2D Silicon-Germanium-Layered Materials as Anodes for Li-Ion Batteries

To address the volume changes of Si-based and Ge-based anode materials during lithiation and delithiation, two-dimensional (2D) composites like siloxene and germanane have recently been developed. These 2D materials can insert alkali cations without an alloying reaction, thereby limiting the associated volume expansion. While Si has a high theoretical capacity and low cost, its electrical conductivity is low; on the other hand, Ge provides a higher electronic conductivity but at a higher cost. Therefore, we propose a series of 2D Si-Ge alloys, that is, Si1-xGex with 0.1 < x < 0.9, referred to as siliganes, with reasonable cost and encouraging electrochemical performance. The layered siliganes were obtained by fully deintercalating Ca cations from the Ca(Si1-xGex)2 parent phases and used as Li-ion battery (LIB) anodes. XRD, SEM, Raman spectroscopy, and infrared spectroscopy were used to characterize the materials and identify the mechanisms occurring during cycling in LIBs. Siligane_Si0.9Ge0.1 was identified as the best candidate; at a current density of 0.05 A g-1, after 10 cycles, it showed a reversible capacity of 1325 mA h g-1, with high capacity retention and coulombic efficiency.

Automated summary

The 2D Si-Ge alloy materials, known as siliganes, have been developed for use as anodes in Li-ion batteries, offering reasonable cost and promising electrochemical performance. Among them, the siligane_Si0.9Ge0.1 showed the best performance, with a reversible capacity of 1325 mA h g-1, high capacity retention, and coulombic efficiency at a current density of 0.05 A g-1 after 10 cycles.