PhD Student, The University of Queensland
Devlopment of high performance sodium-ion batteries using hard carbon material based anodes.
Lithium-ion batteries (LIBs) power most portable electronic devices today. However, the geographical limitation of lithium might increase the battery price in near future and also make the supply chain susceptible to political instabilities. Therefore, the next generation of energy storage must rely on something other than the Li-ion technology. Sodium (Na) is one of the promising candidates that can replace Li, not only because of its abundance but also due to similar chemistries with Li intercalation. To commercialise sodium-ion battery (NIBs) technology, it is imperative to find a suitable anode material that can reversibly interact with sodium ions. Therefore, mywork aims to study carbonaceous materials derived from biomass as high performance anodes in NIBs.
Abstract: Sodium ion batteries (SIBs) have recently attracted considerable attention and are considered as an alternative to lithium ion batteries (LIBs), owing to the cheap price and abundance of sodium resources. However, the commercialization of SIBs has so far been impeded by the low energy density and unstable cycle life of electrodes, especially as cathodes. Although some cathode candidates with a stable cycle life and high energy density have been developed using nanotechnologies, the commercial feasibility is seldom taken into account. This research news article provides an insight into the commercial prospects of existing cathode materials for SIBs in terms of environmental friendliness, manufacturing cost, synthesis methods and electrochemical performance.
Pub.: 11 Jul '17, Pinned: 16 Aug '17
Abstract: Sodium-ion batteries are strategically pivotal to achieving large-scale energy storage. Layered oxides, especially manganese-based oxides, are the most popular cathodes due to their high reversible capacity and use of earth-abundant elements. However, less noticed is the fact that the interface of layered cathodes always suffers from atmospheric and electrochemical corrosion, leading to severely diminished electrochemical properties. Herein, we demonstrate an environmentally stable interface via the superficial concentration of titanium, which not only overcomes the above limitations, but also presents unique surface chemical/electrochemical properties. The results show that the atomic-scale interface is composed of spinel-like titanium (III) oxides, enhancing the structural/electrochemical stability and electronic/ionic conductivity. Consequently, the interface-engineered electrode shows excellent cycling performance among all layered manganese-based cathodes, as well as high-energy density. Our findings highlight the significance of a stable interface and, moreover, open opportunities for the design of well-tailored cathode materials for sodium storage.The interface of layered cathodes for sodium ion batteries is subject to atmospheric and electrochemical corrosions. Here, the authors demonstrate an environmentally stable interface via titanium enriched surface reconstruction in a layered manganese-based oxide.
Pub.: 27 Jul '17, Pinned: 16 Aug '17
Abstract: Tin (II) sulfide (SnS) has been an attractive anode material for sodium ion batteries. Herein, an elegant templating method has been developed for the rational design and synthesis of hierarchical SnS nanotubes composed of ultrathin nanosheets. In order to enhance the electrochemical performance, carbon coated hierarchical SnS nanotubes (denoted as SnS@C nanotubes) have also be obtained by simply adding glucose into the reaction system. Benefiting from their unique structural merits, the SnS@C nanotubes exhibit enhanced sodium storage properties in terms of good cycling performance and superior rate capability.
Pub.: 29 Jul '17, Pinned: 16 Aug '17
Abstract: The hybrid Mg2+/Li+ battery (MLIB) is a very promising energy storage technology that combines the advantage of the Li and Mg electrochemistry. However, previous research has shown that the battery performance is limited due to the strong dependence on the Li content in the dual Mg2+/Li+ electrolyte. This limitation can be circumvented by significantly improving the diffusion kinetics of Mg2+ in the electrode, so that both Li+ and Mg2+ ions can be utilized as charge carriers. Herein, a free-standing interlayer expanded MoS2/graphene composite (E-MG) is demonstrated as a cathode for MLIB. The key advantage of this cathode is to enable the efficient intercalation of both Mg2+ and Li+. The E-MG electrode displays a reversible capacity of ≈300 mA h g−1 at 20 mA g−1 in an MLIB cell, corresponding to a specific energy density up to ≈316.9 W h kg−1, which is comparable to that of the state-of-the-art Li-ion batteries (LIBs) and has no dendrite formation. The composite electrode is stable against cycling with a coulombic efficiency close to 100% at 500 mA g−1. This new electrode design represents a significant step forward for building a safe and high-density electrochemical energy storage system.
Pub.: 26 May '17, Pinned: 16 Aug '17
Abstract: Synthesis of carbon dots (Cdots) via chemical route involves disintegration of carbon materials into nano-domains, wherein, after extraction of Cdots, the remaining carbon material is discarded. The present work focuses on studying even the leftover carbon residue namely, carbon nanobeads (CNBs) as an equally important material for applications on par with that of carbon dot. It employs oxidative treatment of carbonised gum olibanum resin (GOR) to produce the carbons namely Cdots and CNBs (as the residue). The Cdots (~5-10nm) exhibit blue-green fluorescence with an optical absorption at ~300nm unlike the CNBs (40-50nm) which fail to exhibit fluorescence. The fluorescence behaviour exhibited by Cdots were utilized for heavy metal ion sensing of Pb(2+), Hg(2+) and Cd(2+) ions in aqueous media. Interestingly, both Cdots and CNBs are biocompatible to normal cell lines but cytotoxic to cancer cell lines, observed during several in vitro experiments (cell viability assay, cell cycle assay, apoptosis assay, ROS determination assay, caspase-9 activity assay). Additionally, Cdots exhibit bright green fluorescence in B16F10 cells. The Cdots and CNB's demonstrate multifunctional activities (sensor, cellular imaging and cancer therapy) in biomedical applications.
Pub.: 12 Feb '17, Pinned: 27 Jul '17
Abstract: Chemically derived graphene holds great promise as an electrode material for electrochemical energy storage owing to its unique physical and chemical properties. Recent years have witnessed tremendous research breakthroughs in the field of graphene-based materials for electrochemical capacitors. This article presents a review of the latest developments in the functionalization of chemically derived graphene for improving its electrocapacitive properties. Beginning with a brief description of supercapacitors, graphene, and chemically derived graphene, we discuss the preparation, electrocapacitive properties, and drawbacks of chemically derived graphene and its derivatives, followed by a discussion on how to functionalize chemically derived graphene for improving its double-layer capacitance and pseudocapacitance. Emphasis is made on comparing and highlighting demonstrated approaches to functionalizing chemically derived graphene. Future research towards developing advanced electrochemical capacitors, perspectives and challenges are outlined.
Pub.: 29 Apr '16, Pinned: 27 Jul '17
Abstract: The performance of few-layered metal-reduced graphene oxide (RGO) as a negative electrode material in sodium-ion battery was investigated. Experimental and simulation results indicated that the as-prepared RGO with a large interlayer spacing and disordered structure enabled significant sodium-ion storage, leading to a high discharge capacity. The strong surface driven interactions between sodium ions and oxygen-containing groups and/or defect sites led to a high rate performance and cycling stability. The RGO anode delivered a discharge capacity of 272 mA h g−1 at a current density of 50 mA g−1, a good cycling stability over 300 cycles and a superior rate capability. The present work provides new insights into optimizing RGOs for high-performance and low-cost sodium-ion batteries.
Pub.: 12 Aug '16, Pinned: 27 Jul '17
Abstract: In this paper, we report a flame deposition method to prepare carbon nanoparticles (CNPs) from coconut oil. The CNPs were further modified with a piranha solution to obtain surface-carboxylated carbon nanoparticles (c-CNPs). When used as an anode for sodium-ion batteries, the CNPs and c-CNPs respectively delivered discharge capacities of 277 and 278 mAhg−1 in the second cycle at a current density of 100 mAg−1. At the 20th cycle, the capacities of CNP and c-CNPs were 217 and 206 mAhg−1 respectively. The results suggest that modification of the CNPs with the piranha solution improved neither the charge storage capacity nor the stability against cycling in a sodium-ion battery. When the CNP and c-CNP were used an anode in a lithium-ion battery, 2nd-cycle discharge capacities of 741 and 742 mAhg−1 respectively at a current density of 100 mAg−1 were obtained. After 20 cycles the capacities of CNP and c-CNP became 464 and 577 mAhg−1 respectively, showing the cycling stability of the CNPs was improved after modification. The excellent cycling performance, high capacity and good rate capability make the present material as highly promising anodes for both sodium-ion and lithium-ion batteries.
Pub.: 27 May '16, Pinned: 27 Jul '17