Controllable growth of NiCo2O4 nanoarrays on carbon fiber cloth and its anodic performance for lithium-ion batteries

Abstract

Flexible materials are promising materials for wearable devices and have attracted much attention. Among these, carbon fiber cloth (CFC) is a soft carbon substrate on which it is suitable to grow metal oxide nanoarrays. Meanwhile, a high areal mass loading of an electrode is of great significance in practice. Consequently, this work fabricated high areal mass loading NiCo₂O₄ nanoarrays by direct growth onto a CFC without binder and conductive additives. In the experiments, the thickness of the NiCo₂O₄ layer could be controlled to 1.8–4.4 μm by varying the hydrothermal reaction time between 6–18 hours. Since a high areal mass loading of an electrode is of great significance in practice, the thickness of NiCo₂O₄ was controlled to 4.4 μm using an 18 hour hydrothermal reaction time. The electrochemical behavior of the NiCo₂O₄/CFC anode was evaluated with 10 cycles at five different current rates from 100 to 500 mA g⁻¹ in sequence and another 100 cycles at 100 mA g⁻¹. It had a reversible areal capacity of 2.39 mA h cm⁻² (799 mA h g⁻¹) at the 150th cycle when the current density was 0.299 mA cm⁻² (100 mA g⁻¹). The high areal capacity was ascribed to the larger NiCo₂O₄ mass loading on the CFC substrate. The one-dimensional flexible conductive carbon fiber backbone and the free-standing NiCo₂O₄ nanoarrays on it also released the stress generated from the discharge/charge process. The nanostructure of NiCo₂O₄/CFC in this work offers great benefits for high areal capacity anode materials.