Available Technology

BSA 11-12: Intermetallic M-Sn<sub>5</sub> (M=Fe, Cu, Co, Ni) Compounds

Among electrode materials for lithium ion batteries, tin offers a high theoretical capacity about 2.5 times that of graphite by weight. Unfortunately, when lithium alloys with tin the matrix undergoes a very large volume change. This change in volume results in a loss of capacity over a few charge-discharge cycles. By adding a transition metal to the tin, this volume change can be mitigated. The novel phase of FeSn5or CoSn5exhibits a capacity nearly twice that of FeSn2, the previous champion intermetallic.
Patent Abstract: 
Using a modified polyol wet-chemistry method the inventors prepared nanospheres of the new phases, which have tetragonal lattices in the P4/mcc space group. The capacity of FeSn5is nearly twice that of FeSn2. Both FeSn5and CoSn5have a large number of vacancies on the M site, approximately 25%, leading to quasi-one-dimensional behavior. FeSn5is also superparamagnetic, implying that the nanoparticles include at least one component that orders magnetically at or above room temperature.
FeSn5and CoSn5offer very high capacity for lithium ion batteries.
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