Microbundles of carbon nanostructures as binder free highly conductive matrix for LiFePO₄ battery cathode

Microbundles of carbon nanostructures (CNS) have been used to fabricate binder-free LiFePO₄ electrodes. The inherent ability of CNS to form a nano-porous structure after the reassembly of CNS dispersion from solution to film-forming state is used to encapsulate the LiFePO₄ particles. The LiFePO₄/CNS electrode shows high electrical conductivity of 9.1 S cm^-1 compared to 0.4 S cm ^-1 for conventional LiFePO₄/carbon electrodes. LiFePO₄/CNS flexible electrodes shows specific discharge capacity of 56 mAh g^-1, 41 mAh g^-1 and 37 mAh g^-1 at 1C, 3C and 5C rates respectively. These specific discharge capacities are higher than that of conventional LiFePO₄/carbon electrodes i.e. 40 mAh g^-1, 13 mAh g^-1 and 0.01 mAh g^-1 at 1C, 3C and 5C rates respectively. Improvements in the specific discharge capacity at high C-rate is attributed to highly conductive pathways between the CNS and LiFePO₄ particles, which assist fast transport of electrons at the electrode/CNS interfaces and between the electrode particles for rapid electrochemical reactions.