Enhancing the Performance of a Self-Standing Si/PCNF Anode by Optimizing the Porous Structure

Abstract

Embedding silicon nanoparticles into carbon nanofibers is one of the effective methods to fabricate a self-standing and binder-free Si-based anode material for lithium-ion batteries. However, the sluggish Li-ion transport limits the electrochemical performance in the regular strategies, especially under high rate conditions. Herein, a kind of silicon nanoparticle in porous carbon nanofiber structures (Si/PCNFs) has been fabricated through a facile electrospinning and subsequent thermal treatment. By adjusting the mass ratio to 0.4:1, a Si/PCNF anode material with an effective Li + -migration pathway and excellent structural stability can be obtained, resulting in an optimal electrochemical performance. Although increasing the mass ratio of PEG to PAN further can lead to a larger pore size and can be beneficial to Li + migration, thus being profitable for the rate capacity, the structural stability will get worse at the same time as more defects will form and lead to a weaker C−C binding, thus decrease the cycling stability. Remarkably, the rate capacity reaches 1033.4 mA h g −1 at the current density of 5 A g −1 , and the cycling capacity is 933.2 mA h g −1 at 0.5 A g −1 after 200 cycles, maintaining a retention rate of 80.9% with an initial coulombic efficiency of 83.37%.

Revisiting the Preparation Progress of Nano‐Structured Si Anodes toward Industrial Application from the Perspective of Cost and Scalability

“…Methods for fabricating Si‐NTs in the above‐mentioned steps of Si‐NTs fabrication can be decomposed into many categories. The first step of manufacturing nanowire materials includes dipping coating hydrothermal method, solution synthesis method, CVD method, electrostatic spinning method (ES), [ 144–146 ] etc. ; the second step of coating Si materials includes CVD method, sol–gel method (SG), stöber method of depositing SiO 2 ; the third step of removing intermediate nanowires includes acid etching method, high temperature calcination method, magnesium thermal reduction (MR).…”

Silicon‐Based Lithium Ion Battery Systems: State‐of‐the‐Art from Half and Full Cell Viewpoint

“…[ 50–56 ] Therefore, conventional Si‐based full cells usually have limited energy densities, poor lifetime and operating security, which will restrict their further applications in daily life. [ 57,58 ] In order to develop high‐energy Si‐based full cells with superior lifetime and enhanced security, a comprehensive battery system theory needs to be established, including the structural optimization of Si, [ 59–63 ] SiO x , [ 64–66 ] and Si‐alloy [ 67–69 ] anode materials, the selection of cathode materials with high capacities and voltage limits, the design principles of promising electrolytes, [ 70–74 ] binders, [ 75–78 ] and separators, [ 79–81 ] as well as their applications in half and full cells (such as LiCoO 2 (LCO)||Si, [ 69,82 ] LiFePO 4 (LFP)||Si, [ 83,84 ] LiNi x Co y Mn z O 2 (NCM, x + y + z = 1)||Si, [ 85–87 ] and S||Li x Si [ 88,89 ] ). State‐of‐the‐art pre‐lithiation technology focuses on further improving the energy densities and lifetime of Si‐based full cells, due to its powerful ability to compensate for irreversible Li + consumption.…”

“…[50][51][52][53][54][55][56] Therefore, conventional Si-based full cells usually have limited energy densities, poor lifetime and operating security, which will restrict their further applications in daily life. [57,58] In order to develop high-energy Si-based full cells with superior lifetime and enhanced security, a comprehensive battery system theory needs to be established, including the structural optimization of Si, [59][60][61][62][63] SiO x , [64][65][66] and Si-alloy [67][68][69] anode materials, the selection of cathode materials with high capacities and voltage limits, the design principles of promising electrolytes, [70][71][72][73][74] binders, [75][76][77][78] and separators, [79][80][81] as well as their applications in half and full cells (such as LiCoO 2 (LCO)||Si, [69,82] LiFePO 4 (LFP)||Si, [83,84] LiNi x Co y Mn z O 2 (NCM,…”

Engineering Si-Based Anode Materials with Homogeneous Distribution of SiOx and Carbon for Lithium-Ion Batteries

“…Recently, tremendous efforts have been dedicated to developing novel high specific energy electrode materials because the energy density and power density of batteries are directly dependent upon the properties of electrode active materials. − Among the currently reported various anode materials, silicon (Si) is deemed to be a promising candidate for next-generation LIBs. Compared with commercial graphite (Gr, 372 mA h g –1 ), Si possesses a higher theoretical capacity (up to 4200 mA h g –1 , Li 4.4 Si), low delithiation/lithiation potential, and high natural abundance. , However, Si has a large volumetric change (400%) during the charge/discharge process, which leads to the cracking of active particles, pulverization of electrodes, and an unstable solid electrolyte interphase (SEI). , These limit the industrial application of Si-based anode materials in practical LIBs. In recent years, the properties of Si-based electrodes have been improved by designing Si nanostructures, surface coatings, − Si active/inactive composites, − or new binder/electrolyte additives, − but their inherent huge volume variations cannot yet be fully addressed.…”

“…7,8 However, Si has a large volumetric change (400%) during the charge/discharge process, which leads to the cracking of active particles, pulverization of electrodes, and an unstable solid electrolyte interphase (SEI). 9,10 These limit the industrial application of Si-based anode materials in practical LIBs. In recent years, the properties of Si-based electrodes have been improved by designing Si nanostructures, surface coatings, 11−13 Si active/inactive composites, 14−16 or new binder/ electrolyte additives, 17−19 but their inherent huge volume variations cannot yet be fully addressed.…”