Cathode Materials For Li-ion Batteries Research Articles

Critical Barriers to Successful Implementation of Earth-Abundant, Mn-Rich Cathodes: Low SOC Impedance

The ever-growing demand for electric vehicles and grid storage systems has pushed the development of sustainable cathode materials for Li-ion batteries. Lithium- and manganese-rich (LMR) oxides are a promising class of cathode materials in this regard because of their high capacities/energies and reliance on low-cost, earth-abundant manganese (>50%). However, several outstanding issues remain that hinder the performance of these cathodes. While the mechanisms of the now well-known phenomena of voltage fade, hysteresis, and oxygen activity have been intensively studied, relatively little attention has been given to understanding the impedance characteristics of LMR electrodes. Specifically, the anomalous rise in area specific impedance (ASI) at low states-of-charge (SOCs), and the overall impedance rise on extended cycling due to surface issues, are critical barriers to implementation that still need to be further understood and mitigated.This presentation will discuss a comprehensive study at Argonne National Laboratory on understanding impedance behavior in cobalt-free, LMR cathode-electrodes. In this study, we use a unique surface-treatment/electrolyte-additive combination that allows us to separate the major contributions of bulk and surface to the impedance behavior over long-term cycling. The results indicate that the anomalous rise in impedance at lower SOCs is directly associated with the correlated, bulk processes of voltage fade and voltage hysteresis. A conceptual model is presented to understand the impedance behavior of these complex materials.

Dialing in the Voltage Window: Reconciling Interfacial Degradation and Cycling Performance Decay with Cation-Disordered Rocksalt Cathodes

Lithium-excess, cation-disordered rocksalt (DRX) materials have received considerable interest as cathode materials for Li-ion batteries, owing to their high specific capacity and compositional flexibility. Despite these advantages, high interfacial reactivity of DRX materials causes extensive oxidative electrolyte degradation at the cathode-electrolyte interface. In addition to consuming electrolyte, this interfacial degradation is likely to lead to a cascade of deleterious effects throughout the cell, as reactive degradation products drive secondary degradation processes like dissolution of transition metals and decomposition of passivating interfacial species. While in-situ gas evolution measurements conducted by differential electrochemical mass spectrometry (DEMS) allow for the observation and quantification of the degradation processes occurring at the DRX surface, the customized cell configuration with which the technique is conducted is not well suited for capturing the performance decay driven by the interfacial degradation. In particular, a large excess of electrolyte and a large Li metal counter-electrode, both of which are necessary features of DEMS cells, serve to mask the deleterious effects of the interfacial degradation on electrochemical performance. In this work, we reconcile the degradation observed by DEMS with performance decay measured by extended cycling experiments in electrolyte-lean full cells. By comparing DRX outgassing and cycling performance in different voltage windows, we demonstrate a positive correlation between the extent of outgassing and the rate of DRX performance decay during cycling. This result provides a crucial link between the degradation measured by techniques like DEMS and the performance decay measured by cycling experiments, and it allows for the fine-tuning of a cycling voltage window which optimizes the tradeoff between initial performance and long-term stability. Furthermore, this work emphasizes the importance of cell design features, like electrolyte volume and counter-electrode material, and their impact on different electrochemical experiments.

Uncovering the Mysterious Transformations during Cycling in Li-Ni-Mn-O Cathode Materials

Layered transition metal oxides, specifically LiNixMnyCozO2, lead the market for Li-ion battery cathode materials. Cobalt is a problematic metal to include in such a high-volume product like Li-ion batteries, as it is expensive, and it is mined using unethical practices. Contemporary electrodes use metal compositions with < 0.33 Co. However, even as the least abundant element in the material, eliminating Co entirely remains an important objective, but is so far necessary as it increases material stability leading to improved cycle life. Thus, research has been active in the Li-Ni-Mn-O system, looking for potential replacements for Co-containing layered oxides. The Li-Ni-Mn-O pseudo ternary system has been investigated in the past decade, revealing some interesting materials. Several compositions (including Li0.568Ni0.073Mn0.359O2 studied here) have been uncovered that show anomalous increasing capacity while cycling over 100 cycles, with some materials reaching 300 % capacity compared to their first cycle.1 It has been hypothesized that this is due to a phase transition occurring in the material, but to date the precise mechanism remains elusive. Other materials (including Li0.586Ni0.071Mn0.343O2 studied here), though very near to these compositions, show relatively stable capacities but dramatic voltage fade.2 In both materials, structural transformations are clearly at play during extended cycling. This work leverages X-ray absorption spectroscopy (XANES/EXAFS) and X-ray photoemission spectroscopy (XPS) to uncover the subtleties in the local environments of Ni and Mn before, during, and after cycling. XANES/XPS reveal to what extent there is a contrast between the oxidation states of the Ni/Mn cations at the surface vs. the bulk of the particles, which has been shown to be important in Ni containing cathodes.3 Interestingly, in both materials, no important changes are seen in the X-ray diffraction patterns, while the pair distribution functions from EXAFS evolve dramatically as shown in the figure here for the Ni environment. Interestingly, the material that shows capacity growth shows a less reversible , while there is no significant difference in the Mn site between the materials before and after charging. Analysis of the final structures shows conversion towards spinel-like structures in both cases, despite the dramatic differences in progression of the capacities, hinting that the spinel-like phases can behave very differently depending on composition. Figure 1

Lessons Using an Electrochemical Method to Produce Lithium Manganese Oxide Cathodes for Lithium-Ion Batteries

Lithium manganese oxide (LMO) has been a well-studied Li-ion battery cathode material for for many years. It offers high thermal stability for high-temperature battery applications and a prolonged cycle life compared to other materials. LMO also has an acceptably high energy density from a naturally abundant, inexpensive, and environmentally benign material, i.e. manganese (Mn). The cathodes for LIBs are conventionally synthesized via solid-state reaction techniques, which require harsh and complex conditions including high temperature (> 700oC) and high pressure. The resulting powders are incorporated into a slurry that is cast onto a current collector using a binder, additives, and solvent. Though this results in high-performing electrodes, it also usually increases the production cost. Another approach that is gaining traction to make LMOs is electrodeposition. Electrodeposition can allow for the direct synthesis of the active material on the current collector without using any binder or additives. Using electrodeposition not only could eliminate the mass and volume of inactive material but also reduce the cost of electrode fabrication. It also can facilitate recycling by depositing the active material from lower purity, material-digested streams.A few reports in the literature have discussed the electrochemical preparation of LMO cathode from the following steps: electrodeposition of manganese oxide (s) (MnxOy) onto a substrate followed by chemical lithiation and heat treatment of MnxOy [1,2]. Although a few reports showed the active materials with reasonable capacity, it is presently unknown what LiMnxOy phase or phases are active and which MnxOy is responsible. However, without sufficient physicochemical investigation, multiple works have postulated that the LMO is created from crystalline MnO2 or Mn3O4. It is also not known what the typical active phase yield is or what physical structures or conditions are responsible for increased capacity. If electrodeposition-to-LMO is to become a viable commercial pathway, a rational understanding of the solid-state chemistry for the LMO formation is needed.This talk will discuss the deposition and lithiation of multiple manganese oxide phases – linking the chemistry and morphology of the surface features to their charge/discharge properties. It will be shown that traditional crystalline phases are not responsible for the formation of LMOs. It will also be shown that the LMOs do not fully delithiate during charging. Lastly, the precise morphology of the active phase – separated out through new processing approaches – will be identified. The composition, structure, and crystallinity of the Mn oxides and LMOs were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The resulting LMO electrodes were incorporated into coin cells, cycled – achieving a capacity of 261 mAh g-1, and post-characterized.References J. Rana, M. Stan, R. Kloepsch, J. Li, G. Schumacher, E. Welter, I. Zizak, J. Banhart, and M. Winter, Adv. Energy Mater., 4, 1300998 (2014).Z. Quan, S. Ohguchi, M. Kawase, H. Tanimura, and N. Sonoyama, J. Power Sources, 244, 375 (2013).

Tailored Deep Eutectic Solvents for Effective Leaching and Electrochemical Recovery of Spent Li-Ion Battery Cathode Materials

The increase in demand for Lithium-ion battery (LIB) raw materials such as cobalt, nickel and lithium are expected to exacerbate exploitative resource extraction and have negative geopolitical implications. A solution to ameliorate this issue is to recycle LIBs. Unfortunately, the existing LIB recycling market is dominated by energy inefficient and environmentally harmful processes such as pyrometallurgy and hydrometallurgy which produce products that require further processing before downstream use. Deep Eutectic Solvents (DESes) are a class of compounds that are formed by mixing hydrogen bond donors and acceptors and exhibit high capability for dissolving metal oxides. In this work, we tailored the electrochemical stability window of selected, high leaching efficiency DESes by incorporating additives (such as ammonium salts and glymes), thereby expanding their electrochemical window and gaining the ability to electrochemical plate out dissolved metals from the DES in addition to facilitating leaching at high recovery rates. The electrochemical window of our baseline DES, the extensively studied system consisting of choline chloride and ethylene glycol (ChCl: EG), is ca 1-3 V (vs AgCl). This system can be tailored with additives to yield DESes with extended electrochemical stability window of ca 4-5 V (vs AgCl) while retaining its excellent leaching. The ability of this class of DESes to efficiently leach metals from LiCoO2 (LCO) and LiMnxNiyCo(1-x+y)O2 (LMNCO) cathodes and corresponding leaching efficiencies for Li, Co, Mn and Ni was examined over a range of temperatures and by subjecting the mixture to microwave or sonication in addition to (or in lieu of) heating. Selective tailored DES were shortlisted depending on the high leaching efficiency and leached elements were electrochemically recovered. The microstructure of the electrodeposited material was examined using x-ray diffraction and scanning electron microscopy for phase identification, purity, and stability of the individual elements. Keywords: LIB, Cathode, Electrodeposition, Leaching, Sonication, DES Figure 1. Effect of additives on the electrochemical window of a ChCl:EG DES (left); Photograph of leach liquors of different cathode materials (LCO, LNO, LMO and LNMCO from left to right) dissolved in selected DES (right) Figure 1

Synthesis and characterization of the LiFePO4 cathode material for Li-ion batteries from Li2CO3 obtained from the brine of the Salar de Uyuni

Synthesis and characterization of the LiFePO₄ cathode material for Li-ion batteries from Li₂CO₃ obtained from the brine of the Salar de Uyuni

Rational construction of graphitic carbon nitride composited Li-rich Mn-based oxide cathode materials toward high-performance Li-ion battery

Li-rich Mn-based oxides (LRMOs) are considered as one of the most-promising cathode materials for next generation Li-ion batteries (LIBs) because of their high energy density. Nevertheless, the intrinsic shortcomings, such as the low first coulomb efficiency, severe capacity/voltage fade, and poor rate performance seriously limit its commercial application in the future. In this work, we construct successfully g-C3N4 coating layer to modify Li1.2Mn0.54Ni0.13Co0.13O2 (LMNC) via a facile solution. The g-C3N4 layer can alleviate the side-reaction between electrolyte and LMNC materials, and improve electronic conduction of LMNC. In addition, the g-C3N4 layer can suppress the collapse of structure and improve cyclic stability of LMNC materials. Consequently, g-C3N4 (4 wt%)-coated LMNC sample shows the highest initial coulomb efficiency (78.5%), the highest capacity retention ratio (78.8%) and the slightest voltage decay (0.48 V) after 300 loops. Besides, it also can provide high reversible capacity of about 300 and 93 mAh g−1 at 0.1 and 10C, respectively. This work proposes a novel approach to achieve next-generation high-energy density cathode materials, and g-C3N4 (4 wt%)-coated LMNC shows an enormous potential as the cathode materials for next generation LIBs with excellent performance.

First-Principles Investigation on Delithiation Mechanisms in a Li-Rich Monoclinic Li2MoO3 Cathode Material for Li-Ion Batteries.

Li2MoO3 is a promising cathode material for high-capacity Li-ion batteries. However, during cycling, migration of Mo to Li sites results in capacity fading. The present study analyzed structural, electronic, electrochemical, and mechanical characteristics of ordered monoclinic C2/m-Li2MoO3 and found that this phase has improved electrochemical properties compared to the rhombohedral R3̅m phase. Nudged elastic band calculations showed that Mo migration to the Li site is less probable in C2/m-Li2MoO3. The charge and chemical bonding analyses during delithiation showed Mo4+/Mo6+ oxidation and partial oxygen oxidation, but no spontaneous oxygen release occurred. The voltage profile calculated using the SCAN + U method exhibits high voltage, and partial W substitution at Mo sites suppresses intralayer Mo migration to the Li site and improves the voltage characteristics. These findings suggest that monoclinic Li2MoO3 is a potential cathode material for high-capacity Li-ion batteries with reduced Mo migration and maintained Mo4+/Mo6+ oxidation and oxygen stability. Moreover, partial W substitution at Mo sites further enhances the electrochemical properties of C2/m-Li2MoO3.

Application of rare earth elements as modifiers for Ni-rich cathode materials for Li-ion batteries: a mini review

This mini review article summarizes the recent progress in the modification of Ni-rich cathode materials for Li-ion batteries using rare earth elements. Although layered materials with high nickel content are the most promising cathodes due to their high capacity, the significant chemical, structural and thermal instability considerably hinders their practical application. Overcoming these limitations is possible through morphological or structural modifications based on doping and coating. Numerous reports regarding the use of various elements of the periodic table for this type of modification can be found in the literature. Surprisingly, rare earth elements are the least applied and described in the literature so far, even though they possess all the necessary features qualifying them as effective modifiers of layered cathode materials. This work summarizes the up-to-date publications regarding the application of rare earth elements as a highly prospective group of modifiers for layered Ni-rich cathode materials. These reports provide a better understanding of mechanisms of modification by rare earth elements and their beneficial effects on the electrochemical performance of the studied materials. New prospective strategies for layered cathode materials improvement have also been indicated.

Imaging Li Vacancies in a Li-Ion Battery Cathode Material by Depth Sectioning Multi-slice Electron Ptychographic Reconstructions.

Imaging Li Vacancies in a Li-Ion Battery Cathode Material by Depth Sectioning Multi-slice Electron Ptychographic Reconstructions.

Unveiling the potential of surface–beneath region doping by induced-diffusion in nickel-rich single crystal cathode for high-performance lithium-ion batteries

A critical challenge associated with Ni-rich single-crystal cathode materials is the significant degradation of their structural integrity caused by cation mixing during high-temperature sintering. To address this issue, we propose an effective strategy of uniformly doping Zn ions into the region below the surface of Ni0.90Co0.07Mn0.03OH2 using polyvinyl pyrrolidone. This approach enables the localized concentration of Zn ions in the near-surface region, which can effectively reduce the degree of Li/Ni mixing and improve the surface and thermal stability of the material under high-state-of-charge conditions. We observed that the near-surface region doped sample with 1 wt% Zn (SC-NCM90@Zn1) demonstrated superior rate performance (100.01 mA h g−1 at 10C) and excellent capacity retention (87.71% after 100 cycles) compared with those of Pristine SC-NCM90 (LiNi0.90Co0.07Mn0.03O2). Overall, this study provides a design approach for enhancing the performance of Ni-rich single-crystal cathode materials for Li-ion batteries.

Nanotechnology Applications in Cathode and Anode Materials of Li-Ion Battery

Lithium-ion batteries (LiBs), with their high energy/specific density, extended cycle life, and minimal self-discharge rate, have gained considerable popularity in the manufacturing of portable devices and electric vehicles, where space and weight constraints are of utmost importance. Additionally, LiBs have played a pivotal role in the advancement of electric vehicles, promoting sustainable energy practices, and reducing greenhouse gas emissions. However, the limitations that stem from the inherent structures and properties of the conventional component materials of batteries might pose obstacles to the application and development of LiBs, despite their numerous advantages. Nevertheless, significant strides have been made towards improving the capacity, cycling performance, and rate performance of these batteries using nanotechnology. This approach leverages the outstanding properties of nanomaterials to enhance the electrochemical performance of battery components, such as cathode materials, which includes NMC, NCA, LMO, LFP, and anode materials such as Silicon and LTO. This paper provides a comprehensive discussion of the applications of nanotechnology in lithium-ion batteries, offering insights into the future of this promising field.

Introduction of LFP and Ternary Cathode Materials of Lithium Battery

In recent years, with rapid development of mobile devices and electric vehicles, lithium-ion battery as an efficient and clean battery technology has attracted wide attention. Cathode material of Li ion batteries (LIBs) is the core part that determines the battery performance. This paper aims to review the research status and latest progress of cathode materials for Li ion batteries, analyze their advantages and disadvantages, and discuss their application prospects in batteries. The review includes two kinds of cathode materials which are widely used and have the best performance in commercial uses for now: lithium iron phosphate (LFP) cathode material and ternary cathode material. The structure, properties, synthesis and modification methods are analyzed and summarized. Based on the analysis of the two materials respectively, the influence factors and countermeasures on the capacity, cycling life and safety of cathode materials for LIBs are emphatically discussed, and the future development is prospected, too.

Characterization of garnet-type Li6SrLa2Bi2O12 ceramic electrolyte for all-solid-state Li-ion batteries

We investigated electrochemical properties of garnet-type Li6SrLa2Bi2O12 (LSLBO) ceramic electrolyte for all-solid-state Li-ion batteries. Hot pressing at 750 °C was applied for the densification of LSLBO and the relative density of obtained sample reached 94 %. Hot-pressed LSLBO showed bulk and total ionic conductivity of 1.8 × 10−4 S cm−1 and 1.1 × 10−4 S cm−1, which is much higher than sintered LSLBO by a conventional furnace sintering and spark plasma sintering reported in previous works. Cyclic voltammogram of LSLBO showed the electrochemical stability at the operating potential for most cathode materials for Li-ion batteries. It was found that LSLBO has a certain degree of thermal compatibility with LiCoO2 cathode up to about 700 °C. The obtained results indicates the possibility of LSLBO for the application to catholyte in oxide-based all-solid-state batteries.

Defect Chemistry of Spinel Cathode Materials-A Case Study of Epitaxial LiMn2O4 Thin Films.

Spinels of the general formula Li2-δM2O4 are an essential class of cathode materials for Li-ion batteries, and their optimization in terms of electrode potential, accessible capacity, and charge/discharge kinetics relies on an accurate understanding of the underlying solid-state mass and charge transport processes. In this work, we report a comprehensive impedance study of sputter-deposited epitaxial Li2-δMn2O4 thin films as a function of state-of-charge for almost the entire tetrahedral-site regime (1 ≤ δ ≤ 1.9) and provide a complete set of electrochemical properties, consisting of the charge-transfer resistance, ionic conductivity, volume-specific chemical capacitance, and chemical diffusivity. The obtained properties vary by up to three orders of magnitude and provide essential insights into the point defect concentration dependences of the overall electrode potential. We introduce a defect chemical model based on simple concentration dependences of the Li chemical potential, considering the tetrahedral and octahedral lattice site restrictions defined by the spinel crystal structure. The proposed model is in excellent qualitative and quantitative agreement with the experimental data, excluding the two-phase regime around 4.15 V. It can easily be adapted for other transition metal stoichiometries and doping states and is thus applicable to the defect chemical analysis of all spinel-type cathode materials.

Phenanthrenequinone-Based Linear Polymers as Sustainable Cathode Materials for Rechargeable Li-Ion Batteries

Phenanthrenequinone-Based Linear Polymers as Sustainable Cathode Materials for Rechargeable Li-Ion Batteries

Tailoring the Electrochemical Performance of Olivine Phosphate Cathode Materials for Li-Ion Batteries by Strain Engineering: Computational Experiments

The open-circuit voltage (OCV), Li-ion diffusion, and electronic properties of a cathode material can significantly affect the performance of lithium-ion batteries (LIBs). In this work, DFT + U was carried out to investigate the effect of strain engineering in terms of biaxial compressive and tensile strains (BCS and BTS) on the electrochemical properties of olivine-based LiMPO4 (M = Co and Ni). The results show that biaxial compressive strain decreased the average bond lengths of O–Co/Ni and O–P, which means a good improvement in the structural stability of LiCoPO4 (LCP) and LiNiPO4 (LNP). The deployment of BCS and BTS reduced the open-circuit voltage of the LCP and LNP systems. Precisely, imposing a biaxial strain of about ε = ±3.5% for LCP and ε = ±5.5% for LNP reduced the high OCV to values below 4.5 V vs Li/Li+, which is recommended for most commercial liquid electrolyte operation. In addition, it was found that biaxial strain reduces the energy barrier for Li+ diffusion, which promotes Li+ diffusion and increases its mobility in these olivine crystal structures. Further analysis of the electronic structures shows that BTS reduces the material’s band gap and improves electronic conductivity. These results are promising for the commercial utilization of LCP and LNP as potential cathode material in next-generation LIBs like their famous big brother LFP.

Enhancing the Electrode Gravimetric Capacity of Li1.2Mn0.4Ti0.4O2 Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation.

Mn-based cation-disordered rocksalt oxides (Mn-DRX) are emerging as promising cathode materials for next-generation Li-ion batteries due to their high specific capacities and cobalt- and nickel-free characteristic. However, to reach the usable capacity, solid-state synthesized Mn-DRX materials require activation via postsynthetic ball milling, typically incorporating more than 20 wt % conductive carbon that adversely reduces the electrode-level gravimetric capacity. To address this issue, we first deposit amorphous carbon on the surface of the Li1.2Mn0.4Ti0.4O2 (LMTO) particles to increase the electrical conductivity by 5 orders of magnitude. Although the cathode material gravimetric first charge capacity reaches 180 mAh/g, its highly irreversible behavior leads to a first discharge capacity of 70 mAh/g. Subsequently, to ensure a good electrical percolation network, the LMTO material is ball-milled with a multiwall carbon nanotube (CNT) to obtain a 78.7 wt % LMTO active material loading in the cathode electrode (LMTO-CNT). As a result, a 210 mAh/g cathode electrode gravimetric first charge and 165 mAh/g first discharge capacity values are obtained, compared to the respective capacity values of 222 and 155 mAh/g for the LMTO material ball-milled with 20 wt % SuperP C65 electrode (LMTO-SP). After 50 cycles, LMTO-CNT delivers a 121 mAh/g electrode gravimetric discharge capacity, largely outperforming the value of 44 mAh/g of LMTO-SP. Our study demonstrates that while ball milling is necessary to achieve a significant amount of capacity of LMTO, a careful selection of additives, such as CNT, effectively reduces the required carbon quantity to achieve a higher electrode gravimetric discharge capacity.

Effect of sodium and yttrium co-doping on electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathode material for Li-ion batteries: Computational and experimental investigation

LiNi0.8Co0.15Al0.05O2 (NCA) has attracted a lot of attention owing to its high voltage, specific energy density, and specific capacity. However, the cycle durability of the NCA material is still a challenge. Oxygen evolution, migration of nickel cations to the lithium layers (cation mixing), and the destruction of the layered structure of NCA are the most important reasons for thermal and structural instability, reducing capacity, and increasing impedance. Doping is one of the most effective ways to improve the thermal and structural stability of the NCA. In this study, the addition of sodium (Na) on Li-site and yttrium (Y) on metal-site, as well as the simultaneous addition of these elements to NCA material, were investigated experimentally and theoretically. For the first time, we proposed a framework for parameterization of the structural and thermal stability of NCA during the lithiation/delithiation process in terms of first-principle density functional theory (DFT) calculations. It is shown that variation in the Bulk modulus can reflect structural responses, and the calculated Bader charge on oxygen atoms is directly connected to thermal stability concerns. The computational results confirmed the positive effect of Na+ and Y3+ on the structural and thermal stability of the NCA cathode systematically. Following those outcomes, different percentages of the dopants were added to the cathode material experimentally, and electrochemical tests such as cyclability, electrochemical impedance spectroscopy, cyclic voltammetry, and rate capability were performed. The electrochemical tests revealed that in single-doped samples, the optimal amount of Na+ and Y3+ was 0.5 % (mol%), and in co-doped samples, 0.5 % of each dopant (0.5Na-0.5Y-NCA) produced the best results. The optimal 0.5Na-0.5Y-NCA sample retained 92.34 % of its capacity after 100 charge and discharge cycles at a rate of 0.5C, compared to 67.11 % for the pristine NCA. The cooperative addition of sodium and yttrium with different mechanisms such as reducing released oxygen, reducing the formation of insulating compounds, increasing the diffusion coefficient, reducing charge transfer resistance, and improving structural and thermal stability demonstrated synergistic effects on stabilizing the layered structure and improving cycling performance. The underlying mechanisms of observed experimental improvements were interpreted and discussed according to computational outcomes.

Engineering robust biopolymer-derived carbon growth of Ni-rich cathode materials for high-performance Li-ion batteries

Nickel-rich ternary layered oxide (NCM811) is one of the most promising electrode materials for next-generation lithium ion batteries, offering high reversibility, ecofriendly, and low cost. However, this type of cathode material also has low thermal stability, phase changes during charge-discharge, and safety concerns, requiring considerable improvement to be commercially viable. This study induced carbon growth on a modified nickel-rich layered oxide NCM811 cathode material as positive electrodes for Li ion batteries, and subsequently performed electrochemical, structural, and post-mortem characterization for the material. Specific capacity retention for the best case cathodes improved to 75 % after 100 cycles at 0.1C rate under atmospheric conditions compared with current standard NCM electrodes. Full cell fabricated using that best case electrodes achieved 220 mAh g−1 initial charge capacity, retaining 81 % charge capacity after 50 cycles. Initial coulombic efficiency and cycle stability for the prepared best case cathode material was enhanced by optimum carbon growth due to the reconstructed layer structure's capacity to inhibit side reactions at the interface and stabilize bulk structure over cycles.