Modulating Cation Migration and Deposition with Xylitol Additive and Oriented Reconstruction of Hydrogen Bonds for Stable Zinc Anodes.

Highly reversible plating/stripping in aqueous electrolytes is one of the critical processes determining the performance of Zn-ion batteries, but it is severely impeded by the parasitic side reaction and dendrite growth. Herein, a novel electrolyte engineering strategy is first proposed based on the usage of 100 mM xylitol additive, which inhibits hydrogen evolution reaction and accelerates cations migration by expelling active H2 O molecules and weakening electrostatic interaction through oriented reconstruction of hydrogen bonds. Concomitantly, xylitol molecules are preferentially adsorbed by Zn surface, which provides a shielding buffer layer to retard the sedimentation and suppress the planar diffusion of Zn2+ ions. Zn2+ transference number and cycling lifespan of Zn∥Zn cells have been significantly elevated, overwhelmingly larger than bare ZnSO4 . The cell coupled with a NaV3 O8 cathode still behaves much better than the additive-free device in terms of capacity retention.

Engineering hierarchical porous ternary Co-Mn-Cu-S nanodisk arrays for ultra-high-capacity hybrid supercapacitors.

Transition-metal sulfides have been recognized as one of the promising electrodes for high-performance hybrid supercapacitors (HSCs). However, the poor rate performance and short cycle life heavily impede their practical applications. Herein, an advanced electrode based on hierarchical porous cobalt-manganese-copper sulfide nanodisk arrays (Co-Mn-Cu-S HPNDAs) on Ni foam is fabricated for high-capacity HSCs, using metal-organic frameworks as the self-sacrificial template. The synergistic effects of ternary Co-Mn-Cu sulfides and the hierarchical porous structure endow the as-obtained electrode with fast redox reaction kinetics. As expected, the resultant Co-Mn-Cu-S HPNDAs electrode delivers an ultrahigh specific capacity of 536.8 mAh g-1 (3865 F g-1) at 2 A g-1 with a superb rate performance of 63% capacity retention at 30 A g-1. Remarkably, an energy density of 63.8 W h kg-1 at a power density of 743 W kg-1 with a long cycle life is also achieved with the quasi-solid-state Co-Mn-Cu-S HPNDAs//ZIF-8-derived carbon HSC. This work offers a new pathway to fabricate high-performance multiple transition-metal-sulfide-based electrode materials for energy storage devices.

H0.92K0.08TiNbO5 Nanowires Enabling High-Performance Lithium-Ion Uptake.

HTiNbO5 has been widely investigated in many fields because of its distinctive properties such as good redox activity, high photocatalytic activity, and environmental benignancy. Here, this work reports the synthesis of one-dimensional H0.92K0.08TiNbO5 nanowires via simple electrospinning followed by an ion-exchange reaction. The H0.92K0.08TiNbO5 nanowires consist of many small "lumps" with a uniform diameter distribution of around 150 nm. Used as an anode for lithium-ion batteries, H0.92K0.08TiNbO5 nanowires exhibit high capacity, fast electrochemical kinetics, and high performance of lithium-ion uptake. A capacity of 144.1 mA h g-1 can be carried by H0.92K0.08TiNbO5 nanowires at 0.5 C in the initial charge, and even after 150 cycles, the reversible capacity can remain at 123.7 mA h g-1 with an excellent capacity retention of 85.84%. For H0.92K0.08TiNbO5 nanowires, the diffusion coefficient of lithium ions is 1.97 × 10-11 cm2 s-1, which promotes the lithium-ion uptake effectively. The outstanding electrochemical performance is ascribed to its morphology and the formation of a stable phase during cycling. In addition, the in situ X-ray diffraction and ex situ transmission electron microscopy techniques are applied to reveal its lithium storage mechanism, which proves the structure stability and electrochemical reversibility, thus achieving high-performance lithium-ion uptake. All these advantages demonstrate that H0.92K0.08TiNbO5 nanowires can be a possible alternative anode material for rechargeable batteries.

Sol-Gel Synthesis and in Situ X-ray Diffraction Study of Li3Nd3W2O12 as a Lithium Container.

In this work, garnet-framework Li3Nd3W2O12 as a novel insertion-type anode material has been prepared via a facile sol-gel method and examined as a lithium container for lithium ion batteries (LIBs). Li3Nd3W2O12 shows a charge capacity of 225 mA h g-1 at 50 mA g-1, and with the current density increasing up to 500 mA g-1, the charge capacity can still be maintained at 186 mA h g-1. After cycling at 500 mA g-1 for 500 cycles, Li3Nd3W2O12 retains about 85% of its first charge capacity changed from 190.2 to 161 mA h g-1. Furthermore, in situ X-ray diffraction technique is adopted for the understanding of the insertion/extraction mechanism of Li3Nd3W2O12. The full-cell configuration LiFePO4/Li3Nd3W2O12 is also assembled to evaluate the potential of Li3Nd3W2O12 for practical application. These results show that Li3Nd3W2O12 is such a promising anode material for LIBs with excellent electrochemical performance and stable structure.