Dense carbon nanofiber self-supporting electrode fabricated by orientation/compaction strategy for high volumetric lithium storage capacity

Abstract

Low bulk density greatly restricts the large-scale application of electrospun carbon-based fiber membrane as electrode in energy storage devices. To solve the above challenges, herein an orientation-compaction densification strategy is proposed to enhance the bulk density and volumetric capacity of PAN-based carbon nanofiber membranes as self-supporting electrode used in lithium-ion batteries (LIBs). Specifically, highly-oriented fibers are achieved by high-speed roller collecting during electrospinning, and compaction densification is conducted by hot-pressing treatment. The effects of collecting speed and hot-pressing pressure on the morphology, conductivity, bulk density, tensile strength, and flexibility of the obtained carbon nanofiber membrane are investigated. Compared to conventional fiber membranes, of which fibers are disorderly stacked, the oriented fiber membrane is much easier to achieve dense stacking by compaction. The obtained dense carbon nanofiber membrane demonstrates a bulk density of 0.566 ​g ​cm⁻³, and shows a significantly-enhanced volumetric capacity (318.3 ​mA ​h cm⁻³), high-rate performance (86.6 ​mA ​h cm⁻³ at 5 ​A ​g⁻¹), and satisfactory cycling stability when used as self-supporting electrode of LIBs.