As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium-sulfur (Li-S) batteries. In this paper, a mesoporous nitrogen-doped carbon (MPNC)-sulfur nanocomposite is reported as a novel cathode for advanced Li-S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verifi ed by X-ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC-sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm −2 with a high sulfur loading (4.2 mg S cm −2 ) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm −2 ) is demonstrated by using the novel cathode, which is crucial for the practical application of Li-S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon-sulfur composite cathodes for Li-S batteries.

Nitrogen-Doped Mesoporous Carbon Promoted Chemical Adsorption of Sulfur and Fabrication of High-Areal-Capacity Sulfur Cathode with Exceptional Cycling Stability for Lithium-Sulfur Batteries

A Comprehensive Understanding of Lithium–Sulfur Battery Technology

Nanostructured magnesium nickel oxide (Mg₀.₆Ni₀.₄O) was synthesized by a self-propagating high temperature synthesis method followed by heat treatment. The particles of the resulting oxide were used as additives to prepare the sulfur/polyacrylonitrile/Mg₀.₆Ni₀.₄O (S/PAN/Mg₀.₆Ni₀.₄O) composite via wet ballmilling. The SEM observation revealed that the composite morphology was drastically changed by the addition of Mg₀.₆Ni₀.₄O, from smooth bulky particles of S/PAN to rough nanostructured agglomerates with two times the increase in the specific surface area, favouring the reactivity of the composite, and a homogeneous component distribution. Cyclic voltammetry, discharge–charge tests and ac impedance spectroscopy have shown improved conductivity and electrochemical properties of the composite by the addition of Mg₀.₆Ni₀.₄O, leading to high sulfur utilization and interfacial stabilization in a Li/S cell upon discharge–charge cycling. The cell demonstrated enhanced reversibility, resulting in a discharge capacity of about 1223 mA h g⁻¹ at the second cycle and retained about 100% of this value over 100 cycles. Furthermore, the S/PAN/Mg₀.₆Ni₀.₄O composite cathode exhibited a good rate capability with discharge capacities of 887, 710 and 445 mA h g⁻¹ at 0.5, 0.7 and 1 C, respectively.

Ternary sulfur/polyacrylonitrile/Mg₀.₆Ni₀.₄O composite cathodes for high performance lithium/sulfur batteries

Recently, due to the excessive consumption of fossil energy and the intermittent nature of clean energy resources, electricity storage has attracted great attention from both academia and industry. Lithium ion batteries (LIBs) with high energy density have been widely used for portable energy storage systems. However, limited lithium resources cannot meet the demands for large-scale applications, especially the grid-scale energy storage. Owing to the abundant natural resources of sodium and the low price, sodium ion batteries (SIBs) have become potential substitutes for LIBs. Cathode materials are key components that determine the overall performance and entire cost of SIBs. However, the unstable structure and limited electrochemical performance make them difficult to meet the requirement of practical applications. This review summarizes the recent development of the cathode materials used for SIBs, and the modified strategies applied to improve their electrochemical performance. Finally, critical challenges and perspectives to promote the development of SIBs are also presented.

Recent progress of emerging cathode materials for sodium ion batteries

Photocatalytic degradation of microcystin-LR by modified TiO2 photocatalysis: A review.

The lack of high-performance cathode materials is a great challenge for the development of large-scale energy storage sodium ion batteries. Here, a new resource-rich P2-type Na0.44Mn0.6Ni0.4−xCuxO2 (0 ≤ x ≤ 0.3) sodium-ion battery (NIBs) cathode material was designed and synthesized by a sol–gel method. Na ions occupy the Naf sites and the Nae sites in a proportion of 1 : 1, which maintains the high symmetry and stability of the P2-type structure. The charging/discharging tests show that Na0.44Mn0.6Ni0.3Cu0.1O2 has a high initial capacity of 149 mA h g−1 and 80% capacity retention after 50 cycles at 0.1C, showing a high energy density of 469 W h kg−1. The addition of inactive copper enhances the lattice spacing, obviously reducing the irreversible reaction resistance (Rf) during the intercalation and deintercalation of Na+, thereby reducing the internal resistance of the battery and improving the cycle performance. In order to maintain the P2-type structure, the voltage is controlled at 1.5–4.0 V during charging and discharging, which inhibits the phase transition of P2-O2, leading to the improvement of cycling performance. Therefore, the Cu-substituted Na0.44Mn0.6Ni0.3Cu0.1O2 possibly serves as a promising high capacity, high energy density and stable cathode for sodium ion battery applications.

A P2-type Na0.44Mn0.6Ni0.3Cu0.1O2 cathode material with high energy density for sodium-ion batteries

Three-dimensional TiO2-B nanotubes/carbon nanotubes intertwined network as sulfur hosts for high performance lithium−sulfur batteries

Lithium–sulfur batteries have been investigated as promising energy storage systems due to their high energy density of 2600 W h kg−1. Although various materials as sulfur hosts can improve the performance of lithium–sulfur batteries, expensive raw materials, complex synthesis and lower sulfur loading impede their practical application. Herein, ultrafine Ti4O7 nanoparticle-embedded porous carbon (PC@Ti4O7) as an efficient sulfur host was facilely prepared using commercial TiO2 nanoparticles and phenolic resin. In this strategy, the highly conductive ultrafine Ti4O7 nanoparticles with abundant active adsorption sites can efficiently trap polysulfides and accelerate their conversion. In addition, the size of the Ti4O7 nanoparticles, depending on the commercial TiO2 nanoparticles, could be easily controlled. Moreover, the sufficient interspaces around the Ti4O7 nanoparticles are beneficial for maximizing the confinement of polysulfides. The hybrid cathode exhibits excellent cycling stability at a high rate of 4C over 1000 cycles. Particularly, the electrode with a sulfur loading of up to 15.6 mg cm−2 retains an ultrahigh areal capacity of 8.6 mA h cm−2 at 0.3C over 100 cycles. The low-cost and facile preparation of the PC@Ti4O7 composite provides new insight for the practical application of lithium–sulfur batteries.

Facile preparation of ultrafine Ti4O7 nanoparticle-embedded porous carbon for high areal capacity lithium–sulfur batteries

Simply and rapidly synthesized composites of MnO2 nanosheets anchoring on carbon nanotubes as efficient sulfur hosts for Li-S batteries

The rechargeable lithium-sulfur batteries were investigated as the most promising energy storage system. Although the composites of carbonaceous materials and metal oxides as the hosts of sulfur ha...

Ao Chen

Papers

A P2-type Na0.44Mn0.6Ni0.3Cu0.1O2 cathode material with high energy density for sodium-ion batteries

Three-dimensional TiO2-B nanotubes/carbon nanotubes intertwined network as sulfur hosts for high performance lithium−sulfur batteries

Facile preparation of ultrafine Ti4O7 nanoparticle-embedded porous carbon for high areal capacity lithium–sulfur batteries

Simply and rapidly synthesized composites of MnO2 nanosheets anchoring on carbon nanotubes as efficient sulfur hosts for Li-S batteries

A novel separator modified by titanium dioxide nanotubes/carbon nanotubes composite for high performance lithium-sulfur batteries