Multiple Dynamic Bonds-Driven Integrated Cathode/Polymer Electrolyte for Stable All-Solid-State Lithium Metal Batteries.

All-solid-state lithium metal batteries (LMBs) are considered as the promising higher-energy and improved-safety energy-storage systems. Nevertheless, the electrolyte-electrodes interfacial issues due to the limited solid physical contact lead to discontinuous interfacial charge transport and large interfacial resistance, thereby suffering from unsatisfactory electrochemical performance. Herein, we construct an integrated cathode/polymer electrolyte for all-solid-state LMBs under the action of polymer chains exchange and recombination originating from multiple dynamic bonds in our well-designed dynamic supramolecular ionic conductive elastomers (DSICE) molecular structure. The DSICE acts as polymer electrolytes with excellent electrochemical performance and mechanical properties, achieving the ultrathin pure polymer electrolyte thickness (12 µm). Notably, the DSICE also functions as lithium iron phosphate (LiFePO4 , LFP) cathode binders with enhanced adhesive capability. Such well-constructed Li|DSICE|LFP-DSICE cells generate delicate electrolyte-electrodes interfacial contact at the molecular level, providing continuous Li+ transport pathways and promoting uniform Li+ deposition, further delivering superior long-term charge/discharge stability (>600 cycles, Coulombic efficiency, >99.8 %) and high capacity retention (80 % after 400 cycles). More practically, the Li|DSICE|LFP-DSICE pouch cells show stable electrochemical performance, excellent flexibility and safety under abusive tests.

Building Fast Ion-Conducting Pathways on 3D Metallic Scaffolds for High-Performance Sodium Metal Anodes.

Building 3D electron-conducting scaffolds has been proven to be an effective way to alleviate severe dendritic growth and infinite volume change of sodium (Na) metal anodes. However, the electroplated Na metal cannot completely fill these scaffolds, especially at high current densities. Herein, we revealed that the uniform Na plating on 3D scaffolds is strongly related with the surface Na+ conductivity. As a proof of concept, we synthesized NiF2 hollow nanobowls grown on nickel foam (NiF2@NF) to realize homogeneous Na plating on the 3D scaffold. The NiF2 can be electrochemically converted to a NaF-enriched SEI layer, which significantly reduces the diffusion barrier for Na+ ions. The NaF-enriched SEI layer generated along the Ni backbones creates 3D interconnected ion-conducting pathways and allows for the rapid Na+ transfer throughout the entire 3D scaffold to enable densely filled and dendrite-free Na metal anodes. As a result, symmetric cells composed of identical Na/NiF2@NF electrodes show durable cycle life with an exceedingly stable voltage profile and small hysteresis, particularly at a high current density of 10 mA cm-2 or a large areal capacity of 10 mAh cm-2. Moreover, the full cell assembled with a Na3V2(PO4)3 cathode exhibits a superior capacity retention of 97.8% at a high current of 5C after 300 cycles.

Synthetic-Clay-Assisted Carrier Transport in Solid Polymer Electrolytes for Enhanced All-Solid-State Lithium Metal Batteries.

As a potential alternative to liquid organic electrolytes, solid polymer electrolytes provide good processability and interfacial properties. However, insufficient ionic conductivity limits its further development. To overcome these challenges, we propose the solution of synthetic clay Laponite as a filler in this work. Specifically, the ionic conductivity increases to 1.71×10-4  S cm-1 (60 °C) after adding 5 wt.% of Laponite to the PEO-LiClO4 system. The Laponite surface's negative charge enhances lithium ions dissociation and transport in the electrolyte: the lithium-ion transference number increases from 0.17 to 0.34, and the exchange current density increases from 46.84 µA cm-2 to 83.68 µA cm-2 . The improved electrochemical properties of composite electrolytes improve the symmetric cell's stability to at least 600 h. Meanwhile, the Li||LiFePO4 cells' rate and long-cycle performance are also significantly enhanced. This work's concept of Laponite filler demonstrates a novel strategy to enhance ion transport in polymer-based electrolytes for solid-state batteries.