ABSTRACT
Aqueous rechargeable zinc-based batteries have recently gained tremendous attention because of their low cost and high safety. However, the issues associated with the zinc metal anode, including corrosion, H2 evolution, and dendrite growth, hinder their practical applications. Herein, we design a hybrid organic/inorganic interphase composed of poly(vinylidene fluoride-co-hexafluoropropylene), silica, and zinc triflate to stabilize the zinc metal anode in a mild aqueous electrolyte. It is proven that the artificial interphase reduces corrosion of the Zn metal in the ZnSO4 electrolyte and suppresses dendrite growth by regulating Zn2+ deposition. Therefore, the lifespan of symmetrical cells with coated Zn could be enhanced to over 960 h with a stripping/plating capacity of 0.5 mAh cm-2. In addition, zinc-ion batteries including a sodium vanadate cathode and a coated Zn anode could achieve 3000 cycles with nearly no capacity fading at 5 A g-1.
ABSTRACT
Exploring flexible lithium-ion batteries is required with the ever-increasing demand for wearable and portable electronic devices. Selecting a flexible conductive substrate accompanying with closely coupled active materials is the key point. Here, a lightweight, flexible, and freestanding MXene/liquid metal paper is fabricated by confining 3 °C GaInSnZn liquid metal in the matrix of MXene paper without any binder or conductive additive. When used as anode for lithium-ion cells, it can deliver a high discharge capacity of 638.79 mAh g-1 at 20 mA g-1 . It also exhibits satisfactory rate capacities, with discharge capacities of 507.42, 483.33, 480.22, 452.30, and 404.47 mAh g-1 at 50, 100, 200, 500, and 1000 mA g-1 , respectively. The cycling performance is obviously improved by slightly reducing the charge-discharge voltage range. The composite paper also has better electrochemical performance than liquid metal coated Cu foil. This study proposes a novel flexible anode by a clever combination of MXene paper and low-melting point liquid metal, paving the way for next-generation lithium-ion batteries.
ABSTRACT
Silicon is considered as one of the most favorable anode materials for next-generation lithium-ion batteries. Nanoporous silicon is synthesized via a green, facile, and controllable vacuum distillation method from the commercial Mg2Si alloy. Nanoporous silicon is formed by the evaporation of low boiling point Mg. In this method, the magnesium metal from the Mg2Si alloy can be recycled. The pore sizes of nanoporous silicon can be secured by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 °C, 0.5 h) delivers a discharge capacity of 2034 mA h g-1 at 200 mA g-1 for 100 cycles, a cycling stability with more than 1180 mA h g-1 even after 400 cycles at 1000 mA g-1, and a rate capability of 855 mA h g-1 at 5000 mA g-1. The electrochemical properties might be ascribed to its porous structure, which may accommodate large volume change during the cycling process. These results suggest that the green, scalable, and controllable approach may offer a pathway for the commercialization of high-performance Si anodes. This method may also be extended to construct other nanoporous materials.
ABSTRACT
We achieved excellent anode performance for PIBs based on a metal-organic framework MIL-125(Ti) for the first time. It can deliver a capacity of 208 mA h g-1 at a rate of 10 mA g-1 and a high capacity retention of 90.2% after 2000 cycles at a high rate of 200 mA g-1 with a high coulombic efficiency. The K+ storage mechanism is investigated by the ex situ XRD and IR techniques and confirms that potassium ions are reversibly inserted into the organic moiety without direct engagement of Ti ions.
ABSTRACT
Ultrafine TiO2 confined in porous-nitrogen-doped carbon is synthesized from a single metal-organic framework precursor. As a novel interlayer for lithium-sulfur batteries, the TiO2@NC composite can act as both a high efficiency lithium polysulfide barrier to suppress the side reactions and an additional current collector to enhance the polysulfide redox reactions. The lithium-sulfur battery with a TiO2@NC interlayer delivers a high reversible capacity of 1460 mAh g-1 at 0.2 C and capacity retention of 71% even after 500 cycles with high rate capability.
