Duihai Tang

Chemically bonded phosphorus/graphene hybrid as a high performance anode for sodium-ion batteries.

Room temperature sodium-ion batteries are of great interest for high-energy-density energy storage systems because of low-cost and natural abundance of sodium. Here, we report a novel phosphorus/graphene nanosheet hybrid as a high performance anode for sodium-ion batteries through facile ball milling of red phosphorus and graphene stacks. The graphene stacks are mechanically exfoliated to nanosheets that chemically bond with the surfaces of phosphorus particles. This chemical bonding can facilitate robust and intimate contact between phosphorus and graphene nanosheets, and the graphene at the particle surfaces can help maintain electrical contact and stabilize the solid electrolyte interphase upon the large volume change of phosphorus during cycling. As a result, the phosphorus/graphene nanosheet hybrid nanostructured anode delivers a high reversible capacity of 2077 mAh/g with excellent cycling stability (1700 mAh/g after 60 cycles) and high Coulombic efficiency (>98%). This simple synthesis approach and unique nanostructure can potentially be applied to other phosphorus-based alloy anode materials for sodium-ion batteries.

Phosphorus‐Graphene Nanosheet Hybrids as Lithium‐Ion Anode with Exceptional High‐Temperature Cycling Stability

A red phosphorus‐graphene nanosheet hybrid is reported as an anode material for lithium‐ion batteries. Graphene nanosheets form a sea‐like, highly electronically conductive matrix, where the island‐like phosphorus particles are dispersed. Benefiting from this structure and properties of phosphorus, the hybrid delivers high initial capacity and exhibits promising retention at 60 °C.

Polyanthraquinone as a Reliable Organic Electrode for Stable and Fast Lithium Storage

In spite of recent progress, there is still a lack of reliable organic electrodes for Li storage with high comprehensive performance, especially in terms of long-term cycling stability. Herein, we report an ideal polymer electrode based on anthraquinone, namely, polyanthraquinone (PAQ), or specifically, poly(1,4-anthraquinone) (P14AQ) and poly(1,5-anthraquinone) (P15AQ). As a lithium-storage cathode, P14AQ showed exceptional performance, including reversible capacity almost equal to the theoretical value (260 mA h g(-1); >257 mA h g(-1) for AQ), a very small voltage gap between the charge and discharge curves (2.18-2.14=0.04 V), stable cycling performance (99.4% capacity retention after 1000 cycles), and fast-discharge/charge ability (release of 69% of the low-rate capacity or 64% of the energy in just 2 min). Exploration of the structure-performance relationship between P14AQ and related materials also provided us with deeper understanding for the design of organic electrodes.

Bis(2,2,2-trifluoroethyl) ether as an electrolyte co-solvent for mitigating self-discharge in lithium-sulfur batteries.

Lithium-sulfur batteries suffer from severe self-discharge because of polysulfide dissolution and side reaction. In this work, a novel electrolyte containing bis(2,2,2-trifluoroethyl) ether (BTFE) was used to mitigate self-discharge of Li-S cells having both low- and high-sulfur-loading sulfur cathodes. This electrolyte meaningfully decreased self-discharge at elevated temperature, though differences in behavior of cells with high- and low-sulfur-loading were also noted. Further investigation showed that this effect likely stems from the formation of a more robust protective film on the anode surface.

Self-Templated Synthesis of Mesoporous Carbon from Carbon Tetrachloride Precursor for Supercapacitor Electrodes.

A high-surface-area mesoporous carbon material has been synthesized using a self-templating approach via reduction of carbon tetrachloride by sodium potassium alloy. The advantage is the reduction-generated salt templates can be easily removed with just water. The produced mesoporous carbon has a high surface area and a narrow pore size distribution. When used as a supercapacitor electrode, this material exhibits a high specific capacitance (259 F g(-1)) and excellent cycling performance (>92% capacitance retention for 6000 cycles).

Titanium nitride coating to enhance the performance of silicon nanoparticles as a lithium-ion battery anode

Titanium nitride (TiN) coated silicon nanoparticles were synthesized via reduction of TiO2-coated silicon nanoparticles under nitrogen. When evaluated as an anode for lithium-ion batteries, the material exhibited stable performance and excellent coulombic efficiency for 100 charge–discharge cycles at 0.1 C rate, in addition to significantly enhanced rate performance.

A study of a fluorine substituted phenyl based complex as a 3 V electrolyte for Mg batteries

An electrolyte with a wide electrochemically stable window and high efficiency for reversible Mg deposition/dissolution is a key component of Mg battery systems. In the present study, functional-group-substituted phenyl-based Mg battery electrolytes have been prepared by direct reactions between the Lewis acid AlCl3 and various fluorine substituted Lewis bases. The substitution effects of these functional groups on the anodic stability of the electrolyte and the efficiency for Mg deposition/dissolution have been studied by electrochemical analysis and first-principles density functional theory calculations. This study indicates that the para-substituted fluorine complex (4-F-PhMgBr)2-AlCl3/THF is an excellent 3 V electrolyte for Mg batteries with respect to the electrochemical stability and efficiency of reversible Mg deposition/dissolution. Both the experimental results and theoretical calculations are consistent and indicate that electron-withdrawing groups with small steric effects on phenyl rings improve the electrolyte stability and reversibility by decreasing the HOMO and increasing the LUMO energy levels of the complex component, while electron-donating groups have profound detrimental influences. This investigation provides further understanding of the electrolyte chemistry of Mg batteries and advances the design and optimization of new electrolytes.

Functionalized mesoporous silica nanoparticles as a catalyst to synthesize a luminescent polymer/silica nanocomposite

A bi-functionalized silica nanoparticle catalyst was synthesized by both generating rare earth oxide nanoparticles in the pore channels of the mesoporous silica support and grafting salicylaldimine cobalt complex on the surface of the silica. The nanocatalyst shows a strong green luminescence upon irradiation with ultraviolet light and also shows high activity for the polymerization of isoprene. The core–shell structure of this nanocomposite can protect the rare earth oxide from dissolving in hydrochloric acid. This process could produce a novel luminescent polymer/silica composite, and the polymer/silica nanocomposite formed also shows green luminescence.