We report for the first-time a, 3D-intermetallic antiperovskite carbide, Fe 3 SnC, as Li-ion battery anode. The single phase Fe 3 SnC showed a reversible Li-ion capacity of 426mAhg -1 which was noted to increase significantly (600mAhg -1 ) by its in-situ synthesis via electrospinning and pyrolysis, rendering a conducting carbon nano-fibre (CNF) based composite. Importantly, the Fe 3 SnC@CNF composite also showed excellent stability up to 1000-cycles with remarkable 96% retention of capacity. Rate performance was equally impressive with a high capacity of 500mAhg -1 delivered at a high current density of 2Ag -1 . Estimation of Li-ion diffusion based on the electrochemical impedance data showed a major enhancement of the rate by a factor of 2 in the case of Fe 3 SnC@CNF as compared to the single phase Fe 3 SnC sample. The post cyclic characterizations reveal that the unit cell could hold itself in-spite of a volume expansion upon inclusion of 4-Li atoms per unit cell, as calculated from the capacity value. The CV plot clearly shows four distinctive peaks which could be identified with the sequential incorporation of upto 4-Li atoms. First principles Density Functional Theory (DFT) calculations are performed to elucidate the favourable sites for inclusion of 1-4 Li atoms inside the Fe 3 SnC unit cell along with the associated strain.