Effect of Fe substitution on electrochemical properties of Sn3.95Fe0.05P3 alloy anode for lithium ion batteries

Sn3.95Fe0.05P3 alloy was synthesized via a solvothermal method, using tin metal, iron metal and amorphous red phosphorous. The XRD and TEM results showed that Fe ion was successfully substituted on original the Sn4P3 layered structure without any structure changes. The Sn3.95Fe0.05P3 alloy anode showed a higher initial charge capacity and coloumbic efficiency of 1304 mAh g−1 and 73% compared with the Sn4P3 alloy anode, respectively. Additionally, a relatively large capacity of about 420 mAh g−1 after 100th cycles was achieved in the Sn3.95Fe0.05P3 anode, whereas the capacity of the Sn4P3 anode remained at only about 100 mAh g−1 after 100 cycles. Fe atoms as an inactive matrix could be dispersed between the tin atoms, resulting in the suppression of tin agglomeration in Sn3.95Fe0.05P3 during cycling. It is confirmed from the voltage profile and differential capacity plots that the Fe ion in the Sn3.95Fe0.05P3 structure could stabilize the structure and improve the electrochemical properties during cycling.