Construction of Structure-Tunable Si@Void@C Anode Materials for Lithium-Ion Batteries through Controlling the Growth Kinetics of Resin

Abstract

Silicon (Si), a promising candidate for next-generation lithium-ion battery anodes, is still hindered by its volume change issue for (de)­lithiation, thus resulting in tremendous capacity fading. Designing carbon-modified Si materials with a void-preserving structure (Si@void@C) can effectively solve this issue. The preparation of Si@void@C, however, usually depended on template-based routes or chemical vapor deposition, which involve toxic reagents, tedious operation processes, and harsh conditions. Here, a facile templateless approach for preparing Si@void@C materials is reported through controlling the growth kinetics of resin, without the use of toxic hydrofluoric acid or harsh conditions. This approach allows great flexibility in tuning the crucial parameters of Si@void@C, such as the carbon shell thickness, the reserved void size, and the number of Si cores coated by a carbon shell. The optimized Si@void@C delivers a large specific capacity (1993.2 mAh g–1 at 0.1 A g–1), excellent rate performance (799.4 mAh g–1 at 10.0 A g–1), and long cycle life (73.5% capacity retention after 1000 cycles at 2.0 A g–1). In addition, a full cell fabricated with a Si@void@C anode and commercial LiFePO4 cathode also displays an impressive cycling performance.

β‐cyclodextrin as Lithium‐ion Diffusion Channel with Enhanced Kinetics for Stable Silicon Anode

“…As shown in Figure , the lithium‐ion diffusion coefficients (D Li ) of Si@β‐CD electrode and Si electrode were studied by the galvanostatic intermittent titration technique (GITT), according to the following formula:where τ is the galvanic titration time, m B , M B , and V M are corresponding to the mass, molar mass, and molar volume of Si@β‐CD electrode and Si electrode, respectively, S represents the surface area of the electrode, Δ E S is the voltage variation during a single whole GITT titration, and Δ E τ represents the total voltage variation during a galvanic titration time of a single GITT titration without the consideration of the IR‐drop. [ 57‐59 ] During the GITT test, the current pulse was 100 mA g −1 , and it was applied on the battery for 15 min in order to obtain the closed‐circuit voltage (CCV) and then for 15 min without the current to obtain the quasi‐open‐circuit voltage (QOCV). The GITT comparison plots of Si@β‐CD electrode and Si electrode during the 1st and 5th discharge/charge process are shown in Figure 3a,b.…”

Facile and Scalable Synthesis of Si@void@C Embedded in Interconnected 3D Porous Carbon Architecture for High Performance Lithium‐Ion Batteries

“…Commercial pure silicon particles (purchased from the company of Siping Changchun, China) were chosen as the starting materials. Owing to the positive charge from the Si particles, [ 23,24 ] the synthesis process takes advantage of hydrophilicity of silicon powder (Figure 1a and Figure S1a in the Supporting Information). First, in the water/oil system (Figure 1b), the added (3‐Aminopropyl) triethoxysilane coupling agent is compatible with organic substances (styrene monomer acted as oil phase).…”

Scalable Synthesis of Porous SiFe@C Composite with Excellent Lithium Storage

“…The mesoporous structure can greatly shorten the lithium‐ion diffusion pathways and, at the same time, alleviate the volume change during cycling. The carbon‐coating layer as well as the partially retained FeSi 2 phase may improve the overall electronic conductivity and structural stability of the composite, thus improving its rate capability and electrochemical cycling [19, 57, 58] …”