Free-Standing Stable Silicon-Based Anode with Exceptional Flexibility Realized by a Multifunctional Structure Design in Multiple Dimensions

Abstract

Cyclized polyacrylonitrile (cPAN) with decently flexible, elastic, and conductive properties is a promising substrate or binder material for flexible devices. However, it is infeasible to accommodate the large volume expansion and contribute the exceptional rate capability of silicon anodes in lithium-ion batteries only counting on the limited elasticity and conductivity of cPAN. Herein, we report a robust silicon/carbon-cPAN-graphene (SC-CP-G) composite membrane with excellent flexibility based on a multifunctional structure design in multiple dimensions, which can be used as a free-standing integrated anode for lithium ion batteries. In this integrated electrode, silicon nanoparticles are encapsulated in porous carbon with in situ formed confined space, and the silicon/carbon particles are further embedded in cPAN nanofibers, which are inextricably interwoven with a reduced graphene oxide film, forming an interpenetrating network architecture. The unique hierarchical and functional structure design greatly improves the mechanical performance, cycling stability, and capacity accessibility of silicon electrodes, delivering a specific capacity of 1847 mA h g–1 at 2 A g–1 and a capacity retention of 87% after 150 cycles.

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

“…where i 0 , A, R, T, n, F, and E a are the exchange current density, temperature-independent coefficient, gas constant, absolute temperature, number of electrons transferred, Faraday constant, and apparent activation energy for ion transport, respectively. The EIS plots of Si, Si@P, Si@FeNO@P, and Si@FeNO@P-Et electrodes (after 10 cycles at 100 mA g −1 ) are carried out at different temperatures (30,40,50,60, and 70 °C), as shown in Fig. 5m-o and S18, respectively.…”

“…This phenomenon of the structures of the carbon tending to disorder with temperatures increase is also found in the reported Si/C-based material. 60 The porous structure may be the main cause of this phenomenon, which provides carbon more defects and hence a low content of the graphitized structure. Due to the optimal structure, Si@FeNO@P exhibits the best overall electrochemical performance.…”

Constructing a Stable Integrated Silicon Electrode with Efficient Lithium Storage Performance through Multidimensional Structural Design

“…The variations in C and N elements provide evidence of PAN cyclization. 38 The C−C bond in the three electrodes is significantly enhanced around 285 eV compared to that of I4, primarily attributed to the presence of G or CNT. The slight variation in SiO x content may be associated with the electrode composition or the detection depth of XPS (∼10 nm).…”

“…37 However, the inherent conductivity of cPAN is still insufficient to match that of carbonaceous materials such as graphene sheet (G) and CNT. 38 Therefore, the combination of cPAN with materials that possess high electrical conductivity and mechanical strength proves advantageous in further enhancing its characteristics.…”

Unveiling Challenges and Opportunities in Silicon‐Based All‐Solid‐State Batteries: Thin‐Film Bonding with Mismatch Strain

“…[13] However, like being used in LIBs with LEs, huge volume change (≈300%) during alloying/dealloying and poor electrical conductivity are still the major impediments to the application in ASSBs. [14][15][16] Compared to cathode materials with smaller volume-specific capacity, the interface challenges between SEs and anode materials with higher volume-specific capacity are more significant. The formation of interfacial gaps can result in uneven distribution of current density and temperature, which can have a detrimental impact on battery lifespan.…”