Mingsen Zheng

α-MnO2 nanorods grown in situ on graphene as catalysts for Li–O2 batteries with excellent electrochemical performance

Through in situ nucleation and growth of α-MnO2 nanorods on graphene nanosheets (GNs), a α-MnO2 nanorod/GN hybrid was synthesized and employed as the catalyst for non-aqueous lithium oxygen (Li–O2) batteries. The α-MnO2/GN hybrid showed excellent catalytic property. It was demonstrated that the catalytic performance of α-MnO2 for ORR and OER was not only associated with the morphology and size of the particles but also with their combination with graphene. The developed in situ synthetic strategy can also be applied to prepare analogous MOx/GN hybrids used in Li–O2 batteries and other energy storage systems.

A novel synergistic composite with multi-functional effects for high-performance Li–S batteries

The rechargeable lithium–sulfur battery is regarded as a promising option for electrochemical energy storage systems owing to its high energy density, low cost and environmental friendliness. Further development of the Li–S battery, however, is still impeded by capacity decay and kinetic sluggishness caused by the polysulfide shuttle and electrode/electrolyte interface issues. Herein, a new type of metal–organic-framework-derived sulfur host containing cobalt and N-doped graphitic carbon (Co–N-GC) was synthesized and reported, in which the catalyzing for S redox, entrapping of polysulfides and an ideal electronic matrix were successfully achieved synchronously, leading to a significant improvement in the Li–S performance. The large surface area and uniform dispersion of cobalt nanoparticles within the N-doped graphitic carbon matrix contributed to a distinct enhancement in the specific capacity, rate performance and cycle stability for Li–S batteries. As a result of this multi-functional arrangement, cathodes with a high sulfur loading of 70 wt% could operate at 1C for over 500 cycles with nearly 100% coulombic efficiency and exhibited an outstanding high-rate response of up to 5C, suggesting that the S@Co–N-GC electrode was markedly improved by the proposed strategy, demonstrating its great potential for use in low-cost and high-energy Li–S batteries.

A multiple coating route to hollow carbon spheres with foam-like shells and their applications in supercapacitor and confined catalysis

Recent advances in the sol–gel process derived resorcinol-formaldehyde (RF) coating strategies offer new opportunities for the synthesis and applications of hollow carbon spheres (HCS). Due to the lack of an effective route for controlling the pore structures, the synthesis of RF resin derived HCS with a high specific surface area for promising applications is still a challenge. In this work, we present a facile and effective template-directed multiple coating route to synthesize RF resin derived HCS with foam-like shells (HCSF). The as-synthesized HCSF exhibit a significantly higher specific surface area (1286 m2 g−1) and larger pore volumes (2.25 cm3 g−1) than the RF resin derived HCS (639 m2 g−1 and 0.56 cm3 g−1). Our experiments demonstrated that the cationic surfactant CTAB plays a critical role in forming the foam-like pore structure. Compared with the RF resin derived HCS, the as-synthesized HCSF show advantageous performances in supercapacitor and confined catalysis due to their unique pore structures.

The Nickel Oxide/CNT Composites with High Capacitance for Supercapacitor

NSFC [200933005, 20903077, 50702047]; National 973 Program [2009CB220102]; Key Project Founded by Fujian Province [2008H0087]

Co4N Nanosheet Assembled Mesoporous Sphere as a Matrix for Ultrahigh Sulfur Content Lithium–Sulfur Batteries

High utilization and loading of sulfur in cathodes holds the key in the realization of Li-S batteries. We here synthesized a Co4N mesoporous sphere, which was made up of nanosheets, via an easy and convenient method. This material presents high affinity, speedy trapping, and absorbing capacity for polysulfides and acts as a bifunctional catalysis for sulfur redox processes; therefore it is an ideal matrix for S active material. With such a mesoporous sphere used as a sulfur host in Li-S batteries, extraordinary electrochemistry performance has been achieved. With a sulfur content of 72.3 wt % in the composite, the Co4N@S delivered a high specific discharge capacity of 1659 mAh g-1 at 0.1 C, almost reaching its theoretic capacity. Also, the battery exhibited a large reversible capacity of about 1100 mAh g-1 at 0.5 C and 1000 mAh g-1 at 1 C after 100 cycles. At a high rate of 2 C and 5 C, after 300 cycles, the discharge capacity finally stabilized at 805 and 585 mAh g-1. Even at a 94.88% sulfur content, the cathode can still deliver an extremely high specific discharge capacity of 1259 mAh g-1 with good cycle performance.

High-Performance Polyoxometalate-Based Cathode Materials for Rechargeable Lithium-Ion Batteries.

The polyoxovanadate cluster Li7[V15O36(CO3)] is shown to be an active cathode material in Li-ion batteries, delivering a capacity of 250 mA h g(-1) at 50 mA g(-1) and 140 mA h g(-1) at 10 A g(-1). Li-ion diffusion is rapid in this material and gives rise to an impressive maximum power density output of 25.7 kW kg(-1) (55 kW L(-1)).

Solid-state microscale lithium batteries prepared with microfabrication processes

National 973 Program [2009CB220102]; National Defence [XMDX2008176]; Fujian province [2006H0090]

Sulfur and nitrogen co-doped hollow carbon spheres for sodium-ion batteries with superior cyclic and rate performance

Sodium ion batteries (SIBs), based on earth-abundant and cost-effective elements, have attracted increasing attention. Carbon-based materials are still the most potential anode materials for SIBs. Because of insufficient interlayer spacing, graphite-based materials used currently in lithium ion batteries are not suitable for SIB anodes. Herein, combining macro-construction and micro-modification, we design and prepare novel SN-co-doped hollow carbon spheres (SN-HCSs) by a new method. The S and N play different roles during sodium ion storage. Due to the hierarchical porous structure and heteroatoms including S and N, the SN-HCS anode exhibits superior performance, especially with high rate capability (110 mA h g−1 at a current density of 10 A g−1) and excellent cyclic stability (cycle as long as 2000 cycles with only 0.0195 mA h g−1 specific capacity decay for each cycle).

An Amorphous Carbon Nitride Composite Derived from ZIF-8 as Anode Material for Sodium-Ion Batteries

An composite comprising amorphous carbon nitride (ACN) and zinc oxide is derived from ZIF-8 by pyrolysis. The composite is a promising anode material for sodium-ion batteries. The nitrogen content of the ACN composite is as high as 20.4 %, and the bonding state of nitrogen is mostly pyridinic, as determined by X-ray photoelectron spectroscopy (XPS). The composite exhibits an excellent Na(+) storage performance with a reversible capacity of 430 mA h g(-1) and 146 mA h g(-1) at current densities of 83 mA g(-1) and 8.33 A g(-1) , respectively. A specific capacity of 175 mA h g(-1) was maintained after 2000 cycles at 1.67 A g(-1) , with only 0.016 % capacity degradation per cycle. Moreover, an accelerating rate calorimetry (ARC) test demonstrates the excellent thermal stability of the composite, with a low self heating rate and high onset temperature (210 °C). These results shows its promise as a candidate material for high-capacity, high-rate anodes for sodium-ion batteries.

Study on SnO2/graphene composites with superior electrochemical performance for lithium-ion batteries

In this study, the in situ growth of tin dioxide (SnO2) nanoparticles on reduced graphene oxide (rGO) has been realized using a hydrothermal method. The size of the SnO2 nanoparticles in the SnO2/rGO composites prepared by three different procedures is about 5 nm, and they are well dispersed on rGO. When applied as anode materials for lithium-ion batteries, we found that the composites synthesized from the stannous oxalate precursor showed the best rate performance and highest cyclic stability. The surface status of the composites, including interactions between SnO2 and rGO and surface chemical components, was investigated in detail in order to understand why the composites prepared using different procedures displayed vastly different electrochemical performances. The results presented here describe a new approach for the synthesis of uniform and nanosized metal-oxide/rGO composites with excellent electrochemical performance.