Shiyong Zhao

3D Interconnected Electrode Materials with Ultrahigh Areal Sulfur Loading for Li–S Batteries

Sulfur electrodes based on a 3D integrated hollow carbon fiber foam (HCFF) are synthesized with high sulfur loadings of 6.2-21.2 mg cm(-2) . Benefiting from the high electrolyte absorbability of the HCFF and the multiple conductive channels, the obtained electrode demonstrates excellent cycling stability and a high areal capacity of 23.32 mAh cm(-2) , showing great promise in commercially viable Li-S batteries.

More Reliable Lithium-Sulfur Batteries: Status, Solutions and Prospects

Lithium-sulfur (Li-S) batteries have attracted tremendous interest because of their high theoretical energy density and cost effectiveness. The target of Li-S battery research is to produce batteries with a high useful energy density that at least outperforms state-of-the-art lithium-ion batteries. However, due to an intrinsic gap between fundamental research and practical applications, the outstanding electrochemical results obtained in most Li-S battery studies indeed correspond to low useful energy densities and are not really suitable for practical requirements. The Li-S battery is a complex device and its useful energy density is determined by a number of design parameters, most of which are often ignored, leading to the failure to meet commercial requirements. The purpose of this review is to discuss how to pave the way for reliable Li-S batteries. First, the current research status of Li-S batteries is briefly reviewed based on statistical information obtained from literature. This includes an analysis of how the various parameters influence the useful energy density and a summary of existing problems in the current Li-S battery research. Possible solutions and some concerns regarding the construction of reliable Li-S batteries are comprehensively discussed. Finally, insights are offered on the future directions and prospects in Li-S battery field.

Toward More Reliable Lithium-Sulfur Batteries: An All-Graphene Cathode Structure.

Lithium-sulfur (Li-S) batteries are attracting increasing interest due to their high theoretical specific energy density, low cost, and eco-friendliness. However, most reports of the high gravimetric specific capacity and long cyclic life are not practically reliable because of their low areal specific capacity derived from the low areal sulfur loading and low sulfur content. Here, we fabricated a highly porous graphene with high pore volume of 3.51 cm(3) g(-1) as the sulfur host, enabling a high sulfur content of 80 wt %, and based on this, we further proposed an all-graphene structure for the sulfur cathode with highly conductive graphene as the current collector and partially oxygenated graphene as a polysulfide-adsorption layer. This cathode structural design enables a 5 mg cm(-2) sulfur-loaded cathode showing both high initial gravimetric specific capacity (1500 mAh g(-1)) and areal specific capacity (7.5 mAh cm(-2)), together with excellent cycling stability for 400 cycles, indicating great promise for more reliable lithium-sulfur batteries.

A 3D bi-functional porous N-doped carbon microtube sponge electrocatalyst for oxygen reduction and oxygen evolution reactions

A flexible, large-area three-dimensional porous N-doped carbon microtube (NCMT) sponge was prepared via a simple and low-cost process of pyrolyzing facial cotton. Due to its unique structure with a micron-scale hollow core and well-graphitized and interconnected porous walls, the NCMT sponge exhibits incomparable electrocatalytic activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) with a small potential difference of 0.63 V between the OER current density at 10 mA cm−2 and the ORR current density at −3 mA cm−2, which is the best to date.

High-Quality, Highly Concentrated Semiconducting Single-Wall Carbon Nanotubes for Use in Field Effect Transistors and Biosensors

We developed a simple and scalable selective synthesis method of high-quality, highly concentrated semiconducting single-wall carbon nanotubes (s-SWCNTs) by in situ hydrogen etching. Samples containing ~93% s-SWCNTs were obtained in bulk. These s-SWCNTs with good structural integrity showed a high oxidation resistance temperature of ~800 °C. Thin-film transistors based on the s-SWCNTs demonstrated a high carrier mobility of 21.1 cm(2) V(-1) s(-1) at an on/off ratio of 1.1 × 10(4) and a high on/off ratio of 4.0 × 10(5) with a carrier mobility of 7.0 cm(2) V(-1) s(-1). A biosensor fabricated using the s-SWCNTs had a very low dopamine detection limit of 10(-18) mol/L at room temperature.