High-Performance Germanium Nanowire-Based Lithium-Ion Battery Anodes Extending over 1000 Cycles Through in Situ Formation of a Continuous Porous Network

• Published in: Nano letters Vol. 14; no. 2; pp. 716 - 723
• Main Authors: Kennedy, Tadhg, Mullane, Emma, Geaney, Hugh, Osiak, Michal, O’Dwyer, Colm, Ryan, Kevin M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12.02.2014
• Subjects: Anodes; Applied sciences; Arrays; Cross-disciplinary physics: materials science; rheology; Direct energy conversion and energy accumulation; Electric vehicles; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Formations; Lithium-ion batteries; Materials science; Methods of nanofabrication; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanowires; Networks; Physics; Quantum wires; Scanning electron microscopy; porous; tin seed; rate capability; lithium-ion battery; Germanium nanowires; network; Lithium battery; Scanning electron microscopy; Transmission electron microscopy; High density; Porous materials; Germanium; Nanowires; Arrays; Nanostructured materials; Nanomaterial synthesis
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl403979s

Here we report the formation of high-performance and high-capacity lithium-ion battery anodes from high-density germanium nanowire arrays grown directly from the current collector. The anodes retain capacities of ∼900 mAh/g after 1100 cycles with excellent rate performance characteristics, even at very high discharge rates of 20–100C. We show by an ex situ high-resolution transmission electron microscopy and high-resolution scanning electron microscopy study that this performance can be attributed to the complete restructuring of the nanowires that occurs within the first 100 cycles to form a continuous porous network that is mechanically robust. Once formed, this restructured anode retains a remarkably stable capacity with a drop of only 0.01% per cycle thereafter. As this approach encompasses a low energy processing method where all the material is electrochemically active and binder free, the extended cycle life and rate performance characteristics demonstrated makes these anodes highly attractive for the most demanding lithium-ion applications such as long-range battery electric vehicles.