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

초록

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 the 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 embedded with lithiophilic ZnO nanoparticles (P-HCNF@ZnO) is fabricated using a dual-nozzle electrospinning technique followed by carbonization. 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 plating 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 exterior surface even under fast lithiation conditions, while numerous Li dendrites are formed on the exterior surface of the non-porous hollow fiber electrode (HCNF@ZnO). As a result, 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 HCNF@ZnO in a symmetric cell test. Furthermore, in full cell tests, the LiFePO4 (LFP) battery made of lithiated P-HCNF@ZnO anode exhibits a high capacity of 175.3 mAh g-1 and a lower over-potential by 0.29 V than the reference sample. Analytical works and theoretical interpretations, elucidated that the Li metal anode made of the P-HCNF@ZnO significantly improves the performance of LMBs.

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