Tin-Based Oxide, Alloy, and Selenide Li-Ion Battery Anodes Derived from a Bimetallic Metal-Organic Material

Here we report the formation of three distinct Sn-based active materials for Li-ion battery anodes, formed from the same metal-organic material (MOM) precursor sql-1-Cu-SNIFSIX. The materials were obtained under three different anneal conditions in air, Ar, and a Se-rich atmosphere, leading to the selective formation of SnO2/CuO/C (oxide), Cu6Sn5/C (stannide), and Cu2SnSe3/SnSe2/C (selenide) composites. The lithiation and delithiation mechanisms were investigated for each material in the potential range of 0-3 V. Over extended cycling periods, the reversible alloying of Li with Sn was the only process evident for the stannide, with minimal activity occurring at potentials greater than 1 V. In contrast to this, the oxide and selenide composites exhibit both conversion (1-3 V) and Li/Sn alloying (0-1 V) behavior in this potential range; however, the stability of the conversion reaction was found to be poor, inhibiting the capacity retention of both materials. Notably, when the reaction mechanisms were restricted to Li/Sn alloying only by limiting the potential range to 0-1 V, all three composite materials significantly outperformed a Sn nanopowder electrode, illustrating the benefits of utilizing composite electrodes to stabilize the Sn alloying reaction over extended cycling periods.