TiO2 as a multifunction coating layer to enhance the electrochemical performance of SiOx@TiO2@C composite as anode material

Ren

et al. 2021

Adv Funct Materials

SiO x /C composites with a void-reserving structure are promising anodes for lithium-ion batteries. However, the facile and controllable synthesis of uniformly dispersed SiO x and carbon components, simultaneously incorporating ample voids, still remains a great challenge. Herein, a molecular polymerization strategy is devised to construct SiO x /C hollow particles for lithium-ion batteries. 3-aminopropyltriethoxysilane and dialdehyde molecules are judiciously engineered as silicon and carbon precursors to produce the polymer hollow spheres (PHSs) through a one-step aldimine condensation without any template and additive. A range of PHSs is obtained using terephthalaldehyde, glutaraldehyde, and glyoxal as the crosslinkers, demonstrating the high tunability of the strategy. Importantly, in situ pyrolysis of the PHSs warrants the homogeneous incorporation of SiO x (<5 nm) in carbon hollow capsids at a nanocluster scale. The obtained SiO x /C hollow spheres exhibit excellent Li + -ion storage behaviors, including cycling lifespan, coulombic efficiency, and rate performance. The superior performance is attributed to the well-dispersed SiO x nanoclusters in carbon substrate and the hollow structure. This molecular polymerization approach not only enables Si-based hollow composites effective and scalable anode materials but also opens up a new avenue for the controllable synthesis of template-free hollow architectures.

Section: Resultsmentioning

confidence: 99%

Engineering Molecular Polymerization for Template‐Free SiO_x/C Hollow Spheres as Ultrastable Anodes in Lithium‐Ion Batteries

Zhou

Ren

et al. 2021

Adv Funct Materials

“…N doping would create more defects and more active sites for ion adsorption, deservedly, the NG/SiO x /NG electrode delivered a higher initial charge capacity of 1182.3 mAh g −1 with a higher coulombic efficiency of 66.6%. The overlapped GCD curves in the following cycles indicated the high electrochemical reversibility of NG/SiO x /NG [ 1 , 23 , 43 ]. The improved coulombic efficiency from 49.6% for SiO x to 66.6% for NG/SiO x /NG and the high reversibility verified the NG/SiO x /NG electrode to be a promising anode for LIBs ( Table S1 ).…”

Section: Resultsmentioning

confidence: 99%

“…Slope lines in the low-frequency region are ascribed to Warburg impedance (Z w ), which is associated with Li + diffusion in bulk electrode materials [ 18 , 47 , 54 ]. And the lithium ion diffusion coefficient (D Li+ ) could be calculated with Equation (4) through linear fitting between Z’ and ω −1/2 (ω = 2πf) in low frequencies of Nyquist diagrams [ 1 , 3 ]. In Equation (4), R, T, A, n, F, and C are the gas constant, absolute temperature, surface area of the electrode, number of transferred electrons per molecule in the material, Faraday’s constant and concentration of Li + , respectively; while σ represented the Warburg coefficients and could be determined by the slopes of Z′ − ω −1/2 plots ( Figure 5 c,d) [ 3 , 29 , 52 ].…”

Section: Resultsmentioning

confidence: 99%

Green and Scalable Fabrication of Sandwich-like NG/SiOx/NG Homogenous Hybrids for Superior Lithium-Ion Batteries

Wei

et al. 2021

Nanomaterials

SiOx is considered as a promising anode for next-generation Li-ions batteries (LIBs) due to its high theoretical capacity; however, mechanical damage originated from volumetric variation during cycles, low intrinsic conductivity, and the complicated or toxic fabrication approaches critically hampered its practical application. Herein, a green, inexpensive, and scalable strategy was employed to fabricate NG/SiOx/NG (N-doped reduced graphene oxide) homogenous hybrids via a freeze-drying combined thermal decomposition method. The stable sandwich structure provided open channels for ion diffusion and relieved the mechanical stress originated from volumetric variation. The homogenous hybrids guaranteed the uniform and agglomeration-free distribution of SiOx into conductive substrate, which efficiently improved the electric conductivity of the electrodes, favoring the fast electrochemical kinetics and further relieving the volumetric variation during lithiation/delithiation. N doping modulated the disproportionation reaction of SiOx into Si and created more defects for ion storage, resulting in a high specific capacity. Deservedly, the prepared electrode exhibited a high specific capacity of 545 mAh g−1 at 2 A g−1, a high areal capacity of 2.06 mAh cm−2 after 450 cycles at 1.5 mA cm−2 in half-cell and tolerable lithium storage performance in full-cell. The green, scalable synthesis strategy and prominent electrochemical performance made the NG/SiOx/NG electrode one of the most promising practicable anodes for LIBs.

“…To date, a great deal of strategies, including nanostructuring, [ 12–16 ] conductive hybridization, [ 17–19 ] and binder stabilization, [ 20–23 ] have been proposed to develop advanced Si‐based anodes with outstanding performance. In particular, hybridization with conductive materials, such as carbon, has been considered to be a promising route.…”

Section: Introductionmentioning

confidence: 99%

“…[8] Given these fatal shortcomings, rational exploration of efficacious design and synthesis strategies is highly desirable. [9][10][11] To date, a great deal of strategies, including nanostructuring, [12][13][14][15][16] conductive hybridization, [17][18][19] and binder stabilization, [20][21][22][23] have been proposed to develop advanced Si-based anodes with outstanding performance. In particular, hybridization with conductive materials, such as carbon, has been considered to be a promising route.…”

mentioning

confidence: 99%

Nanocaging Silicon Nanoparticles into a Porous Carbon Framework toward Enhanced Lithium‐Ion Storage

Hou

Part & Part Syst Charact

Pan-pan

et al. 2021

Silicon (Si) shows overwhelming promise as the high‐capacity anode material of Li‐ion batteries with high energy density. However, Si‐based anodes are subjected to a limited electrochemical cycling lifetime due to their large volume change. Herein, a honeycomb‐like biomass‐derived carbon nanosheet framework is reported to encapsulate Si nanoparticles via a facile molten salt templating method. The carbon framework provides sufficient void space for effectively accommodating the large volume expansion of Si upon Li+ insertion. Moreover, the interconnected carbon skeletons afford fast electron/ion transport pathways for improving the reaction kinetics. Consequently, the porous Si/carbon composite could exhibit a high and stable Li storage capacity of 1022 mAh g−1 at 0.2 A g−1 over 100 cycles along with superior rate capability (555 mAh g−1 at 5 A g−1). This study demonstrates an effective structural design strategy for Si‐based anodes toward stable lithium energy storage.