Alloy Anode Materials Research Articles

Alloying Motif Confined in Intercalative Frameworks toward Rapid Li-Ion Storage.

High‐capacity alloying‐type anodes suffer poor rate capability due to their great volume expansion, while high‐rate intercalation‐type anodes are troubled with low theoretical capacity. Herein, a novel mechanism of alloying in the intercalative frameworks is proposed to confer both high‐capacity and high‐rate performances on anodes. Taking the indium‐vanadium oxide (IVO) as a typical system, alloying‐typed In is dispersed in the stable intercalative V2O3 to form a solid solution. The alloying‐typed In element provides high lithium storage capacity, while the robust, Li‐conductive V−O frameworks effectively alleviate the volume expansion and aggregation of In. Benefiting from the above merits, the anode exhibits a high specific capacity of 1364 mA h g−1 at 1 A g−1 and an extraordinary cyclic performance of 814 mA h g−1 at 10 A g−1 after 600 cycles (124.9 mA h g−1 after 10 000 cycles at 50 A g−1). The superior electrochemical rate capability of (In,V)2O3 solid solution anode rivals that of the reported alloying anode materials. This strategy can be extended for fabricating other alloying/intercalation hybrid anodes, such as (Sn,V)O2 and (Sn,Ti)O2, which demonstrates the universality of confining alloying motifs in intercalative frameworks for rapid and high‐capacity lithium storage.

Tailoring Ultrafast and High-Capacity Sodium Storage via Binding-Energy-Driven Atomic Scissors.

Controllably tailoring alloying anode materials to achieve fast charging and enhanced structural stability is crucial for sodium-ion batteries with high rate and high capacity performance, yet remains a significant challenge owing to the huge volume change and sluggish sodiation kinetics. Here, a chemical tailoring tool is proposed and developed by atomically dispersing high-capacity Ge metal into the rigid and conductive sulfide framework for controllable reconstruction of GeS bonds to synergistically realize high capacity and high rate performance for sodium storage. The integrated GeTiS3 material with stable Ti-S framework and weak GeS bonding delivers high specific capacities of 678 mA h g-1 at 0.3 C over 100 cycles and 209 mA h g-1 at 32 C over 10000 cycles, outperforming most of the reported alloying type anode materials for sodium storage. Interestingly, in situ Raman, X-ray diffraction (XRD), and ex situ transmission electron microscopy (TEM) characterizations reveal the formation of well-dispersed Nax Ge confined in the rigid Ti-S matrix with suppressed volume change after discharge. The synergistically coupled alloying-conversion and surface-dominated redox reactions with enhanced capacitive contribution and high reaction reversibility by a binding-energy-driven atomic scissors method would break new ground on designing a high-rate and high-capacity sodium-ion batteries.

Preparation and properties of Mg-doped Li-B alloy anode materials for high specific-capacity thermal batteries

Thermal batteries with kilowatt power are crucial for improving the maneuverability of underwater weapons. Due to its high capacity, safety and stability, the new Li alloy anode has attracted extensive attention. In this study, Mg-doped Li-B alloy with high Li content was prepared by high temperature melting technology, and its Li loading was up to 64% and free Li content was more than 40%. The specific capacity of Mg-doped Li-B alloy was as high as 4270 As/g at the current density of 100 mA/cm2. Compared with the conventional Li-B alloy, the capacity of Mg-doped Li-B alloy is increased by 14.24%, and the specific energy can reach more than 140 Wh/kg. This work has guiding significance and great practical value for the research on high specific capacity anode for thermal battery.

Micrometer-Sized SiMgy Ox with Stable Internal Structure Evolution for High-Performance Li-Ion Battery Anodes.

In recent years, micrometer-sized Si-based anode materials have attracted intensive attention in the pursuit of energy-storage systems with high energy and low cost. However, the significant volume variation during repeated electrochemical (de)alloying processes will seriously damage the bulk structure of SiOx microparticles, resulting in rapid performance fade. This work proposes to address the challenge by preparing in situ magnesium-doped SiOx (SiMgy Ox ) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMgy Ox contributes to building a bonding network inside the particle so that it raises the modulus of lithiated state and restrains the internal cracks due to electrochemical agglomeration of nano-Si. The prepared micrometer-sized SiMgy Ox anode shows high reversible capacities, stable cycling performance, and low electrode expansion at high areal mass loading. A 21700 cylindrical-type cell based on the SiMgy Ox -graphite anode and LiNi0.8 Co0.15 Al0.05 O2 cathode demonstrates a 1000-cycle operation life using industry-recognized electrochemical test procedures, which meets the practical storage requirements for consumer electronics and electric vehicles. This work provides insights on the reasonable structural design of micrometer-sized alloying anode materials toward realization of high-performance Li-ion batteries.

Second nearest-neighbor modified embedded atom method interatomic potentials for Na-M−Sn (M = Cu, Mn, Ni) ternary systems

Interatomic potentials for Mn-Sn, Ni-Sn, Na-Cu, Na-Mn, and Na-Ni binary systems and Na-Cu-Sn, Na-Mn-Sn, and Na-Ni-Sn ternary systems have been developed on the basis of the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. The potentials can describe various fundamental materials properties such as structural, elastic, thermodynamic, and thermal properties in reasonable agreement with experiments and DFT calculations. It is demonstrated that the potentials can be used for atomistic simulations to understand material phenomena and to search for optimal tin-based alloy anode materials for sodium ion batteries.

Reversible potassium-ion alloying storage in crystalline silicene

Silicon has been recognized as one of the most appealing alloying anode materials for lithium/sodium-ion storage. However, the K-Si alloying reaction is still missing in potassium-ion batteries produced so far, even though the theoretical phase diagram allows the existence of corresponding products. Herein, we synthesize crystalline silicene from Zintl phase CaSi2 and demonstrate that potassium-ions can be inserted/extracted efficiently in it with enhanced cycle stability (without capacity fading over 3000 cycles in silicene//K battery with Coulombic efficiency remains above 99.4 %). Contrary to established perceptions of “inert silicon”, the reversible kinetics-controlled K-Si phase transition occurring in silicene is illustrated by in situ synchrotron X-ray diffraction, and enables the formation of KSi as the dominant discharged product realizing a reliable reversible potassiation storage capacity of 180.1 mA h g−1. The versatile alloying electrochemistry of silicon observed here is expected to spur the development of durable potassium-ion batteries.

Carbon microsphere encapsulated SnS for use as an anode material in full‐cell sodium‐ion battery

Tin(II) sulfide (SnS) has long been regarded as an attractive anode material for sodium-ion batteries (SIBs). However, structural pulverization and severe volume expansion result in a poor cycle life for SnS, making its use in practical battery systems difficult. To address these issues, we propose a surfactant-assisted one-pot hydrothermal approach for successfully encapsulating in situ formed SnS particles in a micro-carbon sphere (MCS). The morphology and the electrochemical behavior of the products were investigated by varying the controlling parameters, such as the concentration of surfactants, polyvinylpyrrolidone (PVP), and cetyltrimethylammonium bromide (CTAB), as well as the concentration of SnS precursors in the reaction system. When used as an anode material for SIBs, the MCS embedded SnS electrode delivered a reversible specific capacity of 465 mAhg−1 at 0.1 Ag−1 and retained a reversible capacity of 371 mAhg−1 at 0.5 Ag−1 after 250 cycles. Moreover, the [email protected] electrode maintained specific capacities of approximately 256, 206, and 160 mAhg−1 at very high specific current densities of 5, 10, and 20 Ag−1, respectively. Certainly, the carbon matrix served as a cushion to absorb volume expansion and facilitate the movement of the Na+ ions and the electrons within the electrode. Consequently, a honeycomb-structured Na3Ni2SbO6 cathode was synthesized using a solid-state approach to evaluate the feasibility of the [email protected] anode in a full-cell configuration. The full-cell operated at an average voltage of 3.25 V, with a specific capacity of 80 mAhg−1, and demonstrated a specific energy density of ≈266.7 Whkg−1. This work could serve as a research guide for the future investigation of alloy and conversion-based anode materials in SIBs.

Recent Progress and Perspectives on Alloying Anodes for Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (PIBs) have been regarded as one of promising alternatives to lithium‐ion batteries (LIBs) due to the wide distribution, low‐cost potassium resources and high working voltage. Anode materials play a vital role in the future development of PIBs. Among the various anode materials, alloying anodes such as tin, antimony, phosphorus, bismuth and silicon show promising future and attracted wide attention owning to their wide distributed resources, favorable working voltage, and theoretically high capacities. However, the severe volume expansion during potassiation/depotassiation leads to pulverization and exfoliation from the current collector, resulting in capacity decay of PIBs. Efficient approaches, such as micro‐/nanostructures designing, carbon coating, and optimizing the interface between electrode and electrolyte have been utilized to solve these issues. In the present review, the research progress on alloying anode materials in PIBs is summarized. Considering the synthesis strategies, battery performance, battery working mechanisms, and structure‐performance relationships of these materials, the challenges and future development directions of alloying anode materials are suggested. Herein, we will provide an outlook for the development of high‐performance alloy‐based anode materials for PIBs and also indicate the future direction of electrode materials in PIBs.

Si85Fe15Ox Alloy Anode Materials with High Thermal Stability for Lithium Ion Batteries

The synthesis, microstructure and electrochemical properties of ball milled Si85Fe15Ox alloys with different oxygen contents are investigated. These materials combine the features of Si-M alloys (low irreversible capacity) and SiOx materials (high thermal stability). This makes Si85Fe15Ox alloys compatible with high temperature processing. As shown here, these properties allow Si85Fe15Ox alloys to be incorporated into carbon-coated graphite composite particles that can cycle well even without the use of advanced binders or electrolyte additives.

Stable SEI Formation on Al-Si-Mn Metallic Glass Li-Ion Anode

Alloying anodes are of great interest as a replacement for graphite in lithium-ion batteries (LIBs) since they can store one or more Li atoms per host atom. Si has received the most attention in this regard due to its very high theoretical specific capacity (3579 mAh/g, ~8300 mAh/cm3)1 and relatively low cost. However, the durability of batteries with high Si content is limited due to the unstable solid-electrolyte interphase (SEI) on Si2 and its large volume change upon lithiation and delithiation which leads to cracking and pulverization3, 4. Among alloying anodes, amorphous materials generally outperform crystalline materials5, 6. The absence of grain boundaries can improve passivity7-9, and amorphous materials generally lithiate in a continuous manner, which eliminates phase boundaries and the mechanical strains associated with them. In addition, amorphous materials composed solely of metals and/or metalloid elements, termed metallic glasses, have been shown to exhibit exceptional hardness, yield strength, and fracture toughness7-9.This study explores an Al-Si-Mn glass as an alternative LIB anode. Si-based metallic glasses are appealing because they maintain Si, which can alloy with up to 3.75 Li6, 10, as the main Li-binding element, but distribute it homogeneously within an amorphous matrix. A dense amorphous Al64Si25Mn11 metallic glass (a-AlSiMn) was successfully produced via splat quenching, a rapid cooling technique that is scalable and commonly used to produce amorphous materials for a variety of applications. This process is shown schematically in the figure below. The a-AlSiMn glass exhibits greater specific capacity (>900 mAh/g) than graphite and a low lithiation potential, making it suitable for high-energy density LIBs. The glass remains amorphous throughout cycling, maintaining any improved mechanical properties conferred by the amorphous structure.Crucially, parasitic electrolyte reduction is found to be much reduced in comparison to pure Si or Al, and comparable to that on Cu. The charge consumed by electrolyte reduction in each cycle is given in the figure below for a-AlSiMn and an amorphous Si reference anode. The resulting SEI on a-AlSiMn is very thin, and rich in fluorinated species such as LiF, F-P-O groups, and fluorinated oxides of silicon and aluminum, whereas very few organic species are present. In particular, lithium ethylene decarbonate (LiEDC), which plays a large role in SEI formation on Si, is entirely absent, and a thinner, more stable SEI results. This study shows that metallic glasses can become a viable new class of alloying anode materials for LIBs with improved surface passivity. Li, J.; Dahn, J. R., An In Situ X-Ray Diffraction Study of the Reaction of Li with Crystalline Si. Journal of The Electrochemical Society 2007, 154 (3), A156.Yin, Y.; Arca, E.; Wang, L.; Yang, G.; Schnabel, M.; Cao, L.; Xiao, C.; Zhou, H.; Liu, P.; Nanda, J.; Teeter, G.; Eichhorn, B. W.; Xu, K.; Burrell, A. K.; Ban, C., Non-Passivated Silicon Anode Surface. ACS applied materials & interfaces 2020.Kasavajjula, U.; Wang, C.; Appleby, A. J., Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. Journal of Power Sources 2007, 163 (2), 1003-1039.Liang, B.; Liu, Y.; Xu, Y., Silicon-based materials as high capacity anodes for next generation lithium ion batteries. Journal of Power Sources 2014, 267, 469-490.Beaulieu, L. Y.; Hatchard, T. D.; Bonakdarpour, A.; Fleischauer, M. D.; Dahn, J. R., Reaction of Li with Alloy Thin Films Studied by In Situ AFM. Journal of The Electrochemical Society 2003, 150 (11), A1457.Hatchard, T. D.; Topple, J. M.; Fleischauer, M. D.; Dahn, J. R., Electrochemical Performance of SiAlSn Films Prepared by Combinatorial Sputtering. Electrochemical and Solid-State Letters 2003, 6 (7), A129.Chen, M., A brief overview of bulk metallic glasses. NPG Asia Materials 2011, 3 (9), 82-90.Jafary-Zadeh, M.; Praveen Kumar, G.; Branicio, P. S.; Seifi, M.; Lewandowski, J. J.; Cui, F., A Critical Review on Metallic Glasses as Structural Materials for Cardiovascular Stent Applications. Journal of Functional Biomaterials 2018, 9 (1), 19.Telford, M., The case for bulk metallic glass. Materials Today 2004, 7 (3), 36-43.Fleischauer, M. D.; Dahn, J. R., Combinatorial Investigations of the Si-Al-Mn System for Li-Ion Battery Applications. Journal of The Electrochemical Society 2004, 151 (8), A1216. Figure 1

Stoichiometry-Controlled Reversible Lithiation Capacity in Nanostructured Silicon Nitrides Enabled by in Situ Conversion Reaction.

In modern Li-based batteries, alloying anode materials have the potential to drastically improve the volumetric and specific energy storage capacity. For the past decade silicon has been viewed as a “Holy Grail” among these materials; however, severe stability issues limit its potential. Herein, we present amorphous substoichiometric silicon nitride (SiNx) as a convertible anode material, which allows overcoming the stability challenges associated with common alloying materials. Such material can be synthesized in a form of nanoparticles with seamlessly tunable chemical composition and particle size and, therefore, be used for the preparation of anodes for Li-based batteries directly through conventional slurry processing. Such SiNx materials were found to be capable of delivering high capacity that is controlled by the initial chemical composition of the nanoparticles. They exhibit an exceptional cycling stability, largely maintaining structural integrity of the nanoparticles and the complete electrodes, thus delivering stable electrochemical performance over the course of 1000 charge/discharge cycles. Such stability is achieved through the in situ conversion reaction, which was herein unambiguously confirmed by pair distribution function analysis of cycled SiNx nanoparticles revealing that active silicon domains and a stabilizing Li2SiN2 phase are formed in situ during the initial lithiation.

Si-TiN alloy anode materials prepared by reactive N2 gas milling: thermal stability and electrochemistry in Li-cells

Si-TiN alloys were synthesized through a novel N2 gas milling method and a conventional inert gas milling approach. Thermal stability of these two kinds of Si-TiN alloys and their electrochemistry as negative electrodes in Li-ion cells were evaluated before and after heating. Si70(TiN)30 prepared by N2 gas milling was found to have high temperature tolerance, evidenced by low crystallization and fine grain structure after heat treatment. The Si70(TiN)30 (N2) alloy after heat treatment shows resistance to Li15Si4 formation during electrochemical lithium insertion, which is presumably due to its fine grain structure. Si70(TiN)30 (N2) was further modified by carbon coating at 800°C, resulting in a high capacity retention after 50 cycles of 94%, while achieving a large reversible volumetric capacity of 1490 Ah/L.

Effect of Ce content on performance of AZ31 magnesium alloy anode in air battery

In this work, five AZ31-xCe magnesium alloy anode materials were prepared, and their microstructure, electrochemical properties and discharge properties were studied to reveal the effect of Ce content on the casting anode of magnesium air battery. The introduction of the Ce element can refine the grain and purify the α-Mg matrix. AZ31–1Ce magnesium alloy has the best corrosion resistance, and the activity of magnesium alloy enhances with the increase of Ce content. Compared with AZ31 magnesium alloy, AZ31-xCe magnesium alloy has higher discharge activity, which is due to the introduction of Ce element to purify the magnesium alloy, and the Al4Ce phase can promote the uniform dissolution of Mg matrix. When the discharge current density is 10 mA cm−2 the AZ31–4Ce anode shows the highest energy density of 1552.370 mWh g−1 and the best specific capacity of 1282.051 mAh g−1 which are 46.05% and 29.901% higher than the AZ31 anode. Compared with AZ31 magnesium alloy, the anode of AZ31–4Ce magnesium alloy has a smoother discharge surface morphology, which is beneficial to the desquamation of the discharge products.

Co-electrodeposited Al-Ga composite electrode from ionic liquid with volume expansion adaptability in energy storage

The high specific capacity and cycle stability of Li-ion alloy anode materials have been the focus of researchers. However, the alloy anode materials are easy to be broken and cracked after cycling. In this study, we have co-electrodeposited Al-Ga composite from ionic liquid, and the obtained composite has a higher specific capacity and the longer cycling life than single Ga/Al electrode. Initial discharge capacity is 1554.7 mAh/g, and Coulombic efficiency is 82.6% at 0.1 A/g. Co-electrodeposited Al-Ga composite from ionic liquid provides a new way to solve the electrode materials that are easily fractured and cracked after cycling, and improves cycle stability and high capacity to a certain extent.

Optimization of Magnesium-Doped Lithium Metal Anode for Lithium Metal Batteries: Simulation and Experiment

To further improve the energy density of the current lithium ion batteries, tremendous effort has been made on the development of anode materials with higher capacities than the widely commercialized graphite. Lithium metal is considered as the most attractive anode candidate for lithium batteries because of its ultrahigh specific capacity (3860 mAh g-1) and extremely low redox potential (-3.040 V vs. standard hydrogen electrode). While the uncontrolled lithium dendrite growth and the interfacial instability, leading to low Coulombic efficiency, are two big problems for pure lithium metal anodes. Lithium-magnesium alloy has been considered as a potential alternative anode material. There have been some studies of magnesium amount on lithium-magnesium alloy anode with a wide range. It is found that even a marginal amount of magnesium can improve the battery performance. However, the optimum content of magnesium in lithium-magnesium alloy anode and the mechanism on cell performance are still not well understood. Quantum chemistry and molecular dynamics simulation methods have been widely used in advanced electrode materials design to accelerate the material discovery and development. Computational and experimental approaches are combined to optimize the amount of magnesium in lithium-magnesium alloy anode materials and investigate the cell performance. This work focuses on lithium-magnesium alloy with limited magnesium amount. The density functional theory calculation is employed to investigate the effect of doping magnesium amount in lithium-magnesium alloy anode. Simulation results show that the additional magnesium atom in lithium-magnesium alloy can control the plating/stripping of lithium atoms on the alloy anode surface. Moreover, an optimum ratio of magnesium in lithium-magnesium alloy is found when calculating the absorption energy of lithium atom on lithium-magnesium alloy surface. Electrochemical experiments further demonstrate that the alloy anode material with the optimal ratio of magnesium exhibits the best cycling stability in lithium metal batteries with high nickel layered oxide cathode. This work provides an effective approach to identify optimal alloying-type lithium metal anodes for improving long-term cycling stability of high-energy-density lithium metal batteries. More details will be discussed at the presentation.

Preparation and electrochemical properties of silicon copper alloy for high performance anode

To improve the electrochemical performance of silicon-based anode materials, herein, silicon-copper (Si-Cu) incompatible alloy anode material were prepared via facile chemical reduction and ball milling methods. Subsequently, nitrogen-doped carbon-coated Si-Cu alloy (Si-Cu/N-C) composites were prepared via in-situ polymerization with aniline in the high-temperature calcinations process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were performed to analyze the physical characterization of these materials. Besides, the electrochemical performance of the catalysis was studied by constant current charging and discharging, cyclic voltammetry and electrochemical AC impedance spectroscopy (EIS). Electrochemical tests demonstrate that Si-Cu anode performs a high electrocatalytic activity when the ratio of Si to Cu is 1.5∶1 and the ball milling time is 7 h. The anode exhibits an initial discharge capacity of 1 018.6 mAh/g and a capacity of 499.2 mAh/g after 100 cycles. After the coating modification, TEM result shows that this composite anode material possesses a core-shell structure. When the coating mass of N-doped carbon is 0.45, the Si-Cu/N-C electrode exhibits an initial discharge capacity of 1 147.7 mAh/g and maintains a specific capacity of 857.9 mAh/g after 100 cycles. Furthermore, the capacity retention rate of Si-Cu/N-C anode increases by 10.8% as compared with that of Si-Cu. The improved electrochemical performance after modification is attributed to the unique core-shell structure of Si-Cu/N-C. On the one hand, the N-doped carbon coating layer not only improves the conductivity, but also reduces the contact resistance between the electrolyte and electrode. On the other hand, the nitrogen doping of Si-Cu/N-C composite can increase the active site of lithium storage on the surface, reduce lithium storage potential and form a stable solid electrolyte interface (SEI) film during the cycling process.

The Role of Polymer and Inorganic Coatings to Enhance Interparticle Connections Diagnosed by In Situ Techniques.

Surface coating on alloy anodes renders an effective remedy to tolerate internal stress and alleviate the side reaction with electrolytes for long-lasting reversible lithium redox reactions in lithium-ion batteries. However, the role of surface coating on the interparticle connections of alloy anodes remains not fully understood. Herein, we exploit real-time lithiation and mechanic measurement of SnO2 nanoparticles via in situ TEM with different coating layers, including conducting polymer polypyrrole and metal oxide MnO2. As a result, polypyrrole is more flexible to accommodate the volume expansion issue. More importantly, the polypyrrole coating layers offer a large contact area and strong adhesion force between the SnO2 nanoparticles, ensuring fast lithiation kinetics and high cycling stability. These observations provide new insight into how the interparticle connections of alloy anodes with diverse coating approaches can impact battery performance, shedding light on the practical processing of the alloy anode materials for high-energy Li-ion batteries.

Microscopic Observation of Solid Electrolyte Interphase Bilayer Inversion on Silicon Oxide

Silicon has been investigated in recent years as an alloying anode material to enhance gravimetric energy density in lithium-ion batteries. While recent developments have suggested that silicon oxi...

Electrochemo-Mechanical Properties of Red Phosphorus Anodes in Lithium, Sodium, and Potassium Ion Batteries

Summary Red phosphorus (RP) is a promising anode material for alkali-ion batteries due to a high theoretical capacity at low potentials when alloying with lithium, sodium, and potassium. Most alloy anode materials display large volume changes during cycling, which can lead to particle fracturing, low Coulombic efficiency, loss of electrical contact, and ultimately poor cycle life. In this paper we outline, through comprehensive electrochemo-mechanical characterization and modeling of the cycling stresses, why RP can be cycled at high current densities without fracture. Application of in situ nanoindentation and powder compression allows for measurement of the elastic, plastic, and fracture properties of RP. In situ transmission electron microscopy observation with extreme conditions (anisotropic ion diffusion and high current density) was used to validate the model, observing no catastrophic failure of RP particles. Electrochemo-mechanical characterization with geometry and stress modeling allows for predictions to be made for application of RP in alkali-ion batteries.

Evolution of solid electrolyte interphase and active material in the silicon wafer model system

Alloying anode materials for lithium-ion batteries, such as silicon (Si), are an important focus of materials research due to the demand for increased energy density for electric vehicles and stationary grid storage. However, progress towards next generation anode materials has been hindered by poor capacity retention due to the instability of the Si active material and the solid electrolyte interphase (SEI). In this work, the evolution of the active Si material and the SEI are simultaneously investigated from the perspective of chemical, structural, morphological, and electronic evolution in the Si wafer model system through its cycling life, using time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), and scanning spreading resistance microscopy (SSRM). The results illustrate a dynamic evolution of the SEI and active Si material through cycling. Through an improved understanding of evolution of SEI and Si active material within the Si wafer model system, mitigation strategies may be designed to extend the lifetime of Si anodes.