Reversible Intercalation of Li Ions in an Earth-Abundant Phyllosilicate Clay

The phyllosilicate family of clays is an intriguing collection ofmaterials that make ideal models for studying the intercalation of alkali ions dueto their layered topology and broadly tunable composition space. In this spirit,we present a hydrothermal method to prepare a layered iron phyllosilicate clay,Fe2Si4O10(OH)2, and an evaluation of its electrochemical performance for the(de)insertion of Li ions. Through careful structural refinement, we determinedthat this iron clay contains a 2:1 stacking sequence, which is directly analogousto the widely studied mineral montmorillonite, with the crystallites adopting aplatelike morphology. Cyclic voltammetry and galvanostatic cycling revealreversible insertion of lithium into the interstitial layers via a solid solutionmechanism. Comparison of ion (de)intercalation with reports on other clay systems like muscovite, KFe2.75Si3.25O10(OH)2, whichfeatures a rigidly bound interlayer cation, demonstrates that controlling the net charge on the layers with phyllosilicate minerals is aroute to enabling reversible cationic intercalation within the structure.

Automated summary

The phyllosilicate family of clays with layered topology and tunable composition is an ideal model for studying alkali ion intercalation. This study presents a hydrothermal method to prepare a layered iron phyllosilicate clay and evaluates its electrochemical performance for Li ion (de)insertion. Results show reversible insertion of lithium into interstitial layers via a solid solution mechanism. Comparison with other clay systems demonstrates the importance of controlling net charge on the layers for reversible cationic intercalation.