Advanced Lithium-ion Batteries Research Articles

Fluorine-Doping Carbon-Modified Si/SiOx to Effectively Achieve High-Performance Anode.

To address the significant challenges encountered by silicon-based anodes in high-performance lithium-ion batteries (LIBs), including poor cycling stability, low initial coulombic efficiency (ICE), and insufficient interface compatibility, this work innovatively prepares high-performance Si/SiOx@F-C composites via in situ coating fluorine-doping carbon layer on Si/SiOx surface through high-temperature pyrolysis. The Si/SiOx@F-C electrodes exhibit superior LIB performance with a high ICE of 79%, exceeding the 71% and 43% demonstrated by Si/SiOx@C and Si/SiOx, respectively. These electrodes also show excellent rate performance, maintaining a capacity of 603 mAhg-1 even under a high current density of 5000 mAg-1. Notably, the Si/SiOx@F-C electrode sustains a high reversible capacity of 829 mAh g-1 at 1000mA g-1 over 1400 cycles, and 588 mAhg-1 at 3000 mAg-1 even over 2400 cycles, capacity retention of up to 82.12%. Comprehensive characterization and analysis of the fluorine-doped carbon layer reveal its role in enhancing electrical conductivity and preventing structural degradation of the material. The abundant fluorine in the coating layer significantly increases the LiF concentration in the solid electrolyte interface (SEI) film, improving interfacial compatibility and overall lithium storage performance. This method is both straightforward and effective, providing a promising blueprint for the broader application of Si-based anodes in advanced lithium batteries.

Pre-lithiation synergized with magnesiothermic reduction to enhance the performance of SiO anode for Advanced lithium-ion batteries

Due to its high theoretical specific capacity, micron-sized silicon monoxide (SiO) is regarded as one of the most competitive anode materials for lithium-ion batteries with high specific energy density. However, originating from the low initial Coulombic efficiency (ICE) and large volume expansion, its large-scale application is seriously hindered. Herein, an easy-to-implement solid-state pre-lithiation method synergized with the magnesiothermic reduction process was performed to enhance the ICE of SiO and a common bimetallic hydride was used as a prelithiation reagent. Moreover, the effects of different pre-lithiation reagent amounts on the physical and electrochemical properties of SiOx are investigated. Notably, the SiOx-LA@C composite anchored by in-situ generated LiAl(SiO3)2 shows a more stable microstructure and excellent electrochemical properties, which delivers an ultrahigh ICE of 89.4 % and an excellent initial capacity of 1864.4 mAh g−1. Furthermore, the full cells were successfully assembled by using the prepared anodes, which exhibit relatively stable cycle performance over 150 cycles. This work suggests a safe and feasible route to enhance the ICE of SiOx for the applicable SiO-based anode materials.

Constructing high performance dry-processing oxide composite electrolyte via interfacial interactions for durable solid-state lithium batteries

Composite solid electrolytes (CSEs) have considerable combination properties, which have been considered as the most promising choice for realizing advanced solid-state lithium batteries. Yet the ionic conductivity of CSEs fails to meet the practical requirements. Herein, we develop a dry-processing CSEs based on Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and succinonitrile (SN) through polytetrafluoroethylene fibrillation. On the one hand, SN can enable fast ion transport in ceramic network and serve as high-speed conducive path. On the other hand, the strong affinities of LAGP towards SN and anions can significantly improve the conductive behavior and restrict side reactions at electrolyte/Li interface. Under such regulations, the composite electrolyte exhibits high ionic conductivity (0.64 mS cm−1 at 30 °C), high transference number (0.50), and high oxidation potential (>5.0V vs. Li+/Li). The assembled lithium metal batteries demonstrate excellent stability over 300 cycles at 1.0C. This work demonstrates the ion migration mechanism and the interactions at the heterogeneous interface for SN enhanced CSEs, contributing to the development of durable solid lithium metal batteries with extended lifespan.

Structurally-constrained wrinkled NiO nanomembranes for high-performance lithium and sodium storage

In light of its exceptional capacity and safety features, nickel oxide (NiO) has emerged as a highly promising electrode material for advanced lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), which operate through conversion mechanisms, meeting the growing demand for high-efficiency rechargeable batteries. To address the capacity degradation challenges associated with NiO anodes, we present an innovative approach involving the fabrication of wrinkled NiO nanomembranes through magnetron sputtering deposition followed by thermal treatment. This distinctive three-dimensional, ultra-thin architecture integrates nanostructural and microstructural features that effectively reduce ionic diffusion distances and mitigate dimensional fluctuations during cycling, thereby markedly enhancing the electrochemical performance and reliability. Specifically, for lithium storage, these wrinkled NiO nanomembranes achieve an impressive reversible specific capacity of 773 mA h g−1 at 100 mA g−1, with excellent rate capability of 468 mA h g−1 at 5000 mA g−1 and long-term cycling performance, maintaining 523 mA h g−1 at 500 mA g−1 even after 1000 cycles. Likewise, for sodium storage, they exhibit a substantial reversible capacity of 288 mA h g−1 at 50 mA g−1 and retain 202 mA h g−1 at 200 mA g−1 after 100 cycles. These findings underscore the promising application of wrinkled NiO nanomembranes as robust anodic materials for high-performance LIBs and SIBs.

Defect-Mediated Formation of Oriented Phase Domains in a Lithium-Ion Insertion Electrode.

The performance and robustness of electrodes are closely related to transformation-induced nanoscale structural heterogeneity during (de)lithiation. As a result, it is critical to understand at atomic scale the origin of such structural heterogeneity and ultimately control the transformation microstructure, which remains a formidable task. Here, by performing in situ studies on a model intercalation electrode material, anatase TiO2, we reveal that defects─both preexisting and as-formed during lithiation─can mediate the local anisotropic volume expansion direction, resulting in the formation of multiple differently oriented phase domains and eventually a network structure within the lithiated matrix. Our results indicate that such a mechanism operated by defects, if properly harnessed, could not only improve lithium transport kinetics but also facilitate strain accommodation and mitigate chemomechanical degradation. These findings provide insights into the connection of defects to the robustness and rate performance of electrodes, which help guide the development of advanced lithium-ion batteries via defect engineering.

Fully sp2 Carbon-Conjugated Covalent Organic Frameworks with Multiple Active Sites for Advanced Lithium-Ion Battery Cathodes.

Covalent organic frameworks (COFs) hold great promise for rechargeable batteries. However, the synthesis of COFs with abundant active sites, excellent stability, and increased conductivity remains a challenge. Here, chemically stable fully sp2 carbon-conjugated COFs (sp2c-COFs) with multiple active sites are designed by the polymerization of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde) (BTT) and s-indacene-1,3,5,7(2H,6H)-tetrone (ICTO) (denoted as BTT-ICTO). The morphology and structure of the COF are precisely regulated from "butterfly-shaped" to "cable-like" through an in situ controllable growth strategy, significantly promoting the exposure and utilization of active sites. When the unique "cable-like" BTT-ICTO@CNT is employed as lithium-ion batteries (LIBs) cathode, it exhibits exceptional capacity (396 mAh g-1 at 0.1 A g-1 with 97.9 % active sites utilization rate), superb rate capacity (227 mAh g-1 at 5.0 A g-1), and excellent cycling performance (184 mAh g-1 over 8000 cycles at 2.0 A g-1 with 0.00365 % decay rate per cycle). The lithium storage mechanism of BTT-ICTO is exhaustively revealed by in situ Fourier transform infrared, in situ Raman, and density functional theory calculations. This work provides in-depth insights into fully sp2c-COFs with multiple active sites for high-performance LIBs.

Understanding the impact of porosity on Li-ion diffusion enhancement in micro-sized silicon particles for advanced batteries

Lithium-ion batteries (LIBs) require advanced and practical anode materials, such as porous silicon (PSi), which can meet these expectations due to their rapid Li-ion diffusion rates and structural relaxation. Several studies have focused on the structural design of PSi or its composites to improve Li-ion diffusion; however, no systematic and quantitative evaluations of the impact of porosity on Li-ion diffusion and battery performance have been reported. Therefore, to understand the impact of porosity on Li-ion diffusion, we developed micro-sized porous silicon (m-PSi) particles with various porosities via metal-assisted chemical etching (MACE) method using different concentrations of AgNO3 (0.02–0.08 M). Among the as-prepared samples, m-PSi-0.06 (prepared using 0.06 M AgNO3) with ∼70 % porosity achieved a maximum Li-ion diffusion rate of 2.35 × 10−9 cm2 s−1. This led to a high-rate capability, enhanced Li-ion storage, and better cyclic retention of 61.4 % compared to the non-porous micro-sized Si (m-Si) (5.8 %) sample at a current density of 0.1 A g−1. Furthermore, the optimal porosity of m-PSi-0.06 resulted in an impressive rate capability of 760 mAh g−1 at a high current density of 4 A g−1 with a recovery rate of 80 %. The improved efficiency of m-PSi-0.06 is attributed to its optimized mesoporosity, which ensures sufficient space for Li-ion storage and shortens the effective transmission path to accelerate Li-ion diffusion. Moreover, the mesopores provide a greater number of active sites for the reversible adsorption of Li ions, thereby improving the capacitive behavior of the anode. In contrast, the highly nanoporous m-PSi-0.08, with a pore diameter of 1–3 nm, impeded Li-ion movement and restricted diffusion. These results reveal that a high nano porosity hinders Li-ion diffusion, whereas an optimal mesoporosity ensures swift diffusion in m-PSi anodes. These insights could guide the design of Si-based anode materials for advanced LIBs.

A cubic perovskite fluoride anode with the surface conversion reactions dominated mechanism for advanced lithium-ion batteries.

Perovskite fluorides are attractive anode materials for lithium-ion batteries (LIBs) because of their three-dimensional diffusion channels and robust structures, which is advantageous for the rapid transmission of lithium ions. Unfortunately, the wide band gap results in poor electronic conductivity, which limits their further development and application. Herein, the cubic perovskite iron fluoride (KFeF3, KFF) nanocrystals (~100 nm) are synthesized by a one-step solvothermal strategy. Thanks to the good electrical conductivity of carbon nanotubes (CNTs), the overall electrochemical performance of composite anode material (KFF-CNTs) has been significantly improved. In particular, the KFF-CNTs delives a high specific capacity (363.8 mAh g-1), good rate performance (131.6 mAh g-1 at 3.2 A g-1), and superior cycle stability (500 cycles). Noted that the surface conversion reactions play a dominant role in the electrochemical process of KFF-CNTs, together with the stable octahedral perovskite structure and nanoscale particle sizes achieving high ion diffusion coefficients. Furthermore, the specific lithium storage mechanism of KFF has explored by the distribution of relaxation times (DRT) technology. This work opens up a new way for developing cubic perovskite fluorides as high-capacity and robust anode materials for LIBs.

Roles of MXene-Based Hybrids in Fabricating Flexible Anodes for Advanced Lithium-Ion Batteries: A Mini Review

Roles of MXene-Based Hybrids in Fabricating Flexible Anodes for Advanced Lithium-Ion Batteries: A Mini Review

Construction of ternary Sn/SnO2/nitrogen-doped carbon superstructures as anodes for advanced lithium-ion batteries

Construction of ternary Sn/SnO2/nitrogen-doped carbon superstructures as anodes for advanced lithium-ion batteries

Lithium-Rich Porous Aromatic Framework Doped Quasi-Solid Polymer Electrolyte for Lithium Battery with High Cycling Stability.

Lithium-ion batteries (LIBs) have revolutionized the energy storage landscape and are the preferred power source for various applications, ranging from portable electronics to electric vehicles. The constant drive and growth in battery research and development aim to enhance their performance, energy density, and safety. Advanced lithium batteries (LIBs) are considered to be the most promising electrochemical storage devices, which can provide high specific energy, volumetric energy density, and power density. However, the trade-off between ionic conductivity and cycling stability is still a major contradiction for SPEs. In this work, a novel hydroxylated PAF-1 was designed and synthesized through post-modification, and the lithium-rich single-ion porous aromatic framework PAF-1-OLi was thereafter prepared by lithiation, achieved with a specific surface area to be 155 m2 g-1 and a lithium content of 2.01 mmol g-1. PAF-1-OLi, lithium bis(trifluoromethanesulfony)limine (LiTFSI), and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) were compounded to obtain PAF-1-OLi/PVDF by solution casting, which had good mechanical, thermodynamic, and electrochemical properties. The ion conductivity of PAF-1-OLi/PVDF infiltrated with plasticizer was 2.93 × 10-4 S cm-1 at 25 °C. The tLi+ was 0.77, which was much higher than that of the traditional dual-ion polymer electrolytes. The electrochemical window of PAF-1-OLi/PVDF can reach 4.9 V. The Li//PAF-1-OLi/PVDF//LiFePO4 battery initial discharge specific capacity was 147 mAh g-1 and reached 134.9 mAh g-1 after 600 cycles with a capacity retention rate of 91.2%, demonstrating its good cycling stability. The anionic part of lithium salt was fixed on the framework of PAF-1 to increase the Li+ transfer number of PAF-1-OLi/PVDF. The lithium-rich PAF-1-OLi and the LiTFSI provided abundant Li+ sources to transfer, while PAF-1-OLi helped to form a continuous Li+ transport channel, effectively promoting the migration of Li+ in the PAF-1-OLi/PVDF and effectively improving the Li+ conductivity. This study afforded a novel polymer electrolyte based on lithium-rich PAF-1-OLi, which has excellent electrochemical performance, providing a new choice for the polymer electrolyte of lithium batteries.

Electrochemical-mechanical coupled lithium growth in fiber-structured electrodes

Lithium plating (stripping) on the electrode surface and embedding inside the electrode occur simultaneously in lithium-ion batteries during fast (dis)charging, which involves both deposition and diffusion mechanisms. The paper presents a developed finite-element procedure that accommodates these two mechanisms, facilitating the modeling of the (dis)charging process in electrodes. The framework, which integrates interface electrochemical reaction kinetics, electrochemical-mechanical coupling, comprehensive constitutive models for silicon/graphite/lithium, and a surface growth re-meshing algorithm, is capable of real-time simulation of the surface deposition and coupled diffusion-deformation processes on the electrode substrate. We examined the effects of charging rate, diffusion rate and volumetric expansion on the stress of the plated lithium layer in a fiber-structured electrode. By accounting for creep in lithium metal and subsequent stress relaxation, we obtained time-dependent stress profiles in the plated lithium layer. As an application, we quantified electroplating stresses in both fiber-structured graphite and silicon electrodes. Taking the silicon electrode as a model case, we demonstrate that hollow fiber structural electrodes can also alleviate the stress in the surface lithium-plating layer. The numerical framework may be further applied to explorations for the optimization of electrode structures in advanced high performance lithium-ion batteries.

Designing Novel Solvents for High Voltage Li-Ion Batteries

The pursuit of higher energy density in lithium-ion batteries has led to the development of new cathode materials that can operate at elevated voltages and provide increased specific capacities. [1-2] One such class of materials is the nickel-rich layered oxide cathodes known as LiNixMnyCozO2 (NMC). These cathodes offer high specific capacities and demonstrate electrochemical stability at high cutoff voltages, making them promising candidates for advanced lithium-ion batteries. [3-4] However, NMC cathodes face a significant challenge in the form of capacity fading during cycling. This issue primarily arises from the voltage instability of the conventional carbonate-based electrolytes used in lithium-ion batteries, which are typically designed for the 4-V lithium-ion chemistry. [5-6] As a result, researchers and scientists have directed extensive efforts toward developing new and improved electrolyte systems that can withstand the high voltage requirements of NMC cathodes and other high-energy applications. [7-8]Designing and synthesizing new molecules for use as electrolyte solvents in lithium-ion batteries is indeed a complex and challenging task. Researchers often focus on optimizing one specific property, which can lead to the development of molecules that excel in that aspect while potentially overlooking other crucial features that are necessary for stable battery cycling. For example, the development of α-fluorinated sulfones as electrolyte solvents was driven by their exceptional anodic stability. [9] This stability is achieved by introducing strong electron-withdrawing trifluoromethyl groups directly attached to the sulfonyl group. However, while this electron-withdrawing effect enhances anodic stability, it can also significantly increase the reduction potential of α-fluorinated sulfones. This heightened reduction potential renders them unstable when used with graphite anodes, highlighting the delicate balance required in designing electrolyte solvents that perform well across various aspects of battery operation.In this presentation, we embraced the concept of a "golden middle way" when designing and synthesizing new electrolyte solvents. The recently developed β-fluorinated sulfone, TFPMS, doesn't claim to be the best in any single property, but it strikes a balance across various key characteristics. This equilibrium has proven to be highly effective in ensuring the long-term stability of high-voltage graphite||NMC622 full cells. Positioned at the β site of the sulfone molecule, the strong electron-withdrawing trifluoromethyl group renders β-fluorinated sulfone sufficiently stable against the high-voltage NMC622 cathode, even if it possesses a slightly lower oxidation potential compared to its α-fluorinated counterparts. Furthermore, its reduction potential is lower than that of α-fluorinated sulfone, making it considerably more stable when paired with the graphite anode. While it may not possess the same high lithium solvating power as the typical sulfone (EMS), the lithium solvating capacity of β-fluorinated sulfone falls somewhere in between, mitigating transition metal dissolution and deposition in the graphite||NMC622 full cell that utilizes a β-fluorinated sulfone-based electrolyte. As a result, the full cell equipped with TFPMS-based electrolyte demonstrates superior cycling performance, with a significantly higher average capacity than cells using regular sulfone or α-fluorinated sulfone-based electrolytes. In summary, our approach exemplifies the successful application of the "golden middle way" in designing and synthesizing new electrolyte solvents.Reference: Santhanam, R.; Rambabu, B., Power Sources 2010, 195, 5442.Lin, F.; Markus, I. M.; Nordlund, D.; Weng, T.-C.; Asta, M. D.; Xin, H. L.; Doeff, M. M., Commun. 2014, 5, 3529.Li, W.; Song, B.; Manthiram, A., Chemical Society Reviews 2017, 46 (10), 3006.Xu, J.; Lin, F.; Doeff, M. M.; Tong, W., Journal of Materials Chemistry A 2017, 5 (3), 874.Xia, J.; Petibon, R.; Xiong, D.; Ma, L.; Dahn, J., Journal of Power Sources 2016, 328, 124.Chen, S.; Wen, K.; Fan, J.; Bando, Y.; Golberg, D., Journal of Materials Chemistry A 2018, 6 (25), 11631.Zheng, J.; Lochala, J. A.; Kwok, A.; Deng, Z. D.; Xiao, J., Advanced Science 2017, 4 (8), 1700032.Yamada, Y.; Wang, J.; Ko, S.; Watanabe, E.; Yamada, A., Nature Energy 2019, 4 (4), 269.Su, C.-C.; He, M.; Redfern, P. C.; Curtiss, L. A.; Shkrob, I. A.; Zhang, Z., Environ. Sci. 2017, 10 (4), 900.

Study and Optimization of the Formation Step of Next Generation Li-Ion Cells Using Design of Experiments (DOE) Methodology

The importance of the formation step in the Li-ion cell assembly process is often underestimated both in terms of economic impact due to its elevated cost [1] (Left Figure 1, with more than one third of cell finishing cost), but also in terms of electrochemical performance influence mainly driven by the Solid-Electrolyte-Interphase (SEI) formation during this first charge of the Li-Ion cell after its activation by electrolyte [2].In this study concerning the optimization of the formation step, we will use the design of experiments (DOE) methodology as this approach is a powerful tool that allows evaluating the effect of numerous parameters (including their linear, quadratic or interaction terms) on selected responses of interest with a limited number of trials when the experimental resources (including testing time, number of cells...) are limited.The formation step is generally divided in several sub-steps that includes many parameters [3,4] with some of them illustrated on the right figure 1: different current densities during the successive constant current steps, the different temperatures associated for each of these sub-steps that can also be of different durations and/or associated with limitations in states of charge. Additionally, specific electrolyte additives maybe used to improve the efficiency and quality of the formation step especially to modify the chemistry of the SEI....In our case, we present here a first approach using a screening design that is a specific type of DOE particularly adapted when the number of factors is elevated. Screening designs especially allow precising the first order input factors on the selected responses of interest, in our case Initial Coulombic Effciciency (ICE), resistance, discharge capacity; cyclability...The experimental data are generated thanks to the use of industrial dry (i.e. unactivated) NMC532/Graphite pouch-cells of 0.435 Ah. These dry cells allowed us including electrolyte factors in the DOE. Considering 8 different factors, a total of 17 trials were defined in the DOE that was set with MINITAB software. The full analysis of the DOE will be presented with the main effects for each response combined with the Pareto diagrams. These results will give general trends to define better conditions for the formation step and improve the cell performances.In a next step, we plan to pursue this approach with a surface response design on the selected first order factors, to enable a quantification of the performances and an optimization of the formation step. The study will also be completed by post-mortem analysis such as XPS studies to better correlate the formation step parameters with the SEI characteristics (chemistry, thickness...). Boston Consulting Report (2018). E Peled, S. Menkin. SEI: Past, Present and Future. Electrochem. Soc. 164 (7), 2017, A1703-C. Chiang, M.-S. Wu, J.-C. Lin. A Novel Dual-Current Formation Process for Advanced Lithium-Ion Batteries. Electrochem. Solid State Letters 8 (8), 2005, A423S. Zhang, K. Xu, T. R. Jow. Optimization of the Forming Conditions of the Solid-State Interface in the Li-Ion Batteries. J. Power Sources 130 (1-2) 2004, 281–285 Figure 1

Scalable Synthesis of Single Crystal Ni-Rich Cathodes for Advanced Lithium-Ion Batteries

Long-range electrical vehicles require high energy density lithium-ion batteries that utilize stable, high-energy cathode materials. Among various cathodes, Ni-rich NMC cathodes with a layered structure, knows for their high capacity, high voltage, and cost-effectiveness, stand out as one of the most promising cathodes. Traditional polycrystalline Ni-rich NMC encounter issues such as pulverization, gas generation and moisture sensitivity, limiting their widespread use in EV batteries on large scale. The single crystal format of Ni-rich cathode can effectively eliminate and mitigate these issues. However, synthesizing of high-performance single crystal Ni rich NMC, especially when Ni ≥0.8, presents a significant challenge.We’ve explored an innovative phase separation approach for direct synthesis of high-performance single crystal NMC811. The comprehensive investigation into the reaction mechanism of single crystal growth was conducted to understand the relationship between synthesis, morphology, and performance in growing single crystal NMC811. The enhanced performance of these materials was realized through the precise morphological and structural control of precursors and has been confirmed in practical 2Ah pouch cells. The developed approach is readily adaptable to current industry manufacturing processes and provides valuable new insights that can be broadly applied to cost-efficient large-scale synthesis of single crystals and various advanced battery materials technologies.

Exploring the Impact of Oxygen Doping in Li2FeS2 Cathode Materials for Li-Ion Batteries

Over the past few decades, rechargeable lithium-ion batteries have become popular for a variety of applications, such as electric vehicles, smart grids, and portable energy devices. However, due to their limited capacity, stability, and lifespan, they are not suitable for advanced transportation applications. To overcome these challenges, researchers have investigated the use of low-cost, high-energy-density, and safe positive electrode materials for secondary lithium batteries, including lithium iron sulfide. In this particular study, our focus is to investigate the effect of highly electronegative anion doping on the properties of lithium iron sulfide cathode through the solid-state method. Our approach involves using both in-situ and ex-situ observations to establish a correlation between the Redox behavior and structural properties of the prepared cathode materials. We have designed and characterized the material using various techniques, such as X-ray absorption spectroscopy (XAS) and synchrotron-based X-ray diffraction (XRD). Scanning electron microscope (SEM) measurement was conducted to study the morphology of the cathode material. Transmission electron microscopy (TEM) was employed to further study the microstructure of the cathode material at an atomic level. We analyzed the electron density distribution of the modified cathode material using XANES measurement and studied the structural properties through synchrotron-based XRD. Our study has revealed that oxygen-doping helps to improve material stability. As a result, the modified cathode (with optimal oxygen doping) exhibited a 50% capacity enhancement compared to pristine after 100 cycles. We also observed a shift to a higher voltage oxidation plateau of the oxygen-doped cathode material which is due to the influence of anion substitution on the electrochemistry and charge storage mechanisms. In summary, our detailed characterization and experimental results demonstrate the potential of oxygen-doped Li2FeS2 as a promising cathode material for advanced lithium-ion battery applications. The study's detailed characterization and experimental results will be presented, along with future perspectives.

High-Valence Ion Doped Compositionally Partitioned Li[Ni0.78Co0.10Mn0.12]O2 Cathode for Advanced Lithium-Ion Batteries

Numerous approaches have been employed to reduce the intrinsic instability of Ni-rich cathodes. Among them, the introduction of concentration gradient (CG), i.e., a strategy to protect the labile Ni-enriched compartment with a chemically protective Mn-rich shell, has proven successful in commercial applications.1 However, because the segmentation of transition metal (TM) constituents and the formation of unique geometric configurations are characteristics inherited from the CG hydroxide precursor; it is crucial to select the optimal calcination temperature and precisely control it.2 Excessive thermal energy input can result in concentration planarization because the CG of the hydroxide precursor is intrinsically susceptible to the interdiffusion of TM elements during lithiation. Moreover, the immoderate coarsening of the primary particles can eliminate the advantageous features of the CG design by producing equiaxed primary particles.2 In this study, we propose a strategy that can effectively ameliorate the deterioration of Ni-rich CG cathodes resulting from excessive thermal energy input and remarkably improve their electrochemical cycling performance. It was revealed that a trace amount of tungsten incorporation during the cathode calcination can effectively mitigate the high-temperature-induced cathode degeneration and maintain outstanding product quality over a wide range of temperatures. Thus, the proposed strategy opens new avenues for the facile synthesis of long-life Ni-rich CG cathodes. Reference s : [1] Y.-K. Sun, S.-T. Myung, B.-C. Park, J. Prakash, I. Belharouak, K. Amine, Nat. Mater. 8 (2009) 320-324.[2] G.-T. Park, H.-H. Ryu, T.-C. Noh, G.-C. Kang, Y.-K. Sun, Mater. Today 52 (2022) 9-18.

Batch-Scale Synthesis and Interfacially Enhanced Stability of Silicon Suboxide-Based Anodes toward High-Performance Lithium-Ion Batteries.

SiOx anode materials are among the most promising candidates for next-generation high-energy-density lithium-ion batteries (LIBs). However, their commercial application is hindered by poor conductivity, low initial Coulombic efficiency (ICE), and an unstable solid electrolyte interface. Developing cost-effective SiOx anodes with high electrochemical performance is crucial for advanced LIBs. To tackle these issues, this study utilized APTES as a silicon source and carbon nanotubes (CNTs) as additives to prepare a T-SiOx/C/CNTs composite material with N doping and in situ carbon coating using a "molecular assembly combined with controlled pyrolysis" strategy under mild conditions. The in situ carbon coating, formed by the pyrolysis of organic groups on the molecular precursor, effectively protects the inner SiOx active material. The introduced CNTs enhance electron migration and improve the rigidity of the carbon coating layer. The prelithiated T-SiOx@C/CNTs electrode achieves an ICE of 91.6%, with a specific capacity of 622 mAh g-1 after 400 cycles at 1 A g-1 and 475.8 mAh g-1 after 800 cycles. Full cell tests with commercial NCM811 cathodes further demonstrate the potential of T-SiOx@C/CNTs as a highly promising anode material. This work provides some insights into the rational design of advanced anode materials for LIBs, paving the way for their future development and application.

Novel anatase-rutile TiO2 dual-phase coupling with NiS2 nanoparticles wrapped in carbon nanotubes for enhanced lithium ion storage

As a promising anode with non-obvious volume change during the intercalation/extraction of Li+ for advanced lithium-ion batteries (LIBs), the application of TiO2 is hindered by the poor electronic/ionic conductivity. Herein, a coherent strategy is carried out to obtain anatase-rutile TiO2 dual-phase composited with NiS2 nanoparticles confined in carbon nanotubes (A/R-TiO2/NiS2/CNTs) derived from Ti-MOF. The inclusion of NiS2 can significantly enhance the capacity of the composite. Simultaneously, the biphasic anatase-rutile TiO2 can induce plenty of oxygen vacancies to expedite the diffusion of lithium ions. The transfer of electrons can be accelerated by the surrounding carbon nanotubes with outstanding conductivity, which also enhance the structural stability of the whole composite. Thanks to the above appealing properties, the A/R-TiO2/NiS2/CNTs electrode delivers excellent rate capacity of 707.4 mA h g−1 at 0.1 A g−1 and 131.9 mA h g−1 at 5 A g−1 and displays 401.5 mA h g−1 at 0.5 A g−1 after 600 cycles.

Effect of Zr–Y Double Doping and Al2O3 Coating on Properties of Nickel-Rich Monomer LiNi0.6Co0.2Mn0.2O2 Cathode Material for Li-Ion Batteries

Among the cathode materials for advanced lithium-ion batteries, Nickel-rich single crystalline LiNixCoyMn1–x–yO2(NCM) attracts great interest as promising materials owing to their excellent properties, such as superior energy density, high voltage platform, and low cost. However, Nickel-rich single NCM has insufficient cycle stability and cannot meet the demand for the high-rate capacity, which limits its application in EV and HEV. This work applied the strategies of Zr–Y dual doping and Al2O3 coating to improve the electrochemical performance of single crystalline NCM622 cathode. A series of single crystalline LiNi0.6Co0.2Mn0.2O2(NCM622), Zr–Y doped single crystalline NCM622, Al2O3-coated single crystalline NCM622 and Al2O3-coated Zr–Y dual-doped single crystalline NCM622 cathode materials were synthesized through the same roasting process. The Zr–Y double-doped single crystalline NCM622 material shows that Zr–Y ions are successfully doped into the lattice structure, with remarkable 0.1 C, 0.5 C, and 1 C discharge capacities 195.89 mAh·g−1, 181.77 mAh·g−1, and 174.82 mAh·g−1, respectively. The Al2O3 coated Zr–Y dual-doped single crystalline NCM622 materials show that Al2O3 particles are uniformly dispersed and attached to the surface of the coated samples, with cycling performance with retention achieving 98.84% after 50 cycles at 1 C.