Synergistic carbon coating of MOF-derived porous carbon and CNTs on silicon for high performance lithium-ion batteries

Hollow Porous N and Co Dual-Doped Silicon@Carbon Nanocube Derived by ZnCo-Bimetallic Metal–Organic Framework toward Advanced Lithium-Ion Battery Anodes

“…Therefore, p-CoNC@Si80 showed superior performance with higher capacity, even in a longer cycle life, compared with previously reported silicon-/carbonbased core−shell structure anode materials (Figure 6e). 42,43,46−48,51,53,63−65 To highlight our results, the content of silicon encapsulated in p-CoNC@Si80 material is compared with those of various carbon-based composite materials related with Figure 6e (Table S1, Supporting Information), 42,43,46,47,53,64,65 demonstrating that p-CoNC@Si80 affords a superior high energy density at the high C-rate of 1 A g −1 and the outstanding long-life cycling performance with an immediate achievement of 97.96% CE within 10 cycles despite the relatively low silicon content (∼28.74 wt %) of the p-CoNC@Si80 material. We also tested the CV curves and the charging/discharging performance at the lower voltage window of 0.005−1.2 V for p-CoNC@Si80 (Figure S10, Supporting Information).…”

“…SEM images of (b) ZnCo-ZIF, (c) ZnCo-ZIF@Si50, (d) ZnCo-ZIF@Si80, (e) ZnCo-ZIF@Si100 before pyrolysis, and (f) p-CoNC, (g) p-CoNC@Si50, (g) p-CoNC@Si80, and (i) p-CoNC@Si100 after pyrolysis process. ∼1155 mA h g −1 at 2 A g −1 , and long-life cyclic stability of 1109 mAh g −1 at 3 A g −1 and 804 mAh g −1 at 5 A g −1 ), 44 saclike-silicon nanoparticles anchored spongy matrix through ZIF-8 to anchor saclike silicon via molten salt magnesiothermic reduction method (Si@N-C with a content 77.58% Si NPs; ∼1448 mAh g −1 at 2 A g −1 and 848 mAh g −1 at 4 A g −1 ), 45 silicon-wrapped N-doped carbon nanotubes prepared by controllable thermal pyrolysis with ZIF-67 (Si@N-doped CNTs; ∼1144 mAh g −1 at 1 A g −1 and 1264 mAh g −1 at 1/ 4 C), 46 ZIF-67 encapsulated Si@CNTs by chemical vapor deposition and MOF self-template methods (Si@CNTs@ZIF; ∼568.8 mAh g −1 at 1 A g −1 ), 47 and mesoporous cobalt (Co), N co-doped double carbon-coated silicon/carbon/MOF multicore yolk-shell obtained by Sol-gel and MOF selftemplate methods (Si@C@ZIF-67−800N; ∼1107 mAh g −1 at 0.5 A g −1 and 852 mAh g −1 at 1 A g −1 ), 48 have been scrutinized as high-capacity anode materials with tiny volume changes for long-life-span LIBs. Among these aforementioned strategies, the carbonization of ZIF-based MOFs encapsulated with Si NPs is a more repeatable process for generating the hollow porous external carbon shell and abundant internal void, which can effectively improve the electronic conductivity of ZIF-based electrode materials and buffer against the volume change effect of Si NPs during (de)lithiation processes.…”

“…Among the various MOFs, bimetallic zeolitic imidazolate frameworks (ZnCo-ZIFs; ZIF-8 and ZIF-67) have emerged as excellent self-sacrificial templates for synthesizing various nitrogen-doped Co-based carbon nanocomposite anode materials for realizing exceptional energy storage in LIBs, owing to their high surface area, adjustable pore size by imidazole linker modification, and exceptional chemical and thermal stability . Moreover, ZIF-derived nanocomposites consist of N-doped mesoporous to porous carbon skeletons with high graphitization, which can efficiently buffer against the large volume expansion of Si NPs, improve the electronic conductivity, and shorten the diffusion length for Li + . , Recently, ZIFs-derived materials, including porous cage-like carbon/nano-Si nanocomposites prepared by nano-Si@zeolitic imidazolate frameworks (ZIF-8)-templated method (cage-like nano-Si/C; ∼1168 mA h g –1 at 100 mA g –1 ), mesoporous silicon hollow nanocubes through magnesiothermic reduction reaction (MRR) of silica-coated ZIF-8 (m-Si HCs; ∼1050 mAh g –1 at 15 C), hollow cube-like Si/SiO 2 @C nanocomposite by carbonization of ZIF-8 coated with SiO 2 (hollow cube-like Si/SiO 2 @C; ∼1280 mA h g –1 at 500 mA g –1 ), cage-like mesoporous Si@ZIF-67 core–shells obtained by carbonization of ZIF-67 coated with a 20 nm Si NPs (cage-like Si@ZIF-67-600; ∼1230 mA h g –1 at 0.5 A g –1 , and ∼1180 mA h g –1 at 1 A g –1 ), Si-nanoparticle core and N-doped/Co-incorporated carbon shell prepared by carbonization of ZIF-67 wrapped with Si NPs (Si@Co–NC; ∼191.4 mA h g –1 at 1000 mA g –1 ), micron bread-like N-doped Si/C core–shell by carbonization of ZIF-8 incorporated with Si NPs (micron bread-like Si/C composite with a high Si content of 71 wt %; ∼1155 mA h g –1 at 2 A g –1 , and long-life cyclic stability of 1109 mAh g –1 at 3 A g –1 and 804 mAh g –1 at 5 A g –1 ), saclike-silicon nanoparticles anchored spongy matrix through ZIF-8 to anchor saclike silicon via molten salt magnesiothermic reduction method (Si@N-C with a content 77.58% Si NPs; ∼1448 mAh g –1 at 2 A g –1 and 848 mAh g –1 at 4 A g –1 ), silicon-wrapped N-doped carbon nanotubes prepared by controllable thermal pyrolysis with ZIF-67 (Si@N-doped CNTs; ∼1144 mAh g –1 at 1 A g –1 and 1264 mAh g –1 at 1/4 C), ZIF-67 encapsulated Si@CNTs by chemical vapor deposition and MOF self-template methods (Si@CNTs@ZIF; ∼568.8 mAh g –1 at 1 A g –1 ), and mesoporous cobalt (Co), N co-doped double carbon-coated silicon/carbon/MOF multicore yolk-shell obtained by Sol-gel and MOF self-template methods (Si@C@ZIF-67–800N; ∼1107 mAh g –1 at 0.5 A g –1 and 852 mAh g –1 at 1 A g –1 ), have been scrutinized as high-capacity anode materials with tiny volume changes for long-life-span LIBs. Among these aforementioned strategies, the carbonization of ZIF-based MOFs encapsulated with Si NPs is a more repeatable process for generating the hollow porous external carbon shell and abundant internal void, which can effectively improve the electronic conductivity of ZIF-based electrode materials and buffer against the volume change effect of Si NPs during (de)­lithiation processes.…”

Recent Applications of Molecular Structures at Silicon Anode Interfaces

“…The resin and the MOF formed double carbon coating, which helped to deliver reversible capacities of 1107 mAh g −1 at 0.5 A g −1 after 100 cycles and 852 mAh g −1 at 1 A g −1 over 300 cycles. Qiao et al reported the decoration of Si nanoparticles with CNTs, which assisted their subsequent encapsulation in ZIF-67 [55,56]. After pyrolysis, the obtained Si@CNTs@c-ZIF composite delivered a capacity of 568.8 mAh g −1 at 1 A g −1 after 200 cycles (60.1% retention) [55].…”

“…Qiao et al reported the decoration of Si nanoparticles with CNTs, which assisted their subsequent encapsulation in ZIF-67 [55,56]. After pyrolysis, the obtained Si@CNTs@c-ZIF composite delivered a capacity of 568.8 mAh g −1 at 1 A g −1 after 200 cycles (60.1% retention) [55].…”