Induction/Inhibition Effect on Lithium Dendrite Growth by a Binary Modification Layer on a Separator

Hybrid Dynamic Covalent Network-Based Protecting Layer for Stable Li-Metal Batteries

Metallic lithium (Li) is considered as the "Holy Grail" anode material for next-generation energy storage systems due to its extremely high theoretical capacity and low electrochemical potential. Before the commercialization of the Li electrode, dendritic Li growth and the unstable solid electrolyte interphase layer should be conquered. Herein, a hybrid covalent adaptable polymer network (HCAPN) is prepared via the random copolymerization of poly(ethylene glycol) methyl ether methacrylate and -acetoacetoxyethyl methacrylate, followed by chemical cross-linking with polyethylenimine (PEI) and amine-modified silicon dioxide (SiO2). Such a hybrid network, where PEI and amine-modified SiO2 formed a vinylogous urethane-based dynamic covalent bond with the copolymer, respectively, shows improved mechanical properties, solvent resistance, and excellent healability/recyclability. As the protecting layer on the Li electrode, the assembled HCAPN@Li||HCAPN@Li symmetric cell shows a long cycle life of 800 h with low overpotential at a current density of 1 mA cm-2, and superior electrochemical performance can be achieved in the HCAPN@Li||LiFePO4 full cell (capacity retention of 77% over 400 cycles at 1.5 C) and HCAPN@Li||NCM811 cell (capacity retention of 79% after 300 cycles). Surface morphology analysis is also performed for physical insight into their role as protecting layer. This work provides a new perspective for constructing a hybrid dynamic covalent network-based polymer protecting layer for inhibiting Li dendrite growth.

Versatile MXenes for Aqueous Zinc Batteries

Aqueous zinc-ion batteries (AZIBs) are gaining popularity for their cost-effectiveness, safety, and utilization of abundant resources. MXenes, which possess outstanding conductivity, controllable surface chemistry, and structural adaptability, are widely recognized as a highly versatile platform for AZIBs. MXenes offer a unique set of functions for AZIBs, yet their significance has not been systematically recognized and summarized. This review article provides an up-to-date overview of MXenes-based electrode materials for AZIBs, with a focus on the unique functions of MXenes in these materials. The discussion starts with MXenes and their derivatives on the cathode side, where they serve as a 2D conductive substrate, 3D framework, flexible support, and coating layer. MXenes can act as both the active material and a precursor to the active material in the cathode. On the anode side, the functions of MXenes include active material host, zinc metal surface protection, electrolyte additive, and separator modification. The review also highlights technical challenges and key hurdles that MXenes currently face in AZIBs.

Constructing a Uniform and Stable Mixed Conductive Layer to Stabilize the Solid-State Electrolyte/Li Interface by Cold Bonding at Mild Conditions

Garnet-type Li_6.4 La₃ Zr_1.4 Ta_0.6 O₁₂ (LLZ) electrolyte is a promising candidate for high-performance solid-state batteries, while its applications are hindered by interfacial problems. Although the utilization of functional coatings and molten lithium (Li) effectively solves the LLZ interfacial compatibility problem with Li metal, it poses problems such as high cost, high danger, and structural damage. Herein, a mixed conductive layer (MCL) is introduced at the LLZ/Li interface (RT-MCL) via an in situ cold bonding process at room temperature. Such a stable and compact RT-MCL can effectively suppress side reactions and protect the crystal structure of LLZ, and it also inhibits growth of Li dendrites and promotes uniform Li deposition. The critical current density (CCD) of the Li symmetric cell composed of RT-MCL-LLZ is increased to 1.8 mA cm^-2 and provides stable cycling performance over 2000 h under 0.5 mA cm^-2 . Additionally, this in situ cold bonding treatment can significantly reduce cost and eliminate potential safety issues caused by the high-temperature processing of Li metal. This work highlights tremendous potential of this cold bonding technique in the reasonable design and optimization of the LLZ/Li interface.

Self-Assembly Monolayer Inspired Stable Artificial Solid Electrolyte Interphase Design for Next-Generation Lithium Metal Batteries

Lithium metal is widely regarded as the "ultimate" anode for energy-dense Li batteries, but its high reactivity and delicate interface make it prone to dendrite formation, limiting its practical use. Inspired by self-assembled monolayers on metal surfaces, we propose a facile yet effective strategy to stabilize Li metal anodes by creating an artificial solid electrolyte interphase (SEI). Our method involves dip-coating Li metal in MPDMS to create an SEI layer that is rich in inorganic components, allowing uniform Li plating/stripping under a low overpotential over 500 cycles in carbonate electrolytes. In comparison, pristine Li metal shows a rapid increase in overpotential after merely 300 cycles, leading to failure soon after. Molecular dynamics simulations demonstrate that this uniform artificial SEI suppresses Li dendrite formation. We further demonstrated its enhanced stability pairing with LiFePO₄ and LiNi_1-x-yCo_xMn_yO₂ cathodes, highlighting the proposed strategy as a promising solution for practical Li metal batteries.