In Situ Synthesis of Graphene‐Coated Silicon Monoxide Anodes from Coal‐Derived Humic Acid for High‐Performance Lithium‐Ion Batteries

Abstract

Silicon monoxide (SiO) is attaining extensive interest amongst silicon‐based materials due to its high capacity and long cycle life; however, its low intrinsic electrical conductivity and poor coulombic efficiency strictly limit its commercial applications. Here low‐cost coal‐derived humic acid is used as a feedstock to synthesize in situ graphene‐coated disproportionated SiO (D‐SiO@G) anode with a facile method. HR‐TEM and XRD confirm the well‐coated graphene layers on a SiO surface. Scanning transmission X‐ray microscopy and X‐ray absorption near‐edge structure spectra analysis indicate that the graphene coating effectively hinders the side‐reactions between the electrolyte and SiO particles. As a result, the D‐SiO@G anode presents an initial discharge capacity of 1937.6 mAh g−1 at 0.1 A g−1 and an initial coulombic efficiency of 78.2%. High reversible capacity (1023 mAh g−1 at 2.0 A g−1), excellent cycling performance (72.4% capacity retention after 500 cycles at 2.0 A g−1), and rate capability (774 mAh g−1 at 5 A g−1) results are substantial. Full coin cells assembled with LiFePO4 electrodes and D‐SiO@G electrodes display impressive rate performance. These results indicate promising potential for practical use in high‐performance lithium‐ion batteries.

Insights into the Effect of Heat Treatment and Carbon Coating on the Electrochemical Behaviors of SiO Anodes for Li‐Ion Batteries

“…We used humic acid as the carbon source to create a conductive and resilient nano‐graphene coating during the heat‐treatment process. [ 28 ] The synthesized D‐SiO@G composites (Figure 1m) possess a similar particle size to P‐SiO but with a rounded‐edge shape because of the graphene coating. Importantly, no Si nanowire is found from the powder.…”

“…D-SiO@G Preparation: Humic acid, extracted and purified from North Dakota lignite according to our previous reports, was used as the carbon source in the carbon coating process. [28] Humic acid (2.5 g) and 10 g of P-SiO powder were mixed in 100 mL of DI water, then 1 mL of ammonium (28-30%, LabChem, USA) was added dropwise into the mixture to dissolve the humic acid completely. This slurry was stirred vigorously for 1 h then spray dried (Spray Dryer TP-S15, Toption) with an inlet temperature of 200 °C.…”

Phosphorus‐Based Anodes for Fast Charging Lithium‐Ion Batteries: Challenges and Opportunities

“…[ 8 ] To improve the electrochemical performance of SiO x , a recent report synthesized an in situ graphene‐coated disproportionated SiO (D‐SiO@G) anode, which presented a high rate capability of 774 mAh g −1 at 5 A g −1 . [ 60 ] Other carbon species also worked. By in situ growing of carbon nanotubes (CNTs) and graphitic carbon on the surface of SiO x , the as‐prepared SiO x @CNTs/C delivered a remarkable capacity of 327 mAh g −1 after 1000 cycles at 5 A g −1 .…”

Construction of a N,P doped 3D dendrite-free lithium metal anode by using silicon-containing lithium metal

“…The metal lithium anode has a high theoretical capacity (3860 mA h g −1 ), a low negative electrochemical potential (−3.040 V compared to a standard hydrogen electrode), and a low gravimetric density (0.534 g cm −1 ). 11,12 Therefore, Li metal has long been regarded as the "Holy Grail" of battery technologies. 13,14 Lithium metal batteries (LMBs) are considered to be the most promising substitute for the traditional carbon anode of LIBs.…”