Li1.2Mn0.54Ni0.13Co0.13O2 nanosheets with porous structure as a high-performance cathode material for lithium-ion batteries.

The morphological and structural optimizations of electrode materials are efficient ways to enhance their electrochemical performance. Herein, we report a facile co-precipitation and subsequent calcination method to fabricate Li1.2Mn0.54Ni0.13Co0.13O2 nanosheets consisting of interconnected primary nanoparticles and open holes through the full thickness. By comparing the nanosheets and the agglomerated nanoparticles, the effects of the morphology and structure on the electrochemical performance are investigated. Specifically, the nanosheets exhibit a discharge capacity of 210 mA h g-1 at 0.5C with a capacity retention of 85% after 100 cycles. The improved electrochemical performance could be attributed to their morphological and structural improvements, which may facilitate sufficient electrolyte contacts, short diffusion paths and good structural integrity during the charge/discharge process. This work provides a feasible approach to fabricate lithium-rich layered oxide cathode materials with 2D morphology and porous structure, and reveals the relationships between their morphology, structure and electrochemical performance.

Controllable preparation of one-dimensional Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials for high-performance lithium-ion batteries.

Lithium-rich layered oxides are attractive candidates of high-energy-density cathode materials for high-performance lithium ion batteries because of their high specific capacity and low cost. Nevertheless, their unsatisfactory rate capability and poor cycling stability have strongly hindered commercial applications in lithium ion batteries, mainly due to the ineffectiveness of the complicated synthesis techniques to control their morphologies and sizes. In this work, the Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with a one-dimensional rod-like morphology were synthesized via a facile co-precipitation route followed by a post-calcination treatment. By reasonably adding NH3·H2O in the co-precipitation reaction, the sizes of the metal oxalate precursors could be rationally varied. The electrochemical measurements displayed that the Li1.2Mn0.54Ni0.13Co0.13O2 short rods delivered a high capacity of 286 mA h g-1 at 0.1C and excellent capacity retention of 85% after 100 cycles, which could be contributed to the improvement of the electrolyte contact, Li+ diffusion, and structural stability of the one-dimension porous structure.

Multiscale regeneration scaffold in vitro and in vivo.

Biocompatible scaffolds play an important role in modulating tissue growth. A gelatin and sodium alginate scaffold with a unique structure produced by a combination of 3-D printing, electrospinning, and vacuum freeze-drying has been developed for tissue engineering. The scaffold is composed of a macrostructure, a honeycomb microporous surface morphology, and nanofibers. This structure meets the design criteria for an ideal tissue engineering scaffold. The scaffold degrades and has low cytotoxicity. The biocompatibility of the scaffold is improved by the favorable cell-matrix interaction; cells attach to the scaffold well and secrete large amounts of extracellular matrix in vitro. Rats with the scaffold implanted survived without signs of complications and the host cells infiltrated the interior of the scaffold. After 2 months in vivo, the scaffold was vascularized and contained collagen fibers. This multiscale regeneration scaffold may be suitable for tissue engineering because of its unique structure, degradation, mechanical properties, and lower cytotoxicity, which support cell infiltration and growth, and promote vascularization and generation of granulation tissue in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1218-1225, 2018.

Inheritance of spherical morphology and optimization of assembled structures during preparation of LiMnPO4 cathodes for high electrochemical properties.

Microspherical structures of cathodes facilitate high tap densities and good cycling stabilities, but their inferior rate capabilities due to low surface permeability for the electrolyte, remains a hurdle. An effective strategy to address this issue would be the optimization of the assembled microspheres structure. In this work, LiMnPO4 hollow microspheres assembled by radially aligned nanoprisms with fully exposed (010) facets are prepared by the solvothermal method using Li3PO4 as the self-sacrificed templates to improve the rate capability. By simply varying ammonium based salts during the solvothermal reaction, the nanoprisms-randomly assembled and the wedges-radially assembled microspheres are also fabricated. A plausible formation mechanism is carefully proposed. When the three kinds of microspheres are evaluated by charge/discharge measurements, their electrochemical properties are highly dependent on the variation of the assembled structures. In particular, microspheres with radially aligned nanoprisms exhibit high rate capabilities, delivering discharge capacities of 125 mA h g-1 at 1C and 113 mA h g-1 at 2C. These results originate from the unique structure of the microspheres, which not only ensures rapid electrolyte penetration to the interior of the shells due to the radial pore channels, but also guarantees fast Li+ insertion into the nanoprisms owing to their fully exposed (010) facets.