Fe saponite, a layered silicate for reversible lithium-ions storage with large diffusion coefficient

摘要

A kind of layered Li;MSiO;material,Fe saponite with Na;pillaring (Na^(+)-FSAP) was developed as a lowcost and environment-friendly lithium-ion storage material.The Na^(+)-FSAP follows the insertion/deinsertion working mechanism accompanied by valence change of Fe from Fe^(1.86+) to Fe^(2.71+) (average value) after stabilization,and displays a specific capacity of 125 m Ah g^(-1) at 50 m A g^(-1) with retention ratio of 80.8%after 75 cycles.The Na^(+)-pillaring effect and abundant structural water in the gallery urge Li^(+) migrate rapidly,resulting in a large Li^(+) diffusion coefficient within a range of 10^(-6.5)–10^(-7.5) cm^(2)s^(-1).Thus,the Na^(+)-FSAP provides a model material to design electrode materials with rapid lithium-ion migration and has great potential to take place of polyanionic-type Li_(2)MSiO_(4)(M=Mn,Fe,Co) cathode materials.