CuO Quantum Dots Embedded in Carbon Nanofibers as Binder‐Free Anode for Sodium Ion Batteries with Enhanced Properties

Abstract

The design of sodium ion batteries is proposed based on the use of flexible membrane composed of ultrasmall transition metal oxides. In this paper, the preparation of CuO quantum dots (≈2 nm) delicately embedded in carbon nanofibers (denoted as 2-CuO@C) with a thin film via a feasible electrospinning method is reported. The CuO content can be controlled by altering the synthetic conditions and is optimized to 54 wt%. As binder-free anode for sodium ion batteries, 2-CuO@C delivers an initial reversible capacity of 528 mA h g at the current density of 100 mA g , an exceptional rate capability of 250 mA h g at 5000 mA g , and an ultra-stable capacity of 401 mA h g after 500 cycles at 500 mA g . The enhancement of electrochemical performance is attributed to the unique structure of 2-CuO@C, which offers a variety of advantages: highly conductive carbon matrix suppressing agglomeration of CuO grains, interconnected nanofibers ensuring short transport length for electrons, well-dispersed CuO quantum dots leading to highly utilization rate, and good mechanical properties resulting in strong electrode integrity.

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

“…These features suggest it is suitable for the anode material in LIBs [15,16,17]. However, just like the other TMO-based anode materials, CuO displays large volume expansion (174%) and particle pulverization during the cyclic charge/discharge process [18,19]. Additionally, CuO has a low electrical conductivity (p-type semiconductor), and many studies have been done to improve it by adding conductive carbon materials, such as graphene, carbon nanotubes (CNTs), fullerene, and so on.…”

Electrospun NaVPO4F/C Nanofibers as Self‐Standing Cathode Material for Ultralong Cycle Life Na‐Ion Batteries

“…[31,32,34] Hence, it is significant to enhance the kinetics of Na-ion transfer in NaVPO 4 F. In order to achieve this goal, strategies mainly include decreasing the crystallite size and altering morphology of the material. [7,22,35,36] As far as we know, electrospinning is a versatile technique to prepare various 1D carbon-containing composites and produce flexible membrane, [6,8,[37][38][39] which encourages us to fabricate NaVPO 4 F with novel morphology combined the method of electrospinning to improve its electrochemical performance.Herein, we first synthesized 1D NaVPO 4 F/C nanostructure via an electrospinning method. Such a structure combines a variety of advantages for battery electrodes: (I) the small nanoparticles (≈6 nm) shorten the length of Na-ion transport; (II) NaVPO 4 F has received a great deal of attention as cathode material for Na-ion batteries due to its high theoretical capacity (143 mA h g −1 ), high voltage platform, and structural stability.…”

Flexible Electrodes for Sodium‐Ion Batteries: Recent Progress and Perspectives

“…When evaluated as half cells, the NVP/rGO paper-like cathode delivered a reversible capacity of 113 mA h g −1 at 100 mA g −1 and high capacity retention of ≈96.6% after 120 cycles, and the Sb/rGO paper-like anode gave a highly reversible capacity of 612 mA h g −1 at 100 mA g −1 and an excellent rate capacity up to 30C. Moreover, the Na-ion full cell assembled by coupling a Sb/rGO anode and an NVP/rGO cathode was able to deliver a reversible capacity of 400 mA h g −1 after 100 cycles at 100 mA g −1 and had the ability to power a Carbon nanofibers Electrospinning and carbonization 50 mA h g −1 at 1 A g −1 ≈200 mA h g −1 after 100 cycles at 0.1 A g −1 [56] Carbon nanofibrous webs Electrospinning and carbonization 80 mA h g −1 at 1 A g −1 247 mA h g −1 after 200 cycles at 0.1 A g −1 [57] Porous carbon nanofibers Electrospinning and carbonization 40 mA h g −1 at 20 A g −1 140 mA h g −1 after 1000 cycles at 0.5 A g −1 [58] Nitrogen-doped carbon nanofibers Electrospinning, imidation, and carbonization 154 mA h g −1 at 15 A g −1 210 mA h g −1 after 7000 cycles at 5 A g −1 [59] Graphene@porous carbon nanofibers Electrospinning and carbonization 261.1 mA h g −1 at 10 A g −1 330 mA h g −1 after 1000 cycles at 2 A g −1 [60] Sb@carbon fibers Electrospinning and carbonization 88 mA h g −1 at 6 A g −1 350 mA h g −1 after 300 cycles at 0.1 A g −1 [61] CuO@carbon nanofibers Electrospinning and carbonization 250 mA h g −1 at 5 A g −1 401 mA h g −1 after 500 cycles at 0.5 A g −1 [62] MoS 2 @carbon nanofibers Electrospinning and carbonization 89 mA h g −1 at 5 A g −1 283.9 mA h g −1 after 600 cycles at 0.1 A g −1 [63] Sn@nitrogen-doped carbon nanofiber Electrospinning and carbonization 450 mA h g −1 at 10 A g −1 483 mA h g −1 after 1300 cycles at 2 A g −1 [64] www.advmat.de www.advancedsciencenews.com commercial light-emitting diode (LED), even when the cell was subjected to bending (Figure 2b-d). It is obvious that this work shows a high capacity, good cycling stability, and excellent rate performance for both half cells and full cells, which provides an effective route to bendable and high-performance electrode materials for next-generation flexible SIBs.…”

“…In addition, the carbon nanofibrous mat can act as a flexible substrate to either encapsulate various active materials into the carbon nanofibers or grow active materials on their surface. Up to now, a variety of active materials, including mono-/ bilayer graphene, [60] Sb nanoparticles, [61] CuO quantum dots, [62] MoS 2 nanosheets, [63] and Sn nanodots, [64] have been embedded in flexible carbon nanofibers. For example, Liu et al [64] encapsulated Sn nanodots with ultrasmall size (1-2 nm) and high content (>60 wt%) into porous N-doped carbon nanofibers (Sn NDs@PNC).…”