P-type binary copper oxide semiconductor films for various O₂ flow rates and total pressures (P_t) were prepared using the reactive magnetron sputtering method. Their morphologies and structures were detected by X-ray diffraction, Raman spectrometry, and SEM. A phase diagram with Cu₂O, Cu₄O₃, CuO, and their mixture was established. Moreover, based on Kelvin Probe Force Microscopy (KPFM) and conductive AFM (C-AFM), by measuring the contact potential difference (V_CPD) and the field emission property, the work function and the carrier concentration were obtained, which can be used to distinguish the different types of copper oxide states. The band gaps of the Cu₂O, Cu₄O₃, and CuO thin films were observed to be (2.51 ± 0.02) eV, (1.65 ± 0.1) eV, and (1.42 ± 0.01) eV, respectively. The resistivities of Cu₂O, Cu₄O₃, and CuO thin films are (3.7 ± 0.3) × 10³ Ω·cm, (1.1 ± 0.3) × 10³ Ω·cm, and (1.6 ± 6) × 10¹ Ω·cm, respectively. All the measured results above are consistent.

The solid electrolyte interphase in rechargeable Li-ion batteries, its dynamics and, significantly, its nanoscale structure and composition, hold clues to high-performing and safe energy storage. Unfortunately, knowledge of solid electrolyte interphase formation is limited due to the lack of in situ nano-characterization tools for probing solid-liquid interfaces. Here, we link electrochemical atomic force microscopy, three-dimensional nano-rheology microscopy and surface force-distance spectroscopy, to study, in situ and operando, the dynamic formation of the solid electrolyte interphase starting from a few 0.1 nm thick electrical double layer to the full three-dimensional nanostructured solid electrolyte interphase on the typical graphite basal and edge planes in a Li-ion battery negative electrode. By probing the arrangement of solvent molecules and ions within the electric double layer and quantifying the three-dimensional mechanical property distribution of organic and inorganic components in the as-formed solid electrolyte interphase layer, we reveal the nanoarchitecture factors and atomistic picture of initial solid electrolyte interphase formation on graphite-based negative electrodes in strongly and weakly solvating electrolytes.

All-solid-state Li-metal batteries (ASSLBs) are highly desirable, due to their inherent safety and high energy density; however, the irregular and uncontrolled growth of Li filaments is detrimental to interfacial stability and safety. Herein, we report on the incorporation of piezo-/ferroelectric BaTiO ₃ (BTO) nanofibers into solid electrolytes and determination of electric-field distribution due to BTO inclusion that effectively regulates the nucleation and growth of Li dendrites. Theoretical simulations predict that the piezoelectric effect of BTO embedded in solid electrolyte reduces the driving force of dendrite growth at high curvatures, while its ferroelectricity reduces the overpotential, which helps to regularize Li deposition and Li ⁺ flux. Polarization reversal of soft solid electrolytes was identified, confirming a regular deposition and morphology alteration of Li. As expected, the ASSLBs operating with LiFePO ₄ /Li and poly(ethylene oxide) (PEO)/garnet solid electrolyte containing 10% BTO additive showed a steady and long cycle life with a reversible capacity of 103.2 mAh g ⁻¹ over 500 cycles at 1 C. Furthermore, the comparable cyclability and flexibility of the scalable pouch cells prepared and the successful validation in the sulfide electrolytes, demonstrating its universal and promising application for the integration of Li metal anodes in solid-state batteries.

Flower-like NiCo₂O₄consisting of nanosheets are synthesized by hydrothermal technique and subsequently surface-modified with a TiO₂ultrathin layer by a hydrolysis process at low temperature.