Multipod Bi(Cu<sub>2-x</sub>S)<sub><i>n</i></sub> Nanocrystals formed by Dynamic Cation-Ligand Complexation and Their Use as Anodes for Potassium-Ion Batteries.

Kapuria, Nilotpal; Imtiaz, Sumair; Sankaran, Abinaya; Geaney, Hugh; Kennedy, Tadhg; Singh, Shalini; Ryan, Kevin M · Nano Lett · 2022

basic_science · Level V

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Abstract

We report the formation of an intermediate lamellar Cu-thiolate complex, and tuning its relative stability using alkylphosphonic acids are crucial to enabling controlled heteronucleation to form Bi(Cu<sub>2-<i>x</i></sub>S)<sub><i>n</i></sub> heterostructures with a tunable number of Cu<sub>2-<i>x</i></sub>S stems on a Bi core. The denticity of the phosphonic acid group, concentration, and chain length of alkylphosphonic acids are critical factors determining the stability of the Cu-thiolate complex. Increasing the stability of the Cu-thiolate results in single Cu<sub>2-<i>x</i></sub>S stem formation, and decreased stability of the Cu-thiolate complex increases the degree of heteronucleation to form multiple Cu<sub>2-<i>x</i></sub>S stems on the Bi core. Spatially separated multiple Cu<sub>2-<i>x</i></sub>S stems transform into a support network to hold a fragmented Bi core when used as an anode in a K-ion battery, leading to a more stable cycling performance showing a specific capacity of ∼170 mAh·g<sup>-1</sup> after 200 cycles compared to ∼111 mAh·g<sup>-1</sup> for Bi-Cu<sub>2-<i>x</i></sub>S single-stem heterostructures.

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