Bismuth-Nanoparticles-Embedded Porous Carbon Derived from Seed Husks as High-Performance for Anode Energy Electrode

In energy application technology, the anode part of the electrode is typically composed of carbon-coated materials that exhibit excellent electrochemical performance. The carbon-coated electrodes facilitate electrochemical reactions involving the fuel and the oxidant. Energy electrodes are used in stationary power plants to generate electricity for the grid. These large-scale installations are known as distributed generation systems and contribute to grid stability and reliability. Understanding the practical applications of energy materials remains a significant hurdle in the way of commercialization. An anode electrode has one key limitation, specifically with alloy-type candidates, as they tend to exhibit rapid capacity degradation during cycling due to volume expansion. Herein, biomass-derived carbon from sunflowers (seeds husks) via pyrolysis and then bismuth nanoparticles are treated with carbon via a simple wet-chemical method. The electrode Bi@C offers several structural advantages, such as high capacity, good cycling stability, and exceptional capability at the current rate of 500 mA g-1, delivering a capacity of 731.8 mAh g-1 for 200 cycles. The biomass-derived carbon coating protects the bismuth nanoparticles and contributes to enhanced electronic conductivity. Additionally, we anticipate the use of low-cost biomass with hybrid composition has the potential to foster environment-friendly practices in the development of next-generation advanced fuel cell technology.

SnCo Nanoparticles Loaded in Hollow Carbon Spheres Interlinked by N-Doped Carbon Fibers for High-Performance Sodium-Ion Batteries

The development of Sn-based materials with electrochemically inactive matrices is a novel strategy to alleviate the volume expansion and giant structure strain/stress during the sodiation/desodiation process. In this work, a freestanding membrane based on the unique bean pod-like host composed by nitrogen-doped carbon fibers and hollow carbon spheres (HCSs) encapsulated with SnCo nanoparticles is synthesized by electrospinning (B-SnCo/NCFs). In this unique bean pod-like structure, Sn acts as a host for Na⁺ storage, while the Co plays the important role of an electrochemically inactive matrix that can not only buffer the volume variations but also inhibit aggregation and particle growth of the Sn phase during the electrochemical Na-Sn alloying process. Meanwhile, the introduction of hollow carbon spheres can not only provide enough sufficient void space to withstand the volume expansion during the (de)sodiation processes but also improve the conductivity of the anode along the carbon fibers. Furthermore, the B-SnCo/NCF freestanding membrane can increase the contact area between the active material and the electrolyte, which can provide more active sites during the cycling process. When used as an anode material for Na-ion batteries, the freestanding B-SnCo/NCF anode exhibits an outstanding rate capacity of 243.5 mA h g^-1 at 1.6 A g^-1and an excellent specific capacity of 351 mA h g^-1 at 0.1 A g^-1 for 300 cycles.

Electrostatic Shielding Boosts Electrochemical Performance of Alloy-Type Anode Materials of Sodium-Ion Batteries

The applications of alloy-type anode materials for Na-ion batteries are always obstructed by enormous volume variation upon cycles. Here, K⁺ ions are introduced as an electrolyte additive to improve the electrochemical performance via electrostatic shielding, using Sn microparticles (μ-Sn) as a model. Theoretical calculations and experimental results indicate that K⁺ ions are not incorporated in the electrode, but accumulate on some sites. This accumulation slows down the local sodiation at the "hot spots", promotes the uniform sodiation and enhances the electrode stability. Therefore, the electrode maintains a high specific capacity of 565 mAh g^-1 after 3000 cycles at 2 A g^-1 , much better than the case without K⁺ . The electrode also remains an areal capacity of ≈3.5 mAh cm^-2 after 100 cycles. This method does not involve time-consuming preparation, sophisticated instruments and expensive reagents, exhibiting the promising potential for other anode materials.

Microsized Gray Tin as a High-Rate and Long-Life Anode Material for Advanced Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are developed to address the serious concern about the limited resources of lithium. To achieve high energy density, anode materials with a large specific capacity and a low operation voltage are highly desirable. Herein, microsized particles of gray Sn (α-Sn) are explored as an anode material of SIBs for the first time. The distinct structure of α-Sn endows it the reduced volume change, the improved interaction with polymer binders and the in situ formation of amorphous Sn, as supported by in situ XRD, TEM and DFT calculations. Therefore, α-Sn exhibits an excellent electrochemical performance, much better than β-Sn widely used before. Even microsized particles of α-Sn without any treatments deliver a capacity of ∼451 mAh g^-1 after 3500 cycles at 2 A g^-1 or ∼464 mAh g^-1 at 4 A g^-1 in a rate test. The results indicate the promising potential of α-Sn in SIBs.