Constructing an Anion-Braking Separator to Regulate Local Li⁺ Solvation Structure for Stabilizing Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) offer significant advantages in energy density and output voltage, but they are severely limited by uncontrollable Li dendrite formation resulting from uneven Li + behaviors and high reactivity with potential co-solvent plating. Herein, to uniformly enhance the Li behaviors in desolvation and diffusion, the local Li + solvation shell structure is optimized by constructing an anion-braking separator, hence dynamically reducing the self-amplifying behavior of dendrites. As a prototypal, two-dimensional lithiated-montmorillonite (LiMMT) is blade-coated on the commercial separator, where abundant −OH groups as Lewis acidic sites and electron acceptors could selectively adsorb corresponding FSI − anions, regulating the solvation shell structure and restricting their migration. Meanwhile, the weakened anion mobility delays the time of breaking electrical neutrality, and the Li nucleation density is quantified through the respective experimental, theoretical and spectroscopical results, providing a comprehensive understanding of modifying anion and cation behaviors on dendritic growth suppression. As anticipated, a long Li plating/stripping lifespan up to 1800 h and a significantly increased average Coulombic efficiency of 98.8% are achieved under 3.0 mAh cm −2 . The fabricated high-loading Li-LFP or Li-NCM523 full-cells display the cycle durability with enhanced capacity retention of nearly 100%, providing the instructive guide towards realizing dendrite-free LMBs.

Rational Molecular Engineering via Electron Reconfiguration toward Robust Dual-Electrode/Electrolyte Interphases for High-Performance Lithium Metal Batteries

“…Moreover, the interaction between electrodes and electrolyte components plays an essential role in interfacial chemistry by influencing the electric double layer (EDL) . As for the salutary SEI properties, the growing consensus is that an inorganic-rich SEI with superior ionic conductivity and high interfacial energy is favorable for LMBs. , However, in conventional carbonate electrolytes, organic solvent molecules possess a large ionic–dipole interaction with Li + and a low lowest unoccupied molecular orbital (LUMO) value, thus dominate primary Li + solvation sheaths and preferentially decompose to a fragile organic-rich SEI which cannot withstand dendritic penetration and interface side reactions. , Furthermore, the negatively charged Li metal surface drives Li + enrichment, thereafter recruiting organic molecules of solvation shells into the EDL, which further exacerbates the formation of an undesired organic-rich SEI . Consequently, conventional carbonate electrolytes are incompatible with LMBs and required to be comprehensively modulated, including thermodynamic properties of electrolyte components, solvation structure, and interaction with electrodes.…”

Novel Strategy for Designing rGO@LLZTO@Li Composite Lithium Powder Anodes with a Dual Conducting Ion-Electron Channel for High-Energy-Density Lithium Metal Batteries

“…In order to prevent the formation and growth of Li dendrites, several efforts have been attempted. These include polymer electrolytes, − inorganic solid electrolytes, − modified separator, functional electrolyte additives, artificial solid electrolyte interphase, − and so on. − However, they still cannot reach the target of practical electrochemical performance. A promising alternative is the lithium powder anode (LPA) instead of traditional plain Li foil anode whose high surface area can reduce the local current density during the process of Li plating/stripping .…”

Engineering High-Performance Li Metal Batteries through Dual-Gradient Porous Cu-CuZn Host

“…Lithium (Li) metal anodes (LMAs) represent a promising energy storage technology based on electrochemical conversion reactions, offering a theoretical specific capacity of up to 3860 mAh g –1 , surpassing conventional Li-ion intercalation chemistry. − This surpasses the gravimetric capacity offered by conventional Li-ion intercalation chemistry, playing a pivotal role in advancing high-energy-density battery systems. − However, the progress of LMAs faces two primary challenges: the nonuniform nucleation and deposition behavior of Li metal, as well as the subsequent growth of Li dendrites resulting from these processes. − Researchers have extensively explored strategies to stabilize LMAs, encompassing anode structure design, − anode interface engineering, − separator engineering, − and electrolyte modification. − Through these efforts, the growth model of Li dendrites has been essentially elucidated. The suppression of Li dendrites and the development of techniques for inducing uniform nucleation/deposition of metallic Li have made significant advancements and garnered widespread consensus. − …”