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In this report, the porous Fe3O4/C nanocomposites were successfully synthesized by using ferrocene as raw material and dilute nitric acid as solvent via extremely convenient and low-cost one-step calcining method. The formation of porous structure resulted from the aggregation and assembly of numerous nanoparticles. The experimental results show that the crystallinities, morphologies and electrochemical performance of samples were affected by the calcining temperature and carbon content. As an anode for lithium-ion batteries (LIBs), the Fe3O4/C nanocomposites obtained at calcination temperature of 500∘C (Fe3O4/C-a500) exhibited remarkable initial specific discharge capacity of 1418 mA h g − 1 and a reversible capacity retention of 721 mA h g − 1 after 100 cycles at the current density of 100 mA g − 1 . The excellent properties can be attributed to the high theoretical capacity of Fe3O4, the high conductivity of carbon and especially the porous structure, which offered more sites for the storage and insertion of Li ions. Even at the current density of 1000 mA h g − 1 , the reversible capacity of Fe3O4/C-a500 can be up to 291 mA h g − 1 , indicating the prepared typical nanocomposite presented excellent electrochemical performances and lithium storage capacity, which may be a promising candidate as the anode material for LIBs. The porous Fe3O4/C nanocomposite is successfully synthesized via extremely convenient and low-cost one-step calcining method. The calcination temperature and carbon content play the key role in morphology and properties. The Fe3O4/C-a500 as anode for lithium-ion batteries exhibits favorable specific capacity and excellent cycling stability. [ABSTRACT FROM AUTHOR]

Copper phosphide has shown remarkable development potential in the anode materials of lithium ion batteries (LIBs) due to its high mass/volume ratio capacity. Nevertheless, the low conductivity and volumetric expansion in the cycling process restrict its practical application. Herein, we ingeniously designed and successfully prepared copper phosphide (Cu 3 P)@carbon (C) nanocomposite with multi-stage pore inverse opals (Cu 3 P@C MSPIOs), including possessed the ordered macropores with the mean aperture of ∼100 nm induced by polystyrene (PS) sphere templates and the mesoporous structure with the pore size range of 3.0-9.5 nm and 16–27 nm derived from metal-organic framework (MOF) precursor. Compared to the Cu 3 P@C particles prepared without PS sphere templates, the Cu 3 P@C MSPIOs as the anode materials demonstrated exceptional lithium storage performance. At a high current density of 2 A g-1, the discharge specific capacity of Cu 3 P@C MSPIOs was 295 mA h g-1 in the 1st cycle while that dropped to 204 mA h g-1 during the 2nd one, and then gradually stabilized. After 1500 cycles, the discharge specific capacity can still reach to 166.3 mA h g-1, maintaining 81% capacity compared to the 2nd discharge specific capacity, which indicates the Cu 3 P@C MSPIOs as the anode material presented good cycling stability. Apparently, the multi-stage pore structure, which can effectively resolve the volumetric change problem during lithium ion (Li+) intercalation/deintercalation as well as facilitate contact between electrolyte and anode, is primarily responsible of the superior Li-ion storage property of Cu 3 P@C MSPIOs. At the same time, MOF derived carbon can improve electrical conductivity, accelerate the formation of a stable solid electrolyte interface membrane and also provide buffer layers to further alleviate volumetric expansion. [ABSTRACT FROM AUTHOR]

CoP@N/P-(C/CNTs) with porous nanocubic structure exhibited outstanding electrochemical property with high specific capacity, high-rate performance and cycle stability which benefiting from the synergistic effects between highly active CoP nanoparticles and N/P-C/CNTs. • CoP@N/P-(C/CNTs) with porous nanocubic structure were prepared by ZIF-67 through a pyrolysis-phosphorization strategy. • CNTs formed by the auto-catalysis of Co nanoparticles generated at high temperature pyrolysis in-situ in Ar. • CoP@N/P-(C/CNTs) exhibited outstanding electrochemical performance as LIBs anodes. A rational and convenient method was selected to prepare CoP@N/P-co-doped-(C/CNTs) (CoP@N/P-(C/CNTs)) composites with porous nanocubic structure through a pyrolysis-phosphorization strategy derived from ZIF-67. The production of N, P-doped carbon and CNTs formed by in-situ autocatalysis improved the electrical conductivity of the nanocomposite greatly and made the combination of N, P-(C/CNTs) with CoP nanoparticles (NPs) very tightly. The CoP NPs were well encapsulated into the N/P-(C/CNTs) polyhedron. The prepared CoP@N/P-(C/CNTs) had a large specific surface area with 114 m2 g−1 and an average pore diameter of about 10 nm, which were helpful for the efficient diffusion of electrolyte and transfer of ions/electrons. Benefiting from the synergistic effects between highly active CoP NPs and wonderfully conductive N/P-C/CNTs, the CoP@N/P-(C/CNTs) composites exhibited outstanding electrochemical performance. As anodes for lithium-ion batteries (LIBs), the CoP@N/P-(C/CNTs) composites exhibited an excellent initial discharge capacity of 1215 mA h g−1 and reversible capacity of 600 mA h g−1 after 200 cycles at 0.5 A g−1. Even at the high current density of 2 A g−1, it still retained a capacity of 385 mA h g−1. It proved that the autocatalytic formation of CoP@N/P-(C/CNTs) resulted from Co-MOFs is an economical and convenient approach to synthesize electrode materials with high performance for LIBs. [ABSTRACT FROM AUTHOR]

A novel graphene oxide encapsulated Ni 3 S 2 multi-layer nanosheet arrays were designedly grown on Ni foam (Ni 3 S 2 @GO/NF) via a simple and low-cost method. The prepared nanocomposite was converted from a pyramid shape to a multi-layer nanosheet array because Sn4+, Ni2+ and thioacetamide performed a coprecipitation transformation during the hydrothermal reaction. As a binder-free anode material for lithium ion batteries, the Ni 3 S 2 @GO/NF nanocomposite showed an initial charge and discharge of 797.8 and 1182.3 mA h g−1 at a current density of 0.5 A g−1, respectively. After 100 reversible cycles, the specific discharge capacity of the composite can still remain 1006.6 mA h g−1, presenting excellent cycle stability. The enhanced electrochemical performance is due to that the multi-layer sheet array structure can increase the Li+ energy storage active site and alleviate the volume expansion caused by Li+ insertion and extraction, which was beneficial to the sufficient contact of the active material with the electrolyte, enhancing the lithium ion transmission rate. Additionally, the coating of oxide graphene on the composite further stabilized the structural morphology, thereby improving the stability of the electrochemical cycle performance of the nanocomposite. • The novel nanosheet arrays were directly grown in situ on NF skeleton. • The addition of Sn4+ could regulate the shape of the arrays. • Ni 3 S 2 @GO/NF nanosheet arrays can be used as binder-free anodes for LIBs. • The nanosheet arrays structure could increase the active sites of Li+ storage and alleviate the volume expansion. • The GO coating could improve the conductivity, total capacity and cycle stability of Ni 3 S 2 @GO/NF. [ABSTRACT FROM AUTHOR]

• The SnO 2 /Bi 2 O 3 /NF IOs can improve lithium ion diffusion rate and enhances the reaction kinetic. • The materials can effectively buffer volume expansion. • The SnO 2 /Bi 2 O 3 /NF IOs exhibited excellent electrochemical activity. • The prepared SnO 2 /Bi 2 O 3 /NF IOs possessed connected macroporous and mesoporous structures with the diameter of 150 nm and 10.5 nm, respectively. So far, the high theoretical specific capacity metal oxide is considered as a promising anode material for lithium-ion batteries (LIBs). Unfortunately, the intrinsic poor conductivity and structural stability of metal oxide, the huge volume expansion during the cycling cause serious capacity fading and unstable cycle. Here, the three-dimensional (3D) ordered inverse opal (IO) heterojunction structure of SnO 2 /Bi 2 O 3 on commercial nickel foam (NF) were fabricated. When used as a binder-free anode material for LIBs, the initial discharge specific capacity and charge specific capacity of the IOs electrode were 1229 mA h g−1 and 1098 mA h g−1. The SnO 2 /Bi 2 O 3 /NF IOs exhibited excellent electrochemical activity and delivered a discharge capacity about 493 mA h g−1 after 500 cycles at the current density of 1000 mA g−1, the Coulomb efficiency (CE) had been maintained at around 100%, which was much more than the control groups of SnO 2 /NF IOs (247 mA h g−1) and Bi 2 O 3 /NF IOs (124 mA h g−1). Furthermore, the prepared was successfully assembled with commercial LiFePO 4 to a full cell that displayed stable capacity about 101.2 mA h g−1 at the current density of 100 mA g−1 after 100 cycles. The excellent performance of SnO 2 /Bi 2 O 3 /NF IOs is due to that the 3D interconnected macroporous and mesoporous structures can shorten the transmission path of ions/electrons and buffer volume expansion. In addition, the heterojunction structure with obvious lattice defects can effectively promote the contact between electrode material and electrolyte. The strategy in this study lights on the illuminating design of 3D inverse opal heterostructure binder-free anode, and the obtained product has a great potential as the anode material applied in next-generation LIBs. [ABSTRACT FROM AUTHOR]