Construction of rice husk-derived SiOx nanoparticles encapsulated with graphene aerogel hybrid for high-performance lithium ion batteries

Tannic acid etching construction of hollow heterogeneous CoSe2-FeSe2@nitrogen-doped carbon rhombic dodecahedron for high-performance sodium storage

Metal selenides are very promising anode materials for sodium ion batteries (SIBs) due to their rich redox behaviors, low cost, high theoretical capacity, and environmentally benign. However, the poor cycle performance and rate capability greatly hinder their widespread applications. In this paper, we have proposed a tannic acid etching zeolitic imidazolate framework-67 (ZIF-67)-derived selenide strategy to construct hollow heterogeneous CoSe2-FeSe2@N-doped carbon rhombic dodecahedron (CoSe2-FeSe2@NC) as anode for high-performance SIBs. The special microstructural characteristics with hollow rhombic dodecahedron can reduce the Na+/electron migration path and alleviate the volume variations during cycling. The NC can improve conductivity and reduce volume effects during cycling. What's more, the built-in electric fields (BIEF) at the CoSe2-FeSe2 heterointerfaces can modulate the electronic structure and accelerate the kinetics of ionic diffusion, resulting in the improvement electrochemical properties. When applied as anodes for SIBs, the CoSe2-FeSe2@NC can deliver a remarkable electrochemical performance in terms of sodium storage capacity (648.5 mAh g-1 at 0.2 A/g), initial coulombic efficiency (82.0 %), cycle performance (92.6 % capacity retention after 100 cycles), and rate capability of 450.6 mAh g-1 after 1000 cycles at a high rate of 1 A/g. The kinetic analysis indicates that the discharging-charging process of CoSe2-FeSe2@NC is ascribed to both capacitive behavior and controlled diffusion.

Heterogeneous bimetallic selenides encapsulated within graphene aerogel as advanced anodes for sodium ion batteries

Metal selenides are promising anode candidates for sodium ion batteries (SIBs) because of their high theoretical capacity, low cost, and environmental friendship. However, the low rate capability at high current density due to its inherent low electrical conductivity and poor cycle stability caused by inevitable volume variations during cycling frustrate its practical applications. Herein, we have developed a simple metallic-organic frameworks (MOFs)-derived selenide strategy to synthesize a series of heterogeneous bimetallic selenides encapsulated within graphene aerogels (GA) as anodes for SIBs. The bimetallic selenides/GA composites have unique structural characteristics that can shorten the migration path for Na+/electrons and accommodate the volume variations via additional void space during cycling. The built-in electric fields induced at the heterointerfaces can greatly reduce the activation energy for rapid charge transfer kinetics and promote the diffusion of Na+/electrons. GA is also beneficial for accommodating the volume variations during cycling and improving conductivity. As an advanced anode for SIBs, the MoSe2-Cu1.82Se@GA with a special porous octahedron can deliver the highest capacity of 444.8 mAh/g at a high rate of 1 A/g even after 1000 cycles among the bimetallic selenides/GA composites.

The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Hollow CoSe2-ZnSe microspheres inserted in reduced graphene oxide serving as advanced anodes for sodium ion batteries

Transition metal selenides are promising anode candidates for sodium ion batteries (SIBs) because of their higher theoretical capacity and conductivity than metal oxides. However, the disadvantages of severe capacity degradation and poor magnification performance greatly limit their commercial applications. Herein, we have developed a new hollow bimetallic selenides (CoSe2-ZnSe)@reduced graphene oxide (rGO) composite with abundant heterointerfaces. The rGO could not only alleviate the volume variations of hollow CoSe2-ZnSe microspheres during cycling, but also improve the conductivity of composite. The presence of the heterointerfaces could help to accelerate ionic diffusion kinetics and improve electron transfer, resulting in the improved sodium storage performance. As an advanced anode for SIBs, the CoSe2-ZnSe@rGO exhibits an enhanced initial coulombic efficiency of 75.1% (65.2% of CoSe2@rGO), extraordinary rate capability, and outstanding cycling stability (540.3 mAh/g at 0.2 A/g after 150 cycles, and 395.2 mAh/g at 1 A/g after 600 cycles). The electrochemical mechanism was also studied by kinetic analysis, showing that the charging/discharging process of CoSe2-ZnSe@rGO is mostly related to a capacitive-controlled behavior.

Honeycomb-like 3D ordered macroporous SiOx/C nanoarchitectures with carbon coating for high-performance lithium storage

SiOx anodes are garnering significant interest in lithium-ion batteries (LIBs) due to theirs low voltage plateau and high capacity. However, critical drawbacks, including high expansion rate and low electronic conductivity, severely limit their practical applications. While 0D, 1D, and 2D scale nanostructures have been proven to mitigate these issues, these materials tend to accumulate after prolonged cycling, leading to adverse effects on the mass transfer processes within the electrode. Herein, we have developed a honeycomb-like SiOx/C nanoarchitecture with carbon coating based on a 3D ordered macroporous (3DOM) structure. The 3D interconnected pore windows facilitate the diffusion and transport of lithium ions (Li+) in the electrolyte, and the extremely thin walls (<15 nm) provide a shorter transport path for Li+ in the solid. The carbon cladding buffers volume expansion and enhances electronic conductivity. The as-prepared anode demonstrates a high reversible capacity of 1068 mAh/g and an initial coulombic efficiency of 70.7 %. It maintains a capacity of 644 mAh/g (capacity retention of 84.63 %) even at a high current of 1.0 A/g after 700 cycles. The unique honeycomb-like structure offers enormous insights into the study of energy storage in 3D materials.