The Effects of Trace Sb and Zn Additions on Cu₆Sn₅ Lithium-Ion Battery Anodes

Sn-based compounds are promising candidates for application as anodes in lithium-ion batteries (LIBs) due to the favourable storage capacity of Sn at 993 mAh g^-1 compared to carbon at 372 mAh g^-1. The use of Sn-based anodes also avoids some of the safety concerns associated with carbon anodes. However, the large volume changes during lithiation and delithiation of pure Sn anodes often results in poor cyclic performance. Alloying Sn with Cu, an element inactive with respect to Li, buffers the expansion stresses and can improve cycling performance. Cu⁶Sn₅ is therefore a promising candidate anode material. In this work, the effects of Sb and Zn additions on the morphology, crystal structure, atomic arrangements and the electrochemical performance of the anodes were evaluated. Characterisation with synchrotron X-ray powder diffraction and C-corrected transmission electron microscopy revealed the larger lattice parameters, higher symmetry crystal structures and well-ordered atomic arrangements in the Sb and Zn modified electrodes, which resulted in a more than 50% increase in cycling capacity from 490 mAh g^-1 to 760 mAh g^-1.