As a promising high energy density electrode material for rechargeable batteries, lithium (Li) metal is still suffering from air/water instability due to its highly reactive nature. In addition, the Li dendrite issue in Li metal batteries needs to be resolved to ensure the safety of batteries and for wide applications. Herein, we demonstrate that a simple compact GaO x layer formed using liquid metal (LM) can act as an artificial solid electrolyte interphase to block moisture and oxygen in the air from corroding the lithium metal. Interestingly, GaO x that covered the electrode effectively inhibits Li dendrite growth in electrochemistry cycling, ensuring the safety of Li metal batteries. The exposed composite Li metal anode (exposed under ambient air with relative humidity (RA) ≈ 75% for 5 h) not only shows a superior stability (symmetrical cell) but also delivers an elevated cycling stability (>500 cycles at 0.5 and 1 C) with a sulfur@C cathode in the full-cell configuration. Our work provides a new pathway for the large-scale applications of the air/watertolerant Li metal anode in rechargeable batteries.

Here we present an innovative, universal, scalable, and straightforward strategy for cultivating a resilient, flexible lithium-ion battery (LIB) based on the bacterial-based self-growing approach. The electrodes and separator layers are integrated intrinsically into one unity of sandwich bacterial cellulose integrated film (SBCIF), with various active material combinations and tailored mechanical properties. The flexible LIB thereof showcases prominent deformation tolerance and multistage foldability due to the unique self-generated wavy-like structure. The LTO|LFP (Li4Ti5O12 and LiFePO4) SBCIF-based flexible LIB demonstrates reliable long-term electrochemical stability with high flexibility, by exhibiting a high capacity retention (>95%) after 500 cycles at 1C/1C after experiencing a 10 000 bending/flattening treatment. The LTO|LFP SBCIF battery subjected to a simultaneous bending/flattening and cycling experiment shows an extraordinary capacity retention rate (>68%) after 200 cycles at 1C/1C. The biobased self-growing approach offers an exciting and promising pathway toward the tailored, integrated high-performance flexible LIBs.

The lithium metal battery with solid-state polymer electrolyte (SPE) is a promising candidate for solid-state batteries with high safety and high energy density. However, the low room temperature ionic conductivity and poor electrolyte/electrode interfacial stability of the SPEs seriously hinder the practical application. Herein, we adopt a polymer-in-salt electrolyte (PISE) strategy on the comb-like polycaprolactone (PCL) to circumvent the low ionic conductivity and poor interfacial stability of the conventional SPE, thus enabling the fully function of room temperature lithium metal batteries. The all-solid-state PISE exhibits a high ionic conductivity of 3.9×10-4 S cm-1 at 30°C, a superior lithium-ion transference number of 0.61 and an improved oxidative stability of ~4.8 V vs Li/Li+. Due to the ultra-stable interface generated by the superconcentrated lithium salt, the all-solid-state LiFePO4||Li cells exhibit prominent high cycling stability, with high capacity retention (92%) after 300 cycles at ambient temperature. The fully function of the ambient temperature PISE offers a promising pathway towards high energy density and high safety room temperature LMBs.

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