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    Multifunctional Janus Separators for Safer and Dendrite-Free Lithium-Metal Batteries

    Year: 2023

    Journal: Batteries & Supercaps, Volume 6, 2023

    Authors: Callegari, Daniele; Davino, Stefania; Parmigiani, Miriam; Medina-Llamas, Maria; Malavasi, Lorenzo; Quartarone, Eliana

    Keywords: Janus membrane; battery safety; battery separator; dendrites growth; Li metal

    The design of multifunctional separators can address crucial drawbacks of the lithium-metal batteries. Here, a novel Janus separator (JS) is developed with tunable properties to prevent internal short circuiting and improve the cathode/electrolyte interface. JS is a P(VdF-HFP) composite with LLZO facing lithium (Li) anode (Layer A) and N-CQDs contacting the NMC cathode. Layer A acts as Li-ion flux regulator to hinder dendrite propagation; Layer B plays multiple roles: i) promotion of better carrier migration, ii) protection from side reactions at the NMC cathode and iii) action as physical barrier against dendrite penetration. Galvanostatic cycling of Li/NMC cells with JS including 5 wt% CQDs demonstrated that JS was effective to avoid self-discharge and internal short-circuiting due to dendrite perforation, resulting in enhanced cell lifespan. Specific capacity >150 mAh g−1 with capacity retention of 91 % was delivered over 130 cycles at 1C. This result contrasted with higher capacity loss (>25 %) and cell failure in case of P(VdF-HFP) and Single Layer A separators, respectively. Post-mortem SEM on JS confirmed that the introduced functionalities successfully intercept dendrites. ARC overheating tests on JS-based cells demonstrated a remarkably higher thermal resistance and lower severity of the exothermic phenomena compared to Celgard separators.
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