High rate capability and long cycle stability of Cr2O3 anode with CNTs for lithium ion batteries

Abstract

The present study describes the synthesis of nanocomposite materials based on chromium oxide (Cr2O3) nanoparticles and carbon nanotubes (CNTs) (Cr2O3–CNT(x%)) by in-situ chemical co-precipitation method. The physical studies of these materials using a wide range of analytical techniques reveal high surface area and narrow pore size distribution of these nanocomposite materials, indicating homogenous dispersion of Cr2O3 nanoparticles (particle sizes ∼20-30nm) on the surface of CNTs. The first cycle discharge capacity of 1120mAhg-1 for electrodes fabricated from Cr2O3 alone, which is improved for Cr2O3–CNT(0.08%) nanocomposite (1199mAhg-1). This nanocomposite material achieved an overall reversible capacity of 995.3mAhg-1 after 200 cycles, which can be attributed to the high surface area and the large mesoporous volume of Cr2O3 nanoparticles interconnected with highly conducting network of CNTs. At higher current densities, the Cr2O3–CNT(x%) nanocomposite electrodes exhibited high lithium storage capacity compared to the electrode fabricated from Cr2O3 nanoparticles alone. Overall, the Cr2O3–CNT(0.08%) nanocomposite electrode displayed high stability under varying current rates with overall high capacity retention and highest reversible capacity of 719mAhg-1 at a current rate of 2000mAhg-1. This highly enhanced rate capability and excellent cycling stability of Cr2O3–CNT(0.08%) nanocomposite electrode can be ascribed to the synergistic effect of CNTs (anchored with the Cr2O3 nanoparticles). The outcome of this study offers a possibility of improving lithium ion storage of Cr2O3 nanoparticles by carefully controlling their size and shape along with the use of a suitable buffering matrix like CNTs.