Porous Amorphous Co2 P/N,B-Co-doped Carbon Composite as an Improved Anode Material for Sodium-Ion Batteries

Engineering Heterostructured Fe-Co-P Arrays for Robust Sodium Storage

Transition metal phosphides attract extensive concerns thanks to their high theoretical capacity in sodium ion batteries (SIBs). Nevertheless, the substantial volume fluctuation of metal phosphides during cycling leads to severe capacity decay, which largely hinders their large-scale deployment. In this regard, heterostructured Fe-Co-P (FeP/Co2P) arrays are firstly constructed in this work for SIBs. The novel self-supported construction without insulated binders favors fast charge migration and Na+ ion diffusion. In addition, the special heterostructure with abundant heterointerfaces could considerably mitigate the volume change during (de)sodiation and provide increased active sites for Na+ ions. Density functional theoretical (DFT) calculations confirm the built-in electric field in the heterointerfaces, which greatly hastens charge transfer and Na+ ion transportation, thereafter bringing about enhanced electrochemical performance. Most importantly, the FeP/Co2P heterostructure discloses higher electrical conductivity than that of bare FeP and Co2P based on the theoretical calculations. As anticipated, the heterostructured Fe-Co-P arrays demonstrate superior performance to that of Fe-P or Co-P anode, delivering high reversible capacities of 634 mAh g-1 at 0.2 A g-1 and 239 mAh g-1 at 1 A g-1 after 300 cycles.

Amorphous Materials for Lithium-Ion and Post-Lithium-Ion Batteries

Lithium-ion and post-lithium-ion batteries are important components for building sustainable energy systems. They usually consist of a cathode, an anode, an electrolyte, and a separator. Recently, the use of solid-state materials as electrolytes has received extensive attention. The solid-state electrolyte materials (as well as the electrode materials) have traditionally been overwhelmingly crystalline materials, but amorphous (disordered) materials are gradually emerging as important alternatives because they can increase the number of ion storage sites and diffusion channels, enhance solid-state ion diffusion, tolerate more severe volume changes, and improve reaction activity. To develop superior amorphous battery materials, researchers have conducted a variety of experiments and theoretical simulations. This review highlights the recent advances in using amorphous materials (AMs) for fabricating lithium-ion and post-lithium-ion batteries, focusing on the correlation between material structure and properties (e.g., electrochemical, mechanical, chemical, and thermal ones).  We  review both the conventional and the emerging characterization methods for analyzing AMs and present the roles of disorder in influencing the performances of various batteries such as those based on lithium, sodium, potassium, and zinc. Finally,  we  describe the challenges and perspectives for commercializing rechargeable AMs-based batteries.

Novel Bifunctional Nitrogen Doped MoS2/COF-C4N Vertical Heterostructures for Electrocatalytic HER and OER

Highly active and earth-abundant catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) play vital roles in developing efficient water splitting to produce hydrogen fuels. Here, we reported an effective strategy to fabricate a completely new nitrogen-doped MoS2/COF-C4N vertical heterojunction (N-MoS2/COF-C4N) as precious-metal-free bifunctional electrocatalysts for both HER and OER. Compared with MoS2 and COF-C4N, the obtained vertical N-MoS2/COF-C4N catalyst showed enhanced HER with a low overpotential of 106 mV at 10 mA cm−2, which is six times lower than MoS2. The superior acidic HER activity, molecular mechanism, and charge transfer characteristic of this vertical N-MoS2/COF-C4N were investigated experimentally and theoretically in detail. Its basic OER activity is almost equal to that of COF-C4N with an overpotential of 349 mV at 10 mA cm−2, which showed that the in-situ growing method maintains the exposure of the C active sites to the greatest extent. The preparation and investigation for vertical N-MoS2/COF-C4N provide ideas and a research basis for us to further explore promising overall water-splitting electrocatalysts.

The Progress of Cobalt-Based Anode Materials for Lithium Ion Batteries and Sodium Ion Batteries

Limited by the development of energy storage technology, the utilization ratio of renewable energy is still at a low level. Lithium/sodium ion batteries (LIBs/SIBs) with high-performance electrochemical performances, such as large-scale energy storage, low costs and high security, are expected to improve the above situation. Currently, developing anode materials with better electrochemical performances is the main obstacle to the development of LIBs/SIBs. Recently, a variety of studies have focused on cobalt-based anode materials applied for LIBs/SIBs, owing to their high theoretical specific capacity. This review systematically summarizes the recent status of cobalt-based anode materials in LIBs/SIBs, including Li+/Na+ storage mechanisms, preparation methods, applications and strategies to improve the electrochemical performance of cobalt-based anode materials. Furthermore, the current challenges and prospects are also discussed in this review. Benefitting from these results, cobalt-based materials can be the next-generation anode for LIBs/SIBs.

A S/N-doped high-capacity mesoporous carbon anode for Na-ion batteries

In this work, we have used the electrospinning method to successfully fabricate mesoporous S/N-doped carbon nanofibers (S/N-C), which show a high capacity and high-rate capability in a Na-ion battery. The S/N-C nanofibers delivered a high reversible capacity of 552.5 and 355.3 mA h g⁻¹ at 0.1 and 5 A g⁻¹, respectively.

Assembly of Multifunctional Ni2P/NiS0.66 Heterostructures and Their Superstructure for High Lithium and Sodium Anodic Performance

The combination of structure designs at the microscopic and macroscopic level can efficiently enable electrode materials with greatly enhanced lithium and sodium storage. In this paper, the construction of Ni₂P/NiS_0.66 heterostructures and their assembly into a superstructure at the nanoscale were successfully achieved by a facile and effective strategy. In the obtained superstructure, the Ni₂P/NiS_0.66 heterostructures are homogeneously coated with ultrathin carbon layers (HT-NPS@C) and, at the same time, assembled into a yolk-shell nanosphere. Upon evaluation as the anode materials for Li-ion batteries, the HT-NPS@C delivers a high reversible capacity of 430 mA h g^-1 after 200 cycles at 200 mA g^-1 and ultrastable cyclability with negligible capacity loss over 500 cycles. Furthermore, the coin-type full cell with the LiNi_1/3Co_1/3Mn_1/3O₂ (LNCMO) cathode and HT-NPS@C anode deliver a high specific capacity of 323.5 mA h g^-1 after 50 cycles at 0.3 A g^-1. Apart from an excellent performance as promising anode materials for LIBs (Li-ion batteries), the Na-ion batteries with HT-NPS@C sphere electrodes also manifest a remarkable electrochemical performance.