A new one‐step ion‐exchange/activation combination method using a metal‐ion exchanged resin as a carbon precursor is used to prepare a ultrahigh surface area and three‐dimensional hierarchical porous ...graphene‐like networks for fast and highly stable supercapacitors.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•Ternary GaSiP solid solution with a disordered lattice and liquid metallic phase is synthesized.•Ternary GaSiP presents ultrafast Li-ion and electronic conductivity.•Ternary GaSiP ...anode demonstrates excellent Li-storage performances.
Silicon (Si) has become the most promising next-generation anode to replace commercial graphite for Li-ion batteries (LIBs) profiting from its large reversible capacity of 4,200 mA h g−1. However, its sluggish reaction kinetics and large volume effect need to be resolved. Herein, we prepare a ternary GaSiP solid solution with a disordered lattice by a facile mechanochemistry method. As anodes of LIBs, the GaSiP provides a reversible capacity of 1,527 mA h g−1 at 100 mA g−1 with an initial Coulombic efficiency (ICE) of 90.8% based on the reversible Li-storage mechanism integrated intercalation and subsequent conversion processes as confirmed by crystallography characterization and electrochemical measurements. Importantly, the GaSiP carbon composite presents a long cycling stability of maintaining 1,362 mA h g−1 after 50 cycles at 0.1 A g−1, and 75% capacity retention rate after 1,200 cycles at 2 A g−1, and a high-rate performance of remaining 440 mA h g−1 at 20 A g−1. Broadly, this work opens the door to develop ternary phosphides with disordered lattice and liquid metallic phase using for electrochemical energy conversion and storage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Silicon-based anode materials enable the development of commercial lithium-ion batteries (LIBs) with higher gravimetric energy densities than are currently available. However, the inherently low ...electronic and ionic conductivity as well as large volume expansion upon lithiation of Si hinder their use in practical applications. Here we report a cation-disordered CuSi2P3 material, synthesized using high-energy ball milling, that shows improved stability, larger capacity, and higher ionic and electronic conductivity than pure Si. When used as an anode for LIBs, CuSi2P3 demonstrates a high reversible capacity of 2069 mA h g−1 with an initial Coulombic efficiency of 91% and a suitable working potential of 0.5 V (vs. Li+/Li). Further, after a two-step ball milling of CuSi2P3 with graphite, a yolk-shell structured carbon-coated CuSi2P3@graphene nanocomposite is formed that shows enhanced long-term cycling stability (1394 mA h g−1 after 1500 cycles at 2 A g−1; 1804 mA h g−1 after 500 cycles at 200 mA g−1) and rate capability (530 mA h g−1 at 50 A g−1), surpassing those for other Cu-Si, Cu-P, and Si-P compounds or single-component Si- and P-based composites. When coupled with a LiNi0.5Co0.2Mn0.3O2 (NCM) cathode in a full cell, the NCM//CuSi2P3 @graphene battery exhibits a high capacity of 140 mA h g−1 after 200 cycles, demonstrating the potential of CuSi2P3 anodes for the next-generation high-performance LIBs.
Ternary CuSi2P3 has high electronic conductivity and low Li-ion diffusion energy barrier, thus delivering better Li-storage properties than related binary and single-component electrodes. Display omitted
•Ternary CuSi2P3 has high electronic conductivity.•CuSi2P3 has a low Li-ion diffusion energy barrier.•CuSi2P3 shows better Li-storage properties than related binary and single-component electrodes studied.•A dual-carbon protection architecture is created by a two-step ball milling process.•A full battery based on CuSi2P3/C anode also shows long-term cycling stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A dynamic model for mechanical systems of TBM is established with variable loads from the cutterhead.•General evaluation criteria for estimating the dynamic performance of TBM is proposed.•The ...uncertain mechanical behaviors of rocks are described with interval analysis method.•The criteria could be used to avoid unexpected shutdown of the tunneling project.
The complex and uncertain geological structures may cause difficult prediction for dynamic performance of tunnel boring machines (TBMs). The dynamic model of the thrusting and supporting system of TBM is established, in which the uncertain loads from cutterhead and the contact stiffness on tunnel interface are considered. An evaluation model for dynamic performance is proposed by considering the characteristics of translational and angular velocities of TBMs. The fuzzy analytic hierarchy process (FAHP) is used for determining the weights in the evaluation model. The uncertain geological strata are described in terms of the interval analysis method. The dynamic performance is evaluated when TBMs excavate in straight and curvilinear tunnels considering the uncertain fractions of soft and hard rocks and different inclined angles of two rocks. The results show that the dynamic performance becomes worse with the increasing proportion of soft rock. TBMs excavating in the vertical layer interface perform better than those in horizontal one. So the probability of jamming and excavating deviation increases with the increasing proportion of soft rock when the interface of the mixed strata is horizontal. The evaluation standard is effectively verified by using the real jamming case of TBM when it excavated in the mixed strata containing both siltstone (70%) and argillite (30%).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Both electronic and ionic conductivities are of high importance to the performance of anode materials for Li-ion batteries. Many large capacity anode materials (such as Ge) do not have sufficiently ...high electronic and ionic conductivities required for high-rate cycling. Here, we report a novel ternary compound, copper germanium phosphide (CuGe
2
P
3
), as a high-rate anode. Being synthesized
via
a facile and scalable mechanochemistry method, CuGe
2
P
3
has a cation-disordered sphalerite structure and offers higher ionic and electronic conductivities and better tolerance to volume change during cycling than Ge, as confirmed by first principles calculations and experimental characterization, including high-resolution synchrotron X-ray diffraction, HRTEM, SAED, XPS and Raman spectroscopy. Furthermore, the results suggest that CuGe
2
P
3
has a reversible Li-storage mechanism of conversion reaction. When composited with graphite by virtue of a two-stage ball-milling process, the yolk-shell structure of the amorphous carbon-coated CuGe
2
P
3
nanocomposite (CuGe
2
P
3
/C@Graphene) delivers a high initial coulombic efficiency (91%), a superior cycling stability (1312 mA h g
1
capacity after 600 cycles at 0.2 A g
−1
and 876 mA h g
−1
capacity after 1600 cycles at 2 A g
−1
), and an excellent rate capability (386 mA h g
−1
capacity at 30 A g
−1
), surpassing most Ge-based anodes reported to date. Moreover, a series of cation-disordered new phases in the Cu(Zn)-Ge-P family with various cation ratios offer similar Li-storage properties, achieving high reversible capacities with high initial coulombic efficiencies and desirable redox chemistry with improved safety.
The Cu(Zn)-Ge-P compounds have high ionic and electronic conductivity and good tolerance to volume change during cycling, thus delivering excellent Li-storage performance.
Designing dense thick sulfur cathodes to gain high‐volumetric/areal‐capacity lithium–sulfur batteries (LSBs) in lean electrolytes is extremely desired. Nevertheless, the severe Li2S clogging and ...unclear mechanism seriously hinder its development. Herein, an integrated strategy is developed to manipulate Li2S redox kinetics of CoP/MXene catalyst via electron‐donor Cu doping. Meanwhile a dense S/Cu0.1Co0.9P/MXene cathode (density = 1.95 g cm−3) is constructed, which presents a large volumetric capacity of 1664 Ah L−1 (routine electrolyte) and a high areal capacity of ≈8.3 mAh cm−2 (lean electrolyte of 5.0 µL mgs−1) at 0.1 C. Systematical thermodynamics, kinetics, and theoretical simulation confirm that electron‐donor Cu doping induces the charge accumulation of Co atoms to form more chemical bonding with polysulfides, whereas weakens CoS bonding energy and generates abundant lattice vacancies and active sites to facilitate the diffusion and catalysis of polysulfides/Li2S on electrocatalyst surface, thereby decreasing the diffusion energy barrier and activation energy of Li2S nucleation and dissolution, boosting Li2S redox kinetics, and inhibiting shuttling in the dense thick sulfur cathode. This work deeply understands the atomic‐level manipulation mechanism of Li2S redox kinetics and provides dependable principles for designing high‐volumetric‐energy‐density, lean‐electrolyte LSBs through integrating bidirectional electro‐catalysts with manipulated Li2S redox and dense‐sulfur engineering.
The authors develop an integrated strategy to manipulate Li2S redox kinetics of CoP/MXene catalyst via electron‐donor Cu doping and meanwhile construct a dense S/Cu0.1Co0.9P/MXene cathode, which presents large volumetric capacity of 1664 Ah L−1 and high areal capacity of ≈8.3 mAh cm−2 (lean electrolyte) at 0.1 C, and its atomic‐level manipulation mechanism of Li2S redox kinetics is uncovered.
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A facile method has been used to synthesize boron and nitrogen-dual-self-doped graphene sheets (BNGs). The procedures include a borane-tert-butylamine complex as the precursor to impregnate with a ...certain amount of cobalt ions, then thermolysis in a tube furnace. The synthesized boron and nitrogen-dual-self-doped graphene sheets are systematically characterized by XRD, Raman spectra, XPS, SEM, EDS, TEM and EELS. Analysis results show that nitrogen and boron atoms are successfully self-doped into the graphene sheets. The BNG-1000 indicates the nitrogen and boron doping levels of 7.72 at.% and 7.18 at.%, respectively. The BNGs show a remarkable activity and high stability for the oxygen reduction reaction (ORR). An onset potential of 0.95 V which is close to that of Pt/C and a well-defined limiting current plateau for the ORR is observed in alkaline media. It has been evidenced that the catalyst is very stable and without degradation after 5000 cycles.
Herein, three-dimensional mesoporous graphene conductive networks supporting bimetallic PtAg alloyed nanoparticles ( i.e. PtAg/3DMGS) with a superior composited nanostructure have been fabricated for ...advanced oxygen reduction reaction electrocatalysts. The unique architecture of 3D porous graphene exhibits a high surface area (1382 m 2 g −1 ), a well-defined mesoporous structure (an average pore size of 3.28 nm), as well as an excellent electronic conductivity (1350 S m −1 ). Inside the PtAg/3DMGS, high-density and ultrafine PtAg NPs (∼2.5 nm) were well dispersed on the porous surface of 3DMGS. The combination of ultrafine PtAg NPs and 3DMGS conductive networks provides a relatively stable macroporous composite architecture, which offers convenient binary channels for both electron transport and ion diffusion. This promising PtAg/3DMGS composite material reveals an ultrahigh mass activity (at 0.9 V) of 392 mA mg Pt −1 , which is nearly 4 times that of Pt/C (TKK) (102 mA mg Pt −1 ). After 1000 CV cycles, the retention rates of mass activity are 81.6% and 66.7% for PtAg/3DMGS and Pt/C (TKK), respectively. These results demonstrate that the PtAg/3DMGS composite material is a promising electrocatalyst with high catalytic activity and high stability for the oxygen reduction reaction.
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) Ti3C2Tx MXene and graphene dual-encapsulated nano-Sb monolith architectures (HD-Sb@Ti3C2Tx-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 dual-encapsulated Sb architecture of Ti3C2Tx and graphene; these effectively mitigate against volume expansion and the pulverization of Sb, offering good electrolyte penetration and rapid ionic/electronic transmission. Ti3C2Tx also decreases the K+ diffusion 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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Non-isothermal crystallization process of polyoxymethylene (POM) from the melts was studied by two-dimensional correlation infrared spectroscopy. A hybrid structure of FCC (1135 cm
−1) and ECC ...(904 cm
−1) during the crystallization from the molten state was found. Non-isothermal kinetics of POM crystallization was also investigated using DSC curves. A newly perturbation-correlation moving-window two-dimensional (PCMW2D) technique was used to explore the complex crystallization process. We determined three processes in crystallization. The first is the initial stage of the crystal nucleus growing or the formation of certain local ordered structures in the melts. It can be inferred the formation of the crystal nucleus of FCC is earlier than that of the ECC. The second is the maximum crystallization temperature of POM. The last is the further improvements of crystals (especially in ECC) and the crystallization of the cyclic POM of low molecular weight. However, this process of FCC is slower than ECC. The temperature-dependent IR spectra at reheating were also analyzed using PCMW2D.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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