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

Abstract

Silicon (Si) has been recognized as a promising alternative to graphite anode materials for advanced lithium-ion batteries (LIBs) owing to its superior theoretical capacity and low discharge voltage. However, Si-based anodes undergo structural pulverization during cycling due to the large volume expansion (ca. 300–400%) and continuous formation of an unstable solid electrolyte interphase (SEI), resulting in fast capacity fading. To address this challenge, a series of different amounts of silicon nanoparticles (Si NPs)-encapsulated hollow porous N-doped/Co-incorporated carbon nanocubes (denoted as p-CoNC@SiX, where X = 50, 80, and 100) as anode materials for LIBs are reported in this paper. These hollow nanocubic materials were derived by facile annealing of different contents of Si NPs-encapsulated Zn/Co-bimetallic zeolitic imidazolate frameworks (ZIF@Si) as self-sacrificial templates. Owing to the advantages of well-defined hollow framework clusters and highly conductive hollow carbon frameworks, the hollow porous p-CoNC@SiX significantly improved the electronic conductivity and Li+ diffusion coefficient by an order of magnitude higher than that of Si NPs. The as-prepared p-CoNC@Si80 with 80 wt % Si NPs delivered a continuously increasing specific capacity of 1008 mAh g–1 at 500 mA g–1 over 500 cycles, excellent reversible capacity (∼1361 mAh g–1 at 0.1 A g–1), and superior rate capability (∼603 mAh g–1 at 3 A g–1) along with an unprecedented long-life cyclic stability of ∼1218 mAh g–1 at 1 A g–1 over 1000 cycles caused by low volume expansion (9.92%) and suppressed SEI side reactions. These findings provide new insights into the development of highly reversible Si-based anode materials for advanced LIBs.

High-performance Si@C anode for lithium-ion batteries enabled by a novel structuring strategy

“…S11, † the N 1s signal is detected in Si@FeNO@P and shows two forms of N, with two peaks at 398.1 eV and 400.2 eV, corresponding to pyridinic N and pyrrolic N, respectively. 36 This means that the carbon matrix has an N-doped structure. The N originates from PVP.…”

“…18 Besides, the N dopants, along with defective carbon, can not only upgrade the electrical conductivity of the electrode but also accelerate ion transport in the electrode. 36 With the advantages of highly graphitized foam-like porous N-doped carbon matrix, highly conductive Fe 3 C, and robust Si-O-C chemical bond bonding, Si@FeNO@P will display much enhanced conductivity, improved lithium-ion diffusion coefficient, and superior structural stability when used as LIB anode. Thus, the electrochemical performance study of the as-prepared samples is performed using CR2016-type coin cells.…”

“…The Li + diffusion coefficients (D Li +) of the Si and Si@FeNO@P electrodes are further compared by Fick's second law. 36 The used equations are as follows.…”

“…The Li + diffusion coefficients ( D Li + ) of the Si and Si@FeNO@P electrodes are further compared by Fick's second law. 36 The used equations are as follows.where R , T , A , n , F , C , σ ω , Z ′, R e , R ct , and ω are the gas constant, absolute temperature, electrode contact area, electron transfer number, Faraday constant, molar concentration of Li + , Warburg factor, real portion of the complex impedance, electrolyte resistance, charge transfer resistance, and angular frequency, respectively. 62 The σ ω reflects the D Li + of the electrodes, the value of which can be determined by the slope of Z ′ vs. ω −1/2 .…”

Interpenetrating gel-enabled uniform integration of metal and carbon dual matrices with nanoporous silicon for high-performance lithium storage

“…[13][14][15] As common hybridization matrices, metal and carbon with high conductivity could promote charge transport. [16][17][18][19][20][21][22] Moreover, a metallic component could serve as a diffusion barrier to restrain the complete lithiation of amorphous Li-Si alloy to crystalline Li 15 Si 4 , [23][24][25] whereas carbon can stabilize the electrode/electrolyte interface, yielding a stable SEI layer. [26][27][28][29] Therefore, the uniform and simultaneous integration of metal and carbon with nanoporous silicon is highly desirable for overcoming these issues and obtaining ideal overall Li-storage performance, yet remains a big challenge owing to the different physicochemical properties of Si, M, and C tri-components.…”