High Energy Density Cathode Materials Research Articles

Cross-scale deciphering thermal failure process of Ni-rich layered cathode

Ni-rich LiNixCoyMn1-x-yO2 (NCM) layered oxides are low-cost high-energy density cathode materials, but plagued by its poor thermal stability incurred safety concerns. The thermal failure process of the layered cathode is accompanied by heat generation and oxygen release, which drives the battery into thermal runaway (TR). Aiming to fully understand the TR process and the structure evolution, this work applies diverse characterization techniques onto a polycrystalline Ni-rich layered cathode (LiNi0.83Mn0.05Co0.12O2 (PCN83)) to comprehensively investigate its thermal failure process at multiple scales. From macro level, we validate that it is the cathode thermal failure that drives the battery from the heat accumulation stage into TR in adiabatic conditions. From micro level, transmission electron microscopy (TEM) verifies that the thermal failure of PCN83 starts from 150 °C, which is much lower than the TR temperature measured from macro level tests. We reveal that the PCN83 cathode experiences sequential phase transitions before the TR, where the phase transition mechanism is illustrated from the atomic scale and the pore evolution process is unraveled. In situ heating TEM further reveals that thermal failure is preferentially initiated from grain boundaries and defect regions. These findings provide an in-depth understanding of the whole thermal failure process of NMC-based layered cathode materials and sheds new lights on the rational design of Ni-rich cathode materials with improved thermal safety.

Solid-state synthesis of low-cost and high-energy-density sodium layered-tunnel oxide cathodes: Dynamic structural evolution, Na+/vacancy disordering, and prominent moisture stability

Manganese-based layered oxides show promise as cathode materials for sodium-ion batteries (SIBs). However, several challenges including sluggish Na+ kinetics, complex phase transitions, and poor air stability hinder their practical application. Herein, we proposed a dual-function strategy that not only precisely manipulates dynamic structural evolution from layered to tunnel structure, but also effectively suppresses Na+/vacancy and charge ordering by inhibiting electron delocalization. A series of Ti-substituted Na2/3Mn1-xTixO2 (x=0, 1/9, 2/9, 1/3) as proof of concept materials were designed to demonstrate the dual-function strategy. As a result, the optimized Na2/3Mn8/9Ti1/9O2 cathode material delivers a high specific capacity of 202.9 mAh g−1 at 0.1 C within 1.5−4.3 V, equivalent to 536.6 Wh kg−1 of energy density, and exhibits 71.0% of capacity retention after 300 cycles at 1 C. Meanwhile, a highly reversible P2/Tunnel-OP4/Tunnel phase transition process and interlocking effect between the layered and tunnel structure as well as prominent moisture stability even after soak water treatment are further confirmed by in-situ charge and discharge XRD and other advanced characterization techniques. Noting that the electrode assembled with water-solution binder still displays a high capacity retention of 85.4% after 400 cycles at 1 C. Our dual-function strategy provides valuable guidance for developing high energy density and water stable practical SIB cathode materials.

PO43--doped layer @ spinel @ rGO sandwich-structured lithium-rich manganese-based cathode material with enhancing rate capability and cycle stability for Li-ion battery

The Li-rich Mn-based cathode (LRM) material faces challenges like low initial coulombic efficiency (ICE) and reduced capacity retention, which limit their commercial viability in high energy density lithium-ion batteries (LIBs). These challenges primarily arise from the irreversible migration of transition metal ions (TMn+) and the escape of lattice oxygen. Herein, this study proposes a novel approach to enhance Li-rich cathodes by implementing a PO43--doped layer @ spinel @ rGO sandwich structure, which effectively addresses the aforementioned challenges. Through the synergistic effects of PO43- doping and rGO surface modification, the modified samples demonstrate remarkable electrochemical properties. These include an impressive initial coulombic efficiency (ICE) of 87.54%, and a superior capacity of 187.12 mAhg−1 and 149.44 mAhg−1 at 25°C and 45°C, respectively, following 200 cycles at 1 C. Additionally, they exhibit an outstanding rate capability of 82.3 mAhg−1 at 10 C and a minimal voltage decrease of 0.504 V after 200 cycles. The synergetic strategy presented in this work serves as an inspiring source for the exploration of high energy density and long-cycle cathode materials.

Experimental and theoretical investigation of cobalt and manganese substitution in Na4Fe3(PO4)2P2O7 as a high energy density cathode material for sodium-ion batteries

As an inexpensive and environmentally-friendly cathode for sodium-ion batteries, Na4Fe3(PO4)2P2O7 (NFPP) is considered to be a promising candidate for practical applications. However, the theoretical capacity of NFPP is limited to 129 mAh g−1, due to the fact that only three electrons can be participated in the reaction during the charge/discharge process. Herein, the critical role of cobalt and manganese in elevating the energy density of the pristine NFPP structure was investigated, and Na4Co0.5Mn0.5Fe2(PO4)2P2O7 (NCMFPP) is prepared in order to trigger a redox reaction with 3.5 electrons during the charge/discharge process. It is found that the NCMFPP can provide a high initial discharge capacity of 139 mAh g−1 at 0.1C (1C = 129 mA g−1), with an excellent rate capacity (75 mAh g−1 at 10C) and a remarkable long cycling stability with a capacity retention of 65.2 % after 2000 cycles at 10C. The reaction of the Mn3+/Mn4+ redox couple was characterized by X-ray photoelectron spectroscopy analysis during the charge/discharge process. These results verified the effectiveness of cobalt and manganese in elevating the energy density of NFPP as a cathode as a cathode material for low-cost sodium-ion batteries.

Effects of electrolyte/cathode ratio on investigation of their thermal behaviors using differential scanning calorimetry

Battery materials with high-energy density and good safety performance have been regarded as the ultimate target for larger-scale applications of lithium-ion batteries in electric transportation and grid energy storage. Thermal safety of high energy density cathode materials has been a hot topic for battery safety research in recent years. Differential scanning calorimetry (DSC) is widely used to investigate thermal reaction characteristics of battery materials, but the results are always affected by multiple variables, e.g., sample pre-processing and testing conditions. The variety of DSC results reported in literature have been perplexing the research community. Herein, the cathode-electrolyte system is chosen to reveal the changes of reaction mechanisms with different electrolyte/cathode ratios, since this system has been widely adopted to characterize thermal stability of cathodes and electrolytes in previous studies. Lithium-rich manganese-based layered oxide cathode and ester-based electrolyte are selected as representative samples. Our results reveal that flooded, sufficient, insufficient, and lean electrolyte conditions may lead to distinct thermal behaviors from probably different reaction routines, which may hold different reference values for battery-level safety analysis. This study also suggests the importance of systematic investigations on test conditions in battery material thermal safety research.

Rapid preparation of cobalt-free lithium rich cathode materials with layered structure and excellent performance via capillary microreactors

High voltage and high energy density cathode materials are the future development trend of power batteries. Li-and Mn-rich layered oxide (LMR) materials exhibit high capacity, low cost, and environmental friendliness, making them a promising cathode material for the next generation of lithium-ion batteries. In this study, a continuous-flow process for rapid co-precipitation synthesis of LMR precursor (Mn0.75Ni0.25CO3) in capillary microreactors was developed. Due to the good mixing characteristics of the microreactor (tm=54 ms), Mn0.75Ni0.25CO3 displays a complete spherical morphology and uniform elemental distribution without adding any complexing agent during the synthesis. The reaction time can be controlled within 11.78 s. The prepared Li1.2Mn0.6Ni0.2O2 (LMR) cathode exhibits excellent properties with a high initial discharge capacity of 266.52 mAh•g−1 at 0.1C and a superior capacity retention of 93.7 % after 200 cycles at 1C. This work demonstrates that microfluidic technology presents a viable and promising approach for quickly producing lithium battery cathode precursors.

(Digital Presentation) Understanding the Electrochemical Stability of Potential Current Collectors in Zinc Sulfate Electrolyte for Rechargeable Aqueous Zinc Ion Battery Application

The need for clean and sustainable energy sources has witnessed a sudden upsurge in recent years owing to rising environmental degradation and climate disruption brought on by an overdependence on fossil fuels [1-3]. Electrochemical energy conversion technology is a crucial complement to the storage and on-demand utilization of renewable energy resources [4-6]. Rechargeable aqueous zinc ion batteries (AZIBs) have gained a significant research upsurge in recent times owing to their attractive potential for large-scale energy storage applications. In addition to low cost and naturally abundant raw materials, AZIBs technology offers competitive electrochemical performance and compatibility with water-based electrolyte systems, thereby eliminating the safety concerns associated with prevalent lithium-based battery technology. Moreover, multivalent AZIBs offer the opportunity to attain high energy and power density by permitting multiple electron transfers during reversible electrochemical operations [7]. In the context of AZIBs, significant research efforts are being actively pursued to develop high energy density cathode materials and to address the issue of Zn dendrite formation [8]. However, the selection of stable and low-cost current collectors is equally important as it serves as a bridge between the battery components and the external circuit, thereby influencing the battery capacity and its rate capability [9-10]. In this work, we have analyzed the electrochemical behavior of potential current collectors that are used globally in battery applications, namely Ni, Al, carbon paper, Cu mesh, graphite, and stainless steel in near-neutral aqueous ZnSO4 electrolyte (pH value = 5-6). The electrochemical stability of different current collectors has been investigated using linear sweep voltammetry and chronoamperometry techniques for their application as anode and cathode collectors. Scanning electron microscopy analysis has also been performed to understand the sign of corrosion post-electrochemical study. With stability up to 2.3 V w.r.t. Zn/Zn2+, Ni has proved to be the most corrosion-resistant current collector among the tested collectors on the cathode side. Although Zn itself is sufficiently stable at the anode side than any other current collector under the ZnSO4 electrolyte environment, Ni has shown considerable stability. Nonetheless, understanding the electrochemical stability of current collectors for AZIBs is a vital step in their design and future practical applications.

Pyrene-TEMPO-Modified Carbon Electrodes for Organic Radical Lithium-Ion Batteries

Organic radical batteries (ORBs) are a promising alternative to traditional lithium-ion batteries (LIBs) because of their environmentally friendly materials and potential to be low-cost, light weight, and mechanically flexible. Among ORB materials, stable organic radical polymers have great potential as high energy density and high power density cathode materials due to their small molecular weight and fast, reversible redox reactions. A stable radical polymer for LIB applications contains an organic radical unit with redox potentials suitable for the LIB anode or cathode that is immobilized on an electrode via a main chain polymer. Conductive and light-weight polymer main chains are necessary to ensure fast electron transfer to the current collector, without adding significant weight to the cell. Despite extensive research, organic radical materials present some key challenges which limit their present use in electrochemical cells. Many polymer backbones are non-conductive, leading to increased electrode resistance and poor cell performance at high charge/discharge rates. Many organic radical materials also have relatively low thermal stability and low packing density. Moreover, many organic radicals are soluble in typical organic battery electrolytes, resulting in capacity fading.In this research, we apply pyrene as a polymer backbone to 2,2,6,6-tetramethyl-piperidine-1-oxyl radical (TEMPO) for the first time in LIB applications to reduce the solubility of the active organic radical and enable π−π stacking interactions with aromatic carbons. We prepared a surface-immobilized p–TEMPO on fullerene C60 and graphene foam (GF) electrodes via π−π stacking interactions to increase electrode conductivity. Pyrene is used to modify certain carbon allotropes via π−π stacking interactions. It was hypothesized that this approach would enable strong bond formation of the TEMPO radical with the electrode, while providing a non-destructive and simple modification approach of conductive carbon surfaces. The successful conjugation of pyrene and TEMPO molecules was established by NMR spectroscopy. The redox activity of p-TEMPO in LIB electrolytes was validated in solution. The non-covalent attachment of p-TEMPO to fullerene C60 and GF electrodes was established by XPS. The mechanisms and reversibility of the TEMPO redox reaction was then explored for p-TEMPO immobilized on the carbon electrodes. While both electrodes showed diffusion-limited current, and quasi-reversible reactions, C60-p-TEMPO has better reversibility and less resistance than GF-p-TEMPO. C60-p-TEMPO electrodes exhibit exceptional cycling stability over 600 cycles. These results are outstanding as the C60 has a high tendency to dissolve in LIB electrolytes. LIB half-cell testing identified challenges and opportunities for the p-TEMPO-modified electrodes. C60-p-TEMPO discharge capacity at ~5C rate is comparable to PTMA-based literature, however no distinct TEMPO response was observed in the charge or discharge curves. GF-p-TEMPO electrodes showed a TEMPO response in cycle 1 only, suggesting possible p-TEMPO dissolution in the electrolyte. Overall, the results show that the use of a noncovalent immobilization method allows facile preparation of p-TEMPO functionalized electrodes and demonstrates the potential of p-TEMPO noncovalent bonding in organic LIB applications. Figure 1

(Invited) Enabling Rechargeable Conversion Cathodes By Modeling the Coupling between Structure, Electrochemistry, and Mechanics

While traditionally used as a primary battery chemistry, there is current interest in using FeS2 as a high-energy density cathode material for specialized rechargeable battery applications. However, the combination of intercalation and conversion processes, large volume change upon reaction, and the formation of polysulfides complicate its cycling behavior and therefore wider adoption. We present computational models at both the mesoscale (particle-resolved) and macroscale (homogenized) that look at the coupled interplay between mechanical stress and strain and electrochemistry to determine the performance and degradation of FeS2 electrodes. These models are used to explore the role of particle size polydispersity and additively manufactured 3D-structured electrode designs (e.g. pillars) to appropriately balance mechanics, transport, and kinetic limitations and optimize electrode performance. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Regulating cation mixing for enhanced structural stability of layered oxide cathodes by ion-exchange strategy

Typical LiNixCoyMn1-x-yO2 (NCM) layered oxides are a promising research area for high-energy–density cathode materials. However, they still suffer from structural disorder due to severe Li/Ni mixing caused by solid-state reactions at high temperatures (700–900 °C). To address these problems, most strategies focus on increasing the energy barrier of Ni2+ migration towards Li+ sites, such as doping or annealing in an O2-rich atmosphere. Herein, we report a new strategy of lowering processing temperature for effectively regulating Li/Ni mixing, achieved by hydrothermal ion exchange. The ion exchange can achieve a rapid substitution of Li+ ions for Na+ ions at relatively low temperatures (160–220 °C), allowing the NCM to maintain low Li/Ni mixing (<1%). Our ab initio calculations further demonstrate that the Ni2+ diffusion rate in ion-exchanged NCM523 at 200 °C is significantly slower in the order of 10−12 than that in NCM523 calcined at 900 °C, indicating that processing temperature is crucial to regulating Li/Ni mixing. That is, Li/Ni mixing of NCM523 materials is effectively regulated during ion exchange, further enhancing the structural stability and electrochemical performance. In addition, the universality of hydrothermal ion exchange was further proved by synthesizing NCM materials with good structural stability for different nickel contents (x = 0.5, 0.65, 0.7, 0.85). We anticipate that our ion-exchange strategy opens a new door towards regulating Li/Ni mixing by lowering processing temperature, enabling layered oxide materials with enhanced structural stability.

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.

High structural stability of graphene coated nickel – rich cathode material in Li – ion battery

The high energy density cathode material, nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (LNCM), has been extensively researched for its potential applications. Nevertheless, its structural instability, weak conductivity and unsafe properties greatly impede its further development. To address these issues, the method of surface coating by graphene and element doping by Mg atom for LNCM is proposed, and its structural and electrochemical properties, as well as the promoting mechanism are comprehensively studied. Such as, the structural and morphological features are investigated by X– ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) coupled with energy dispersive X – ray spectroscopy (EDX) and transmission electron microscopy (TEM). Characterization techniques depict the composites’ dimension, modified construction and components. Electrochemical performances are studied using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge – discharge test. The typical redox peaks of Ni2+/Ni4+ and Co3+/Co4+ are well-defined for LNCM@rGM, and its improved electrochemical performance compared to LNCM are demonstrated. Specifically, LNCM@rGM exhibits a higher capacity retention of 58%, maintaining a capacity of 123.3 mAh g−1 after the 200th cycle, from an initial value of 211.0 mAh g−1. Additionally, LNCM@rGM shows a higher rate capability of 80.2 mAh g−1 at 5 C, as well as improved Li+ diffusion and higher exchange current density. The findings indicate that the composite structure consisting of graphene coating and element doping shows improved electrochemical performance when exposed to an optimal heating temperature, resulting in enhanced structural stability, elevated ionic/electronic conductivity, and synergistic effects on the materials.

Nickel as a key element in the future energy

The review discusses the complex properties of nickel and its role as a critical element for ensuring a confident transition to a new technological paradigm from fossil fuels in favor of using advanced electrochemical storage and energy conversion systems. The main classes of nickel-containing materials of the positive electrode (cathode) for metal-ion batteries are discussed, the place of nickel among other 3&lt;i&gt;d&lt;/i&gt;-metals used in the industry of electrochemical energy storage is determined. The main methods and approaches for the synthesis of state-of-the-art and next generation cathode materials based on layered Ni-containing oxides are presented. The crystal and electronic structures of these materials, including their evolution in the process of (de)intercalation of alkali metal cations, are considered in the context of their electrochemical properties. The most acute problems facing modern materials science on the way to commercialization and industrial production of new generation highenergy density cathode materials are determined. At the end of the review, promising directions for the further development of nickelcontaining cathode materials are outlined.&lt;br&gt; The bibliography includes 252 references.

High Energy Density Sulfur‐Rich MoS6‐Based Nanocomposite for Room Temperature All‐Solid‐State Lithium Metal Batteries

AbstractThe all‐solid‐state lithium–sulfur battery is considered to be a promising energy device due to high energy density and excellent safety. However, sulfur suffers from its insulating nature and large volume changes. Employing transition‐metal sulfide cathodes is an attractive alternative. Herein, a high energy density sulfur‐rich MoS6‐based nanocomposite is designed, where MoS6 nanospheres are homogenously anchored on carbon nanotubes (CNTs) by a wet‐chemical method, providing improved electronic conductivity and reduced volume changes. In addition, a nanosized Li7P3S11 electrolyte is in situ coated on the surface of MoS6‐CNT20 to realize intimate interface contact and form nanoscale electronic/ionic transportation networks. The resultant MoS6‐CNT20@15%Li7P3S11 composite shows high electronic conductivity (1.7 × 10−1 S cm−1) and ionic conductivity (6.7 × 10−4 S cm−1), which are eight and three orders of magnitude improved compared to those of MoS6. The Li/Li6PS5Cl/MoS6‐CNT20@15%Li7P3S11 battery exhibits an initial discharge capacity of 1034.32 mAh g−1 at 0.1 A g−1. In addition, an ultrahigh reversible energy density of 1640 Wh kg−1 for the active material can be realized, which is the highest among all transition‐metal sulfide cathodes. Moreover, it shows a reversible capacity of 550.00 mAh g−1 at 0.5 A g−1 after 1000 cycles, demonstrating that the sulfur‐rich MoS6‐based nanocomposite is a promising highenergy density cathode material for next‐generation all‐solid‐state lithium batteries.

High-performance Li/LiNi0.8Co0.1Mn0.1O2 batteries enabled by optimizing carbonate-based electrolyte and electrode interphases via triallylamine additive

Lithium (Li) metal batteries (LMBs), paired with high-energy–density cathode materials, are promising to meet the ever-increasing demand for electric energy storage. Unfortunately, the inferior electrode–electrolyte interfaces and hydrogen fluoride (HF) corrosion in the state-of-art carbonate-based electrolytes lead to dendritic Li growth and unsatisfactory cyclability of LMBs. Herein, a multifunctional electrolyte additive triallylamine (TAA) is proposed to circumvent those issues. The TAA molecule exhibits strong nucleophilicity and contains three unsaturated carbon–carbon double bonds, the former for HF elimination, the later for in-situ passivation of aggressive electrodes. As evidenced theoretically and experimentally, the preferential oxidation and reduction of carbon–carbon double bonds enable the successful regulation of components and morphologies of electrode interfaces, as well as the binding affinity to HF effectively blocks HF corrosion. In particular, the TAA-derived electrode interfaces are packed with abundant lithium-containing inorganics and oligomers, which diminishes undesired parasitic reactions of electrolyte and detrimental degradation of electrode materials. When using the TAA-containing electrolyte, the cell configuration with Li anode and nickel-rich layered oxide cathode and symmetrical Li cell deliver remarkably enhanced electrochemical performance with regard to the additive-free cell. The TAA additive shows great potential in advancing the development of carbonate-based electrolytes in LMBs.

Impacts of Mg doping on the structural properties and degradation mechanisms of a Li and Mn rich layered oxide cathode for lithium-ion batteries

The Li- and Mn-rich layered oxide cathode material class is a promising cathode material type for high energy density lithium-ion batteries. However, this cathode material type suffers from layer to spinel structural transition during electrochemical cycling, resulting in energy density losses during repeated cycling. Thus, improving structural stability is an essential key for developing this cathode material family. Elemental doping is a useful strategy to improve the structural properties of cathode materials. This work examines the influences of Mg doping on the structural characteristics and degradation mechanisms of a Li1.2Mn0.4Co0.4O2 cathode material. The results reveal that the prepared cathode materials are a composite, exhibiting phase separation of the Li2MnO3 and LiCoO2 components. Li2MnO3 and LiCoO2 domain sizes decreased as Mg content increased, altering the electrochemical mechanisms of the cathode materials. Moreover, Mg doping can retard phase transition, resulting in reduced structural degradation. Li1.2Mn0.36Mg0.04Co0.4O2 with optimal Mg doping demonstrated improved electrochemical performance. The current work provides deeper understanding about the roles of Mg doping on the structural characteristics and degradation mechanisms of Li-and Mn-rich layered oxide cathode materials, which is an insightful guideline for the future development of high energy density cathode materials for lithium-ion batteries.

Regulating Li&lt;sup&gt;+&lt;/sup&gt; Transfer and Solvation Structure via Metal-Organic Framework for Stable Li Anode

Lithium metal batteries (LMBs) possess large application potential for advanced rechargeable batteries due to the high energy density (&gt; 500 Wh kg−1) and alternative cathode materials. Random Li dendrite growth caused by uneven Li+ distribution and local ion depletion near surface of Li anode induces battery failure with inferior long-term stability. Therefore, regulation of ion distribution near anode surface is essential to realize dendrite-free and uniform Li deposition. Herein, a metal-organic framework (MOF), i.e., ZIF-8, is applied to regulate Li+ solvation structure via unsaturated metal-ion sites to achieve uniform Li+ distribution and Li deposition. A stable cycling performance over 800 h for Li symmetrical cell at 3 mA cm−2 and 3 mAh cm−2 without short circuit is realized. The facilitated Li+ solvation via the adsorption effect of metal-ion sites on anions is demonstrated, which further enhances the uniform Li+ distribution near Li anode surface. This work demonstrates an effective strategy for regulating ion coordination and Li+ distribution to stabilize Li anode via MOF-based materials.

Experimentaland computational analysis of metal oxide nanomaterials for lithium-ion batteries

Lighter, more effective, and powered by sustainable energy sources are the goals of electric vehicles. In addition to helping to achieve many of these goals for improved vehicle convenience, performance, and safety, nanotechnology is crucial for reducing size, weight, and power consumption, all of which are crucial for long-range coverage. Nanoscale electrodes have low impedance growth, which prevents significant power loss while cycling. They also have a larger electrode/electrolyte contact surface, which boosts the charge/discharge rate to provide the most power. The new nanostructured cathode materials and their impact on the electrochemical performance of lithium-ion batteries are discussed in this research. The creation of high energy density Cathode materials at the nanoscale enhances battery performance. This article explains how to make lithium manganese spinel and its derivatives, such as transition metal oxide (LiNi0.5Mn1.5O4), using the co-precipitation process. LiNi0.5Mn1.5O4′s structural characteristics, as determined by X-ray diffraction (XRD), showed that the prepared sample primarily belongs to cubic crystal form with Fd3m space group, with lattice parameter a = 8.265 A° and an average crystal size of 31.59 nm. The experimental results were compared to computation details from first-principles calculations performed using Material Studio version 6.0 and Atomistic Tool Kit, Quantum wise softwares. Methods of first-principles computation play a significant role in the development and improvement of electrode materials. In this paper, we provide a summary of the computational strategy used to create LiNi0.5Mn1.5O4 as the cathode material for lithium-ion batteries.

Enhanced electrochemical performance of Na4MnCr(PO4)3@C cathode by multi-walled carbon nanotubes interconnection for Na-ion batteries

• The Na 4 MnCr(PO 4 ) 3 @C@MWCNTs composites are synthesized for sodium ion batteries. • 3D well-interconnected architecture was designed by implanting CNTs into NMCP@C. • MWCNTs can enhance the rate capability and cycling stability of Na 4 MnCr(PO 4 ) 3 @C . • With WS 2 as anode, electrochemical performances were tested in full batteries. The development of high energy density and stable cathode materials for Na-ion batteries is an enormous puzzle. NASICON-structured Na 4 MnCr(PO 4 ) 3 (NMCP) has been reported as a novel and viable cathode material lately. Nonetheless, the inferior rate property and disappointing cycle stability hinder its commercial usage. Herein, a series of NMCP@C structurally interconnected with multi-walled carbon nanotubes (NMCP@C@x%MWCNTs, x = 0, 5, 10 and 15) were produced via a simple sol–gel strategy followed by an annealing treatment. The results indicate that the MWCNTs network could contribute to improving the electrochemical properties by accelerating electronic conductivity and increasing ionic diffusion property. As expected, the optimal composite (NMCP@C@10%MWCNTs) delivers the specific capacity of 66.1 mAh/g at 500 mA g −1 and capacity retention of 61.8% after 100 cycles at 1000 mA g −1 , while the pristine NMCP@C presents the specific capacity of 2.8 mAh/g at 500 mA g −1 and capacity retention of 27.5% after 100 cycles at 1000 mA g −1 . Moreover, When NMCP@C@10%MWCNTs is applied as cathode to assemble full battery with WS 2 anode, this battery delivers an initial discharge capacity of 181.3 mAh/g , acquiring a superior energy density of ∼435 Wh kg −1 with a working voltage of ∼2.4 V. These findings demonstrate that the MWCNTs network is favorable for the electrochemical enhancement of Na 4 MnCr(PO 4 ) 3 @C, which offers a hopeful prospect for Na 4 MnCr(PO 4 ) 3 as a cathode for sodium-ion batteries in practical application.

More Reversible Anionic Redox Chemistry for Sodium Storage Triggered By Transition Metal Regulation

As one of the next generation battery system, sodium-ion batteries (SIBs) have been attached great interest for its abundant resources, low cost and good safety. Recently, high energy density cathode materials with anionic redox chemistry in SIBs have become the mainstream. The working potential of oxygen redox in layered transition metal oxide cathodes is about 4.2 V (vs. Na+/Na), which can not only elevate the battery potential but also harvest extra capacity. Thus, reasonably utilizing the oxygen redox can drastically increase the energy density of the batteries. However, the undesired phase transition and structural distortion resulted from oxygen redox usually lead to severe voltage hysteresis and capacity decay of the cathodes. Therefore, it is of great significance to investigate the relationship between the transition metal components and cycling stability of the cathodes, which provides valuable understanding for discovering novel cathodes with more reversible and higher capacity. To improve the structure stability and promote more anionic redox, we have been focusing on tuning the structure of P2-layered cathode materials with the different transition metal ligands such as Al/Ti/Zn-Mn. We have performed in-situ XRD and ex-situ XAS characterizations to investigate the charge compensation mechanism of the cathodes. The O K-edge XAS results indicated O e g orbits variation at fully charged state and provided solid evidence of oxygen redox chemistry. Moreover, we combined EXAFS results and DFT calculations to construct the model of local structure distortion. These results provide further understanding of the oxygen redox chemistry mechanism and promote the development of high energy density SIBs. Acknowledgement The work was supported by the National Natural Science Foundation of China (No. 52071085).