Porous carbon nanofiber webs derived from bacterial cellulose as an anode for high performance lithium ion batteries

Carbon nanofiber webs with a hierarchically porous structure and a large surface area were developed by KOH activation of the pyrolyzed bacterial cellulose (denoted as pBC), which was extracted from the low-cost, eco-friendly and industrially producible coconut juice. The activated-pBC (denoted as A-pBC-x, x represents the mass ratio of KOH to pBC, x = 5, 6 and 7) is composed of inter-welded homogeneous carbon nanofibers, which construct a mechanically robust three-dimensional (3D) conductive porous network. As an anode material for the lithium ion batteries (LIBs), the A-pBC-x exhibits significantly improved electrochemical performance compared to the pBC and current commercial graphite. Remarkably, the A-pBC-6 electrode can deliver a specific capacity of over 857.6 mAh g^-1 after 100 cycles at 100 mA g^-1 and retain high capacity of 325.38 mAh g^-1 even cycled at high current density of 4000 mA g^-1. The significant improvement for the lithium storage performance of the A-pBC-6 sample could be attributed to its hierarchical micropore-mesopore structure and high surface area, which can greatly enhance the contact area of the electrode-electrolyte, decrease the diffusion resistance of lithium ions, shorten the diffusion length of lithium ions and provide a solid and continuous pathway for electron transport.