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Low Coulombic efficiency and significant capacity decay resulting from an unstable solid electrolyte interphase (SEI) and dendritic growth pose challenges to the practical application of lithium‐metal batteries. In this study, a highly efficient protection layer induced by octaphenylsilsesquioxane (OPS) with LiFSI salt is investigated. The OPS exhibits a strong adsorption energy with lithium, its multi‐site gradient adsorption ability enables the simultaneous capture of 8 Li+ and the uniform regulation of Li ion flux. Moreover, the mechanical strength and electronic insulation of the OPS layer induces Li deposition under the protection layer and effectively inhibits lithium dendrite growth. Such a protection layer contributes to the stable and dendrite‐free performance of a lithium‐metal battery employing LiNi0.8Co0.1Mn0.1O2 (NCM811) as a cathode and an ultrathin OPS‐protected lithium foil (20 µm) as the anode. A remarkable capacity retention of 91.4% is achieved after 300 cycles at 1C. The OPS‐protected Li anodes and NCM811 are also tested in combination with a Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte, showing extended cyclability up to 300 cycles with an average Coulombic efficiency of 99.58% and capacity retention of 85.7%. [ABSTRACT FROM AUTHOR]

NASICON-type electrolytes such as Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 (LAGP) potentially enable high safety and high energy for solid-state batteries. However, the poor interfacial stability with lithium metal remains a main issue. To overcome this challenge, we proposed a bilayer solid electrolyte architecture implementing a novel ultrathin solid polymer electrolyte (SPE) film in combination with LAGP to improve the interface with lithium metal. The SPE film is composed of a bis(fluorosulfonyl)imide-based ionic liquid and polyethylene oxide, which shows a remarkable ionic conductivity of 1.25 × 10−3 S cm−1 at room temperature. The application of this thin interlayer leads to an outstanding interface stability, allowing >2000 h of continuous Li stripping/plating in symmetric Li|SPE/LAGP/SPE|Li cells without any increase in polarization or indication of a short circuit. As a result, this approach enables Li|SPE/LAGP|NCM811 cells with a discharge capacity of ∼200 mAh g−1 at 0.1C and stable cycling for >400 cycles at 0.2C with a capacity retention of 83%. Additionally, the cell shows an extremely high average Coulombic efficiency of 99.96% demonstrating that the approach enables to achieve high-energy and long-term stable solid-state lithium-metal batteries. [Display omitted] • High energy lithium metal batteries. • Hybrid electrolytes enabled solid-state batteries. • Artificial interphases in high energy batteries. [ABSTRACT FROM AUTHOR]

Li-rich composite alloys have received increasing attention as a method of inhibiting lithium dendrites. The Al-Li alloy has earned favor as a viable option to stabilize Li metal anodes due to its low cost, low flammability, natural abundance, and ease of operation. However, the mechanism responsible for the inhibition of lithium dendrites in the Al-Li alloy has yet to be thoroughly researched. Through Density Functional Theory (DFT) calculations, we analyzed the adsorption energies of Li atoms on various lattice planes of bare Li metal and Al-Li alloy. We discovered that Al-Li alloy provides higher absorption energies of Li atoms, ultimately leading to the preferred orientation of lithium atoms on Al-Li alloy. Experimental data confirmed our hypothesis, the symmetric cells with an Al-Li alloy demonstrated superior cycling properties over 140 hours, particularly at a current density of 5 mA cm−2, compared to the bare Li anode. Furthermore, full cells with an LiFePO 4 (LFP) cathode exhibited better cycle and rate performance. This work provides a reasonable explanation for the inhibition of lithium dendrites on Al-Li alloy. • DFT calculations predict the better lithiophilicity of the Al-Li alloy than the bare Li. • Dendrite-free lithium anode is enabled by lithium atom preferred orientation on Al-Li alloy. • A reasonable explanation for the inhibition of lithium dendrites on Al-Li alloy is provided. [ABSTRACT FROM AUTHOR]