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Tin has been considered an ideal anode material for lithium ion batteries because of its high theoretical capacity. However, its practical application is limited due to the poor cycling stability, which is induced by the huge volume variation upon lithiation/delithiation. Moreover, amorphous and crystalline structures can significantly influence the electrochemical performance of Sn-based electrode for lithium ion batteries. Herein, the specific capacity, cycling performance, rate capability, and kinetic process of amorphous-Sn@C (am-Sn@C) and crystalline-Sn@C (cr-Sn@C) as anodes for lithium ion batteries have been compared. The am-Sn@C electrode exhibits higher capacity, better cycling stability (711 mAh g−1 after 200 cycles at 0.1 A g−1; 510 mAh g−1 after 500 cycles at 1 A g−1) and rate capability than cr-Sn@C electrode (574 mAh g−1 after 200 cycles at 0.1 A g−1; 156 mAh g−1 after 500 cycles at 1 A g−1) as anode for lithium ion batteries. The enhanced electrochemical performance of the am-Sn@C electrode can be attributed to the enhanced strain regulation to accommodate volume change and defect sites to improve lithium storage capacity. The preparation method can be viewed as a reference for the further development of alloy-based anodes with high capacity and long cycle life for lithium ion batteries.

Developing a high-performance anode with high reversible capacity, rate performance, and great cycling stability is highly important for sodium-ion batteries (SIBs). MoS2 has attracted extensive interest as the anode for SIBs. Herein, the vertically oxygen-incorporated MoS2 nanosheets/carbon fibers are constructed via a facile hydrothermal method and then by simple calcination in air. Oxygen incorporation into MoS2 can increase the defect degree and expand the interlayer spacing. Vertical MoS2 nanosheet array coated on carbon fibers not only can expose rich active sites and reduce the diffusion distance of Na+, but also improve the electronic conductivity and enhance structural stability. Meanwhile, interlayer-expanded MoS2 can decrease Na+ diffusion resistance and increase accessible active sites for Na+. In this work, the electrode combining the oxygen-incorporated strategy with vertical MoS2 nanosheet-integrated carbon fibers displays high specific capacities of 330 mAh g–1 over 100 cycles at a current...

Carbon materials with high initial Coulombic efficiency (ICE) and specific capacity in lithium-ion batteries are highly attractive. Herein, P-doped carbon has been prepared, and as an anode for lithium-ion batteries, it exhibits remarkably improved ICE and reversible capacity. P atoms are apt for the formation of the P–O bond in carbon with oxygen-containing groups. The doped P content strongly depends on the O content in carbon. The high-doped P content of 5.79 at. % can be obtained through changing the O content in carbon. Carbon with high contents of P and O displays high ICE and capacity as an anode for lithium-ion batteries. The P–O bond in carbon changes the morphology and composition of the solid electrolyte interface (SEI) layer and is beneficial to the formation of a thin and dense SEI layer. The P–O bond in carbon prevents the permeation and decomposition of solvated PF6– in the interior of the electrode during cycling, resulting in the improved ICE, reversible capacity, and rate capability. As ...

MoO2 with low electrical resistivity and high specific capacity as anode for lithium ion batteries is hindered because of its large volume variation during Li+ insertion/extraction process, which leads to fast capacity fading. Herein, three-dimensional (3D) core-shell MoO2@few-layered MoS2 covered by S-doped graphene (MO/MS/SG) aerogel has been fabricated through hydrothermal reaction and freeze-drying process together with sulfidation. MoO2 nanoparticles coated by few-layer MoS2 can promote good dispersion of MoO2 nanoparticles and avoid the restacking of MoS2. S doping in graphene can increase the defects and active sites. S-doped graphene aerogel as flexible framework and conductive network not only provides the transmission path for ions and electrons, but also maintains the structural integrity of electrode during cycles. Core-shell MoO2@few-layer MoS2 hybrid well-dispersed in S-doped graphene matrix buffers the volume changes during cycles and contributes to high reversible capacity. Free-standing electrode without binder and current collector prevents the separation of electrode materials from current collector during cycles. Benefitting from the unique structures, the MO/MS/SG aerogel as anode for lithium ion battery exhibits high reversible capacities of 683 mAh g−1 at 0.1 A g−1 after 100 cycles and 533 mAh g−1 at 0.5 A g−1 after 350 cycles together with excellent rate capability. This work demonstrates the potential application of the Mo-based materials in lithium ion batteries.

Three-dimensional foam with integrated core-shell carbon nanotubes-MoS2 with reduced graphene oxide (MoS2/CNT/rGO) has been fabricated by a hydrothermal reaction together with freeze drying. Thin MoS2 nanosheets are coated on the carbon nanotubes (CNT) and distributed on the surface of reduced graphene oxide (rGO) nanosheets. One-dimensional CNT and two-dimensional rGO conductive network not only effectively improves the electron transport and mechanical property, but also prevents the aggregation of MoS2 nanosheets. MoS2 with large interlayer spacing provides more active sites and channels for insertion of lithium ions, while CNT and rGO network acts as a conductive skeleton. The 3D porous and interconnected foam can directly as electrode without any binders and conductive agents. After optimizing the ratio of CNT to rGO, the MoS2/CNT/rGO foam as a freestanding electrode for lithium ion batteries exhibits a high specific capacity of 745 mAh g−1 at a current density of 0.1 A g−1 after 170 cycles and 420 mAh g−1 at 0.5 A g−1 after 200 cycles. This method is easily extended to prepare the other electrode materials, especially the freestanding and flexible electrode.

Flexible and thin energy storage devices have attracted enormous attentions. An easy and large-scale method has been employed to fabricate flexible and interwoven N, P dual-doped carbon fibers/graphitic carbon nitride ( hu CP/g-C 3 N 4 ) using filter paper as a precursor. The hu CP/g-C 3 N 4 composite as self-supporting anode for lithium ion batteries exhibits high reversible capacities of 1030 mAh g −1 after 1000 cycles at 1 A g −1 and 360 mAh g −1 after 4000 cycles at 10 A g −1 along with excellent rate performance (133 mAh g −1 at 30 A g −1 ). For sodium ion batteries, hu CP/g-C 3 N 4 as anode delivers high reversible capacities of 345 mAh g −1 after 380 cycles at 0.1 A g −1 and 110 mAh g −1 after 4000 cycles at 1 A g −1 . This excellent electrochemical performance can be attributed to the high contents of doped N and P in hu CP/g-C 3 N 4 and graphitic carbon nitride network, which not only create more defects and active sites but also expand the layer planes and provide interconnected conductive network.