Graphite Anode In Lithium-ion Batteries Research Articles

Direct and rapid thermal shock for recycling spent graphite in lithium-ion batteries

Due to the rapid increase in the number of spent lithium-ion batteries, there has been a growing interest in the recovery of degraded graphite. In this work, a rapid thermal shock (RTS) strategy is proposed to regenerate spent graphite for use in lithium-ion batteries. The results of structural and morphological characterization demonstrate that the graphite is well regenerated by the RTS process. Additionally, an amorphous carbon layer forms and coats onto the surface of the graphite, contributing to excellent rate performance. The regenerated graphite (RG-1000) displays excellent rate performance, with capacities of 413 mAh/g at 50 mA g−1 and 102.1 mAh/g at 1000 mA g−1, respectively. Furthermore, it demonstrates long-term cycle stability, maintaining a capacity of 80 mAh/g at 1000 mA g−1 with a capacity retention of 78.4 % after 600 cycles. This RTS method enables rapid and efficient regeneration of spent graphite anodes for lithium-ion batteries, providing a facile and environmentally friendly strategy for their direct regeneration.

Exploring steric and electronic effects in tailoring lithium-ion solvation using engineered ether solvents through molecular dynamics simulations

Lithium-metal batteries, owing to their remarkable energy density, represent a promising solution for future energy storage needs. However, the widespread adoption of lithium-metal batteries has been impeded by the inherent instability that exists between lithium metal and traditional liquid lithium electrolytes, initially designed for graphite anodes in lithium-ion batteries. Recent insights underscore the efficacy of electrolyte engineering as a strategic avenue to realize the potential of lithium-metal batteries. A notable approach involves the fluorination of solvent molecules, particularly those of the ether class. Nonetheless, a comprehensive understanding of the various factors governing solvent molecular design remains elusive. Here, we examine four solvents derived from 1,2-dimethoxylethane (DME) via molecular dynamics simulation. These solvents are engineered with the introduction of additional alkyl groups or through fluorination. We particularly scrutinize two critical facets: steric effects, arising from the incorporation of bulkier alkyl chains, and electronic effects, originating from fluorination. Our inquiry delves deeply into the stability, ion transport characteristics, and solvation behavior exhibited by these five distinct solvents. Our study underscores the profound impact of adjusting the steric and electronic attributes of solvent molecules on Li+ solvation behavior. This, in turn, influences the coordination strength and the mode of association between Li+ and solvation sites within the first solvation shell, providing key insights into the disparities in ion transport properties within electrolytes.

3D-structured Co9S8@NSG prepared using deep eutectic solvents as high-performance anode material of lithium-ion batteries

Transition metal sulfides (TMSs) are ideal materials for replacing graphite anodes in lithium-ion batteries (LIBs). However, their low conductivities and large volume changes during charge/discharge cycling greatly limit their applications. Herein, a new method for co-doping nitrogen and sulfur in 3D graphene via a one-step method in deep eutectic solvents (DESs) was developed to prepare Co9S8@NSG composites, enhancing the storage performance of LIBs. The obtained Co9S8@NSG nanosheets exhibited excellent lithium-ion storage performance as anode materials. In the first cycle, the electrode material possessed high specific capacity (1647.5 mAh·g−1 at a current density of 2 a·g−1). After 250 cycles, the reversible capacity was still maintained at 516 mAh·g−1. The electrode material also displayed good cycling stability with specific capacity reaching 710 mAh·g−1 after 700 cycles at a current density of 0.5 a·g−1. In sum, the developed route for the synthesis of heteroatom-doped nanocomposites looks promising for modification of sulfide materials as excellent-performance LIBs.

Fast-charging graphite anode for lithium-ion batteries: Fundamentals, strategies, and outlooks

The basic requirements for lithium-ion batteries in the field of electric vehicles are fast charging and high energy density. This will enhance the competitiveness of electric vehicles in the market while reducing greenhouse gas emissions and effectively preventing environmental pollution. However, the current lithium-ion batteries using graphite anodes cannot achieve the goal of fast charging without compromising electrochemical performance and safety issue. This article analyzes the mechanism of graphite materials for fast-charging lithium-ion batteries from the aspects of battery structure, charge transfer, and mass transport, aiming to fundamentally understand the failure mechanisms of batteries during fast charging. In addition, we review and discuss recent advances in strategies for optimizing fast-charging performance and summarize current improvement methods in graphite electrodes, electrolytes, battery structures, and charging algorithms. Moreover, the challenges and promising concepts for developing future fast-charging graphite anode are emphasized. This review is of great significance for better designing and optimizing graphite materials for high-safety and fast-charging lithium-ion batteries.

Electrodeposition preparation and electrochemical properties of silicon anode

The theoretical capacity of silicon is about 4200 mA h g−1, so the silicon anode is the most attractive substitute for the graphite anode of lithium-ion battery. In this paper, amorphous silicon thin films is successfully prepared on the surface of 12 µm thick copper foil by pulsed electrodeposition, then the silicon anode is prepared and the electrochemical performance is tested. The research results show that the silicon anode exhibits higher reversible capacity (1200 mA h g−1) compared with the graphite anode, and there is no obvious capacity fade after 100 cycles at the current density of 200 mA g−1. The amorphous silicon can alleviate the cracking of silicon thin films, and form stable Solid Electrolyte Interphase, which can reduce lithium consumption and improve the coulombic efficiency of lithium-ion battery. In addition, the lithium-ion battery with silicon anode exhibits excellent cycle performance and rate capability.

Stable cycling and low-temperature operation utilizing amorphous carbon-coated graphite anodes for lithium-ion batteries.

With the continuous expansion of the lithium-ion battery market, addressing the critical issues of stable cycling and low-temperature operation of lithium-ion batteries (LIBs) has become an urgent necessity. The high anisotropy and poor kinetics of pristine graphite in LIBs contribute to the formation of precipitated lithium dendrites, especially during rapid charging or low-temperature operation. In this study, we design a graphite coated with amorphous carbon (GC) through the Chemical Vapor Deposition (CVD) method. The coated carbon layer at the graphite interface exhibits enhanced reaction kinetics and expanded lithium-ion diffusion pathways, thereby reduction in polarization effectively alleviates the risk of lithium precipitation during rapid charging and low-temperature operation. The pouch cell incorporating GC‖LiCoO2 exhibits exceptional durability, retaining 87% of its capacity even after 1200 cycles at a high charge/discharge rate of 5C/5C. Remarkably, at -20 °C, the GC-2 maintains a specific capacity of 163 mA h g-1 at 0.5C, higher than that of pristine graphite (65 mA h g-1). Even at -40 °C, the GC-2‖LiCoO2 pouch cell still shows excellent capacity retention. This design realizes the practical application of graphite anode in extreme environments, and have a promising prospect of application.

Towards a Higher Energy Density for Lithium-Ion Battery Anodes Via Hierarchically Structured Silicon/Carbon Supraparticles Using Spray Drying

Silicon has a high potential to replace commercial graphite anodes in lithium-ion batteries (LiBs). It can facilitate achieving excellent energy densities because of its high theoretical specific lithiation capacity (Chan et al. 2008). However, major challenges such as rapid capacity fading and low Coulombic efficiency due to the huge volume change (∼300 %) during cycling have seriously hindered its commercialization (Wu et al. 2013). Although nanostructuring has been successful in minimizing volume expansion issues, the electrochemical performance of nano-sized silicon is still limited due to unstable solid-electrolyte interphase, low coating density and overall poor electrical properties due to the higher interparticle resistance (Liu et al. 2014). To tackle those challenges, here we introduce a new concept of post-synthesis spray drying to produce hierarchically structured micro-agglomerates from silicon/carbon (Si/C) composite nanoaggregates synthesized in the gas phase (Amin et al. 2023; Adil Amin et al.).The resulting agglomerates were characterized i) on the powder level by scanning electron microscopy (Fig. 1a) and N2 sorption, ii) on the dispersion level by rheometry and analytical centrifugation, iii) on the electrode level by atomic force microscopy for structure and iv) via electrochemical testing on half-cells for electrochemical performance (Fig. 1b). These results show that electrodes from Si/C supraparticles with the highest concentration of stabilizer exhibit better redispersion stability and excellent first cycle specific discharge capacity as well as better cycling stability as compared to the Si/C composite nanoaggregates (4 wt.% carbon content). Furthermore, compared to the reference electrodes made of nanoaggregates, the more stable supraparticles (3 wt.% stabilizer) showed the highest first Coulombic efficiency. This is due to the reduction of their surface to volume ratio which helps in forming less volume of solid electrolyte interface.To conclude, our investigation suggests how an established industrial process (gas phase synthesis of nanoparticle in a hot-wall reactor) can be combined with scalable one-step spray drying to get dense active materials for LiBs. This enables to fully utilize the new materials’ potential by the right packaging into optimum electrode structures with high performance and longevity. Furthermore, we are of the opinion that this pioneering method can be utilized as a broadly relevant design principle to enhance other (anode) materials that encounter analogous problems of volume expansion. Publication bibliography Amin, Adil; Özcan, Fatih; Loewenich, Moritz; Kilian, Stefan O.; Wiggers, Hartmut; Segets, Doris; Wassmer, Theresa; Bade, Stefan; Lyubina, Julia: Hierarchically Structured Si/C Agglomerates by Spray-Drying. Patent no. PCT / EP 2022/ 052453.Amin, Adil; Loewenich, Moritz; Kilian, Stefan O.; Wassmer, Theresa; Bade, Stefan; Lyubina, Julia et al. (2023): One-Step Non-Reactive Spray Drying Approach to Produce Silicon/Carbon Composite-Based Hierarchically Structured Supraparticles for Lithium-Ion Battery Anodes. In J. Electrochem. Soc. 170 (2), p. 20523. DOI: 10.1149/1945-7111/acb66b.Chan, Candace K.; Peng, Hailin; Liu, Gao; McIlwrath, Kevin; Zhang, Xiao Feng; Huggins, Robert A.; Cui, Yi (2008): High-performance lithium battery anodes using silicon nanowires. In Nature nanotechnology 3 (1), pp. 31–35. DOI: 10.1038/nnano.2007.411.Liu, Nian; Lu, Zhenda; Zhao, Jie; McDowell, Matthew T.; Lee, Hyun-Wook; Zhao, Wenting; Cui, Yi (2014): A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes. In Nature nanotechnology 9 (3), pp. 187–192. DOI: 10.1038/nnano.2014.6.Wu, Hui; Yu, Guihua; Pan, Lijia; Liu, Nian; McDowell, Matthew T.; Bao, Zhenan; Cui, Yi (2013): Stable Li-ion battery anodes by in-situ polymerization of conducting hydrogel to conformally coat silicon nanoparticles. In Nature communications 4, p. 1943. DOI: 10.1038/ncomms2941. Figure 1

Novel alginate-based binders for silicon–graphite anodes in lithium-ion batteries: effect of binder chemistry on the electrochemical performance

Novel alginate-based binders containing either catechol (d-Alg) or sulfonate (s-Alg) functional groups were developed and characterized to improve the capacity decay performance and better stability of Li-ion batteries. The electrochemical performance of silicon–graphite (Si/Gr) anode with alginate-based binders were compared to the commonly used CMC/SBR binder. The active material in the anodes was the ball-milled Si/Gr (20:80 wt%) powder mixture. A comprehensive electrochemical study was carried out through rate capability test, cycle test, differential capacity analysis (dQ/dV), and electrochemical impedance spectroscopy (EIS). The functionalized s-Alg binder showed the lowest electrolyte uptake (11.5%) and the highest tensile strength (97 MPa). Anodes with s-Alg exhibited high initial capacity (1250 mAh g−1) and improved decay performance (580 mAh g−1 at 0.2 C), by ~ 65% higher compared to CMC/SBR binder. The influence of pH value of s-Alg binder preparation showed that anodes prepared at pH 3 of s-Alg exhibit better performance, reaching 800 and 750 mAh g−1 at 0.1 and 0.2 C, respectively, due to the stronger bonding formation and compactness of anode layer which providing low charge transfer and solid electrolyte interface resistance.Graphical abstract

Effect of mechanical properties on processing behavior and electrochemical performance of aqueous processed graphite anodes for lithium-ion batteries

A combination of styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) is a well-established binder system in aqueous processed anodes for lithium-ion batteries. The main function of SBR is to increase the adhesive strength between the active anode layer and the current collector, providing a robust connection capable of withstanding mechanical stresses encountered during cell manufacturing and cell cycling. To determine the optimal adhesion level ensuring failure-free processing without compromising the electrochemical performance we variated SBR concentration and investigated the effect on the processability and electrochemical performance of graphite anodes with application relevant mass loadings (5.7 mg cm−2 and 10.1 mg cm−2).Our results indicate that the inclusion of SBR enhances cohesion of anodes, a vital factor in preserving the mechanical integrity during bending, winding and cutting, particularly at elevated mass loadings. However, our findings reveal that unnecessarily high adhesion does not yield benefits on the processability of anodes. Furthermore, SBR is virtually dispensable for adhesion during cell cycling, and it proves to be counterproductive, primarily due to the rise in internal resistance and, most likely, SBR degradation. For the system investigated here, optimal adhesion was found for 1.5 % SBR in the current collector-free anode.

Improving the Fast Charging Capability of Lithium-Ion Battery Graphite Anodes by Implementing an Alternative Binder System

An alternative binder system for water-processed graphite anodes for lithium-ion batteries was developed and electrochemically investigated in terms of fast charging capability. The conventionally used binder system for anode coatings, based on CMC and SBR, shows good rheological and mechanical properties, but is limited in its electrochemical performance with respect to high charging currents. However, a marked improvement in fast charging capability is necessary to accelerate the market share of battery electric vehicles. Therefore, we systematically developed an alternative, water-based binder system to improve the fast charging capability of graphite anodes. Thereby, the most promising alternative binder system consisting of alginate, PEO and PVP (2:1:1) showed an improvement in charging performance at 4 C (10 mA cm−2) in the CC-step by more than 150% in 2.5 mAh cm−2 research pouch cells, compared to the reference binder system consisting of CMC and SBR (1:1). The improvement in fast charging capability could be assigned to a reduced ionic pore resistance, as well as a larger active surface area, whereas the pore size distribution, the total surface area, as well as the wettability of the electrode, influence the active surface area. Furthermore, the alternative binder system reveals an improved cycling stability beyond 1,500 cycles.

Enhanced low-temperature performance of multiscale (Nb2O5/TiNb2O7)@C nanoarchitectures with intensified ion diffusion kinetics

Since the performance of commercial graphite anodes for lithium-ion batteries declines significantly at low temperatures, it is significant to pursue novel materials with augmented charge storage ability. Herein, a multiscale (Nb2O5/TiNb2O7)@C nanoarchitecture is designed to satisfy the requirements of low-temperature environments. The unique nanoarchitecture morphology, surface carbon layer coating, and dual-phase structure can lead to short transport paths, favorable conductivity, and abundant grain boundaries, resulting in enhanced ion diffusion kinetics. Specifically, (Nb2O5/TiNb2O7)@C anode exhibits a significantly increased Li+ diffusion coefficient of 1.26 × 10−11 cm2 s−1. Then, a reversible capacity of 184 mAh g−1 (@1.0C) is achieved after 200 cycles at room temperature, while it can maintain 110 mAh g−1 (@0.1C) after 80 cycles at −40 °C, equivalent to 40 % of its room temperature capacity (272.4 mAh g−1, 0.1C). This work provides a multiscale modification strategy to develop novel nanoarchitectures with enhanced ion/electron diffusion kinetics for low-temperature applications.

Optimization of the molecular weight range of coating pitch and its effect on graphite anodes for lithium-ion batteries

Optimization of the molecular weight range of coating pitch and its effect on graphite anodes for lithium-ion batteries

N/O/P ternary-doped coal-based hierarchical porous carbon networks for high lithium-ion storage performance

Constructing porous structure and surface modification are effective ways to enhance the Li-ion storage performance of commercial graphite anode for lithium-ion batteries (LIBs). Herein, nitrogen, oxygen and phosphorus ternary-doped coal-based hierarchical porous carbon networks (N/O/P-CCNs) were prepared through liquid oxidation combined with self-assembly method. The N/O/P-CCNs have a three-dimensional porous carbon network structure formed by cross-linking carbon nanosheets with an appropriate specific surface area (321 m2 g−1) and distribution of micro-, meso- and macropore, while the surfaces of carbon nanosheets are doped with nitrogen, oxygen and phosphorus. Due to unique hierarchical porous structure and the synergistic effect of ternary doping, the N/O/P-CCNs anode exhibits excellent Li-ion storage properties with initial reversible capacity of 1079 mAh g−1, which is much higher than that of coal-based graphite anode (382 mAh g−1). Besides, the N/O/P-CCNs anode also has superior rate capability (336 and 275 mAh g−1 at 1.0 and 2.0 A g−1) and cycle stability with a high capacity retention (near 100 % after 100 cycles). The excellent electrochemical performance is not only related to the hierarchical pore structure that can provide efficient channels for lithium-ion transport, but also to the ternary-doping of nitrogen, oxygen and phosphorus that can provide more active sites for lithium-ion storage and enhance conductivity. This work provides a novel and effective design strategy for developing high-performance anode materials for LIBs.

Sustainable and Cost-Effective Bio-Waste-Derived Hard Carbon Synthesis for Sodium-Ion Batteries

The commercialization of sodium-ion batteries (SIBs) is around the corner to support on electrification of various applications, especially focused on light electromobility and stationary applications. The anode of choice in SIBs is hard carbon (HC) following the success story of graphite anode in lithium-ion batteries. [1-4] One of the greatest advantages of HC is that the bio-waste precursor can be used, enhancing sustainability and provides cheap material price from its abundance. However, bio-waste HC often undergoes a strong acidic/basic pre-/post-treatment for removing impurities and increasing carbon yield but decreases initial Coulombic efficiency (ICE) and total sodium uptake in turn. [5,6] We attempted to find a more sustainable solvent to replace the traditional method for such HCs. In this work, the morphology, microstructure, and electrochemical performance characteristics of hazelnut shells-derived HCs were investigated when processed in different pre-treatment agents (i.e., no pre-treatment, acid treatment, and water washing). [7] The results reveal that hazelnut shell derived-HCs produced via facile and sustainable water washing outperform those obtained via other processing methods in terms of ICE, capacity uptake and retention. Moreover, the applicability of the hazelnut shell-derived HC is demonstrated in a sodium-ion full-cell. Finally, the cost-ecological effectiveness of sustainably processed HC compared to acid processed one was investigated and confirmed by life cycle assessment (LCA) and cost analysis.[1] CATL, “CATL Unveils Its Latest Breakthrough Technology by Releasing Its First Generation of Sodium-ion Batteries,” 2021.[2] L. Cailloce, https://newscnrsfr/articles/a-battery-revolution-in-motion 2015.[3] S. Kuze, J. Kageura, S. Matsimoto, T. Nakayama, M. Makidera, M. Saka, T. Yamaguchi, T. Yamamoto, K. Nakane, R&D Report 2013, 1–13.[4] A. Rudola, A. J. R. Rennie, R. Heap, S. S. Meysami, A. Lowbridge, F. Mazzali, R. Sayers, C. J. Wright, J. Barker, Journal of Materials Chemistry A 2021, 9, 8279–8302.[5] S. Ghosh, R. Santhosh, S. Jeniffer, V. Raghavan, G. Jacob, K. Nanaji, P. Kollu, S. K. Jeong, A. N. Grace, Sci. Rep. 2019, 9, 16315.[6] K. L. Hong, L. Qie, R. Zeng, Z. Q. Yi, W. Zhang, D. Wang, W. Yin, C. Wu, Q. J. Fan, W. X. Zhang, Y. H. Huang, Journal of Materials Chemistry A 2014, 2, 12733–12738.[7] H. Moon, A. Innocenti, H. Liu, H. Zhang, M. Weil, M. Zarrabeitia, S. Passerini, ChemSusChem 2022 DOI: 10.1002/cssc.202201713

Effective upcycling of waste separator and boosting the electrochemical performance of recycled graphite anode for lithium-ion batteries

The forefront of current lithium-ion battery technology in various electronic applications concerns the enormous e-waste that gives rise to end-of-life batteries. Resource sustainability of battery-grade graphite, non-biodegradable polymeric separator, and ever-growing lithium-ion battery manufacturing cost extend a strong impetus for lithium-ion battery recycling. Herein, we report an effective strategy to upcycle the waste separator to valuable carbon. The recycle separator derive carbon is turbostratic with the simultaneous presence of an order-disorder phase. The carbon anode electrochemically delivers 695 mAh g−1 capacity at 100 mA g−1, which is double the capacity of the recover graphite anode (300 mAh g−1). Despite the significant electrochemistry, the poor conversion efficiency and low product yield after carbonization may impede large-scale implementations. However, the Li-ion storage capability of recycle separator derive carbon, in minimal quantity, enhances the capacity of the recycled graphite. The composite of recycle graphite and recycle separator derive carbon outperforms the capacity of recycled graphite with higher Li-ion diffusivity. It delivers a stable discharge capacity of 380 mAh g−1 at a 0.5C rate over 1200 cycles (285 mAh g−1 for recycled graphite). This study entails sustainable recycling of spent separators and boosts the efficiency of recycled graphite for high-performance lithium-ion batteries.

Topology-enhanced mechanical stability of swelling nanoporous electrodes

Materials like silicon and germanium offer a 10-fold improvement in charge capacity over conventional graphite anodes in lithium-ion batteries but experience a roughly threefold volume increase during lithiation, which challenges ensuring battery integrity. Nanoporous silicon, created by liquid-metal-dealloying, is a potentially attractive anode design to mitigate this challenge, exhibiting both higher capacity and extended cycle lifetimes. However, how nanoporous structures accommodate the large volume change is unknown. Here, we address this question by using phase-field modeling to produce nanoporous particles and to investigate their elastoplastic swelling behavior and fracture. Our simulations show that enhanced mechanical stability results from the network topology consisting of ligaments connected by bulbous, sphere-like nodes. The ligaments forcefully resist elongation while the nodes, behaving like isolated spherical particles, experience large stresses driving fracture. However, being smaller compared to a sphere of the same volume as the entire nanoporous particle, the nodes are more protected against fracture.

Gum based functional binder for high-performance artificial graphite anode for lithium-ion batteries

Artificial graphite (AG), in contrast to natural graphite, has received much attention due to its superior rate capabilities and stability under high current density. Although the rate capabilities can be enhanced by employing artificial graphite, there is room for improvement in the cycle retention characteristics of artificial graphite. In particular, further optimization on the binder type on anodes is necessary, as commercially used polyvinylidene fluoride (PVdF) has limitations in long-term cycling stability. Furthermore, PVdF is dissolved in N-Methyl-2-pyrrolidone (NMP), which is not environmentally- and eco-friendly. In this work, we have introduced a water-soluble binder based on deacetylated kondagogu gum (KG) for AG anodes, which are derived from the gum tree. Upon deacetylation, kondagogu gum can be dissolved in water, which can be directly used together with active materials and conductive agents in a slurry. Replacing a PVdF binder with a KG binder results in an enhanced cycle retention and comparable rate capabilities, without the changes in the overall redox reactions with Li+. Postmortem analysis reveals that the improved electrochemical performance of the AG anode contributed to the excellent structural integrity of the KG binder compared with the PVdF binder.

Graphite Nanosheets as a Platform for the Nanosize GeSe2 Anode with Improved Electrode Performance

GeSe2 anode materials possess energy densities higher than those of the commercial graphite anode for lithium-ion batteries (LIBs). However, the limited cycling life and poor inherent conductivity present significant difficulties for their use in various fields. LIBs’ lifetime and capacity density depend on their electrode materials, where structural stability and a slow diffusion control mechanism are crucial factors. In this study, amorphous nanosize GeSe2 uniformly anchored on graphite sheets (GeSe2/G) was prepared using ball milling. For comparison, the cycle performances of pure GeSe2 and GeSe2 with the same ball milling conditions (M-GeSe2) were tested. The results showed that ball milling enabled uniform anchoring of GeSe2 nanoparticles of ∼200 nm on graphite nanosheets without aggregation, where the introduction of graphite not only served as electron transfer layers to effectively improve the electrical conductivity but also assisted in reducing the volume growth and comminution of GeSe2 during Li+ insertion/extraction procedures. When served as anode materials for LIBs, the GeSe2/G nanocomposites showed high Li+ storage properties, i.e., a high reversible capacity of 812.8 mAh g–1 at 0.1 A g–1. After 50 cycles, GeSe2/G still reached 650 mAh g–1, which was much higher than M-GeSe2 (392.3mAh g–1) and GeSe2 (183 mAh g–1). Even at 1 A g–1, the GeSe2/G anode exhibited a high reversible capacity of 409.6 mAh g–1 and remarkable cycling stability, with a high capacity retention of 63% after 300 cycles.

Microsized Silicon/Carbon Composite Anodes through In Situ Polymerization of Phenolic Resin onto Silicon Microparticles for High-Performance Lithium-Ion Batteries

Silicon (Si) has been gradually explored as a next-generation anode material to replace traditional graphite anodes in lithium-ion batteries (LIBs) due to its high specific capacity (3579 mAh g–1 at room temperature). In terms of cost and tap density, silicon microparticles (SiMPs) are more advantageous than silicon nanoparticles (SiNPs) in high energy density LIBs, but they are also plagued by the more serious volume effect. Here, we design a silicon/carbon (Si/C) composite anode through the in situ polymerization of phenolic resin (PF) onto SiMPs, and after pyrolysis, SiMPs are tightly coated with pyrolytic carbon layers. When applied in LIBs, the composite anodes (μSi@PF) exhibit excellent cycling performance (1283 mAh g–1 after 400 cycles at 2 A g–1) and rate performance (a reversible capacity of about 1000 mAh g–1 at 8 A g–1). The full cell with lithium iron phosphate cathodes and μSi@PF anodes can maintain 87.7% capacity retention after 100 cycles. The great electrochemical performance can be ascribed to the rational structure design of μSi@PF in which PF pyrolytic carbon as a shell around SiMPs can accommodate the volume change of SiMPs during cycling and reduce the internal impedance. This is the first attempt to construct Si/C composites by in situ polymerizing PF resin onto SiMPs, and the great performance of Si/C anode provides a reference for the practical application of SiMPs.

Process and Material Analysis of Laser- and Convection-Dried Silicon–Graphite Anodes for Lithium-Ion Batteries

Drying electrodes is very cost-intensive as it is characterized by high energy and space consumption. Laser drying is considered a promising alternative process due to direct energy input and lower operating costs. However, it is unclear whether the same product and process quality can be achieved with laser drying. Silicon–graphite anodes with different silicon contents were processed using either a high-power diode laser or a convection oven. The laser-drying process was investigated using thermography, and the effect of laser drying on the electrode quality was examined using adhesion and residual moisture measurements. Furthermore, thermogravimetric analysis, SEM images and electrical conductivity were used to analyse the laser- and convection-dried anodes. It was shown that silicon–graphite anodes can also be manufactured using laser drying, with a significant reduction in drying time of over 80%.