Quantification of Pseudocapacitive Contribution in Nanocage‐Shaped Silicon–Carbon Composite Anode

Abstract

Pseudocapacitive materials have been highlighted as promising electrode materials to overcome slow diffusion‐limited redox mechanism in active materials, which impedes fast charging/discharging in energy storage devices. However, previously reported pseudocapacitive properties have been rarely used in lithium‐ion batteries (LIBs) and evaluation methods have been limited to those focused on thin‐film‐type electrodes. Hence, a nanocage‐shaped silicon–carbon composite anode is proposed with excellent pseudocapacitive qualities for LIB applications. This composite anode exhibits a superior rate capability compared to other Si‐based anodes, including commercial silicon nanoparticles, because of the higher pseudocapacitive contribution coming from ultrathin Si layer. Furthermore, unprecedent 3D pore design in cage shape, which prevents the particle scale expansion even after full lithiation demonstrates the high cycling stability. This concept can potentially be used to realize high‐power and high‐energy LIB anode materials.

Strategic Pore Architecture for Accommodating Volume Change from High Si Content in Lithium‐Ion Battery Anodes

“…More seriously, repeated huge volume change during cycling can bring about structural degradation and increased space between particles as factors related to losing contact between particles and accelerating electrode swelling, resulting in electrical isolation and low volumetric capacity, respectively . Thus, for the successful implementation of G‐Si system into advanced LIBs, the rational distribution of high Si content in the composite anode is a must to accommodate Si volume expansion . Previously, we reported that volume expansion of Si in G‐Si system can be accommodated via selectively located Si in macropore of mesopore‐degenerated G .…”

“…However, when applied power density was increasing over 3000 W kg −1 , EGS (220 Wh kg −1 at 6000 W kg −1 ) exhibited an outstanding gravimetric energy density than that of HGS (153 Wh kg −1 ) and B‐Si (127 Wh kg −1 ). This result can be ascribed to the benefits of EGS design, which has widely distributed thin Si layers together with significant void space …”

Zn(Cu)Si2+xP3 Solid Solution Anodes for High‐Performance Li‐Ion Batteries with Tunable Working Potentials

“…[25,26] In addition to the XRD analysis, we further performed Raman spectroscopy analysis. More specifically, the cubic ZnS crystal structure can also be confirmed by the observation of the exposed (220) and (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) crystal planes along the zone axis of [001], as indicated by d-spacings of lattice fringes in Figure 1f. The morphology of the ZnSi 2 P 3 powder was further examined using field-emission scanning electron microscopy (FESEM; Figure S1, Supporting Information) and low-magnitude transmission electron microscopy (TEM, Figure 1e).…”

“…As shown in Figure 4e, the Coulombic efficiency remains at ≈100% after 500 cycles at a current density of 300 mA g −1 while maintaining ≈80.5% of the initial discharge capacity (at 1955 mAh g −1 ). Notably, the Li-storage performance of the ZnSi 2 P 3 /C nanocomposite is superior to most reported P-and Si-based anodes [2,3,6,8,9,11,19,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] in terms of initial Coulombic efficiency and cycling stability (Figure 4g). Notably, the Li-storage performance of the ZnSi 2 P 3 /C nanocomposite is superior to most reported P-and Si-based anodes [2,3,6,8,9,11,19,[32][33][34][35][36][37][38][39][40][41][42][43]…”

“…Among all metal-based anode materials, Si is considered the most attractive candidate due to its abundance in the crust of earth, low cost, high theoretical capacity (4200 mAh g −1 according to Li 4.4 Si), and low working potential. [3][4][5][6][7][8][9][10] Unfortunately, the complicated synthesis processes together with low yield greatly increase the cost of LIBs, although the well-designed nanostructure engineering did show better Li-storage performance in certain aspects (e.g., rate performance) compared to the micro-sized Si anodes. To address these issues, various strategies have been developed, including nanostructure engineering, porous structure tuning, and surface modification with coatings.…”