In situ constructing lithiophilic NiFx nanosheets on Ni foam current collector for stable lithium metal anode via a succinct fluorination strategy

Abstract

Metallic lithium is considered as the optimal anode material for the high-energy–density rechargeable lithium-based battery. However, the commercial application of Li metal anode is plagued by uncontrollable dendrites growth and unstable SEI layer derived from the nonuniform nucleation and undesired deposition process. Herein, a hybrid 3D porous Ni foam (NF) current collector decorated by nanostructured lithiophilic layer of interconnected NiFx nanosheets is firstly synthesized by a convenient one-step fluorination strategy. Benefiting from superior lithiophilicity, the NiFx nanosheets can successfully decrease the Li nucleation barrier and act as uniformly distributed nucleation sites for inducing the homogeneous Li deposition. In addition, the interconnected morphology of the NiFx nanosheets and the 3D porous structure of the NF effectively reduce the local current density of the electrode and thus alleviate the dendrites formation. Moreover, a LiF-enriched SEI layer in situ generated from the electrochemical reaction also facilitates the smooth Li plating. As a result, this 3D hybrid NiFx@NF current collector demonstrates dendrite-suppressed Li deposition morphology and excellent stripping/plating reversibility, presenting significantly enhanced Coulombic efficiency of ~ 98% over 450 cycles at 1 mA cm−2. Remarkably, symmetric cell with Li@NiFx@NF anode achieves a prolonged cycling lifespan over 1300 h together with a low overpotential of ~ 20 mV at 1 mA cm−2 under the cycling capacity of 1 mAh cm−2. Furthermore, excellent cycling performance and rate capability of the Li@NiFx@NF anode are also realized in full cells when coupled with LiFePO4 and Li4Ti5O12 cathodes. Our work not only provides an expeditious fluorination strategy to construct 3D fluorinated compound but also illustrates the superiority of synergetic design of lithiophilic sites plus LiF-enriched SEI layer for the current collector of Li metal anode.