Near-Perfect Suppression of Li Dendrite Growth by Novel Porous Hollow Carbon Fibers Embedded with Zno Nanoparticles as Stable and Efficient Anode for Li Metal Batteries

For the practical application of next-generation Li metal batteries (LMBs), a Li metal anode with high safety and efficiency is essential. However, LMBs still suffer from the problems caused by growth of Li dendrites at the Li metal anode. In this study, we introduce a novel way that could dramatically suppress the growth of Li dendrites and improve the performance of LMBs. A free-standing porous hollow carbon nanofiber sheet embedded with lithiophilic ZnO nanoparticles (P-HCNF@ZnO) is fabricated using a dual-nozzle electrospinning technique follow by carbonization. It is found that the nano-sized pores formed in the shell of hollow carbon fiber provide passages for Li ions to penetrate into the core space of the hollow fiber and the lithiophilic ZnO particles play a decisive role in inducing and depositing Li ions inside the core efficiently and uniformly. Therefore, Li ions are mostly electroplated/stripped on the internal surface of the porous hollow fibers and dendrites are rarely formed on their external surface even under a fast electroplating conditions, while numerous Li dendrites are formed on the external surface of the non-porous hollow fiber electrode. The P-HCNF@ZnO electrode exhibits a very low over-potential of about 87 mV, a stable capacity retention of about 95% at a high current density of 1.0 mA cm-2, and a much higher performance than the non-porous hollow fiber electrode (HCNF@ZnO) in a symmetric cell test. Through a comprehensive analytical work and theoretical interpretation, it is clearly elucidated that the Li metal anode made of a porous hollow carbon fiber embedded with ZnO nanoparticles could dramatically suppress the growth of Li dendrites and thus significantly improve the performance of LMBs.