Nano-Cone Structured Lithiophilic Ni Film on Cu Current Collector Facilitates Li+ Ion Diffusion Toward Uniform Lithium Deposition

The uncontrolled growth of lithium (Li) dendrite during long-term cycling has hindered the practical application of the Li metal anode in the next generation rechargeable batteries. A variety of nanostructured current collectors is proposed in Li metal anode to reduce local current density and thus mitigate the Li dendrite formation. Here, the Ni nano-cone@Al (NCA) structure is utilized to guide the uniform metallic Li nucleation and growth, free from the dendrites. This unique nano-cone structure can facilitate the ion diffusion toward the bottom of the Ni nanostructures to make effective use of the nano-cone structure. The surface lithiophilicity is revealed from the view of absorption energy and interface lattice mismatch. It is found that Al on nano-cone Ni surface decreases the elastic strain energy at the interface rather than decreasing the formation energy. The resulting NCA structured substrate possesses small Li nucleation overpotentials (<0.032 V) and good structural stability upon galvanostatic cycling. Superior cycling stability over 2000 h in a Li|Li symmetric cell is realized. Full cell by paring with LiFePO4 achieves a high coulombic efficiency of 98.1% for over 100 cycles at 0.2 C with a capacity retention of over 97.2%.