Amorphous Germanium Nanomaterials as High‐Performance Anode for Lithium and Sodium‐Ion Batteries

Liu, Chao; Jiang, Yiming; Meng, Chao; Liu, Xiao‐Cun; Li, Bo; Xia, Sheng‐Qing

doi:10.1002/admt.202201817

“…We believe that higher ion diffusivity will be achieved with amorphous Ge than with crystalline Ge. Unlike crystalline Ge, amorphous Ge does not have long-range order [43,44]; therefore, it can accelerate the structural opening of the localized transport pathway through which multivalent ions migrate.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Dynamics Investigation of Germanium as an Anode Material in Multivalent-Ion Batteries

Kim,

Hwang,

Lee

et al. 2023

Nanomaterials

1

0

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Germanium, a promising electrode material for high-capacity lithium ion batteries (LIBs) anodes, attracted much attention because of its large capacity and remarkably fast charge/discharge kinetics. Multivalent-ion batteries are of interest as potential alternatives to LIBs because they have a higher energy density and are less prone to safety hazards. In this study, we probed the potential of amorphous Ge anodes for use in multivalent-ion batteries. Although alloying Al and Zn in Ge anodes is thermodynamically unstable, Mg and Ca alloys with Ge form stable compounds, Mg2.3Ge and Ca2.4Ge that exhibit higher capacities than those obtained by alloying Li, Na, or K with Ge, corresponding to 1697 and 1771 mA·h·g–1, respectively. Despite having a slightly lower capacity than Ca–Ge, Mg–Ge shows an approximately 150% smaller volume expansion ratio (231% vs. 389%) and three orders of magnitude higher ion diffusivity (3.0 × 10−8 vs. 1.1 × 10−11 cm2 s−1) than Ca–Ge. Furthermore, ion diffusion in Mg–Ge occurs at a rate comparable to that of monovalent ions, such as Li+, Na+, and K+. The outstanding performance of the Mg–Ge system may originate from the coordination number of the Ge host atoms and the smaller atomic size of Mg. Therefore, Ge anodes could be applied in multivalent-ion batteries using Mg2+ as the carrier ion because its properties can compete with or surpass monovalent ions. Here, we report that the maximum capacity, volume expansion ratio, and ion diffusivities of the alloying electrode materials can be understood using atomic-scale structural properties, such as the host–host and host–ion coordination numbers, as valuable indicators.

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Revealing Capacity Degradation of Ge Anodes in Lithium‐Ion Batteries Triggered by Interfacial LiH

Chen

¹

,

Sun

²

,

Li

³

et al. 2023

Angewandte Chemie

2

0

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The Germanium (Ge), as a fast-charging and high specific capacity (1568 mAh g À 1 ) alloy anode, is greatly hampered in practical application by poor cyclability. To date, the understanding of cycling performance degradation remains elusive. This study illustrates that, contrary to conventional beliefs, most of the Ge material in failed anodes still retains good integrity and does not undergo severe pulverization. It is revealed that capacity degradation is clearly correlated to the interfacial evolution of lithium hydride (LiH). Tetralithium germanium hydride (Li 4 Ge 2 H), as a new species derived from LiH, is identified as the culprit of Ge anode degradation, which is the dominant crystalized component in an ever-growing and ever-insulating interphase. The significantly increased thickness of the solid electrolyte interface (SEI) is accompanied by the accumulation of insulating Li 4 Ge 2 H upon cycling, which severely retards the charge transport process and ultimately triggers the anode failure. We believe that the comprehensive understanding of the failure mechanism presented in this study is of great significance to promoting the design and development of alloy anode for the next generation of lithium-ion batteries.

show abstract

Revealing Capacity Degradation of Ge Anodes in Lithium‐Ion Batteries Triggered by Interfacial LiH

Chen

¹

,

Sun

²

,

Li

³

et al. 2023

Angew Chem Int Ed

6

0

View full text Add to dashboard Cite

The Germanium (Ge), as a fast-charging and high specific capacity (1568 mAh g À 1 ) alloy anode, is greatly hampered in practical application by poor cyclability. To date, the understanding of cycling performance degradation remains elusive. This study illustrates that, contrary to conventional beliefs, most of the Ge material in failed anodes still retains good integrity and does not undergo severe pulverization. It is revealed that capacity degradation is clearly correlated to the interfacial evolution of lithium hydride (LiH). Tetralithium germanium hydride (Li 4 Ge 2 H), as a new species derived from LiH, is identified as the culprit of Ge anode degradation, which is the dominant crystalized component in an ever-growing and ever-insulating interphase. The significantly increased thickness of the solid electrolyte interface (SEI) is accompanied by the accumulation of insulating Li 4 Ge 2 H upon cycling, which severely retards the charge transport process and ultimately triggers the anode failure. We believe that the comprehensive understanding of the failure mechanism presented in this study is of great significance to promoting the design and development of alloy anode for the next generation of lithium-ion batteries.

show abstract

Amorphous Germanium Nanomaterials as High‐Performance Anode for Lithium and Sodium‐Ion Batteries

Cited by 10 publications

References 44 publications

First-Principles Dynamics Investigation of Germanium as an Anode Material in Multivalent-Ion Batteries

First-Principles Dynamics Investigation of Germanium as an Anode Material in Multivalent-Ion Batteries

Revealing Capacity Degradation of Ge Anodes in Lithium‐Ion Batteries Triggered by Interfacial LiH

Revealing Capacity Degradation of Ge Anodes in Lithium‐Ion Batteries Triggered by Interfacial LiH

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