Solid‐state batteries (SSBs) are considered as the most promising next‐generation high‐energy‐density energy storage devices due to their ability in addressing the safety concerns from organic electrolytes and enabling energy dense lithium anodes. To ensure the high energy density of SSBs, solid‐state electrolytes (SSEs) are required to be thin and light‐weight, and simultaneously offer a wide electrochemical window to pair with high‐voltage cathodes. However, the decrease of SSE thickness and delicate structure may increase the cell safety risks, which is detrimental for the practical application of SSBs. Herein, to demonstrate a high‐energy‐density SSB with sufficient safety insurance, an ultrathin (4.2 µm) bilayer SSE with porous ceramic scaffold and double‐layer Li+‐conducting polymer, is proposed. The fire‐resistant and stiff ceramic scaffold improves the safety capability and mechanical strength of the composite SSE, and the bilayer polymer structure enhances the compatibility of Li metal anode and high‐voltage cathodes. The 3D ceramic facilitates Li‐ion conduction and regulates Li deposition. Thus, high energy density of 506 Wh kg−1 and 1514 Wh L−1 is achieved based on LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes with a low N/P ratio and long lifespan over 3000 h. High‐energy‐density anode‐free cells are further demonstrated.

Baseline resolution of two peptides, RVMRGMR and RSHRGHR, of neutral monoisotopic mass, approximately 904 Da, has been achieved by microelectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry at a mass resolving power of approximately 3 300 000. The elemental compositions of these molecules differ by N40 vs. S2H8 (0.000 45 Da), which is less than one electron's mass (0.000 55 Da)! This result establishes a new record for the smallest resolved mass difference between any two molecules. This achievement is made possible by a combination of high magnetic field (9.4 T), large-diameter (4-in.) Penning trap, and low ion density. The implications for proteomics based on accurate mass measurements are discussed briefly.