Uniform nucleation of sodium/lithium in holey carbon nanosheet for stable Na/Li metal anodes

Abstract

Na/Li metals have high theoretical capacity for high-energy-density metal batteries. However, it is difficult to achieve long lifespan due to uneven Na/Li nucleation, succeeding dendrite formation and short circuit. Recently, 3D scaffolds restraining Na/Li dendritic growth to reduce the local current density and improve the cycling stability has come forward. Introducing heteroatoms into matrixes are effective methods to further enhance the affinity to Na/Li atom and reduce nucleation barrier. Nevertheless, these 3D scaffolds that are propitious to completely restrain dendritic Na/Li is arduous, the methods proposed to fabricate 3D scaffolds are often complex and expensive. Herein, a facile route to uniform nucleation of Na/Li in holey carbon nanosheet (HCN) was proposed. The HCN offers high cycling stability of Na/Li plating/stripping (greater than 1000 cycle for Na metal anode and greater than 600 cycles for Li metal anode at 1.0 mA cm−2), attributing to the enhanced affinity to Na/Li atom and effective accommodation Na/Li deposition in the holey structure, demonstrated by DFT calculation. Moreover, Na metal based full cell exhibits excellent cycling performance with a high reversible specific capacity of 105.3 mAh g−1 and capacity retention of 88.4% coupled with Na3V2(PO4)2F3 cathode. Li metal based full cell also achieves a high remaining capacity of 142.6 mAh g−1, with a capacity retention of 74.5% when paired with commercial LiNi0.8Co0.1Mn0.1O2 cathode. This work offers a sight on design of electrode for long cycle and stable Na/Li metal anodes.