Suppressed Volume Change of a Spray-Dried 3D Spherical-like Si/Graphite Composite Anode for High-Rate and Long-Term Lithium-Ion Batteries

Abstract

Morphology plays a vital role in controlling the volume variation in Si-based anode materials and enhances lithiumion battery performances. Here, we demonstrated advanced techniques that combine electrostatic self-assembly and spraydrying methods to form 3D spherical-like silicon/graphite (denoted "Si/G") composite anode materials. This spherical morphology alleviates issues relating to silicon volume changes that occur in high-rate lithium-ion batteries. Commercial graphite (G) flakes were initially mixed with silicon nanoparticles (ca. 50 nm) to form a bare-Si/G composite through electrostatic interaction; sphericallike composite particles were then obtained through single and double spray-drying processes, giving samples SD1-Si/G and SD2-Si/G, respectively. We examined the charge/discharge characteristics of the fabricated electrodes (CR2032-type coin cells) in the voltage range 0.02−1.5 V (vs Li/Li + ). The as-fabricated bare-Si/G, SD1-Si/G, and SD2-Si/G half-cells provided initial discharge specific capacities of 897, 866, and 1020 mA h g −1 , respectively. The SD2-Si/G half-cell shows better cycling stability at a high current rate of 400 mA g −1 than the SD1-Si/G and bare-Si/G half-cells due to effective inhibition of the volume change in the more stable spherical structure of the SD2-Si/G composite, as evidenced through in situ dilatometry. Thus, the spherical Si/G composite material produced through this simple spray-drying process had structural characteristics that could effectively resist silicon's high expansion rate, lower the production rate of broken silicon particles, and improve the electrochemical performance of the anode.

Reinforced Interfacial Interaction between Si and Graphite To Improve the Cyclic Stability of Lithium-Ion Batteries

“…The electrochemical behavior of Si&AG in different cycles was further explored through EIS, as displayed in Figure e. By employing the equivalent circuit (insert in Figure S9), the charge transfer resistance ( R ct ) can be quantified by the diameter of the semicircle in the medium and high-frequency regions. , The fitted Nyquist plots and fitted impedance data are shown in Figure S9 and Table S3, respectively. As shown in Figure f, the R ct values of Si/AG before and after the 10th and 20th cycles are measured to be 70.53, 313.9, and 445.8, respectively, while the R ct values of Si&AG before and after the 10th and 20th cycles are measured to be 100.2, 96.92, and 101.5, respectively.…”

“…5,6 On the other hand, carbon material can act as a buffer to mitigate the impact of volume expansion. 7,8 In order to obtain a Si/C composite material with an exceptional electrochemical performance, several key factors must be carefully considered. For instance, Si should be uniformly dispersed within carbon material to minimize agglomeration.…”

“…Restricted by serious volume expansion and low conductivity, the practical application of silicon (Si) has been impeded. , To address these challenges, the utilization of Si/C composite material emerges as a promising solution. , On the one hand, the incorporation of carbon material with excellent conductivity can effectively promote rapid electrochemical reactions. , On the other hand, carbon material can act as a buffer to mitigate the impact of volume expansion. , In order to obtain a Si/C composite material with an exceptional electrochemical performance, several key factors must be carefully considered. For instance, Si should be uniformly dispersed within carbon material to minimize agglomeration.…”

Comprehensive Study of Lithium Diffusion in Si/C-Layer and Si/C3N4 Composites in a Faceted Crystalline Silicon Anode for Fast-Charging Lithium-Ion Batteries

“…The advanced forms of the Si anode and various carbonaceous materials, including graphite, graphene, and amorphous carbon, have been adopted as buffer matrices for Si composites to alleviate volume changes, block direct exposure of the Si surface to the electrolyte, and provide ionic conductive channels . Shih et al investigated the improvement of volume changes of Si/graphite composite by applying a spray-dried 3D spherical-like anode for the high rate and cycles Li + -ion batteries . Huo et al showed that carbon in powder-pressed Si anodes does not only improve the ionic and electronic transport during cycling but also changes the electro-chemomechanical performance .…”

“… 18 Shih et al investigated the improvement of volume changes of Si/graphite composite by applying a spray-dried 3D spherical-like anode for the high rate and cycles Li + -ion batteries. 19 Huo et al showed that carbon in powder-pressed Si anodes does not only improve the ionic and electronic transport during cycling but also changes the electro-chemomechanical performance. 3 In these composites, the interfaces between Si and carbon (C) reduce interfacial charge-transfer resistance, which enhances lithiation/delithiation reactions and improves the guest-ion penetration rate.…”