Lithiation Process Research Articles

First-principles study on the lithiation process of amorphous SiO anode for Li-ion batteries with Bayesian optimization.

Amorphous silicon monoxide (a-SiO), which contains Si atoms with various valence states, has attracted much attention as a high-performance anode material for lithium (Li) ion batteries (LIBs). Although current experiments have provided some information during charge/discharge cycles, further investigation of structural changes at the atomic scale is needed. To investigate the lithiation process of a-SiO using first-principles simulations and machine learning techniques, we developed a computational code employing Bayesian optimization to efficiently identify stable sites for Li insertion in the large search-space of amorphous models to reproduce the actual lithiation process and compared this approach to the conventional random scheme by applying it to an a-SiO model previously generated with neural network potentials. The lithiation process based on Bayesian optimization resulted in lower formation energies compared to the conventional random scheme, indicating a more stable structure. During lithiation, Li atoms tended to enter the silicon (Si) phase after the SiO2 phase, in agreement with experimental results. We analyzed the structural changes and observed significant differences in the structural evolution between the conventional and new schemes. Our study highlights the significant influence of the lithiation process on the structural transformation of a-SiO materials, which in turn affects the reversible capacity of the material. These findings will provide a framework for improving the performance and lifetime of a-SiO materials.

Improving the Cycle Stability of LiNiO2 through Al3+ Doping and LiAlO2 Coating.

In this study, we addressed the poor cycling and rate performance of LiNiO2, a material with ultrahigh nickel content considered a strong contender for high-energy-density lithium-ion battery cathodes. We introduced nano-Al2O3 during the lithiation process to achieve dual modified material through bulk phase element doping and in situ LiAlO2 coating. Comparison revealed notable improvements in the modified materials. In particular, LiNi0.99Al0.01O2 maintained a capacity retention rate of 73.1% after 300 cycles in a long-cycle test at 0.5C current density, outperforming the undoped material. In rate performance tests, the doped samples consistently exhibited higher discharge-specific capacities than that of the undoped counterpart. Notably, at a high current density of 5C, LiNi0.99Al0.01O2 exhibited a discharge-specific capacity of 101.75 mAh g-1. The results indicate that an appropriate amount of Al doping can effectively stabilize the layered structure of the cathode material and delay the irreversible phase transition from H2 to H3. Further, Al doping facilitates the formation of a LiAlO2 coating on the surface of the particles. This coating acts as a fast-ion conductor, enhancing the transport of lithium ions and reducing the erosion of the active material by the electrolyte.

Towards smart and secure batteries: Linking pressure and temperature profiles with electrochemical behavior through hybrid optical fiber sensors

A hybrid sensing configuration combining fiber Bragg grating (FBG) with a Fabry-Perot interferometer is proposed for highly sensitive detection of pressure and temperature inside a commercial lithium-ion battery (LiB). The battery is also instrumented externally with FBGs to monitor its surface temperature variations. The LiB is operated under several cycling tests at different C-rates and environmental temperatures. High pressure and temperature resolutions of ±0.4 mbar and ±0.5 °C, respectively, are attained for the developed hybrid sensor, along with a minimum response time of 1.7 s. When the LiB is subjected to higher environmental temperatures, reduced thermal variations and higher pressure variations are registered by the optical sensor. Overall, during the cycling tests, the external temperature sensors closely follows the internal sensors behavior. Incremental capacity analysis derivative curves were systematically applied throughout the battery cycling experiments to unveil relevant insights into the interplay between pressure and temperature variations and the LiB electrochemical behavior. It was found that the pressure fluctuations present a “breathing profile” directly linked with the volume electrode lithiation and delithiation processes.

Effect of current collector on the coupled electro-chemo-mechanical performance of graphite electrodes in LiBs.

The current collector, one of the main components in the manufacture of composite electrodes, is mainly used to enhance the mechanical stability and improve the performance and cycle performance of the electrodes. During the electrochemical reaction, the lithium diffusion can induce compressive stress and affect the mechanical performance, lifespan, and performance of batteries. Therefore, this study analyzed the influence of copper foil on the mechanical response and degradation performance of electrodes. In addition, a mathematical model was developed to analyze the effect of copper foil on the stress-strain behavior of the electrodes. The results indicated that the stress and modulus of the graphite electrodes have a non-linear increase with the lithiation process. Based on those findings, utilizing a thinner and more compliant current collector could effectively mitigate the in-plane strain and the stress within electrodes. Thus, developing a thinner and softer copper foil could simultaneously enhance the mechanical properties and specific density of composite electrodes for the next-generation LiBs.

Electrochemical Relithiation in Spent LiFePO4 Slurry for Regeneration of Lithium-Ion Battery Cathode.

Recycling spent lithium-ion batteries (LIBs) in a green and economical way is vital for maintaining the sustainability of the LIB industry. However, given the low content of high-value components in olivine-type lithium iron phosphate (LFP), traditional metallurgical processes are economically unfeasible for recycling due to high chemical/energy consumption and labor-intensive procedures. This study proposes a facile electrochemistry strategy to directly regenerate the spent LFP material by an electrically driven lithiation process as a spent LFP slurry (200 g/L) rather than as electrodes. Minimal energy and chemical consumption are achieved by enabling the healing of spent LFP without destroying the original olivine-type crystal structure. The proposed method utilizes mild healing conditions (25 °C for 2 h) and LiCl solution as the only reagent in the regeneration process, significantly lowering the expenses associated with producing cathode electrodes. The electrochemical performance of the regenerated LFP have been dramatically recovered after regeneration, exhibiting a capacity of 151.5 mA h g-1 at 0.1 C and 96.6% capacity retention over 400 cycles at 1 C. This approach demonstrates a high processing capability and offers considerable economic and environmental benefits, making it an eco-friendly option and supporting the sustainable development of the LFP industry.

Two-dimensional BC12 as an ultra-high performance anode material for lithium-ion batteries

With the gradual development of renewable energy, search for high-performance energy storage materials as anodes for lithium-ion batteries (LIBs) has become urgent. Two-dimensional (2D) materials are considered as candidates for anode materials due to their unique structure and physicochemical properties. Based on first-principles calculations, we propose a 2D material, BC12 monolayer, as an excellent anode for LIBs. BC12 exhibits outstanding dynamic, mechanical, and thermal stability. In addition, BC12 monolayers show not only remarkably high storage capacity (2767.57 mA h g−1) but also low diffusion barrier energy (0.175 eV) and appropriate open circuit voltage (0.3 V). A small volume expansion (0.38%) is also observed during the lithiation process. Furthermore, we undertake a comprehensive analysis on the impact of carbon vacancy in BC12. The presence of carbon vacancy makes the adsorption and diffusion of Li relatively weak, which should be carefully handled in the experimental synthesis process. The above-mentioned investigation offers valuable insights and guidance for the future development and application of 2D anode materials in metal-ion batteries.

Dual-active sites and reversible-structural covalent organic framework for highly stable alkali metal-ion batteries

Organic materials are promising candidates for energy storage due to their sustainability, environmental friendliness, and structural designability. However, their application is severely limited due to short lifespan and sluggish kinetics caused by low redox stability, solubility, and low electronic conductivity. Here, we designed a polyimide-conjugated covalent organic framework (NAA-COF). Its highly covalent framework cannot only endow the organic material with strong π–π interactions and robust network ensuring its structure stability, but also offer open channels for rapid ions/electrons transfer inside. Additionally, the introduction of multiple redox-active sites can significantly enhance ion-storage capacity. Consequently, when evaluated as a cathode for Li-ion batteries, NAA-COF exhibits large capacity of 220mAh/g, superb initial coulombic efficiency (90 %), good voltage platform, long lifespan (10000 cycles), and high-rate performance (110 mAh/g at 10 A/g). More importantly, even for Na-/K-ion batteries, the exceptional electrochemical performances can still be maintained. In situ transmission electron microscopy (TEM) and in/ex situ spectroscopy further elucidate the low volume expansion (12.2 %) during the lithiation process and 8-electron reaction mechanism for the NAA-COF cathode. This work provides a high-performance universal COF cathode material that can simultaneously satisfy the requirements of alkali metal-ion batteries.

The effect of chemical doping on the lithiation processes of the crystalline Si anode ‒ A first-principles study.

We employed first-principles calculations to investigate the effect of chemical doping on the lithiation kinetics and dynamic properties of the c-Si anode. Our abinitio molecular dynamics simulations reveal that phosphorous/arsenic doping can greatly enhance the lithiation kinetics of c-Si, whereas boron doping is unable to produce such an improvement. Our calculations also show that boron doping could enhance Li insertion into c-Si, but phosphorous/arsenic doping tends to increase the insertion energy of Li ions. Although the migration energy barriers of Li ions may slightly increase (decrease) in the boron-(phosphorus-/arsenic-)doped c-Si, these changes were only effective within the range of the nearest-neighbor distance from dopants. Furthermore, it was found that the phosphorus-/arsenic-doped Si can be more ductile and can more easily undergo plastic deformation upon lithiation, while the c-Si matrix becomes more brittle and stiffer when doped with boron. Our simulation results also demonstrate that phosphorous- and arsenic-doping can effectively speed up the Li-induced structural amorphization of c-Si while boron doping appears to severely slow it down. These findings unambiguously indicate that the induced mechanical softening of the c-Si bond network can be the primary factor that leads to the enhanced lithiation kinetics in the n-type doped c-Si anodes.

Advances in Sustainable Battery Technologies: Enhancing Longevity, Recycling, and Alternative Components-- A Review

The field of sustainable battery technologies is rapidly evolving, with significant progress in enhancing battery longevity, recycling efficiency, and the adoption of alternative components. This review highlights recent advancements in electrode materials, focusing on silicon anodes and sulfur cathodes. Silicon anodes improve capacity through lithiation and delithiation processes, while sulfur cathodes offer high energy density, despite inherent challenges. Recycling technologies are also advancing, with mechanical methods achieving 60% efficiency, hydrometallurgical processes reaching 75%, and pyrometallurgical methods achieving 85% efficiency. These improvements in recycling contribute to a more sustainable lifecycle for batteries. Moreover, the shift towards alternative components, such as organic batteries, sodium-ion batteries, and solid-state batteries, is gaining momentum, representing 10%, 20%, and 15% of the market, respectively. These alternatives address environmental concerns and enhance battery performance and reliability. These developments underscore the importance of ongoing innovation in electrode materials and recycling technologies to overcome current challenges. As the industry continues to evolve, these advancements pave the way for more efficient and environmentally friendly energy storage solutions, promising a sustainable future for battery technologies.

FeF3·0.33H2O nanoparticles decorated Ti3C2 MXene as high-performance bifunctional sulfur host for lithium‑sulfur batteries

Lithium‑sulfur batteries are deemed as a potential next-generation energy storage system, but their development is hindered by the shuttle effect of lithium polysulfides. Design and synthesis of multifunctional sulfur host materials are expected to adsorb lithium polysulfides and catalyze their conversion during the lithiation process, thereby suppressing the shuttle effect. In this work, FeF3·0.33H2O nanoparticles is in situ grown on the surface of Ti3C2 nanosheets (FeF3@Ti3C2) and used as the bifunctional sulfur host for lithium‑sulfur batteries. Ti3C2 nanosheets not only provide two-dimensional (2D) conductive substrate for sulfur, but also strongly adsorb lithium polysulfides and suppress the shuttle effect. Meanwhile, FeF3 nanoparticles can accelerate the conversion reaction of lithium polysulfides, which also contributes to inhibiting the shuttle of lithium polysulfides. In addition, decorating Ti3C2 nanosheets with FeF3 nanoparticles can prevent the stacking of Ti3C2 nanosheets and enhance the interaction between Ti3C2 and lithium polysulfides. Therefore, sulfur-loaded FeF3@Ti3C2 (FeF3@Ti3C2@S) displays excellent electrochemical performance, such as a high reversible capacity of 687 mAh g−1 at 2C after 1000 cycles, and the capacity decay rate is only 0.023 %. This work paves a simple way for improving the performance of Ti3C2 as the sulfur host and expanding its application in lithium‑sulfur batteries.

In Situ Electrochemical Interfacial Manipulation Enabling Lithiophilic Li Metal Anode with Inorganic‐Rich Solid Electrolyte Interphases for Stable Li Metal Batteries

Lithium‐metal anodes (LMAs) are the ultimate choice for realizing high‐energy‐density batteries; however, its use is hindered by problematic Li growth in the form of dendrites. To alleviate dendritic Li growth, the preparation of LMAs with a lithiophilic current collector (CC) is effective; however, applying a lithiophilic CC to LMAs is still challenging due to the manufacturing complexity involved in the separate lithiophilic treatment and lithiation processes. Herein, a facile one‐pot LMA fabrication method by utilizing thiourea (TU) as a precursor is proposed. A lithiophilic Cu2S layer is formed on Cu foam (CF) by the in situ electrochemical oxidation of TU (CuxSCF), and the lithiation of CC is performed via subsequent Li electrodeposition (Li@CuxSCF). The Cu2S on CuxSCF can lead to uniform Li deposition by providing lithiophilic sites, and it is converted to form ionic‐conductive Li2S‐rich solid electrolyte interphase layer. Resultantly, CuxSCF significantly enhances the cycling performance of LMAs compared to CF. Specifically, a LiFePO4/Li@CuxSCF full‐cell lithium‐metal battery (LMB) with a low n/p ratio (1.6) exhibits capacity retention of 95.6% at 0.5 C (220 cycles) and can maintain 85.0% of initial capacity (425 cycles, n/p = 4) at 2.0 C. LMBs with LiNi0.6Co0.2Mn0.2 and LiNi0.8Co0.1Mn0.1 also exhibit improved electrochemical performance.

Nonequilibrium fast-lithiation of Li4Ti5O12 thin film anode for LIBs

Li4Ti5O12 (LTO) is known for its zero-strain characteristic in electrochemical applications, making it a suitable material for fast-charging applications. Here, we systematically studied the quasi-equilibrium and non-equilibrium lithium-ion transportation kinetics in LTO thin-film electrodes, across a range of scales from the crystal lattice to the microstructured electrodes. At the crystal lattice scale, during the non-equilibrium lithiation process, lithium ions are dispersedly embedded into the 16c position, resulting in more 8a → 16c migration compared with the quasi-equilibrium lithiation, and forming numerous fast lithium diffusion channels inside the LTO lattice. At the microstructural electrode scale, optical spectrum characterizations supported the “nano-filaments” lithiation model in polycrystalline LTO thin-film electrodes during the lithiation process. Our results reveal the patterns of lithium migration and distribution within the LTO thin film electrode under the non-equilibrium and quasi-equilibrium lithiation process, offering profound insights into the potential optimization strategies for enhancing the performance of fast-charging thin film batteries.

Unraveling the impact of pore length on the conversion reaction of Fe3O4/carbon anodes in lithium-ion batteries

Despite numerous studies investigating Fe3O4/porous carbon anode materials for high-performance lithium-ion batteries (LIBs), the inherent limitations of the Fe3O4 conversion reaction, such as low reversibility and sluggish kinetics, continue to pose significant challenges. While modifying the porous structure of Fe3O4 anodes has demonstrated considerable promise in overcoming these limitations, the precise relationship between the porous structure and Fe3O4 conversion behavior still remains unclear. Here, we explore the impact of the pore length of the anode active material on the electrochemical performance of LIBs. Using two different composites of Fe3O4 and porous carbon with varying pore lengths as model materials, we conduct various in-depth electrochemical and ex-situ analyses. Our findings confirm that a shorter pore length facilitates higher Li+ ion diffusivity compared to longer pore length. Consequently, the conversion reaction of Fe3O4 to Fe and Li2O during lithiation process can be expedited, leading to a decrease in the resistance at the solid electrolyte interphase. As a result, we demonstrate that shortening the pore length of the porous anode composite materials can enhance the initial Coulombic efficiency (CE), reversible capacity, and rate capability of LIBs.

Operando X-Ray CT Analysis of Silicon/Solid Electrolyte Mechanical Interface of All-Solid-State Battery during Charging and Discharging Reaction

Silicon has a theoretical capacity about 10 times that of graphite, so it is expected to be one of the next-generation anode materials to further increase the capacity of batteries. However, silicon has a large volume change during charging and discharging, which result in poor cyclability. Although morphological change of silicon has been shown in a lot of previous studies, most of them are ex-situ observations using electron microscopes such as SEM and are two-dimensional observations1). Moreover, many previous studies target liquid battery. It is necessary to understand the expansion and shrinkage mechanism of silicon to improve all-solid-state battery performance using silicon anode. Synchrotron X-ray computed tomography (X-ray CT) is a technique that can measure the internal structure of a battery in three dimensions with micrometer-order spatial resolution in a short time. In addition, operando X-ray CT measurement is possible under charging and discharging in an all-solid-state battery2). In this study, we analyzed that morphological changes of silicon during charging and discharging by operando X-ray CT measurements.We used LiNi1/3Co1/3Mn1/3O2 (NCM), Li6PS5Cl (LPSCl) and acetylene black (AB), which were mortar-mixed in a mass ratio of 1:1:0.1 as the cathode composite material, and Si, LPSCl and AB in a mass ratio of 1:2.78:0.42 as anode composite material. Si｜LPSCl｜NCM all-solid-state cells were assembled. X-ray CT measurements at SPring-8 BL20XU using 20 keV X-rays while performing constant current charge/discharge measurement at 2.3×10-3 A cm-2. The pixel resolution was 0.5 µm. A silicon particle was extracted from the X-ray CT images obtained from X-ray CT measurements to observe the morphological changes of silicon during charging and discharging reaction. Then, change of the silicon volume and the contact area fraction of silicon particle and LPSCl solid electrolyte were calculated.Volume expansion was observed with lithiation of silicon and volume shrinkage with delithiation of silicon. As the lithiation process, silicon density decreased, and silicon was observed to be darker. As the delithiation process, cracks appeared in the silicon particle as the expanded silicon shrank. In addition, the silicon/solid electrolyte interface changed so that the silicon formed shell voids at the surface of silicon particles. This indicates that the plasticity of the LPSCl solid electrolyte cannot follow the form change of the interface. However, shell voids in the interface were formed for all directions, but some parts remained in contact area between the silicon particle and the solid electrolyte. After the second cycle of lithiation, cracks in the particle and the voids in the interface between the silicon particle and the solid electrolyte that had been formed due to the shrinkage of silicon as the delithiation disappeared by the re-lithiation. However, the re-delithiation caused cracks in the particle in the same area and formed shell voids in the interface again. Moreover, as the second delithiation process, the number of cracks in the particle increased compared with that as the first delithiation. This suggests that the number of cracks in the particle increases as silicon repeated lithiation and delithiation, and so silicon is miniaturized. In addition, a correlation was confirmed between the silicon volume change and the contact area fraction change. After the first cycle, the volume didn’t return to pristine silicon volume and the contact area fraction was reduced compared to pristine silicon. The isolation of the silicon particle from the solid electrolyte interface is suggested to be one of the factors causing the poor cycle performance because of the lithium ion reaction path is limited.1) T. Li, J. Y. Yang, S.G. Lu, H. Wang and H. Y. Ding, Rare Metals, 32, 299-304 (2013).2) Y. Sakka, H. Yamashige, A. Watanabe, A. Takeuchi, M. Uesugi, K. Uesugi and Y. Orikasa, J. Mater. Chem. A, 10, 16602–16609 (2022).

Scaling and Commercializing Continuous Supercritical Hydrothermal Single Crystal Cathode Active Material Manufacturing

Current polycrystalline cathode active materials (CAMs) in the market face a significant challenge during charge-discharge cycles. The lithiation and de-lithiation processes induce volume changes within the CAMs, leading to strain along grain boundaries. This strain, arising from the expansion of crystals in different orientations, often results in material pulverization, creating void fractions. Such deterioration leads to increased impedance, capacity degradation, and shorter cycle life.Addressing these challenges, there is an emerging demand for single crystal (SC) CAMs, which promise enhanced performance by eliminating internal void fractions and grain boundaries. The continuous supercritical hydrothermal process, invented at Argonne National Laboratory, offers an innovative and cost-effective method to produce SC CAMs. This method effectively reduces energy consumption and production costs, while also lowering carbon emissions.In this presentation, we provide a comprehensive overview of the advancements in scaling up and commercializing continuous supercritical hydrothermal process for SC CAM manufacturing. Our focus is on the efforts undertaken by ACT-ion Battery Technologies, the industry commercialization partner, highlighting the significant strides made towards implementing this promising solution on a practical level.

Voltammetric Study of Phase Separating Anode Materials in Li-Ion Battery Using Phase Field Model

The increasing demand for higher energy capacity in lithium-ion batteries has underscored the significance of modeling lithiation with alternative electrode materials, such as silicon (Si) and tin (Sn). This research addresses the need for comprehensive insights into the (dis)charging process, particularly focusing on the intricate phase transformations in the anode. Phase-field modeling has proven effective in capturing these transformations [2], revealing volumetric deformations of up to 300% during (dis)charging cycles [1]. Unfortunately, these deformations compromise material integrity, leading to reduced battery cycle life and reliability.To address these challenges, our work presents a novel framework for modeling lithiation in materials exhibiting two-phase diffusion using phase field modeling. Unlike previous models limited to single-phase diffusion, our framework provides a more realistic representation of the diffusion process. This realism is achieved by incorporating the time-dependent voltage applied to the anode, a crucial factor in understanding the electrochemical response during lithiation [3].Furthermore, we leverage the currents generated during the lithiation and delithiation processes to conduct a comprehensive voltammetric study. This study goes beyond existing research by considering the impact of phase separation on the currents developed during Li-ion battery operation. Our findings aim to contribute valuable insights into optimizing battery performance and addressing challenges associated with phase transformations, ultimately advancing the development of high-capacity anodes for lithium-ion batteries. REFERENCES [1] McDowell M. T., Lee S. W., Nix W. D., Cui Y. 25th Anniversary Article: Understanding the Lithiation of Silicon and Other Alloying Anodes for Lithium-Ion Batteries. Adv. Mater., Vol. 25 (36), pp. 4966–4985, 2013.[2] Chen L., Fan F., Hong L., Chen J., Ji Y. Z., Zhang S. L., Zhu T., Chen L. Q. A Phase-Field Model Coupled with Large Elasto-Plastic Deformation: Application to Lithiated Silicon Electrodes. J. Electrochem. Soc., Vol. 161 (11), pp. F3164–F3172, 2014.[3] Swaminathan, N., Balakrishnan, S., & George, K. Elasticity and Size Effects on the Electrochemical Response of a Graphite, Li-Ion Battery Electrode Particle. Journal of The Electrochemical Society, 163(3), A488–A498, 2016. Figure 1

Efficient Direct Recycling of Spent Cathode Materials in Lithium-Ion Batteries

The demand for lithium-ion batteries (LIBs) has surged in recent years, driven by the rapid growth of electric vehicles (EVs) and emerging energy storage technologies. Yet, this surge in demand has also resulted from a significant increase in the number of spent batteries. Given the potential for environment pollution wastage, it is absolutely crucial to prioritize the recovery and recycling of these used lithium-ion batteries.The common techniques employed in large-scale industrial settings for battery recycling are pyrometallurgy and hydrometallurgy. These are pivotal multi-step processes, particularly suitable for materials containing Cobalt (Co) and Nickel (Ni), such as NMC (LiNixMnyCozO2). Aside from NMC, there has been a surge in the adoption of LFP (LiFePO4) as a cathode material target for lithium-ion batteries in electric vehicles worldwide over the past few decades. However, these established industrial recycling methods are not applicable to LFP due to the comparatively lower value of iron. This necessitates the pursuit of direct recycling approaches.In order to accomplish this goal, direct recycling stands out as the most suitable technique for regenerating spent batteries1. Unlike processes involving solution-based or high-temperature steps that entail potentially wasteful steps, thisapproach aims to reduce energy consumption and costs, all while maintaining environmental integrity through a judicious utilization of resources, materials, and energy. Consequently, our attention is directed towards this specific LFP material, prompting us to detail a direct recycling procedure for spent LFP cathodes via a chemical lithiation process at room temperature in a solution containing lithium iodide (LiI) and various solvents2 (Fig. 1).

Theoretical Investigation of a Novel Two-Dimensional Non-MXene Mo3C2 as a Prospective Anode Material for Li- and Na-Ion Batteries.

A new two-dimensional (2D) non-MXene transition metal carbide, Mo3C2, was found using the USPEX code. Comprehensive first-principles calculations show that the Mo3C2 monolayer exhibits thermal, dynamic, and mechanical stability, which can ensure excellent durability in practical applications. The optimized structures of Lix@(3×3)-Mo3C2 (x = 1-36) and Nax@(3×3)-Mo3C2 (x = 1-32) were identified as prospective anode materials. The metallic Mo3C2 sheet exhibits low diffusion barriers of 0.190 eV for Li and 0.118 eV for Na and low average open circuit voltages of 0.31-0.55 V for Li and 0.18-0.48 V for Na. When adsorbing two layers of adatoms, the theoretical energy capacities are 344 and 306 mA h g-1 for Li and Na, respectively, which are comparable to that of commercial graphite. Moreover, the Mo3C2 substrate can maintain structural integrity during the lithiation or sodiation process at high temperature. Considering these features, our proposed Mo3C2 slab is a potential candidate as an anode material for future Li- and Na-ion batteries.

Unraveling the origin of the high reversibility in entropy-stabilized rocksalt-type (Mg0.2Co0.2Mn0.2Ni0.2Zn0.2)O anodes for lithium-ion storage

Entropy-stabilized rocksalt-type oxides, composed of multiple components, are increasingly recognized as highly promising materials for energy storage applications. In this study, a novel anode material, (Mg0.2Co0.2Mn0.2Ni0.2Zn0.2)O, demonstrates exceptional reversible specific capacity of 773.4 mAh g−1 even after 200 cycles at 0.1 A g−1. Density functional theory (DFT) analysis reveals superior electrical conductivity of (Mg0.2Co0.2Mn0.2Ni0.2Zn0.2)O compared to individual oxides like CoO, which has the potential to enhance electronic transfer to improve electrochemical performance. In situ transmission electron microscopy (TEM) observations confirm the reversible crystal structure of rocksalt-type (Mg0.2Co0.2Mn0.2Ni0.2Zn0.2)O anodes, with only ∼36.8 % volume expansion in four cycles. This investigation offers insights into the (de)lithiation process at a microscopic scale, shedding light on the origins of high reversibility and guiding the design of future high-entropy materials. Entropy-stabilized rocksalt-type (Mg0.2Co0.2Mn0.2Ni0.2Zn0.2)O oxides exhibit excellent properties, positioning them as promising candidates for lithium-ion batteries (LIBs) anode materials.

Bionic Capsule Lithium-Ion Battery Anodes for Efficiently Inhibiting Volume Expansion.

Magnetite (Fe3O4) has a large theoretical reversible capacity and rich Earth abundance, making it a promising anode material for LIBs. However, it suffers from drastic volume changes during the lithiation process, which lead to poor cycle stability and low-rate performance. Hence, there is an urgent need for a solution to address the issue of volume expansion. Taking inspiration from how glycophyte cells mitigate excessive water uptake/loss through their cell wall to preserve the structural integrity of cells, we designed Fe3O4@PMMA multi-core capsules by microemulsion polymerization as a kind of anode materials, also proposed a new evaluation method for real-time repair effect of the battery capacity. The Fe3O4@PMMA anode shows a high reversible specific capacity (858.0 mAh g-1 at 0.1 C after 300 cycles) and an excellent cycle stability (450.99 mAh g-1 at 0.5 C after 450 cycles). Furthermore, the LiNi0.8Co0.1Mn0.1O2/Fe3O4@PMMA pouch cells exhibit a stable capacity (200.6 mAh) and high-capacity retention rate (95.5 %) after 450 cycles at 0.5 C. Compared to the original battery, the capacity repair rate of this battery is as high as 93.4 %. This kind of bionic capsules provide an innovative solution for improving the electrochemical performance of Fe3O4 anodes to promote their industrial applications.