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Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density.

Son IH, Hwan Park J, Kwon S, Park S, Rümmeli MH, Bachmatiuk A, Song HJ, Ku J, Choi JW, Choi JM, Doo SG, Chang H - Nat Commun (2015)

Bottom Line: However, the large volume change of silicon over charge-discharge cycles weakens its competitiveness in the volumetric energy density and cycle life.Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation.The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers.

View Article: PubMed Central - PubMed

Affiliation: Energy Material Lab, Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, Republic of Korea.

ABSTRACT
Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge-discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l(-1) at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology.

No MeSH data available.


Related in: MedlinePlus

In situTEM analysis.(a) Gr–Si NPs attached to the surface of Au wire and a second Li/LiO2 electrode. (b) The same Gr–Si NPs after lithiation. (c) A schematic summary of lithiated Gr–Si NPs for both non-defective and defective graphene encapsulation. (d,e) Close up TEM images for (d) non-defective particle (the one circled with the red line in a and b) and (e) defective particle (the one circled with the blue line in a and b). The EELS spectra in both cases confirm the lithiation. The line profiles from the red boxes in both cases show increased interlayer distances of ca. 3.8 Å, reflective of lithiation into the graphene interlayer space.
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f3: In situTEM analysis.(a) Gr–Si NPs attached to the surface of Au wire and a second Li/LiO2 electrode. (b) The same Gr–Si NPs after lithiation. (c) A schematic summary of lithiated Gr–Si NPs for both non-defective and defective graphene encapsulation. (d,e) Close up TEM images for (d) non-defective particle (the one circled with the red line in a and b) and (e) defective particle (the one circled with the blue line in a and b). The EELS spectra in both cases confirm the lithiation. The line profiles from the red boxes in both cases show increased interlayer distances of ca. 3.8 Å, reflective of lithiation into the graphene interlayer space.

Mentions: We now turn to the use of Gr–Si as an anode material in LIBs. The lithiation of the Gr–Si NPs (1 wt% graphene) was monitored in real time during their volume expansion using in situ TEM analysis29303132. In the actual experiment, some Gr–Si particles were placed onto a gold (Au)-fixed electrode. A second, but movable, electrode with Li/LiO2 at its tip was positioned to just come into contact with the Gr–Si NPs to lithiate them (Fig. 3a). Once contact with the second electrode was made, the particles began to swell (Fig. 3b). Greater details on this process can be seen in Supplementary Fig. 5 and Supplementary Movies 1–3. Two types of expanding structures were observed, namely non-defective particles and defective particles as highlighted in Fig. 3b,c. In cases where the graphene fully encapsulates the particle and has no obvious defects (Fig. 3d), the diameter increased by ∼30% (220% volume expansion). At the end of lithiation, the interlayer distance of the graphene layers increased to 3.8 Å reflective of Li intercalation33, and the layered characteristic of the graphitic coating was preserved all round the NP (Fig. 3d), suggesting a sliding process between layers as illustrated in Fig. 3c. In cases where a defective region exists (see green circle in Fig. 3a), upon swelling, the inner particle pulverizes and ruptures through the defect (Fig. 3e). The observed distinct fracture behaviours are unlikely to be from particle size, as an encapsulated particle bigger than the fractured one in Fig. 3 did not fracture (see the indicated particles at 0 and 40 s in Supplementary Fig. 5). Also, recent observation34 indicates that if not encapsulated, even smaller Si particles (<50 nm) can fracture due to Li concentration gradient within the particles that can create a substantial stress. In fact, the critical size of Si particle fracture is case dependent, and is related on how efficiently the stress built up during volume expansion is able to be released. The critical size can extend to >200 nm (ref. 35).


Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density.

Son IH, Hwan Park J, Kwon S, Park S, Rümmeli MH, Bachmatiuk A, Song HJ, Ku J, Choi JW, Choi JM, Doo SG, Chang H - Nat Commun (2015)

In situTEM analysis.(a) Gr–Si NPs attached to the surface of Au wire and a second Li/LiO2 electrode. (b) The same Gr–Si NPs after lithiation. (c) A schematic summary of lithiated Gr–Si NPs for both non-defective and defective graphene encapsulation. (d,e) Close up TEM images for (d) non-defective particle (the one circled with the red line in a and b) and (e) defective particle (the one circled with the blue line in a and b). The EELS spectra in both cases confirm the lithiation. The line profiles from the red boxes in both cases show increased interlayer distances of ca. 3.8 Å, reflective of lithiation into the graphene interlayer space.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4491181&req=5

f3: In situTEM analysis.(a) Gr–Si NPs attached to the surface of Au wire and a second Li/LiO2 electrode. (b) The same Gr–Si NPs after lithiation. (c) A schematic summary of lithiated Gr–Si NPs for both non-defective and defective graphene encapsulation. (d,e) Close up TEM images for (d) non-defective particle (the one circled with the red line in a and b) and (e) defective particle (the one circled with the blue line in a and b). The EELS spectra in both cases confirm the lithiation. The line profiles from the red boxes in both cases show increased interlayer distances of ca. 3.8 Å, reflective of lithiation into the graphene interlayer space.
Mentions: We now turn to the use of Gr–Si as an anode material in LIBs. The lithiation of the Gr–Si NPs (1 wt% graphene) was monitored in real time during their volume expansion using in situ TEM analysis29303132. In the actual experiment, some Gr–Si particles were placed onto a gold (Au)-fixed electrode. A second, but movable, electrode with Li/LiO2 at its tip was positioned to just come into contact with the Gr–Si NPs to lithiate them (Fig. 3a). Once contact with the second electrode was made, the particles began to swell (Fig. 3b). Greater details on this process can be seen in Supplementary Fig. 5 and Supplementary Movies 1–3. Two types of expanding structures were observed, namely non-defective particles and defective particles as highlighted in Fig. 3b,c. In cases where the graphene fully encapsulates the particle and has no obvious defects (Fig. 3d), the diameter increased by ∼30% (220% volume expansion). At the end of lithiation, the interlayer distance of the graphene layers increased to 3.8 Å reflective of Li intercalation33, and the layered characteristic of the graphitic coating was preserved all round the NP (Fig. 3d), suggesting a sliding process between layers as illustrated in Fig. 3c. In cases where a defective region exists (see green circle in Fig. 3a), upon swelling, the inner particle pulverizes and ruptures through the defect (Fig. 3e). The observed distinct fracture behaviours are unlikely to be from particle size, as an encapsulated particle bigger than the fractured one in Fig. 3 did not fracture (see the indicated particles at 0 and 40 s in Supplementary Fig. 5). Also, recent observation34 indicates that if not encapsulated, even smaller Si particles (<50 nm) can fracture due to Li concentration gradient within the particles that can create a substantial stress. In fact, the critical size of Si particle fracture is case dependent, and is related on how efficiently the stress built up during volume expansion is able to be released. The critical size can extend to >200 nm (ref. 35).

Bottom Line: However, the large volume change of silicon over charge-discharge cycles weakens its competitiveness in the volumetric energy density and cycle life.Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation.The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers.

View Article: PubMed Central - PubMed

Affiliation: Energy Material Lab, Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, Republic of Korea.

ABSTRACT
Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge-discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l(-1) at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology.

No MeSH data available.


Related in: MedlinePlus