Germanium Nanowires via Molten-Salt Electrolysis for Lithium Battery Anode

Abstract

Germanium (Ge)-based materials can serve as promising anode candidates for high-energy lithium-ion batteries (LIBs). However, the rapid capacity decay caused by huge volume expansion severely retards their application. Herein, we report a facile and controllable synthesis of Ge nanowire anode materials through molten-salt electrolysis. The optimal Ge nanowires can deliver a capacity of 1058.9 mAh g–1 at 300 mA g–1 and a capacity above 602.5 mAh g–1 at 3000 mA g–1 for 900 cycles. By in situ transmission electron microscopy and in situ X-ray diffraction, the multiple-step phase transformation and good structural reversibility of the Ge nanowires during charge/discharge are elucidated. When coupled with a lithium-rich Li1.2Mn0.567Ni0.167Co0.067O2 cathode in a full battery, the Ge nanowire anode leads to a relatively stable capacity with a retention of 84.5% over 100 cycles. This research highlights the significance of molten-salt electrolysis for the synthesis of alloy-type anode materials toward high-energy LIBs.

Multiscale Micro‐Nano Hierarchical Porous Germanium with Self‐Adaptive Stress Dispersion for Highly Robust Lithium‐Ion Batteries Anode

“…Compared with other reported unique structural Ge anode materials, the p-Ge anode proposed herein not only displays superior rate performance, but also shows high electrochemical activity, which is comparable to that of Ge quantum dot structures (Figure 3d). [12][13][14][15] Figure 3e displays the cycling performance of the p-Ge and Ge NPs anode materials. The p-Ge exhibits a discharge capacity of 1350 mAh g −1 with 90% capacity retention calculated from the 1st to 200th cycles at a current density of 0.5 A g −1 , which is higher than that of the Ge NPs (70%).…”

“…[5] However, a high degree of Li intake in Ge with the formation of Li 4.4 Ge alloy results in a huge volume expansion of 370% and dramatic internal stress generation, leading to crack nucleation and propagation even fractures inside Ge electrodes, continuous evolution of solid electrolyte interphase (SEI) and eventually rapid capacity fading. [6][7][8] Nano-engineering approaches have been extensively investigated to alleviate the stress derived from volume change and promote the Li + insertion/desertion kinetics of Ge and other alloying anode materials, [9,10] such as the design of nanoparticle, [9] nanotube, [11] nanowire [12] and embedding them in carbonaceous matrix, [13][14][15] which showed both enhanced cycling stability and rate capability. Although nanostructured Ge and their carbon composites can enhance the mechanical stability and facilitate charge transport, they are subjected to low initial Coulombic efficiency (ICE), poor tap density and volumetric performance, and the high production cost and complexity because of high specific surface area and high surface energy.…”

“…Nano‐engineering approaches have been extensively investigated to alleviate the stress derived from volume change and promote the Li + insertion/desertion kinetics of Ge and other alloying anode materials, [ 9,10 ] such as the design of nanoparticle, [ 9 ] nanotube, [ 11 ] nanowire [ 12 ] and embedding them in carbonaceous matrix, [ 13–15 ] which showed both enhanced cycling stability and rate capability. Although nanostructured Ge and their carbon composites can enhance the mechanical stability and facilitate charge transport, they are subjected to low initial Coulombic efficiency (ICE), poor tap density and volumetric performance, and the high production cost and complexity because of high specific surface area and high surface energy.…”

Recent progress in zeolitic imidazolate frameworks (ZIFs)-derived nanomaterials for effective lithium polysulfide management in lithium–sulfur batteries

“…On the other hand, various alloy/conversion-type electrodes, such as some elements and their compounds of IV A to VII A groups ( e.g. Si, 21 Sn, 22 Sb, 23 Ge, 24 red P, 25 O 2 (air), 26 S, 27 I 2 , 28 and their compounds), 29 have inherently higher theoretical energy density than typical LIBs based on different electrochemistry, thus attracting extensive research interest. Frustratingly, however, batteries based on these metals still face a series of problems caused by larger ionic radii.…”

Understanding the behaviour of a niobium oxide cathode in a molten chloride bath using different DC voltammetric techniques

“…The oxide ions then migrate through the molten salt electrolyte towards a graphite anode, where they are discharged in the form of carbon oxide gases [1]. A significant number of laboratory studies have since concentrated on the electrolytic production of numerous metals such as Ti, Th, Gr, Si, Nb, Cr, Hf, Zr; binary alloys and intermetallics such as Co-Cr, W-Ti, NdCo 5 ; ternary alloys such as Nb-Hf-Ti, Ti-6Al-4V; and quaternary alloys such as Ti-29Nb-13Ta-4.6Zr and CoCrFeNi [2][3][4][5][6]. The method has also been used to create nano and micro-sized particles of mono and binary carbides and oxycarbides [7][8][9][10][11].…”