Encapsulating MWNTs into Hollow Porous Carbon Nanotubes: A Tube‐in‐Tube Carbon Nanostructure for High‐Performance Lithium‐Sulfur Batteries

Abstract

A tube-in-tube carbon nanostructure (TTCN) with multi-walled carbon nanotubes (MWNTs) confined within hollow porous carbon nanotubes is synthesized for Li-S batteries. The structure is designed to enhance the electrical conductivity, hamper the dissolution of lithium polysulfide, and provide large pore volume for sulfur impregnation. As a cathode material for Li-S batteries, the S-TTCN composite with 71 wt% sulfur content delivers high reversible capacity, good cycling performance as well as excellent rate capabilities.

Porous AgPd–Pd Composite Nanotubes as Highly Efficient Electrocatalysts for Lithium–Oxygen Batteries

“…Therefore, the diffraction patterns can be indexed as mixed phase AgPd alloy Porous nanotubes (NTs) have become increasingly important nanomaterials in electronics, energy storage, catalysis, and fuel cell applications. [1][2][3][4][5][6][7] In contrast to the intact walls of conventional NTs, this structural feature will result in a much more adsorption effi ciency and abundant active catalytic sites, because molecules and electrolyte can enter into the hollow cavities of porous NTs via not only the two narrow ends but also holes along the tube wall. [ 3,[7][8][9] Especially in the fi eld of energy storage and conversion, these 1D porous nanostructures can also form a continuous conductive network and improve the adsorption of and immersion in electrolyte on the surfaces of electroactive materials in order to facilitate the electrode reaction kinetics for high energy density.…”

“…[1][2][3][4][5][6][7] In contrast to the intact walls of conventional NTs, this structural feature will result in a much more adsorption effi ciency and abundant active catalytic sites, because molecules and electrolyte can enter into the hollow cavities of porous NTs via not only the two narrow ends but also holes along the tube wall. [ 3,[7][8][9] Especially in the fi eld of energy storage and conversion, these 1D porous nanostructures can also form a continuous conductive network and improve the adsorption of and immersion in electrolyte on the surfaces of electroactive materials in order to facilitate the electrode reaction kinetics for high energy density. [10][11][12][13][14] This porous 1D structure will be even more promising for increasing the catalytic activities toward the two key processes in lithium oxygen battery, oxygen reduction reaction (ORR) (O 2 + 2Li + + 2e − → Li 2 O 2 ) and the oxygen evolution reaction (OER) (Li 2 O 2 → O 2 + 2Li + + 2e − ) by facilitating rapid O 2 diffusion and electrolyte accessibility, and providing more catalytic reaction sites for deposition of Li 2 O 2 .…”

Dual‐Confined Flexible Sulfur Cathodes Encapsulated in Nitrogen‐Doped Double‐Shelled Hollow Carbon Spheres and Wrapped with Graphene for Li–S Batteries

“…[ 7,8 ] These problems not only lead to poor cycling stability, inferior rate capability, and low Coulombic efficiency, but also cause the deposition of insulating Li 2 S/Li 2 S 2 on both electrodes, resulting in low sulfur utilization and even triggering a series of safety problems. [9][10][11] To address these issues, signifi cant efforts have been dedicated to fabricate novel nanostructured carbon-sulfur composite electrodes, such as 3D hyperbranched hollow carbon nanorod/sulfur, [ 12 ] hollow carbon sphere/sulfur, [ 10,13 ] hollow carbon nanofi ber or nanotube/sulfur, [ 14,15 ] ordered mesomicroporous core-shell carbon/sulfur, [ 16 ] unstacked double-layer templated graphene/sulfur, [ 17 ] hollow graphene sphere/sulfur, [ 18 ] interconnected carbon nanotube/graphene nanosphere/sulfur, [ 19 ] and tube-in-tube carbon/ sulfur [ 20 ] nanocomposites. These porous carbon matrices are commonly believed to play dual roles in sulfur-carbon composites: suppress the polysulfi de diffusion and build conductive framework facilitating electron/ion transport.…”

Multifunctionality of Carbon-based Frameworks in Lithium Sulfur Batteries

“…Moreover, the specific surface of CNTs is small and lacks porosity, leading to a lack of void spaces to encapsulate sulfur and restrain the shuttle effects of polysulfides. This issue can be resolved, however, by using CNT networks or 3D structures [93][94][95]. One method of overcoming the drawbacks of CNTs is to use multi-walled carbon nanotubes (MCNTs).…”

“…One method of overcoming the drawbacks of CNTs is to use multi-walled carbon nanotubes (MCNTs). For example, Zhao et al [93] used hollow porous carbon to encapsulate MCNTs. (Preparation and synthesis methods are displayed in Fig.…”