Resonances in ultracold collisions involving heavy molecules are difficult to understand, and have proven challenging to detect. Here we report the observation of magnetically tunable Feshbach resonances in ultracold collisions between 23 Na 40 K molecules in the rovibrational ground state and 40 K atoms. We prepare the atoms and molecules in various hyperfine levels of their ground states and observe the loss of molecules as a function of the magnetic field. The atommolecule Feshbach resonances are identified by observing an enhancement of the loss rate coefficients. We have observed three resonances at approximately 101 G in various atom-molecule scattering channels, with the widths being a few hundred milliGauss. The observed atom-molecule Feshbach resonances at ultralow temperatures probe the three-body potential energy surface with an unprecedented resolution. Our work will help to improve the understanding of complicated ultracold collisions, and open up the possibility of creating ultracold triatomic molecules.Understanding collisions involving molecules at the quantum level has been a long-standing goal in chemical physics [1]. Scattering resonance is one of the most remarkable quantum phenomena and plays a critically important role in the study of collisions. It is very sensitive to both the long-range and short-range parts of the molecule interaction potential, and thus offers a unique probe of the potential energy surface (PES) governing the collision dynamics. Although scattering resonances are well known and have been the main features in ultracold atomic gases and nuclear collisions [2], they have proven challenging to observe in molecule systems. Recently, significant progress has been achieved in experimentally studying resonances in cold molecular collisions involving the light particles, e.g., H 2 , HD molecule or He atom, by means of molecular beam techniques. In the crossed-beam or merged-beam experiments, shape resonances or Feshbach resonances have been observed in atom-molecule chemical reactions [3][4][5][6][7][8], atom-molecule inelastic collisions [9][10][11], and molecule-molecule inelas- * These authors contributed equally to this work. tic collisions [12,13]. However, in these experiments, the collision energies are still high (at Kelvin or sub Kelvin), and thus a few partial waves contribute to the scattering cross sections.Ultracold molecules offer great opportunities to study molecular collisions in the quantum regime. At ultralow temperatures, the de Broglie wavelength of the collision partners is much larger than the range of molecular interaction potential, and only the lowest possible partial wave dominates the collision process [14,15]. Consequently, the collisions at ultracold temperatures are highly quantum mechanical. Due to the anisotropy of the PES, the collisions involving ultracold molecules may support many resonances that are contributed by the rotational and vibrational excited states [16,17]. Therefore, it is expected that scattering resonances can be routinely obse...

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To achieve high ionic conductivity for solid electrolyte, an artificial Li‐rich interface layer of about 60 nm thick has been constructed in polymer‐based poly(ethylene oxide)‐lithium bis(trifluoromethanesulfonyl)imide composite solid electrolyte (briefly noted as PEOm) by adding Li‐based alloys. As revealed by high‐resolution transmission electron microscopy and electron energy loss spectroscopy, an artificial interface layer of amorphous feature is created around the Li‐based alloy particles with the gradient distribution of Li across it. Electrochemical analysis and theoretical modeling demonstrate that the interface layer provides fast ion transport path and plays a key role in achieving high and stable ionic conductivity for PEOm‐Li21Si5 composite solid electrolyte. The PEOm‐5%Li21Si5 composite electrolyte exhibits an ionic conductivity of 3.9 × 10–5 S cm−1 at 30 °C and 5.6 × 10−4 S cm−1 at 45 °C. The LiFePO4 | PEOm‐5%Li21Si5 | Li all‐solid‐state batteries could maintain a stable capacity of 129.2 mA h g−1 at 0.2 C and 30 °C after 100 cycles, and 111.3 mA h g−1 after 200 cycles at 0.5 C and 45 °C, demonstrating excellent cycling stability and high‐rate capability.