Tailoring the carbon shell thickness of SnCo@nitrogen-doped carbon nanocages for optimized lithium storage

Bionic Capsule Lithium-Ion Battery Anodes for Efficiently Inhibiting Volume Expansion

Magnetite (Fe3O4) has a large theoretical reversible capacity and rich Earth abundance, making it a promising anode material for LIBs. However, it suffers from drastic volume changes during the lithiation process, which lead to poor cycle stability and low-rate performance. Hence, there is an urgent need for a solution to address the issue of volume expansion. Taking inspiration from how glycophyte cells mitigate excessive water uptake/loss through their cell wall to preserve the structural integrity of cells, we designed Fe3O4@PMMA multi-core capsules by microemulsion polymerization as a kind of anode materials, also proposed a new evaluation method for real-time repair effect of the battery capacity. The Fe3O4@PMMA anode shows a high reversible specific capacity (858.0 mAh g-1 at 0.1 C after 300 cycles) and an excellent cycle stability (450.99 mAh g-1 at 0.5 C after 450 cycles). Furthermore, the LiNi0.8Co0.1Mn0.1O2/Fe3O4@PMMA pouch cells exhibit a stable capacity (200.6 mAh) and high-capacity retention rate (95.5 %) after 450 cycles at 0.5 C. Compared to the original battery, the capacity repair rate of this battery is as high as 93.4 %. This kind of bionic capsules provide an innovative solution for improving the electrochemical performance of Fe3O4 anodes to promote their industrial applications.

Recent Progress of Hollow Carbon Nanocages: General Design Fundamentals and Diversified Electrochemical Applications

Hollow carbon nanocages (HCNCs) consisting of sp2  carbon shells featured by a hollow interior cavity with defective microchannels (or customized mesopores) across the carbon shells, high specific surface area, and tunable electronic structure, are quilt different from the other nanocarbons such as carbon nanotubes and graphene. These structural and morphological characteristics make HCNCs a new platform for advanced electrochemical energy storage and conversion. This review focuses on the controllable preparation, structural regulation, and modification of HCNCs, as well as their electrochemical functions and applications as energy storage materials and electrocatalytic conversion materials. The metal single atoms-functionalized structures and electrochemical properties of HCNCs are summarized systematically and deeply. The research challenges and trends are also envisaged for deepening and extending the study and application of this hollow carbon material. The development of multifunctional carbon-based composite nanocages provides a new idea and method for improving the energy density, power density, and volume performance of electrochemical energy storage and conversion devices.

Lithiophilic Sn-Co nano-seeds sealed in a hollow carbon shell to stabilize lithium metal anodes

A lithiophilic Sn-Co nano-seed sealed in a nitrogen-doped carbon shell is designed to stabilize lithium metal anodes, in which lithiophilic alloys can regulate lithium deposition behavior and the hollow carbon shell is beneficial to prevent agglomeration. The modified lithium anode can be stable for 1350 h and 400 h under 1 mA cm^-2 and 5 mA cm^-2 in symmetric cells. The Sn-Co@C@Li||LiFePO₄ full cell with a low N/P ratio of 2.12 shows a superior capacity retention of >98% over 250 cycles under 1C.

Bilateral Interfaces in In2Se3-CoIn2-CoSe2 Heterostructures for High-Rate Reversible Sodium Storage

Metal selenides are considered as a group of promising candidates as the anode material for sodium-ion batteries due to their high theoretical capacity. However, the intrinsically low electrical and ionic conductivities as well as huge volume change during the charge-discharge process give rise to an inferior sodium storage capability, which severely hinders their practical application. Herein, we fabricated In₂Se₃/CoSe₂ hollow nanorods composed of In₂Se₃/CoIn₂/CoSe₂ by growing cobalt-based zeolitic imidazolate framework ZIF-67 on the surface of indium-based metal-organic framework MIL-68, followed by in situ gaseous selenization. Because of the CoIn₂ alloy phase in between In₂Se₃ and CoSe₂, a heterostructure consisting of two alloy/selenide interfaces has been successfully constructed, offering synergistically enhanced electrical conductivity, Na diffusion process, and structural stability, in comparison to the single CoIn₂-free interface with only two metal selenides. As expected, this nanoconstruction delivers a high reversible capacity of 297.5 and 205.5 mAh g^-1 at 5 and 10 A g^-1 after 2000 cycles, respectively, and a superior rate performance of 371.6 mAh g^-1 at even 20 A g^-1.

New rationally designed hybrid polypyrrole@SnCoS4 as an efficient anode for lithium-ion batteries

Three active materials containing binary metal sulfide (SnCoS₄) were obtained via a simple hydrothermal method. Also, the electrochemical performance of the anode materials was investigated in a lithium-ion half-cell.

Co/FeC core-nitrogen doped hollow carbon shell structure with tunable shell-thickness for oxygen evolution reaction

Herein, multi-core-shell structure Co/FeC@N-doped hollow carbon (Co/FeC@NHC) with tunable carbon shell thickness is well crafted by a novel and simple strategy. Novel core-shell structure consisting of polydopamine (PDA) shell with different thickness and bimetal-based metal-organic frameworks (MOFs) Co/Fe core with cubic morphology are first prepared, followed by a thermal and etching treatments to fabricate hollow composite materials composed of multiple Co/FeC cores evenly distributed in N-doped carbon shell. PDA acts as a carbon and nitrogen source simultaneously to form N-doped hollow carbon in this procedure. Creatively, the N-doped hollow carbon shell protects Co/FeC core and against the degradation, in addition to enhance the conductivity of Co/FeC@NHC. Through adjusting the PDA shell thickness simply, Co/FeC@NHC with tunable N-doped carbon shell thickness is well crafted. The Co/FeC@NHC-1 with the best electrocatalytic performance is obtained by optimizing the thickness of N-doped hollow carbon shell. The Co/FeC@NHC-1 exhibits the highest activity for the oxygen evolution reaction (OER) and outstanding stability and durability. Hence, this research may establish a promising path for the rational design of metals@carbon composite with controllable structure which can act as highly efficient electrocatalysts for (OER).

Cobalt-doping SnS2 nanosheets towards high-performance anodes for sodium ion batteries

Layered SnS₂ is considered as a promising anode candidate for sodium-ion batteries yet suffers from low initial coulombic efficiency, limited specific capacity and rate capability. Herein, we report a cobalt metal cation doping strategy to enhance the electrochemical performance of a SnS₂ nanosheet array anode through a facile hydrothermal method. Benefitting from this special structure and heteroatom-doping effect, this anode material displays a high initial coulombic efficiency of 57.4%, a superior discharge specific capacity as high as 1288 mA h g^-1 at 0.2 A g^-1 after 100 cycles and outstanding long-term cycling stability with a reversible capacity of 800.4 mA h g^-1 even at 2 A g^-1. These excellent performances could be ascribed to the Co-doping effect that can increase the interlayer spacing, produce rich defects, regulate the electronic environment and improve conductivity. Besides, a carbon cloth substrate can maintain the integrity of the electrode material framework and buffer its volume variation, thus boosting intrinsic dynamic properties and enhancing sodium storage performance.

Convenient fabrication of a core–shell Sn@TiO2 anode for lithium storage from tinplate electroplating sludge

A convenient route was developed for the fabrication of a high-performance core–shell Sn@TiO₂ anode for LIBs from tinplate electroplating sludge.