No abstract

In situ AFM reveals the evolution of SEI during initial cycles under the effect of additive.

Understanding and controlling the growth morphology of two-dimensional crystals of transition metal dichalcogenides (TMDs) is essential in developing high-quality crystalline material for spintronics, valleytronics, electronics, and optics. Here we report our studies on the evolution of crystallite morphology of MoS2 observed in chemical vapor deposition. It is shown that as time goes on, the growth morphology of MoS2 flakes undergoes a transition from a triangle to a star shape, then back to a triangle, and finally to a bulgy irregular morphology. By tuning the temperature of the element sources, the atomic ratio of S and Mo on the growing interface can be adjusted. The variation of the S/Mo ratio affects the edge diffusion length and nucleation behavior on the edge of crystallite, leading to different growth morphologies. Our observations provide clues on how to engineer the morphology and control the quality of TMD crystalline sheets.

Aqueous multivalent ion batteries, especially aqueous zinc-ion batteries (ZIBs), have promising energy storage application due to their unique merits of safety, high ionic conductivity, and high gravimetric energy density. To improve their electrochemical performance, polyaniline (PANI) is often chosen to suppress cathode dissolution. Herein, this work focuses on the zinc ion storage behavior of a PANI cathode. The energy storage mechanism of PANI is associated with four types of protonated/non-protonated amine or imine. The PANI cathode achieves a high capacity of 74 mAh g−1 at 0.3 A g−1 and maintains 48.4% of its initial discharge capacity after 1000 cycles. It also demonstrates an ultrahigh diffusion coefficient of 6.25 × 10−9~7.82 × 10−8 cm−2 s−1 during discharging and 7.69 × 10−10~1.81 × 10−7 cm−2 s−1 during charging processes, which is one or two orders of magnitude higher than other reported studies. This work sheds a light on developing PANI-composited cathodes in rechargeable aqueous ZIBs energy storage devices.

We report here a unique in-plane self-templating electrochemical growth of arrays of copper nanopearl chains from an ultrathin layer of CuSO4 electrolyte. Scanning electron microscopy indicates that the electrodeposit filaments form equally spaced bundles, which consist of long, straight, pearl-chain-like copper filaments with corrugated periodic structure. The bundle separation can be tuned by changing the applied electric current in electrodeposition. Experiments show that the periodic morphology on the nanopearl chain corresponds to the periodic distribution of copper and cuprous oxide. The mechanism for the bundle formation is discussed.