Pyrochlore phase Ce₂Sn₂O₇ via an atom-confining strategy for reversible lithium storage

In the search of high-performance anode materials for next-generation Li-ion batteries, more efforts are needed on new structural prototypes. Motivated by the negative thermal expansion effect in a loosely packed crystal structure type, we are intrigued by the possibility of exploiting new anode materials in a suitable phase structure with much-reduced intrinsic volume strain. Herein, we report a new pyrochlore phase anode material, Ce₂Sn₂O₇, which shows atomic Sn confined in a conductive 3D percolating Ce-O framework. Based on the concept of structural openness, pyrochlore Ce₂Sn₂O₇ possesses open structures to tolerate the volume change. Notably, the Ce-O network is quite robust against the charge/discharge process, which accounts for the high structural stability observed in the experiment. Ultimately, Ce₂Sn₂O₇ electrodes achieve a capacity as high as 631.1 mA h g^-1 and excellent cycling stability. This atom-confining strategy of atomic Sn in the conductive 3D percolating Ce-O framework might be exploited as a general strategy for reducing cycling strain in ion-storage materials.  © The Royal Society of Chemistry 2020.