Exploring the Mechanism of Spontaneous and Lithium-Assisted Graphitic Phase Formation in SiC Nanocrystallites of a High Capacity Li-Ion Battery Anode

Abstract

Herein, we employed first-principles density functional theory calculations to understand the structural, electronic, and magnetic properties of pristine and lithiated zinc blende (ZB) SiC(111) surface slabs. Our calculations on below four layer thick slabs reveal the spontaneous formation of a graphitic SiC layer which mimics the two-dimensional boron nitride structure. Though this monolayer shows a direct band gap, the energy bands in bi- and trilayer slabs are nondegenerated owing to weak van der Waal’s interaction between the layers, and they show indirect band gap for those cases. In a pristine slab, the surface states presented in both sides originate magnetism, and they are coupled antiferromagnetically. Its strength decreases with increasing layer thickness. This magnetism is quenched during lithiation and exfoliation of layers. The latter is observed, even for thicker ZB slabs during lithiation. The average lithium intercalation potential is calculated to be 0.20 V, which is quite comparable with the anodic potential of high capacity SiC nanoparticles as reported in experiment. Thus, the mechanism of lithiation in SiC nanoparticles is proposed to be intercalation, rather than alloying.

Graphitic SiC: A potential anode material for Na‐ion battery with extremely high storage capacity

“…In addition, the F I G U R E 1 (Continued) distance between two adjacent SiC layers increases into 8.03 Å after the full sodiation, which is more than two times larger than that of pure graphitic SiC (3.53 Å), this means that the graphitic SiC will expanse mainly along the z direction during the sodiation process. It is noted that our proposed sodiation processes in graphitic SiC is similar to the intercalation of Li ions into zinc blende (ZB) SiC, during which the graphitic SiC layers are formed with double Li layers between two adjacent ZB SiC layers as have been previously identified both experimentally and theoretically [31,33]. In addition, the formation of double Na layers also has been experimentally observed during the sodiation process in MXene [39].…”

“…In particular, it is found that SiC could be the strong candidate as the Li-ion battery anode with extremely high theoretical capacity (1200 mAh/g) and long cycle life [30][31][32]. While the intercalation of Na ions into SiC has been confirmed to be unfeasible [33]. So far, over 250 polytypes of SiC have been identified, while the fabrication of SiC multilayer structures is very difficult due to the its strong sp 3 preference [29].…”

SiCx/TiCx Nanostructured Material from Ti3SiC2 for High Rate Performance of Lithium Storage

“…Therefore, in the following diffusion calculations, we mainly focus on this configuration. Interestingly, a graphitic SiC layer have spontaneously created, which are accord with other calculation results . The interlayer separations have remarkably increased from 2.59 Å to 2.92‐4.35 Å after introducing Li atoms into SiC slab, which is beneficial to improve the transport ability of Li ion.…”

Zinc blende inspired rational design of a β-SiC based resilient anode material for lithium-ion batteries

“…21 Notably, a recent computational study shows that Li-ions can swily intercalate and occupy the interstitial sites of SiC with tetrahedral symmetry. [22][23][24] Experimentally, the ion implantation study of 8 Li in zinc blende SiC further conrms the occupancy of interstitial sites with tetrahedral symmetry by Li + -ions. 25,26 Besides, SiC exhibits excellent structural robustness and has been shown to support the diffusion of light elements like lithium.…”