High-Entropy Engineering of Cubic SiP with Metallic Conductivity for Fast and Durable Li-Ion Batteries

Abstract

A cost-effective, scalable ball milling process is employed to synthesize the InGeSiP₃ compound with a cubic ZnS structure, aiming to address the sluggish reaction kinetics of Si-based anodes for Lithium-ion batteries. Experimental measurements and first-principles calculations confirm that the synthesized InGeSiP₃ exhibits significantly higher electronic conductivity, larger Li-ion diffusivity, and greater tolerance to volume change than its parent phases InGe (or Si)P₂ or In (or Ge, or Si)P. These improvements stem from its elevated configurational entropy. Multiple characterizations validate that InGeSiP₃ undergoes a reversible Li-storage mechanism that involves intercalation, followed by conversion and alloy reactions, resulting in a reversible capacity of 1733 mA h g⁻¹ with an initial Coulombic efficiency of 90%. Moreover, the InGeSiP₃-based electrodes exhibit exceptional cycling stability, retaining an 1121 mA h g⁻¹ capacity with a retention rate of ≈87% after 1500 cycles at 2000 mA g⁻¹ and remarkable high-rate capability, achieving 882 mA h g⁻¹ at 10 000 mA g⁻¹. Inspired by the distinctive characteristic of high entropy, the synthesis is extended to high entropy GaCu (or Zn)InGeSiP₅, CuZnInGeSiP₅, GaCuZnInGeSiP₆, InGeSiP₂S (or Se), and InGeSiPSSe. This endeavor overcomes the immiscibility of different metals and non-metals, paving the way for the electrochemical energy storage application of high-entropy silicon-phosphides.