Nanosize Si anode embedded in super-elastic nitinol (Ni-Ti) shape memory alloy matrix for Li rechargeable batteries

A nanosize Si embedded in super-elastic Nitinol alloy matrix composite was synthesized in large-scale using arc melting followed by a rapid quenching method. Both X-ray diffraction and high resolution transmission electron microscope with energy dispersive spectroscopy analyses confirmed that approximately 50 nm Si crystallites were surrounded by the Ni-Ti matrix. Ex situ synchrotron XRD was performed to elucidate the phase transition of active materials during lithiation and delithiation. The local structural changes of the Ni-Ti inactive matrix during cycling were investigated by ex situ X-ray absorption spectroscopy analyses. This anode material showed an excellent electrochemical stability since the elastic behavior of the inactive Nitinol matrix absorbed the stress generated due to the volume expansion during lithiation of the nanosized Si embedded.