In Situ Construction of Multibuffer Structure 3D CoSn@SnO_x/CoO_x@C Anode Material for Ultralong Life Lithium Storage

Abstract

Rapid progress of lithium‐ion batteries (LIBs) highly relies on high‐performance electrode materials. Herein, a novel nanocomposite of CoSn alloy with a multishell layer structure confined in 3D porous carbon is constructed through a facile freeze drying and annealing treatment method. The skillful design effectively relieves the volume expansion of the Sn‐based alloy and enhances the combination between CoSn and carbon. Profiting from the synergistic effect of the multibuffer structure alloy and cross‐linked porous carbon, CoSn@SnOx/CoOx@C displays high capacity (912.6 mA h g−1 after 100 cycles at 0.1 A g−1) and excellent cycling stability (almost no capacity decay at 10 A g−1 after 1000 cycles) when used as anode for LIBs. The presence of Sn–O/Co–O bond makes the nanoalloy tightly pinned on the carbon substance and the structure stability of electrode material is improved significantly. Furthermore, the porous carbon with plentiful defects offers abundant room for the volume expansion of Sn and ensures fast transport of electrons/ions. Cyclic voltammogram (CV) curves under different scan rates reveal that the charge storage of the nanocomposite is controlled by pseudocapacitive and ion‐diffusion mechanisms. This facile fabrication strategy and unique structure design can be extended to other composite materials for energy storage devices.

Rational Design and Engineering of 1D Heterostructured Porous Sn/CoSnx@C Nanotubes for Superior Lithium Storage

“…First, CV tests were performed at different scanning rates of 0.2–1.0 mV s –1 with a voltage range of 0.01–3 V (Figure a). The relationship between peak current ( i ) and scanning rate ( v ) is consistent with the equation where a is a constant, and the b value can be obtained from the ratio of log­( i ) to log­( v ). The b value close to 0.5 indicates that the electrochemical reaction is a diffusion-dominant process, while the b value close to 1 indicates a pseudocapacitance-dominant process .…”

Investigation of the Negative Process as the Limiting Factor of Vanadium Flow Battery

“…As mentioned in a previous report, [ 24 ] the discharge capacity of a VFB with the equal volumes of negative and positive electrolyte ( V N / V P = 1) is greater than that of a VFB with unmatched volumes of electrolytes. Unlike the equal volume of electrolytes whose discharge capacity is decreasing and then tends to be stable with increasing cycle number, the discharge capacity of an unmatched volume of electrolytes increases first and then tends to be stable.…”

“…Facing the reality that the negative electrode process contributes most of the polarization during the discharging process, it is necessary to pay more attention to reducing the polarization of the negative process. Therein, the excessive negative electrolyte [24] seems very simple and effective, and the decoration of the hydrogen evolution inhibitor on the negative electrode [17,18,37] might be a more ultimate solution.…”

“…One of the possible reasons may be that the newly generated hydrogen gas bubbles during the hydrogen evolution reaction might block the active sites and reduce the utilization of the electrode surface area, which would be unfavorable for the negative electrode reaction. [ 23 ] Furthermore, the key operational variables such as the ratio of both positive ( V P ) and negative ( V N ) electrolyte volume, [ 24 ] cell design, [ 25 ] electrolyte monitoring, [ 26 ] and mass transfer [ 27 ] on the performance of the VFB may be another reason. Nevertheless, there are not any effective measurements to solve the key issue of the coupled negative electrode reaction and hydrogen evolution reaction.…”

Hybrid CuSn nanosphere-functionalized Cu/Sn co-doped hollow carbon nanofibers as anode materials for sodium-ion batteries

“…intermetallic hybrids. [16][17][18][19] In the resultant Sn-M intermetallic hybrids, inactive metals as buffer frames could alleviate volume expansion, inhibit the growth of Sn particles and improve the electrochemical performance to some extent. Recently, there were some reports on the combination of metal compounds with carbon materials (such as carbon nanotubes (CNTs), graphene and other organic macromolecules), which is another effective strategy to improve the Na-storage performances of tin-based materials.…”