Conductive and porous SnCu-coated carbon cloth network for binder-free Li-ion storage anodes

Large volume change occurs during lithiation/delithiation of Sn anodes and result in pulverization, poor cycling, capacity loss and anode degradation that impedes the general use of Li-ion batteries. This study proposes a time-controlled synthesis approach for 1-D SnCu nanoparticles on three-dimensional anode by electrolessly adhering Cu to C cloth and subsequently Sn on the Cu. After annealing at 200 oC, electrically conductive, porous, flexible and mechanically stable CuSn alloy anode results. The CuSn anodes exhibited high conductivity due to copper deposit, accommodated volume changes and stress due to both 1-D-deposit and porosity and have high electrochemical activity due to large surface area. After 100 cycles, the sample deposited for the shortest time (1.5 min) interval and close to 1-D SnCu deposit has a specific discharge capacity of ~605 mAh g ^-1 which contrasts to the ~400 mAh g ^-1 obtained for the sample deposited for 6 min. The specific electrode surface area of the 1.5 min sample was 169 m ² g ^-1 in contrast to 6.4 m ² g ^-1 obtained for the 6 min sample. A rate capability of 520 mAh g ^-1 at a current density of 583 mA g ^-1 was achieved for the thinnest deposit. The porous Sn anode materials demonstrated low resistance during electrochemical impedance analysis and showed high reversible redox reactions during cyclic voltammetry tests. The achievement of high capacity anode (comprising of Sn-SnO ₂ -Cu ₆ Sn ₅ ) with good reversible capacity retention through electroless coating method indicates that electroless deposition on flexible free-standing and porous substrate is an effective Sn anode fabrication technique.