Composite Anode For Lithium-ion Batteries Research Articles

Facile recycling of porous Si waste for stable Si/C anodes

As the rapid development of photovoltaic industry, vast of polycrystalline Si has been produced for photovoltaic products. Meanwhile, large amount of Si waste is generated from mechanical slicing process and retired electronic products. Reasonable recycling the Si waste can save resources and reduce environmental pollution. Herein, porous Si is prepared from Si waste by magnesium thermal reduction and then embedded in industry lignin alkali-based carbon matrix (LAC) via co-precipitation and sintering process to obtain Si/C composite anode for lithium-ion batteries. Owing to the encapsulation structure, the carbon matrix can alleviate the volumetric expansion of Si and improve electronic conductivity of composite, the obtained Si@LAC anode exhibits high charge capacity of 1017.5 mAh g−1 at 0.1 A g−1 and high capacity retention of 94.9 % at 0.5 A g−1 after 200 cycles. Furthermore, the Si@LAC composite displays superior rate performance with high capacity of 596.7 mAh g−1 at 2 A g−1 which is 61.5 % of the value at 0.2 A g−1. Such a high performance Si/C anode from facile preparation demonstrates a viable route to utilization of photovoltaic Si waste and industrial lignin.

Unveiling the Interplay Between Silicon and Graphite in Composite Anodes for Lithium-Ion Batteries.

Si provides an effective approach to achieving high-energy batteries owing to its high energy density and abundance. However, the poor stability of Si requires buffering with graphite particles when used as anodes. Currently, commercial lithium-ion batteries with Si/graphite composite anodes can provide a high energy density and are expected to replace traditional graphite-based batteries. The different lithium storage properties of Si and graphite lead to different degrees of lithiation and chemical environments for this composite anode, which significantly affects the performance of batteries. Herein, the interplay between Si and graphite in mechanically mixed Si/graphite composite anodes is emphasized, which alters the lithiation sequence of the active materials and thus the cycling performance of the battery. Furthermore, performance optimization can be achieved by changing the intrinsic properties of the active materials and external operating conditions, which are summarized and explained in detail. The investigation of the interplay based on Si/graphite composite anodes lays the foundation for developing long-life and high-energy batteries. The abovementioned experimental methods provide logical guidance for future research on composite electrodes with multiple active materials.

SiOx/C Composite Anode for Lithium-Ion Battery with Improved Performance Using Graphene Quantum Dots and Carbon Nanoparticles.

In this study, a composite was manufactured by mixing graphene quantum dots, silicon oxide, and carbon nanoparticles, and the characteristics of the anode materials for secondary batteries were examined. To improve the capacity of the graphene quantum dot (GQD) anode material, the added silicon oxide content was varied among 0, 5, 10, 15, and 30 wt%, and carbon nanoparticles were added as a structural stabilizer to alleviate silicon oxide volume expansion. The physical properties of the prepared GQD/SiOx/C composite were investigated through XRD, SEM, EDS, and powder resistance analysis. Additionally, the electrochemical properties of the manufactured composite were observed through an analysis of the charge-discharge cycle, rate, and impedance of a lithium secondary battery. In the GQD/SiOx/C composite, by adding carbon nanoparticles, an internal cavity was formed that can alleviate the volume expansion of silicon oxide, and the carbon nanoparticles and silicon oxide particles were uniformly distributed. The formed internal cavity had a silicon oxide content of 5 wt%. Low initial efficiency was observed, and above 30 wt%, low cycle stability was observed. The GQD/SiOx/C composite with 15 wt% of silicon oxide added showed an initial discharge capacity of 595 mAh/g, a capacity retention rate of 92%, and a rate characteristic of 81 at 2 C/0.1 C. Silicon oxide was added to improve the capacity of the anode material, and carbon nanoparticles were added as a structural stabilizer to buffer the volume change of the silicon oxide. To use GQD/SiOx/C composite as a highly efficient anode material, the optimal silicon oxide content and carbon nanoparticle mechanism as a structural stabilizer were discussed.

Tailoring the Size of Reduced Graphene Oxide Sheets to Fabricate Silicon Composite Anodes for Lithium-Ion Batteries.

The integration of a silicon (Si) anode into lithium-ion batteries (LIBs) holds great promise for energy storage, but challenges arise from unstable electrochemical reactions and volume changes during cycling. This study investigates the influence of reduced graphene oxide (rGO) size on the performance of rGO-protected Si composite (Si@rGO) anodes. Two sizes of graphene oxide (GO(L) and GO(S)) are used to synthesize Si@rGO composites with a core-shell structure by spray drying and thermal reduction. Electrochemical evaluations show the advantages of the Si@rGO(S) anode with improved cycle life and cycling efficiency over Si@rGO(L) and pure Si. The Si@rGO(S) anode facilitates the formation of a stable LiF-rich solid electrolyte interface (SEI) after cycling, ensuring enhanced capacity retention and swelling control. Rate capability tests also demonstrate the superior high-power performance of Si@rGO(S) with low and stable resistances in Si@rGO(S) over extended cycles. This study provides critical insights into the tailoring of graphene-protected Si composites, highlighting the critical role of rGO size in shaping structural and electrochemical properties. The Si material wrapped by graphene with an optimal lateral size of graphene emerges as a promising candidate for high-performance LIB anodes, thereby advancing electrochemical energy storage technologies.

Preparation of high capacity Sn2S3/Sn3S4/FeS/Fe7S8 heterostructure composite lithium-ion battery anodes from reducing agents Fe and tin-based sulfides

Preparation of high capacity Sn2S3/Sn3S4/FeS/Fe7S8 heterostructure composite lithium-ion battery anodes from reducing agents Fe and tin-based sulfides

Chemo-mechanical processing of hot chamber die cast scrap to design ZnO-based composite anode for lithium-ion batteries

Zn–4Al alloy is mostly processed via high pressure, hot chamber die-casting method. For the first time in the open literature, in this study a novel and useful advice regarding the valorization of zinc die-cast scrap in green energy applications is realized. Herein, firstly a chemo-mechanical process is utilized to form ZnO rich powder (sample 1), then ball milling of this powder with carbon is accomplished to fabricate composite powder (sample 2). Unlike synthetic ZnO, the galvanostatic test demonstrates that the composite electrode (Sample 2) delivers 661.7 mA h/g capacities at 100th cycle when tested under a current load of 50 mA/g and performs 441.7 mA h/g capacities after 500 cycles, when 0.1 A/g current load is applied. Such performance can be related to the particularities in the morphology, the structure, and the chemistry of the designed composite powder.

Facile fabrication of fibrous phosphorus as anode material for lithium-ion batteries with long cycle life and high rate performance

A facile dual-temperature zone heating strategy has been developed to fabricate fibrous phosphorus (FP) through bottom-up growth with the aid of the Sn24P19.3I8 catalyst. The resultant FP exhibits a high purity of over 99 % and a unique long-term ordering lamellar structure. The as-prepared FP is further mixed with graphite (G) to construct a FP-G composite anode for lithium-ion batteries (LIBs). Compared to conventional crystalline red phosphorus, the developed FP shows higher conductance, smaller lateral dimensions, shorter Li+ transport distance, and faster ion diffusion. This ensures that the FP-G anode gains high rate performance and long cycle life for LIBs. The FP-G anode not only exhibits a high specific capacity of 1533.2 mA h g−1 at 0.5 A g−1 but also presents a high retention capacity of 1048.4 mA h g−1 at a high current density of 4.0 A g−1 after 1300 charge/discharge cycles, indicating a high cycle stability and fast reaction kinetics. Such outstanding characteristics are attributed to the unique lamellar fibrous texture and high aspect ratio of the developed FP, which provides more active sites and structural stability for the electrode material. This study provides a new approach for developing phosphorus-based electrode materials and expands their application range in LIBs.

Mitigating the volume expansion and enhancing the cycling stability of ferrous fluorosilicate-modified silicon-based composite anodes for lithium-ion batteries

This study introduces an FeSiF6 additive synthesized via the reaction of HF with Si–Fe alloys. It prevents crystalline Li15Si4 formation and promotes stable SEI film, significantly enhancing the cycling stability of silicon-based anodes.

Alternating Si/C Thin-Films as Model Anode Material for Lithium-Ion Batteries

Graphite is currently the state-of-art material for the anode-side of lithium-ion batteries (LIB) with a theoretical capacity of 372 mAh g-1. However, its technological potential is already largely exhausted, shifting research focus to other materials, such as silicon (Si) with its high theoretical capacity (3579 mAh g-1) [1]. However, Si cannot be used on its own because of its low electrical conductivity. Moreover, it suffers from a strong increase in volume and amorphization during lithiation, which is the primary origin of several degradation mechanisms, e.g. as pulverization, delamination and an unstable solid electrolyte interface. There are various approaches to counteract these issues, amongst them the structuring of Si into nanowires or hollow structures [2]. Silicon is most often used with graphite in a composite material, due to decades of experience in graphite synthesis an application [3].In this work we investigate anodes consisting of alternating Si and C thin-films with a layer thickness of a few hundred nanometers each. In general, Si thin-film anodes show a higher performance than its bulk counterparts [4]. The layers are produced by deposition from the gas phase. This process enables good adhesion between the particles and the substrate, which can counteract delamination and provide a longer cycle life. Additionally, it can also be performed in a binder-free fashion, thereby reducing the need for inactive electrode components.The alternation of carbon and silicon layers improves the electrical conductivity and also separates the silicon layers from each other aiding to reduce the mechanical stress caused by volume expansion. The characterization of the layers is done by cross sectional SEM, EDX and AFM. Furthermore, the crystallinity of the deposited layers is determined via XRD. The manufacturing process influences the morphology of the layers, which in turn affects the electrochemical properties. For this reason, galvanostatic cycling and electrochemical impedance spectroscopy are subsequently carried out in a coin cell type Swagelok half-cell setup with 2- and 3-electrode arrangements. Constant current cycling is used to investigate the long-term stability of the cells in order to analyze the change in the respective Si layers as a function of their distance from the surface. In addition, the electrodes are analyzed post-mortem via SEM and XRD to investigate which degradation mechanisms play a role in the observed behavior.[1] Kasavajjula, U. et al., Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells, J. of Power Sources 163 (2), 1003 – 1039, 2007.[2] Wu, H., Cui Y., Designing nanostructured Si anodes for high energy lithium ion batteries, Nano Today 7 (5), 414 – 429, 2012.[3] You, S. et al., Design Strategies of Si/C Composite Anode for Lithium-Ion Batteries, Chem. Eur. J. 27 (48), 12237 – 12256, 2021 [4] Graetz, J. et al., Highly reversible Lithium storage in nanostructures Silicon, Electrochem. Solid-State Lett. 6 (9), A194, 2003.

A highly effective and controllable chemical prelithiation of Silicon/Carbon/Graphite composite anodes for lithium-ion batteries

Chemical prelithiation has become an increasingly popular method for compensating the initial irreversible capacity loss of lithium ion batteries and improving their initial Coulombic efficiency (ICE). For composite anode materials composed of silicon, amorphous carbon and graphite (SCG), pre-embedding Li+ into all three components simultaneously by chemical prelithiation is challenging because of different activation potential. In this study a chemical prelithiation method using lithium-biphenyl (Li-Bp) as the lithiation reagent and a 2-methyl tetrahydrofuran (2-meTHF) solution as the reducing solvent is designed to enhance the ICE for SCG anodes. The prelithiation reagent by mixed with Li-Bp combined 2-meTHF facilitates the formation of a stable solid electrolyte interface (SEI) film composed of Li2O/Li2CO3 and forms LixSiy alloy. The ICE of prelithiated SCG in half-cell format can be increased from 76.8% to 93.98% when prelithiated twenty minutes (SCG-20). When matched with a LiFePO4 cathode, the coin full cell with prelithiated SCG exhibits an improved ICE from 38.92% to 56.88% and cycling performance than the pristine cells. This work highlights the promise of adopting chemical prelithiation for composite anodes to achieve practical high-energy batteries.

Synthesis and electrochemical properties of nano-Si/C composite anodes for lithium-ion batteries

Phenolic resin was coated on the surface of nano-Si by a microencapsulation technique, and then carbonized under Ar protection to prepare a nano-Si/C composite. The composites were first prepared using 4 different mass ratios (1:2, 1:4, 1:6, 1:8) of phenolic resin to nano-Si. The obtained average thicknesses of amorphous carbon coating were 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when this ratio was 1:4, with a 4.5 nm amorphous carbon coating. The electrochemical properties of this material were then comprehensively evaluated, showing excellent electrochemical performance as an anode material for Li-ion batteries. At a current density of 100 mAg−1, the material had a first specific discharge capacity of 2 382 mAhg−1, a first charge specific capacity of 1667 mAhg−1, and an initial coulombic efficiency of 70%. A discharge specific capacity of 835.6 mAhg−1 was retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, the nano-Si/C composite demonstrated superior rate performance. Under current densities of 100, 200, 500, 1 000 and 2 000 mAg−1, the average specific discharge capacities were 1 716.4, 1 231.6, 911.7, 676.1 and 339.8 mAh g−1, respectively. When the current density returned to 100 mA g−1, the specific capacity returned to 1 326.4 mAh g−1.

Control of Nanoparticle Dispersion, SEI Composition, and Electrode Morphology Enable Long Cycle Life in High Silicon Content, Nanoparticle-Based Composite Anodes for Lithium-Ion Batteries

Striking a balance between high theoretical capacity, Earth abundance, and compatibility with existing manufacturing infrastructure, silicon is one of the few materials that meets the requirements for a next-generation anode for rechargeable lithium-ion batteries. Due to complications with extreme volume changes during charging/discharging and reactive interfacial chemistries, however, the cycle-life of silicon-based composite anodes is unacceptable for broad use. Developing a majority silicon composite anode formulation that overcomes these challenges and is compatible with current industry manufacturing practices requires materials and chemical engineering solutions that account for both electrode morphology and interfacial chemistry. Here, we synthesize surface-functionalized silicon nanocrystals that enable a highly dispersed and homogeneous slurry that can easily be integrated into standard electrode fabrication process. We use this formulation to print a 76 wt. % silicon composite electrode. We show that the contents and the morphology of the silicon electrolyte interphase – a determining factor in the cycle life of silicon-based anodes – can be controlled with a post-synthetic thermal curing procedure. When paired against a capacity-matched lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 cathode, the cell retains 72% of its capacity through 1000 charge/discharge cycles while delivering an initial anode specific capacity of nearly 1000 mAh/g and an areal capacity of 2.55 mAh/cm2. Figure 1

Coordination chemistry-assisted ecofriendly preparation of Fe2O3 nanoparticles embedded in hierarchical carbon for improved lithium storage

The green and facile synthesis of high performance anodes is of significant importance for development of lithium ion batteries (LIBs). Herein, a novel coordination chemistry-assisted method is demonstrated to successfully prepare a superior performance Fe2O3/C composite anode for LIBs. This method does not involve time-consuming pre-preparation of carbon materials and use of expensive sophisticated instruments and multiple harmful reagents, exhibiting relatively green and facile features over most of other methods. This Fe2O3/C composite consists of Fe2O3 nanoparticles embedded in a porous carbon sheets assembled hierarchical matrix. Moreover, it finds that this beneficial architecture endows as-prepared Fe2O3/C with improved conductivity, enhanced kinetics, high capacitive contribution and good structure stability. In consequence, this Fe2O3/C anode exhibits superior electrochemical properties such as high capacity, long life and good rate performance, with 756.1 and 545.4 mA h g−1 after 200 cycles at 200 and 1000 mA g−1, respectively. The relatively ecofriendly and simple preparation process as well as superior electrochemical performance make this Fe2O3/C anode promising for LIB application. This work also offers a guiding significance for designing and developing ecofriendly and facile preparation methods of other metal oxides/carbon composites for advanced LIB anodes.

Investigation of the Direct Contact Prelithiation of Silicon-Graphite Composite Anodes for Lithium-Ion Batteries

Silicon is a promising anode material for lithium-ion batteries due to its high theoretical capacity. However, current lithium-ion batteries with high silicon shares in the anodes suffer from rapid capacity fading. The continuous reformation of the solid electrolyte interphase due to particle volume changes during lithiation consumes cyclable lithium. Direct contact prelithiation is a method to counteract lithium losses during the formation and operation of lithium-ion batteries. By providing excess lithium to the anodes during battery cell production, the cycle life of lithium-ion batteries can be increased. Within this work, the process characteristics of direct contact prelithiation and its effect on battery performance are investigated experimentally. Therefore, silicon-graphite composite anodes were mechanically prelithiated using lithium foil and incorporated in lithium-ion battery pouch cells. The prelithiation time and the cell pressure were systematically varied to obtain insights in to the process behavior. Additionally, the lithium quantity was controlled by lithium foil thickness and sample geometry. The prelithiation state of the anodes was examined by optical analysis and measurements of the cells’ open circuit voltage. The effect of anode prelithiation on the battery cell cycling behavior showed a cycle life increase of up to 150% compared to reference cells with non-prelithiated anodes.

Cycle-stable Si-based composite anode for lithium-ion batteries enabled by the synergetic combination of mixed lithium phosphates and void-preserving F-doped carbon

Silicon-based materials have been considered as the promising anode candidates for next-generation high-energy-density lithium-ion batteries (LIBs). However, their widespread application is unfortunately restricted by severe volume variations during cycling and poor electronic conductivity. To overcome these challenges, we showcase an innovative design of dual core−shell structured Si-based nanocomposites working as anode for LIBs with boosted performance, where the Si nanoparticle core is tightly wrapped by a mixed lithium phosphate (Li3PO4/Li4P2O7) shell and void-preserving F-doped carbon shell (denoted as Si@LPO@void@FC). For such novel structured composite, the inner L3PO4/Li4P2O7 layer acting as artificial solid-electrolyte interphase (SEI) and the outer void-preserving F-doped C can effectively tolerate the volume changes while ensuring the stability of SEI layer, facilitate the Li+ migration and electron transfer, and reinforce the structural stability during cycling. Consequently, the as-fabricated Si@LPO@void@FC anode exhibits a reversible capacity of 569 mAh/g after 500 cycles at 1 A/g, and an exceptional long-term cycling stability with 76% capacity retention over 1000 cycles at 4.0 A/g can be achieved. Additionally, the full cell assembled with Si@LPO@void@FC anode and LiFePO4 cathode also demonstrates a good cycling performance with 117 mAh/g at 1 C for over 150 cycles with 92% capacity retention, suggesting the potentiality for practical application. Furthermore, the mechanisms of the enhanced structural stability of Si@LPO@void@FC anode are carefully elaborated by substantial in situ/ex situ microscopic techniques and electrochemical tests. It is expected that our findings in this work can provide guiding significance for improving the cycling performance of Si-based composite anodes toward high-performance LIBs.

Scalable Synthesis of Pitch-Coated Nanoporous Si/Graphite Composite Anodes for Lithium-Ion Batteries

Scalable Synthesis of Pitch-Coated Nanoporous Si/Graphite Composite Anodes for Lithium-Ion Batteries

Control of nanoparticle dispersion, SEI composition, and electrode morphology enables long cycle life in high silicon content nanoparticle-based composite anodes for lithium-ion batteries

A 74 wt% silicon composite electrode delivers 1000 cycles with 74% capacity retention against NMC811 cathodes and a cell stack energy density of 212 W h kg−1 in a standard carbonate electrolyte with two simple chemical and process improvements.

Durable flexible dual-layer and free-standing silicon/carbon composite anode for lithium-ion batteries

Although silicon is currently recognized as the most promising anode material for lithium-ion batteries, its industrial application is still a major challenge due to its poor electronic conductivity and volume expansion. Herein, a kind of flexible silicon/carbon composite with dual-layer is prepared by microelectronic printing technology and be used as anode for lithium-ion batteries, which can be molded in one shot without addition of binders and conductive agents. A slit structure exists in the layers in the anode which can provide an elastic room to buffer volume expansion during lithiation/delithiation. An amorphous carbon protective shell pyrolyzed from PVP can improve the structure stability and electrochemical performance of the microelectronic printed pole piece. At a current density of 0.1 A/g, a reversible capacity of 941.1 mAh g−1 can be obtained, the first Coulomb efficiency is 79%. After 100 cycles, the capacity retention rate is 81.82%. In the step current rate performance test, it is 421.6 mAhg−1at 1.0 A/g, and the capacity retention rate can reach 98.67% after 50 cycles. This work provides a rational design strategy of flexible anodes for high-capacity lithium-ion batteries.

Coal-derived graphene foam and micron-sized silicon composite anodes for lithium-ion batteries

Silicon-based materials demonstrate significant potential as lithium-ion batteries (LIBs) anode, but their expansion and degradation present engineering design challenges for commercial application. In this study, a porous three-dimensional (3D) graphene and micron-sized silicon composite anode (Si@G foam) was synthesized using humic acid (HA) derived from coal as a graphene precursor. In-situ formation of graphene structure through reducing HA was confirmed by Raman spectra. The reduced HA (rHA) shows similar electrical conductivity compared to the commercial conductive carbon. SEM images depict a 3D skeleton of coal-derived graphene, with silicon particles distributed on the 3D graphene foam's internal surface. The Si@G composite-anode displays a good reversible capacity of ∼656 mAh/g at a current density of 50 mA/g, as well as a high-rate capability of ∼433 mAh/g at a current density of 800 mA/g, and outstanding cycling stability –89.8% capacity retention after 300 cycles, which is significantly higher than that of other foam structures. During lithiation and de-lithiation, the graphene foam serves as a matrix of electrical conductors and a volume expansion support for silicon. This 3D graphene network will be beneficial for developing advanced silicon-based anodes for high-performance LIBs.

High-Value Utilization of Silicon Cutting Waste and Excrementum Bombycis to Synthesize Silicon–Carbon Composites as Anode Materials for Li-Ion Batteries

Silicon-based photovoltaic technology is helpful in reducing the cost of power generation; however, it suffers from economic losses and environmental pollution caused by silicon cutting waste. Herein, a hydrothermal method accompanied by heat treatment is proposed to take full advantage of the photovoltaic silicon cutting waste and biomass excrementum bombycis to fabricate flake-like porous Si@C (FP-Si@C) composite anodes for lithium-ion batteries (LIBs). The resulting FP-Si@C composite with a meso-macroporous structure can buffer the severe volume changes and facilitate electrolyte penetration. Meanwhile, the slightly graphitic carbon with high electrical conductivity and mechanical strength tightly surrounds the Si nanoflakes, which not only contributes to the ion/electron transport but also maintains the electrode structural integrity during the repeated lithiation/delithiation process. Accordingly, the synergistic effect of the unique structure of FP-Si@C composite contributes to a high discharge specific capacity of 1322 mAh g−1 at 0.1 A g−1, superior cycle stability with a capacity retention of 70.8% after 100 cycles, and excellent rate performance with a reversible capacity of 406 mAh g−1 at 1.0 A g−1. This work provides an easy and cost-effective approach to achieving the high-value application of photovoltaic silicon cutting waste, as well as obtaining high-performance Si-based anodes for LIBs.