firstly, the low cost and naturally abundant oxides (e.g. CuO, Fe2O3 and SnO2) were coated on the glass substrate. Secondly, CITS thin films were grown through the sulfurization of oxides precursors in a low toxic sulfur atmosphere. To investigate the phase transformation during sulfurization, the different annealing temperatures were used. It was found that the intermediate phase Cu3SnS4 and Cu2Sn3S7 existed during the CITS growth. Finally, the phase-pure CITS films with large grains were obtained when the sulfurization temperature increased to 580 °C. Furthermore, an obvious photoelectric response of CITS thin film is displayed, which suggests its potential application as one kind of low cost solar absorber materials.

Flower-like NiCo2O4 consisting of nanosheets are synthesized by hydrothermal technique and subsequently surface-modified with a TiO2 ultrathin layer by a hydrolysis process at low temperature. It is found that NiCo2O4@TiO2 exhibits superior electrochemical performances over NiCo2O4 in terms of rate capability and cyclability. After 60 cycles at 100 mA g−1, NiCo2O4@TiO2 showed 78% capacity retention compared with 57% for bare NiCo2O4. Analysis from the electrochemical measurements indicates that the improved electrochemical performances of NiCo2O4@TiO2 might be attributed to a higher lithium diffusion rate, smaller charge-transfer resistance and more structural stability. Kelvin probe force microscopy measurements reveal that NiCo2O4@TiO2 has a lower work function than those of the pristine one, which help to facilitate electron transfer in composites. In addition, the electric field between NiCo2O4 and TiO2 resulting from the difference in work functions is also expected to enhance the electrochemical performances.

Electrode pulverization, low electrochemical reaction kinetics and an unstable SEI layer have prevented the application of transition metal oxides with a conversion-type mechanism. Here, we describe gum arabic (GA) as a green and multi-functional binder for the fabrication of a NiFe2O4 nanotube (NFNT) electrode enabling predominant application in LIBs and NIBs. Firstly, it's revealed that the NFNTs–GA electrode possesses better mechanical properties of a higher friction coefficient, better elastic resilience and higher reduced modulus and hardness compared with a NFNTs–PVDF electrode. Secondly, the NFNTs–GA electrode can restrain the side reactions between the electrode and electrolyte, leading to the formation of a remarkably stable and thin SEI layer during discharge and charge processes. Thirdly, it is demonstrated by KPFM that the NFNTs–GA electrode possesses improved surface electrical properties and lower energy for the escape of electrons. Consequently, the NFNTs–GA electrode demonstrates much improved rate capability, cycling stability and columbic efficiency when used as an anode material for LIBs. It displays a stable capacity of 770 mA h g−1 which can be retained after 500 cycles at 0.5 A g−1. More importantly, the NFNTs–GA electrode exhibits a high initial coulombic efficiency of 73% (only 48% for the NFNTs–PVDF electrode) and enhanced electrochemical reaction kinetics with significantly improved oxidation and reduction peaks in the application of NIBs.

Understanding the formation mechanism of the secondary phases in Cu2ZnSnS4 (CZTS) absorber layer is necessary for the development of CZTS thin films solar cells. With this aim, the XRD, Raman and SEM were used to investigate the phases coexistence in CZTS thin films grown under different copper content. The surface of the Cu-rich CZTS thin films is rough, and the secondary phase CuxS emerges as front surface phases. Besides, another secondary phase ZnS segregates towards both front and back regions of off-stoichiometric CZTS thin films (Cu rich or Cu poor), which was evidenced by the 2nd and 3rd order of ZnS using Raman analysis excitated at 325 nm. The pure phase CZTS exists only as its composition was stoichiometric. So the preparation of pure phase CZTS is sensitive to composition, suggesting that the precise composition control plays an important role in CZTS growth.

Intercalation of lithium in few-layer phosphorene has aroused great concern because of the prospects of few-layer phosphorene as an anode material for high-performance lithium-ion batteries (LIBs). In this paper, we adopt first-principles calculations to explore in detail the effects of stacking structure of bilayer black phosphorene (BBP) on the adsorption and diffusion of lithium in BBP. Our calculated results indicate that Li energetically prefers to intercalate within rather than adsorb outside BBP, and it exists in a cationic state. Moreover, the stacking structure of BBP has very important effects on Li adsorption, the open-circuit voltage, and Li diffusion in BBP. Additionally, Li diffusion in BBP exhibits directional preference, with diffusing along the zigzag direction being easier. The analyses of the potential distribution indicate that the puckered honeycomb structure of monolayer phosphorene and the stacking structure of BBP greatly cause low-potential channels along the zigzag direction, which directly lead to the directional preference in Li diffusion. More interestingly, our results suggest that BBP with AC stacking is the most beneficial for Li adsorption and diffusion. These findings suggest that changing the stacking structure of BBP is one possible way to rationally design the anode material in high charge/discharge rate LIBs based on BBP.

In this study, the formability of woven carbon-fiber (CF)-reinforced polyether-ether-ketone (PEEK) composite sheets in the solid-state thermoforming process were investigated, and the failure mechanisms were discussed. The formability of the woven CF/PEEK sheets were analyzed using flexural tests, Erichsen test, and microscopic observation. The results show that the formability of CF/PEEK sheets significantly increases as the temperature rises from 165 to 325 &deg, C, and slightly decreases as the deformation speed rises from 2 to 120 mm/min. The deformation of the sheets is caused by plastic deformation, shear deformation and squeeze deformation, without plastic thinning and fiber slippage, which is due to the restriction of the solid matrix and locked fibers. Moreover, the wrinkles will cause fiber fracture at lower temperatures and delamination at higher temperatures. At higher temperatures, the wrinkles mainly occur at the position with [0&deg, /90&deg, ] fibers due to the squeezing of the matrix and fibers.