Alpha-Germanium Nanolayers for High-Performance Li-ion Batteries

Abstract

The exfoliation of tridimensional crystal structures has recently been considered a new source of bidimensional materials. The new approach offers the possibility of dramatically enlarging the library of bidimensional materials, but the number of nanolayers produced so far is still limited. Here, we report for the first time the use of a new type of material, α-germanium nanolayers (2D α-Ge). The 2D α-Ge is obtained by exfoliating crystals of α-germanium in a simple one-step procedure assisted by wet ball-milling (gram-scale fabrication). The α-germanium nanolayers have been tested as anode material for high-performance LIBs. The results show excellent performance in semi-cell configuration with a high specific capacity of 1630 mAh g−1 for mass loading of 1 mg cm−2 at 0.1 C. The semi-cell was characterized by a constant current rate of 0.5 C during 400 cycles and different scan rates (0.1 C, 0.5 C, and 1 C). Interestingly, the structural characterization, including Raman spectroscopy, XRPD, and XPS, concludes that 2D α-Ge largely retains its crystallinity after continuous cycling. These results can be used to potentially apply these novel 2D germanium nanolayers to high-performance Li-ion batteries.

Graphite Nanosheets as a Platform for the Nanosize GeSe2 Anode with Improved Electrode Performance

“…The Ge/Se ratio was extremely near the stoichiometric composition of GeSe 2 (1/2), as seen in Figure e,f. The peaks at 31.5 and 32.8 eV can be assigned to the Ge 3d 5/2 and Ge 3d 3/2 , respectively, and the peaks at 55.4 and 56.2 eV can be attributed to the Se 3d 5/2 and Se 3d 3/2 of the bridging selenium atoms in GeSe 2 , respectively . It should be noted that the C 1 s spectra contain only one prominent peak at 284.6 eV, which can be attributed to the C–C/CC transition (Figure g) .…”

X-ray Investigations of Sol–Gel-Derived GeO2 Nanoparticles

“…Eventually, the annealing temperature, as well as the annealing time, have to be further increased, and the methodology used here should accompany future optimization of the preparation procedures. The rather simple synthesis route used in the present work appears, however, interesting for the preparation of larger amounts of α-GeO 2 nanoparticles and also for a technological application, such as, e.g., the use in Li-ion batteries, as recently reported [52,53], for industrial catalysts [54,55], where, in particular, the high-temperature capabilities and durabilities are important, as well as potentially for pharmaceuticals [56].…”

Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide

“…Germanium has higher electrical and ionic conductivity than silicon, which makes it an attractive alternative for high-performance anode material [ 12 , 13 , 14 ]. Despite its high cost, elemental germanium and its compounds are promising electrode materials in metal-ion batteries [ 15 , 16 , 17 , 18 ] due to the large theoretical gravimetric and volumetric specific capacities of germanium (with the formation of Li 15 Ge 4 ), equal to 1384 mAh g −1 and 7366 mAh cm −3 , respectively. Unfortunately, large volume changes (by more than 300%) during Li alloying/de-alloying lead to the pulverization of electrode particles and destabilization of solid electrolyte interphase (SEI) films, which hinders the use of germanium-based materials in LIBs [ 19 , 20 ].…”