Numerous studies have reported that the enhancement of rate capability of carbonaceous anode by heteroatom doping is due to the increased diffusion‐controlled capacity induced by expanding interlayer spacing. However, percentage of diffusion‐controlled capacity is less than 30% as scan rate is larger than 1 mV s−1, suggesting there is inaccuracy in recognizing principle of improving rate capability of carbonaceous anode. In this paper, it is found that the heteroatom doping has little impact on interlayer spacing of carbon in bulk phase, meaning that diffusion‐controlled capacity is hard to be enhanced by doping. After synergizing with tensile stress, however, the interlayer spacing in subsurface region is obviously expanded to 0.40 nm, which will increase the thickness of accessible subsurface region at high current density. So SRNDC‐700 electrodes display a high specific capacity of 160.6 and 69.5 mAh g−1 at 20 and 50 A g−1, respectively. Additionally, the high reversibility of carbon structure insures ultralong cycling stability and hence attenuation of SRNDC‐700 is only 0.0025% per cycle even at 10 A g−1 for 6000 cycles. This report sheds new insight into mechanism of improving electrochemical performance of carbonaceous anode by doping and provides a novel design concept for doping carbon.

Dual carbon-protected MoSe2 nanorods can enable controlled volume fluctuation, permit continuous electron transfer, and offer more active sites and good redox reversibility.

• MoSe 2 /MoC/C multiphase boundaries boost ionic transfer kinetics. • MoSe 2 (5-10 nm) with rich edge sites is uniformly coated in N-doped framework. • The obtained MoSe 2 nanodots achieved ultralong cycle performance in LIBs and high capacity retention in full cell.

No abstract

In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, but the mechanism behind it still needs further study. Herein, an electrochemically in situ defect induction in close‐packed lattice plane of vanadium nitride oxide (VNxOy) in aqueous zinc‐ion battery is reported. It is verified by theoretical calculation and experiment that the original compact structure is not suitable for the insert of Zn2+ ion, while a highly active one after the initial electrochemical activization accompanied by the in situ defect induction in close‐packed lattice plane of VNxOy exhibits efficient zinc ion storage. As expected, activated VNxOy can achieve very high reversible capacity of 231.4 mA h g−1 at 1 A g−1 and cycle stability upto 6000 cycles at 10 A g−1 with a capacity retention of 94.3%. This work proposes a new insight for understanding the electrochemically in situ transformation to obtain highly active cathode materials for the aqueous zinc‐ion batteries.

Heterogeneous structures have been attracting increasing attention in energy storage and conversion applications due to the phase interface and synergistic effect of multiple components.

Silicon oxycarbide (SiOC) is considered as a potential anode material in lithium-ion batteries because of its high theoretical capacity and good structural stability. Despite many such assets, its low electronic conductivity causes poor rate capability and rapid attenuation of capacity. Herein, we report the fabrication of cowpea-like N-doped carbon nanofiber-encapsulated SiOC spheres (SiOC/C NFs) in which the Si−N bridging is introduced into SiOC. Our method not only demonstrates an improved electronic conductivity and a shortened ionic diffusion distance but also prevents agglomeration by avoiding direct contact with the electrolyte. As anode materials for lithium-ion batteries, this SiOC/C NF material delivers a high reversible capacity (707 mA h g −1 at 0.1 A g −1 after 100 cycles), a good rate performance (468 mA h g −1 at 1.6 A g −1 ), and an excellent cycling stability (570 mA h g −1 at 0.4 A g −1 after 800 cycles). Moreover, the full cell of LiFePO 4 // SiOC/C NFs exhibits excellent electrochemical properties, which demonstrates its prospect of great potential as an anode material for high-performance lithium-ion batteries.

Antimony (Sb) has considerable specific capacity as an anode material for sodium-ion batteries. However, the large volume expansion during alloying/dealloying with Na + leads to poor cycling stability. Herein, we report the synthesis of Sb@carbon quantum dots (Sb@CQDs) composite via a facile one-step reduction approach at room temperature. CQDs can modify the nucleation and growth of Sb particles during the reduction process and thus tune the size of Sb. Sb@CQDs particles with size of~7 nm can relieve the volume expansion and reduce the diffusion distance for sodium ions. Moreover, the residual CQDs in the obtained composite enhance the electronic conductivity. Benefited from the modification of CQDs, the Sb@CQDs composite delivers high specific capacity of 635 mA h g À 1 at 0.1 A g À 1 and 334 mA h g À 1 at 2 A g À 1 .