Yi-Tao Liu

Flexible and robust MoS2–graphene hybrid paper cross-linked by a polymer ligand: a high-performance anode material for thin film lithium-ion batteries

A flexible and robust MoS2-graphene hybrid paper with an excellent lithium storage capacity is fabricated through cross-linking by a polymer ligand, PEO, and shows potential for the development of high-performance film anodes.

Self-healable, super tough graphene oxide–poly(acrylic acid) nanocomposite hydrogels facilitated by dual cross-linking effects through dynamic ionic interactions

Here we propose a facile, one-pot in situ free radical polymerization strategy to prepare self-healable, super tough graphene oxide (GO)-poly(acrylic acid) (PAA) nanocomposite hydrogels by using Fe3+ ions as a cross-linker. The 3-dimensional network structure of the GO-PAA nanocomposite hydrogels is facilitated by dual cross-linking effects through dynamic ionic interactions: (i) the first cross-linking points are Fe3+ ions creating ionic cross-linking among PAA chains; (ii) the second cross-linking points are GO nanosheets linking PAA chains through Fe3+ coordination. When the GO-PAA nanocomposite hydrogels are under stretching conditions, the ionic interactions among PAA chains can dynamically break and recombine to dissipate energy, while the GO nanosheets coordinated to the PAA chains maintain the configuration of the hydrogels and work as stress transfer centers transferring the stress to the polymer matrix. In this regard, the GO-PAA nanocomposite hydrogels exhibit superior toughness (tensile strength = 777 kPa, work of extension = 11.9 MJ m-3) and stretchability (elongation at break = 2980%). Furthermore, after being treated at 45 °C for 48 h, the cut-off GO-PAA nanocomposite hydrogels exhibit good self-healing properties (tensile strength = 495 kPa, elongation at break = 2470%). The self-healable, super tough GO-PAA nanocomposite hydrogels lay a basis for developing advanced soft materials holding potential applications in modern biomedical engineering and technology.

Delicate ternary heterostructures achieved by hierarchical co-assembly of Ag and Fe3O4 nanoparticles on MoS2 nanosheets: morphological and compositional synergy in reversible lithium storage

Nanostructured transition metal oxides and dichalcogenides have recently emerged as promising anode candidates for lithium-ion batteries due to their extraordinarily high theoretical capacities. Unfortunately, these nanomaterials still face two problems that are detrimental to their ultimate electrochemical performances. First, the morphological deficiency, imposed by their strong tendency to aggregate, inevitably causes a frustrating loss in reversible capacities. Second, the compositional deficiency, resulting from their inherently low conductivity, further hastens the electrolyte degradation leading to awful cyclability. Herein we propose a facile strategy for the hierarchical co-assembly of Ag and Fe3O4 nanoparticles (NPs) on MoS2 nanosheets, aiming to address the morphological and compositional deficiencies simultaneously. The three building blocks, together, act as an appealing trio: (1) the large, elastic and flexible MoS2 nanosheets serve as an ideal substrate to prevent NP aggregation and accommodate the strains during repeated lithation/delithation; (2) the small Fe3O4 NPs contribute superior capacities and rate capabilities by ensuring short Li+ ion diffusion pathways; (3) the highly conductive Ag NPs allow for efficient charge transport. As such, prominent morphological and compositional synergy is emphasized by superior reversible capacities and rate capabilities, ranking our Ag/Fe3O4–MoS2 ternary heterostructures as high-performance anode materials.

Synergistic effect of Cu2+-coordinated carbon nanotube/graphene network on the electrical and mechanical properties of polymer nanocomposites

A novel hybrid nanofiller system, in which oxidized multi-walled carbon nanotubes (MWCNTs) and chemically modified graphene (CMG) are coordinated by copper ions, is fabricated. The CMG sheets are efficiently isolated and bridged by MWCNTs through copper ion coordination to form a uniform network, and the Cu2+-coordinated MWCNT/CMG network can be easily introduced to a variety of polymer matrices by solution mixing. For example, the Cu2+-coordinated MWCNT/CMG network is successfully incorporated in poly(styrene-co-butadiene-co-styrene) (SBS), one of the most widely used synthetic rubbers. The molecular-level dispersion of the nanofillers in the SBS matrix facilitates efficient electron and load transfer. The Cu2+-coordinated MWCNT/CMG network demonstrates a synergistic effect that cannot be achieved by simple physical mixing of the two nanofillers. The obtained SBS nanocomposites have much better electrical and mechanical properties than those filled with MWCNTs, CMG or a non-coordinated hybrid nanofiller system at the same loading. This fabrication method may open the door to a new class of high-performance polymer-matrix composites.

Coordination‐Driven Hierarchical Assembly of Silver Nanoparticles on MoS2 Nanosheets for Improved Lithium Storage

We report a novel strategy for the hierarchical assembly of Ag nanoparticles (NPs) on MoS2 nanosheets through coordination by using a multifunctional organic ligand. The presence of Ag NPs on the surface of MoS2 nanosheets inhibits their agglomeration, thereby providing increased interlayer spacing for easy Li(+) ion intercalation. Such a unique hybrid architecture also ensures sufficient percolation pathways on the whole surface of the MoS2 nanosheets. Moreover, the high rigidity and low deformability of the Ag NPs effectively preserve the hybrid architecture during the charge-discharge process, which translates into a high cycle stability. A prominent synergistic effect between MoS2 and Ag is witnessed. When the Ag content is only 5 wt %, the Ag-MoS2 hybrid delivers a reversible capacity as high as 920 mA h g(-1) at a current density of 100 mA g(-1), making the Ag-MoS2 hybrid an attractive candidate for next-generation LIBs.

Facile and elegant self-organization of Ag nanoparticles and TiO2 nanorods on V2O5 nanosheets as a superior cathode material for lithium-ion batteries

To address the deficiencies of poor electronic conductivity and strong tendency towards aggregation suffered by V2O5 nanosheets, here we propose a facile and elegant self-organization strategy to decorate them simultaneously with Ag nanoparticles and TiO2 nanorods, resulting in novel two-dimensional hybrid architectures. The addition of TiO2 is able to enhance the Li+ intercalation rate and capacity of V2O5, while the introduction of Ag is capable of allowing for efficient electron transport from the current collector to the electrode. Moreover, the two dopants can effectively isolate the V2O5 nanosheets from restacking, thereby preserving the electroactive surface areas from being sacrificed. The resulting two-dimensional hybrid architectures exhibit synergistic superiorities in reversible capacity, rate capability and cycle stability over neat V2O5 nanosheets, and hold great promise as a cathode material of lithium-ion batteries.

Constructing Novel Si@SnO2 Core–Shell Heterostructures by Facile Self-Assembly of SnO2 Nanowires on Silicon Hollow Nanospheres for Large, Reversible Lithium Storage

Developing an industrially viable silicon anode, featured by the highest theoretical capacity (4200 mA h g(-1)) among common electrode materials, is still a huge challenge because of its large volume expansion during repeated lithiation-delithiation as well as low intrinsic conductivity. Here, we expect to address these inherent deficiencies simultaneously with an interesting hybridization design. A facile self-assembly approach is proposed to decorate silicon hollow nanospheres with SnO2 nanowires. The two building blocks, hand in hand, play a wonderful duet by bridging their appealing functionalities in a complementary way: (1) The silicon hollow nanospheres, in addition to the major role as a superior capacity contributor, also act as a host material (core) to partially accommodate the volume expansion, thus alleviating the capacity fading by providing abundant hollow interiors, void spaces, and surface areas. (2) The SnO2 nanowires serve as a conductive coating (shell) to enable efficient electron transport due to a relatively high conductivity, thereby improving the cyclability of silicon. Compared to other conductive dopants, the SnO2 nanowires with a high theoretical capacity (790 mA h g(-1)) can contribute outstanding electrochemical reaction kinetics, further adding value to the ultimate electrochemical performances. The resulting novel Si@SnO2 core-shell heterostructures exhibit remarkable synergy in large, reversible lithium storage, delivering a reversible capacity as high as 1869 mA h g(-1)@500 mA g(-1) after 100 charging-discharging cycles.

Scalable production of transition metal disulphide/graphite nanoflake composites for high-performance lithium storage

A facile, industrially viable strategy is proposed for the scalable production of transition metal disulphide/graphite nanoflake composites by a combination of ball milling and short-time sonication. The experimental conditions are mild and energy efficient, and the yields are fairly high. This strategy can produce larger MoS2 and WS2 nanoflakes with more lithium storage sites than the conventional, long-time sonication method. Besides, the obtained graphite nanoflakes have a higher degree of lattice integrity than reduced graphene oxide that is structurally permanently damaged, and can thus serve as a high-efficiency conductive additive. A prominent synergy is witnessed between the excellent electrochemical performances of the MoS2 and WS2 nanoflakes and the high electronic conductivity of the graphite nanoflakes. The resulting MoS2 and WS2/graphite nanoflake composites exhibit superior lithium storage capacities, cycling stabilities and rate capabilities, thus providing a basis for developing high-performance anodes of next-generation lithium-ion batteries.

Multi-dimensionally ordered, multi-functionally integrated r-GO@TiO2(B)@Mn3O4 yolk–membrane–shell superstructures for ultrafast lithium storage

TiO2(B) is an attractive new anode candidate for lithium-ion batteries (LIBs) due to its unique and highly desirable properties, including high structural integrity, long cycle life, and low cost. However, despite these merits, its inherent slow lithium and electron transport kinetics hinder its practical application to LIBs. Here, we propose a novel, simple route towards multi-dimensionally ordered, multi-functionally integrated reduced graphene oxide (r-GO)@TiO2(B)@Mn3O4 yolk–membrane–shell superstructures in which r-GO nanosheets, TiO2(B) nanosheets, and Mn3O4 nanoparticles are hierarchically organized to achieve remarkable synergistic interactions. This hybridization design is fundamentally bilateral in nature, aiming to overcome the conductivity and capacity deficiencies of TiO2(B) simultaneously. The resulting r-GO@TiO2(B)@Mn3O4 yolk–membrane–shell superstructures have great potential as advanced anode materials for ultrafast lithium storage, delivering a strikingly high reversible capacity of 662 mA·h·g−1 at 500 mA·g−1 after 500 charge–discharge cycles.

h-BN Nanosheets as 2D Substrates to Load 0D Fe3O4 Nanoparticles: A Hybrid Anode Material for Lithium-Ion Batteries.

h-BN, as an isoelectronic analogue of graphene, has improved thermal mechanical properties. Moreover, the liquid-phase production of h-BN is greener since harmful oxidants/reductants are unnecessary. Here we report a novel hybrid architecture by employing h-BN nanosheets as 2D substrates to load 0D Fe3O4 nanoparticles, followed by phenol/formol carbonization to form a carbon coating. The resulting carbon-encapsulated h-BN@Fe3O4 hybrid architecture exhibits synergistic interactions: 1) The h-BN nanosheets act as flexible 2D substrates to accommodate the volume change of the Fe3O4 nanoparticles; 2) The Fe3O4 nanoparticles serve as active materials to contribute to a high specific capacity; and 3) The carbon coating not only protects the hybrid architecture from deformation but also keeps the whole electrode highly conductive. The synergistic interactions translate into significantly enhanced electrochemical performances, laying a basis for the development of superior hybrid anode materials.