In Situ Formed Lithiophilic LixNbyO in a Carbon Nanofiber Network for Dendrite-Free Li-Metal Anodes

Lithium metal is considered as a strongly attractive anode candidate for the high-energy-storage field, but its dreadful dendrite growth has haunted its commercialization progress. Herein, we develop a lithiophilic Nb₂O₅-embedded three-dimensional (3D) carbon nanofiber network (Nb₂O₅-CNF) as a scaffold to preload molten Li for the fabrication of dendrite-free composite anode. The in situ lithiation reaction between molten Li and Nb₂O₅ nanocrystals results in the formation of nanosize Li_xNb_yO nanoparticles, which can serve as preferred sites that regulate nucleation/growth behavior of Li during the plating process. Besides, due to its high structural stability and abundant internal inner space, the 3D CNF network can function as a reservoir to confine the dimensional expansion of "hostless Li". The resulting Li composite anodes exhibit enlarged active areas and reduced interfacial energy barriers, delivering a prolonged cycling of 1000 h with an ultralow hysteresis of 52 mV and dendrite-free morphology in a symmetric cell (1.0 mA cm^-2). Coupled with the LiFePO₄ cathode, the Li@Nb₂O₅-CNF anode sustains a reversible capacity of 163 mAh g^-1 with an excellent capacity retention of 93.0% after 370 cycles at 0.5C. This all-around strategy of lithiophilic sites coupled with a 3D conductive nanofiber matrix may shed light on promising applications of high-capacity and dendrite-free Li-metal batteries.

Phase-Separation-Induced Porous Lithiophilic Polymer Coating for High-Efficiency Lithium Metal Batteries

Solid-electrolyte interphase (SEI) plays a pivotal role in stabilizing lithium (Li) metal anode for rechargeable batteries. However, electrolyte-derived SEI often suffers from poor stability, leading to Li dendrite growth, consumption of electrolyte, and short cycle life. Here, we report a porous lithiophilic polymer coating induced by phase separation of polyvinylidenefluoride-polyacrylonitrile (PVDF-PAN) blends for stabilizing Li metal anode. Different from single polymer coating, PVDF-PAN blends protective layer with porous structures caused by phase separation can provide effective Li⁺ transport channels and regulate uniform Li⁺ flux. The lithiophilic functional groups of C≡N and C-F can promote uniform Li deposition and accelerate Li⁺ diffusion at the same time during plating/stripping process. As a result, Li||NCM811 full cells using PVDF-PAN coated Li present an apparently improved cycling stability and higher Coulombic efficiency with lean electrolyte (7.5 μL mA h^-1), limited Li supply (N/P ratio = 2.4), and high areal capacity (4.0 mA h cm^-2).