Self-assembled asymmetric membrane containing micron-size germanium for high capacity lithium ion batteries

Abstract

Asymmetric porous structure formedviaa self-assembly phase inversion method can significantly improve the cycling performance of lithium ion anodes made of micron-size germanium powders.

Etching Asymmetric Germanium Membranes with Hydrogen Peroxide for High‐Capacity Lithium‐Ion Battery Anodes

“…However, CA Ge Mem and PAN Ge Mem did suffer from 73.6% and 75.5% capacity losses in 50 cycles at 160 mA g −1 because Ge concentrations are very high (63.0 and 75.2 wt%, respectively), entailing a large electrode volume change that can cause serious electrode delamination and pulverization (Table and Figure a). It is noteworthy that such cyclability is still much better than that of micrometer powder Ge control, whose capacity was eroded to less than 270 mAh g −1 after two formation cycles and further reduced to less than 160 mAh g −1 in as few as ten cycles at 160 mA g −1 (Figure S4, Supporting Information), whose results are consistent with literature reports …”

“…It is noteworthy that such cyclability is still much better than that of micrometer powder Ge control, whose capacity was eroded to less than 270 mAh g À1 after two formation cycles and further reduced to less than 160 mAh g À1 in as few as ten cycles at 160 mA g À1 (Figure S4, Supporting Information), whose results are consistent with literature reports. [11,24] To enhance the cycling stability of asymmetric Ge membranes as the LIB anode, we initially managed to etch CA Ge Mem using concentrated hydrogen peroxide solutions to generate an oxide layer and extra void space to better accommodate the large volume change. But the membrane was relatively fragile and thus broken into pieces during H 2 O 2 etching.…”

Toward Low-Cost, High-Energy Density, and High-Power Density Lithium-Ion Batteries

“…Other alloys such as Ge 164 and Sn 165 have also been investigated for high-energy and high-power density anode materials. Nevertheless, similar challenges to Si remain including significant volume expansion and capacity fade.…”

Micron‐size Silicon Monoxide Asymmetric Membranes for Highly Stable Lithium Ion Battery Anode

“…The formation mechanism of asymmetric membranes can be easily understood using a ternary phase diagram, which has been discussed explicitly in our previous studies . To describe it briefly, the homogeneous phase made of solvent (N‐methyl‐2‐pyrrolidone: NMP) and polymer (Polyacrylonitrile: PAN) is separated into two phases (polymer lean and polymer rich) after being immersed into non‐solvent (deionized water), due to the mixing of solvent and non‐solvent, and de‐mixing of polyacrylonitrile from the solvent/non‐solvent (NMP/water) mixture ,. The intrinsic 3‐D porous structure and carbonaceous coating on SiO powder can efficiently accommodate large volume expansion and stabilize SEI layer, thus leading to an excellent cycling performance as confirmed by the following electrochemical tests.…”

“…Several innovative strategies have been proposed to tackle the problems of Si anodes, most of which are associated with various kinds of nanostructures such as nanoparticles (NPs), nanowires (NWs), nanotubes (NTs), nanofibers (NFs), nanoscale thin films, mesoporous and microporous materials, and SiO x ,. Si is normally engineered into nanomaterials to overcome low diffusion coefficient of Li ions in silicon as compared to graphite (∼10 −10 vs. 10 −6 cm 2 s −1 ) and reduce Li ion diffusion length for high rate performance.…”