Zhanliang Tao

Functional Materials for Rechargeable Batteries

There is an ever-growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large-scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries.

Rapid room-temperature synthesis of nanocrystalline spinels as oxygen reduction and evolution electrocatalysts

Spinels can serve as alternative low-cost bifunctional electrocatalysts for oxygen reduction/evolution reactions (ORR/OER), which are the key barriers in various electrochemical devices such as metal-air batteries, fuel cells and electrolysers. However, conventional ceramic synthesis of crystalline spinels requires an elevated temperature, complicated procedures and prolonged heating time, and the resulting product exhibits limited electrocatalytic performance. It has been challenging to develop energy-saving, facile and rapid synthetic methodologies for highly active spinels. In this Article, we report the synthesis of nanocrystalline M(x)Mn(3-x)O(4) (M = divalent metals) spinels under ambient conditions and their electrocatalytic application. We show rapid and selective formation of tetragonal or cubic M(x)Mn(3-x)O(4) from the reduction of amorphous MnO(2) in aqueous M(2+) solution. The prepared Co(x)Mn(3-x)O(4) nanoparticles manifest considerable catalytic activity towards the ORR/OER as a result of their high surface areas and abundant defects. The newly discovered phase-dependent electrocatalytic ORR/OER characteristics of Co-Mn-O spinels are also interpreted by experiment and first-principle theoretical studies.

MoS2 Nanoflowers with Expanded Interlayers as High-Performance Anodes for Sodium-Ion Batteries†

MoS2 nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries. By controlling the cut-off voltage to the range of 0.4-3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS2 nanoflower electrode shows high discharge capacities of 350 mAh g(-1) at 0.05 A g(-1) , 300 mAh g(-1) at 1 A g(-1) , and 195 mAh g(-1) at 10 A g(-1) . An initial capacity increase with cycling is caused by peeling off MoS2 layers, which produces more active sites for Na(+) storage. The stripping of MoS2 layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na(+) ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high-rate capability. Therefore, MoS2 nanoflowers with expanded interlayers hold promise for rechargeable Na-ion batteries.

FeSe2 Microspheres as a High‐Performance Anode Material for Na‐Ion Batteries

FeSe2 microspheres assembled by nano-octahedra are used as an anode material for Na-ion batteries for the first time, showing a high discharge capacity (447 mA h g(-1) at 0.1 A g(-1)), excellent rate performance (388 mA h g(-1) at 5 A g(-1) and 226 mA h g(-1) at 25 A g(-1)), and long cycling stability (372 mA h g(-1) after 2000 cycles at 1 A g(-1)).

Porous LiMn2O4 nanorods with durable high-rate capability for rechargeable Li-ion batteries

In this paper, we demonstrated the preparation and application of porous LiMn2O4 nanorods as cathode materials for rechargeable lithium-ion batteries. Solid-state lithiation of porous Mn2O3 nanorods, resulting from thermal decomposition of MnC2O4 precursor, led to the formation of porous LiMn2O4 nanorods with high crystallinity and phase purity. Without surface modification, the as-synthesized porous nanorods exhibited superior high-rate capability and cyclability to the counterpart nonporous nanorods and nanoparticles. An initial discharge capacity of 105 mAh g−1 could be delivered at 10 C rate, and capacity retention of about 90% was obtained after 500 cycles at this high rate. The durable high-rate capability was attributed to the unique porous one-dimensional (1D) nanostructure that gave rise to fast Li-intercalation kinetics and good structural stability for the spinel electrodes. The beneficial gains from 1D porous nanoarchitecture may enlighten the design and construction of new spinel-based electrode for high power applications.

Organic Li4C8H2O6 Nanosheets for Lithium-Ion Batteries

Organic tetralithium salts of 2,5-dihydroxyterephthalic acid (Li4C8H2O6) with the morphologies of bulk, nanoparticles, and nanosheets have been investigated as the active materials of either positive or negative electrode of rechargeable lithium-ion batteries. It is demonstrated that, in the electrolyte of LiPF6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC), reversible two-Li-ion electrochemical reactions are taking place with redox Li4C8H2O6/Li2C8H2O6 at ~2.6 V for a positive electrode and Li4C8H2O6/Li6C8H2O6 at ~0.8 V for a negative electrode, respectively. In the observed system, the electrochemical performance of high to low order is nanosheets > nanoparticles > bulk. Remarkably, Li4C8H2O6 nanosheets show the discharge capacities of 223 and 145 mAh g(-1) at 0.1 and 5 C rates, respectively. A capacity retention of 95% is sustained after 50 cycles at 0.1 C rate charge/discharge and room temperature. Moreover, charging the symmetrical cells with Li4C8H2O6 nanosheets as the initial active materials of both positive and negative electrodes produces all-organic LIBs with an average operation voltage of 1.8 V and an energy density of about 130 Wh kg(-1), enlightening the design and application of organic Li-reservoir compounds with nanostructures for all organic LIBs.

Composite of sulfur impregnated in porous hollow carbon spheres as the cathode of Li-S batteries with high performance

AbstractCarbon-sulfur composites as the cathode of rechargeable Li-S batteries have shown outstanding electrochemical performance for high power devices. Here, we report the promising electrochemical charge-discharge properties of a carbon-sulfur composite, in which sulfur is impregnated in porous hollow carbon spheres (PHCSs) via a melt-diffusion method. Instrumental analysis shows that the PHCSs, which were prepared by a facile template strategy, are characterized by high specific surface area (1520 m2·g−1), large pore volume (2.61 cm3·g−1), broad pore size distribution from micropores to mesopores, and high electronic conductivity (2.22 S·cm−1). The carbon-sulfur composite with a sulfur content of 50.2 wt.% displays an initial discharge capacity of 1450 mA·h·g−1 (which is 86.6% of the theoretical specific capacity) and a reversible discharge capacity of 1357 mA·h·g−1 after 50 cycles at 0.05 C charge-discharge rate. At a higher rate of 0.5C, the capacity stabilized at around 800 mA·h·g−1 after 30 cycles. The results illustrate that the porous carbon-sulfur composites with hierarchically porous structure have potential application as the cathode of Li-S batteries because of their effective improvement of the electronic conductivity, the repression of the volume expansion, and the reduction of the shuttling loss.

All-Solid-State Lithium Organic Battery with Composite Polymer Electrolyte and Pillar[5]quinone Cathode

The cathode capacity of common lithium ion batteries (LIBs) using inorganic electrodes and liquid electrolytes must be further improved. Alternatively, all-solid-state lithium batteries comprising the electrode of organic compounds can offer much higher capacity. Herein, we successfully fabricated an all-solid-state lithium battery based on organic pillar[5]quinone (C35H20O10) cathode and composite polymer electrolyte (CPE). The poly(methacrylate) (PMA)/poly(ethylene glycol) (PEG)-LiClO4-3 wt % SiO2 CPE has an optimum ionic conductivity of 0.26 mS cm(-1) at room temperature. Furthermore, pillar[5]quinine cathode in all-solid-state battery rendered an average operation voltage of ∼2.6 V and a high initial capacity of 418 mAh g(-1) with a stable cyclability (94.7% capacity retention after 50 cycles at 0.2C rate) through the reversible redox reactions of enolate/quinonid carbonyl groups, showing favorable prospect for the device application with high capacity.

Selective Synthesis of Manganese Oxide Nanostructures for Electrocatalytic Oxygen Reduction

This work presents two points with respect to manganese oxide (MnO(x)) nanomaterials: their controllable synthesis with desired phases and shapes together with their applications as catalysts for oxygen reduction and Al/air batteries. Solid MnO(x) with crystalline phases of MnOOH, Mn(2)O(3), and MnO(2) as well as shapes of the sphere, wire, rod, and particle were prepared through a simple one-pot hydrothermal route. Selective preparation was achieved by adjusting the surfactant concentration that controls simultaneously the growth thermodynamic and dynamic parameters of MnO(x) nanocrystals. Electrochemical investigations show that the obtained Mn(2)O(3) nanowires, which possess a large aspect ratio and preferentially exposed (222) crystal surfaces, exhibit remarkable catalytic activity (comparable to Pt/C counterparts) toward the electroreduction of oxygen in alkaline media. The tailored MnO(x) nanostructures may find prospective applications as low-cost catalysts for alkaline fuel cells and metal/air batteries.

Efficient hydrogen storage with the combination of lightweight Mg/MgH2 and nanostructures

Efficient hydrogen storage plays a key role in realizing the incoming hydrogen economy. However, it still remains a great challenge to develop hydrogen storage media with high capacity, favourable thermodynamics, fast kinetics, controllable reversibility, long cycle life, low cost and high safety. To achieve this goal, the combination of lightweight materials and nanostructures should offer great opportunities. In this article, we review recent advances in the field of chemical hydrogen storage that couples lightweight materials and nanostructures, focusing on Mg/MgH(2)-based systems. Selective theoretical and experimental studies on Mg/MgH(2) nanostructures are overviewed, with the emphasis on illustrating the influences of nanostructures on the hydrogenation/dehydrogenation mechanisms and hydrogen storage properties such as capacity, thermodynamics and kinetics. In particular, theoretical studies have shown that the thermodynamics of Mg/MgH(2) clusters below 2 nm change more prominently as particle size decreases.