Si‐Based High‐Entropy Anode for Lithium‐Ion Batteries

Abstract

Up to now, only a small portion of Si has been utilized in the anode for commercial lithium‐ion batteries (LIBs) despite its high energy density. The main challenge of using micron‐sized Si anode is the particle crack and pulverization due to the volume expansion during cycling. This work proposes a type of Si‐based high‐entropy alloy (HEA) materials with high structural stability for the LIB anode. Micron‐sized HEA‐Si anode can deliver a capacity of 971 mAhg−1 and retains 93.5% of its capacity after 100 cycles. In contrast, the silicon–germanium anode only retains 15% of its capacity after 20 cycles. This study has discovered that including HEA elements in Si‐based anode can decrease its anisotropic stress and consequently enhance ductility at discharged state. By utilizing in situ X‐ray diffraction and transmission electron microscopy analyses, a high‐entropy transition metal doped Lix(Si/Ge) phase is found at lithiated anode, which returns to the pristine HEA phase after delithiation. The reversible lithiation and delithiation process between the HEA phases leads to intrinsic stability during cycling. These findings suggest that incorporating high‐entropy modification is a promising approach in designing anode materials toward high‐energy density LIBs.

A review of noble metal-free high entropy alloys for water splitting applications

“…Recent studies have exploited the high entropy effect of HEAs for use in various mechanical, 49–51 catalytic, 52–54 and even biomedical applications. 55–57 Lei et al 58 for example used the high entropy effect of Si-based high entropy anode materials synthesized via ball milling and found that the material performed well as an anode for lithium-ion batteries which was able to undergo reversible structural changes during cycling, leading to its overall cycling stability.…”

Structural Reversibility of Nanoscaled Sn Anodes

“…However, there are few novel materials for the anode that can be commercialized. Theoretical calculations and experimental studies have shown that alloying-type materials capable of forming stable intermetallic compounds with lithium, , such as Si, − Sn, , Sb, Bi, and Ge, are more likely to provide energy densities exceeding the currently used carbon anodes. However, the large volume change (200% ∼ 400%) during lithiation of these materials lead to mechanical fracture, loss of electrical contact, and unstable solid electrolyte interface (SEI) layers that impede reaction kinetics and reduce cycling stability. , Optimization of the size and morphology of these alloying-type materials are considered crucial to solving these problems. − …”