Axial Si–Ge Heterostructure Nanowires as Lithium-Ion Battery Anodes

Abstract

Here, we report the application of axially heterostructured nanowires consisting of alternating segments of silicon and germanium with a tin seed as lithium-ion battery anodes. During repeated lithiation and delithiation, the heterostructures completely rearrange into a porous network of homogeneously alloyed SiGe ligaments. The transformation was characterized through ex situ TEM, STEM, and Raman spectroscopy. Electrochemical analysis was conducted on the heterostructure nanowires with discharge capacities in excess of 1180 mAh/g for 400 cycles (C/5) and capacities of up to 613 mAh/g exhibited at a rate of 10 C.

Space‐Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium‐Ion Batteries

“…Subsequently, with further elevation of the temperature to 800 °C, the formed Sn atomic clusters served as catalysts for cleavage of the Si−C bonds of DPS and growth of Si. Notably, the insulation of the carbon framework facilitated catalytic growth of Si within a confined space, which resulted in the formation of Si NDs rather than nanowires that are usually formed in conventional catalytic systems . With catalytic pyrolysis, the superassembly of Si NDs and carbon components occurred, promoted by the continuous generation of Si and carbon.…”

Structural Strategies for Germanium‐Based Anode Materials to Enhance Lithium Storage

“…The electrochemical performance of the Si 1− x Ge x NWs showed that the most Si‐rich compositions exhibited the highest specific capacities, while the most Ge‐rich compositions were found to perform the best at faster charge/discharge rates. Si 0.67 Ge 0.33 showed a capacity of up to 1360 mAh g −1 after 250 cycles at a rate of C/5 and in full cells, against a commercial cathode, where capacities up to 1364 mAh g −1 were retained after 100 cycles 35b. In another study, the Si/Ge core/shell NWs heterostructures enhanced the gravimetric capacity of LIBs anodes under fast charging/discharging rates compared to Si NWs.…”

“…The results showed the addition of fluorethylene carbonate (FEC) to the electrolyte was critical to achieving stable battery cycling and reversible capacities for Ge NWs anode . Killian et al35b reported that Si‐Ge NWs grown onto an evaporated layer of Sn on stainless steel through the SLS mechanism ( Figure ).…”

Electrophoretic Deposition of Tin Sulfide Nanocubes as High‐Performance Lithium‐Ion Battery Anodes

“…This will necessitate the development of high‐performance materials to replace the current commercially‐used graphite anodes in Li‐ion batteries (LIBs). Many Li alloying materials with higher theoretical gravimetric capacities than graphite (372 mAh/g), such as silicon (3,579 mAh/g), germanium (1,384 mAh/g) and tin (994 mAh/g), have been proposed; however problems with cost, scalability and/or long‐term stability have thus far largely prevented commercialization . Tin offers a significant enhancement of gravimetric capacity, combined with material safety and relative abundance .…”

“…Many Li alloying materials with higher theoretical gravimetric capacities than graphite (372 mAh/g), such as silicon (3,579 mAh/g), germanium (1,384 mAh/g) and tin (994 mAh/g), have been proposed; however problems with cost, scalability and/or long-term stability have thus far largely prevented commercialization. [1][2][3]4] Tin offers a significant enhancement of gravimetric capacity, combined with material safety and relative abundance. [5][6][7] Furthermore, the slightly higher discharge voltage of tin (0.4-0.75 V) when compared with Si/Ge means that potential safety problems associated with electroplating of Li are avoided.…”