Nanostructured Cathode Materials Research Articles

Unravelling the Effect of Sodium Doping on Li2MnO3 nanostructured Cathode Materials

The quest to develop affordable, high-performance electrode materials for lithium-ion batteries in electric vehicles is driving scientific innovation forward. Li2MnO3, as a prospective high-capacity (459 mAh.g-1) cathode, suffers from capacity degradation and voltage decay during the cycling process. Nanostructuring and incorporating sodium ions into lithium sites can mitigate voltage decay by limiting transition metal migration, impeding oxygen loss, and improving lithium diffusion by lowering the activation energy of Li-rich layered host materials. Herein, sodium-incorporated nonospherical structures of the form Li2-xNaxMnO3 (0 ≤ x ≤ 2), generated through the amorphisation and recrystallisation (A+R) technique show remarkable structural stability and enhanced Li-ion mobility owing to the enlarged lithium lattice upon sodium entrance. Specifically, the Li1.95Na0.05NaO3 nanosphere, displays more stable Li+/Mn4+ layers which will greatly contribute to its capacity. The microstructures associated with this configuration show well-ordered layers with high lithium kinetics and lower activation energy compared to pristine Li2MnO3. Characterisation of the x-ray diffraction (XRD) patterns revealed peak broadening along with the shifting of peaks at 2Θ~38 to the right due to the enlarged lithium layers occupied by sodium ions to facilitate lithium diffusion. Moreover, the undesired phase transformation from layered to spinel was observed at a later stage of charge for the sodium-doped systems, suggesting that the presence of sodium stabilizes the structure and minimizes the migration of manganese into lithium layers. These findings may lead to solutions for problems such as structural instability, lattice oxygen loss, and capacity decay in layered lithium oxide materials.

Recent Advances in Catalyst Design and Performance Optimization of Nanostructured Cathode Materials in Zinc-Air Batteries.

This review focuses on the advanced design and optimization of nanostructured zinc-air batteries (ZABs), with the aim of boosting their energy storage and conversion capabilities. The findings show that ZABs favor porous nanostructures owing to their large surface area, and this enhances the battery capacity, catalytic activity, and life cycle. In addition, the nanomaterials improve the electrical conductivity, ion transport, and overall battery stability, which crucially reduces dendrite growth on the zinc anodes and improves cycle life and energy efficiency. To obtain a superior performance, the importance of controlling the operational conditions and using custom nanostructural designs, optimal electrode materials, and carefully adjusted electrolytes is highlighted. In conclusion, porous nanostructures and nanoscale materials significantly boost the energy density, longevity, and efficiency of Zn-air batteries. It is suggested that future research should focus on the fundamental design principles of these materials to further enhance the battery performance and drive sustainable energy solutions.

Metal-organic framework-derived self-grown core-shell V2O5 for high-performance zinc ion storage

The nanostructure designing strategy is one of the most effective methods to carry out the optimization of cathode materials for aqueous zinc ion batteries (ARZIBs). The design and synthesis of materials with stable nanostructure and short ion/electron transport paths are expected to alleviate the dilemma faced by vanadium-based materials, such as poor electrical conductivity and structural changes. Ostwald ripening is a promising option in the design and fabrication of special nanostructures such as hollow and core shells. Selecting vanadium-based metal-organic frameworks (V-MOF) as reactants, we successfully obtained vanadium oxide precursors with self-growing core-shell structures in one-step. As the reaction time increases, the vanadium oxide precursors undergo the process of microspheres → core-shell → yolk shell, which is thought to be the result of Ostwald ripening. After annealing, the vanadium oxide precursor becomes a "core-shell" structure vanadium pentoxide (core-shell V2O5). The ARZIBs assembled with core-shell V2O5 cathodes showed superior capacity (309.4 mAh/g at 0.1 A/g) and cycling stability (91.4 % capacity retention after 4000 cycles at 3A/g). Hence, we successfully realized the self-growth of vanadium oxide with core-shell structure in one step but also revealed the crystallization process based on Ostwald ripening and its zinc storage mechanism, which provides new possibilities for the facile synthesis of special nanostructured ARZIB cathode materials.

Oxygen vacancies in MnOx regulating reaction kinetics for aqueous zinc-ion batteries

MnO2 cathode materials have presented challenges due to their poor conductivity, unstable structure, and sluggish diffusion kinetics for aqueous zinc-ion batteries (AZIBs). In this study, a nanostructured MnOx cathode material was synthesized using an acid etching method, Which introduced abundant Mn(III) sites, resulting in the formation of numerous oxygen vacancies. Comprehensive characterizations revealed that these oxygen vacancies facilitated the reversible adsorption/desorption of Zn2+ ions and promoted efficient electron transfer. In addition, the designed mesoporous structure offered ample active sites and shortened the diffusion path for Zn2+ and H+ ions. Consequently, the nanosized MnOx cathode exhibited enhanced reaction kinetics, achieving a considerable reversible specific capacity of 388.7 mAh/g at 0.1 A/g and superior durability with 72.0% capacity retention over 2000 cycles at 3.0 A/g. The material delivered a maximum energy density of 639.7 Wh kg−1 at 159.94 W kg−1. Furthermore, a systematic analysis of the zinc storage mechanism was performed. This work demonstrates that engineering oxygen vacancies with nanostructure regulation provides valuable insights into optimizing MnO2 cathode materials for AZIBs.

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.

Impacts of lithium content on structural and electrochemical properties of nanostructured high-voltage cathode material LixNi0.5Mn1.5O4 (x = 0.96, 0.98, 1.0, 1.02, and 1.04)

Impacts of lithium content on structural and electrochemical properties of nanostructured high-voltage cathode material LixNi0.5Mn1.5O4 (x = 0.96, 0.98, 1.0, 1.02, and 1.04)

High capacity and inexpensive multivalent cathode materials for aqueous rechargeable Zn-ion battery fabricated via in situ electrochemical oxidation of VO2 nanorods

For large-scale energy storage, aqueous rechargeable zinc-ion batteries are one of the most promising battery systems to replace lithium-ion batteries. In this study, a facile and scalable hydrothermal method is used to prepare VO2 nanorods, which are ball-milled with carbon black to prepare VO2@C nanoparticles. Characterizations using several advanced techniques confirm the successful synthesis of pure VO2 nanorods. Prior to electrochemical measurements, the VO2@C nanostructured cathode materials are transformed into V2O5·nH2O via an in situ electrochemical oxidation technique. The VO2@C/Zn aqueous zinc-ion full cell exhibits a reversible capacity of 300 mA h g−1 and a retention capacity of 85% after 1000 cycles at a current density of 5 A g−1 with a 2 M ZnSO4 electrolyte. The full cell also retains a remarkable capacity of 159 mA h g−1, even after 4000 galvanostatic charge–discharge cycles at 5 A g−1. The cell also shows excellent rate capabilities at a wide range of current densities from 0.1 to 20 A g−1, with a reversible discharge capacity and Coulombic efficiency of 100 mA h g−1 and 99%, respectively, at 20 A g−1. The remarkable performance is attributed to the nanoscale size of the prepared nanorods and the in situ electrochemical transformation.

Operando XAFS on Hydrated Calcium Vanadium Bronze Cathode for Aqueous Zn-ion Storage.

Multivalent ion storage and aqueous electrochemical systems continue to build interest for energy application. The Zn-ion system with 2 electron transfer and an ideal metal anode is a strong candidate but is still at the early stage of development. Using both in situ near-edge (XANES) and X-ray absorption fine structure spectroscopy, EXAFS, a nanostructured cathode material, Cax V2 O5 -H2 O (CVO), was probed at the V-K absorption edge. This operando study reveals the local electronic and geometric structure changes for CVO during galvanostatic cycling as the active material in an aqueous Zn-ion cell. The XANES data provides a fine resolution to track the evolution of the vanadium oxidative state and near-neighbor coordination sphere showing subtle shifts and delocalized charge. The Zn-ion influence on the V-K absorption edge is visualized using a difference technique called Δμ. Coupled with theoretical calculations and modelling, the extended region extracted local bonding information further confirms excellent electronic and structural reversibility of this vanadium oxide bronze in an aqueous Zn-ion electrochemical cell.

Nano-Confinement of Insulating Sulfur in the Cathode Composite of All-Solid-State Li-S Batteries Using Flexible Carbon Materials with Large Pore Volumes.

Durable nanostructured cathode materials for efficient all-solid-state Li-S batteries were prepared using a conductive single-walled 3D graphene with a large pore volume as the cathode support material. At high loadings of the active material (50-60 wt %), microscale phase segregation was observed with a conventional cathode support material during the charging/discharging processes but this was suppressed by the confinement of insulating sulfur into the mesopores of the elastic and flexible nanoporous graphene with a large pore volume of 5.3 mL g-1. As such, durable three-phase contact was achieved among the solid electrolyte, insulating sulfur, and the electrically conductive carbon. Consequently, the electrochemical performances of the assembled all-solid-state batteries were significantly improved and feasible under the harsh conditions of operation at 353 K, and improved cycling stability as well as the highest specific capacity of 716 mA h per gram of cathode (4.6 mA h cm-2, 0.2 C) was achieved with high sulfur loading (50 wt %).

Li2FeSiO4/C aerogel: A promising nanostructured cathode material for lithium-ion battery applications

Li2FeSiO4/C aerogel is successfully prepared using a high-temperature, high-pressure supercritical drying method. The prepared Li2FeSiO4/C aerogel is annealed at optimum temperature. The structural information is obtained from Powder X-ray diffraction and Fourier transform infrared spectroscopy results. The Li2FeSiO4/C aerogel annealing temperature is fixed at 700 °C based on the Thermogravimetric and differential scanning calorimetry. The electrical conductivity of the Li2FeSiO4/C aerogel is calculated using alternating current impedance, and it is 1.4738 × 10-8 S cm-1. The presence of carbon and the formation of Li2FeSiO4 is confirmed through Raman analysis. The X-ray photoelectron spectroscopy elemental analysis reveals Si4+, Fe2+, Li+, and C with their respective binding energies. Field emission scanning electron microscopy and transmission electron microscopy images show the formation of randomly distributed tiny particles are linked together within a porous structure. The specific surface area of 59.037 m2 g-1 with an average pore diameter of 22.8 nm is measured through N2 adsorption/desorption isotherm analysis. The electrochemical performance of the Li2FeSiO4/C aerogel exhibits a discharge capacity of 140 mA.h g-1 at 100 mA g-1 current density over 130 cycles with 100% coulombic efficiency. Lithium-ion diffusion co-efficient (DLi+ = 2.63 × 10-8 cm2 s-1) is measured from electrochemical impedance spectroscopy.

Hydrothermally synthesized nanostructured LiMnxFe1\u2212xPO4 (x\u2009=\u20090\u20130.3) cathode materials with enhanced properties for lithium-ion\xa0batteries

Nanostructured cathode materials based on Mn-doped olivine LiMnxFe1−xPO4 (x = 0, 0.1, 0.2, and 0.3) were successfully synthesized via a hydrothermal route. The field-emission scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyzed results indicated that the synthesized LiMnxFe1−xPO4 (x = 0, 0.1, 0.2, and 0.3) samples possessed a sphere-like nanostructure and a relatively homogeneous size distribution in the range of 100–200 nm. Electrochemical experiments and analysis showed that the Mn doping increased the redox potential and boosted the capacity. While the undoped olivine (LiFePO4) had a capacity of 169 mAh g−1 with a slight reduction (10%) in the initial capacity after 50 cycles (150 mAh g−1), the Mn-doped olivine samples (LiMnxFe1−xPO4) demonstrated reliable cycling tests with negligible capacity loss, reaching 151, 147, and 157 mAh g−1 for x = 0.1, 0.2, and 0.3, respectively. The results from electrochemical impedance spectroscopy (EIS) accompanied by the galvanostatic intermittent titration technique (GITT) have resulted that the Mn substitution for Fe promoted the charge transfer process and hence the rapid Li transport. These findings indicate that the LiMnxFe1−xPO4 nanostructures are promising cathode materials for lithium ion battery applications.

Zn-ion hybrid supercapacitors: Achievements, challenges and future perspectives

The newly-emerging Zn-ion hybrid supercapacitors (ZHSCs) are famed for their integration of high-capacity of Zn-ion batteries and high-power of supercapacitors (SCs), which are expected to meet the energy and power demands for both portable electronics and electrical vehicles. The practical application of ZHSCs faces serious challenges of achieving satisfactory energy density and developing suitable cathode materials and electrolytes. A systematic review on ZHSCs, the novel energy storage devices, is necessarily desired to spur the development of ZHSCs, but is still barren. This review provides a timely summary of recent advances on ZHSCs, and highlights the vital role of cathode materials and electrolyte systems in accelerating the prosperity of this kind of SCs. The ZHSCs fundamentals and the advanced engineering of various types of nanostructured cathode materials as well as their electrochemical characteristics and energy storage mechanisms are comprehensively discussed. The most recent development of electrolytes and Zn anode is also summarized and the effects of electrolyte compositions on the electrochemical performance of ZHSCs are elaborated. In the end, this review provides a detailed discussion about the existing critical challenges and presents future development perspectives on the favorable ZHSCs. This review provides a systematic summary of recent advances on ZHSCs including various types of cathode materials (carbon-based materials, conducting polymers, MXenes, TMOs), the most recent developed electrolyte systems, and their energy storage mechanisms. The existing critical challenges and a perspective to future development of favorable ZHSCs are provided. • A comprehensive summary of the techniques and the progress of ZHSCs is reviewed. • The fundamentals and recent developed cathode materials, electrolytes and anodes for ZHSCs are elaborated. • The existing critical challenges and a perspective to future development of ZHSCs are provided.

Understanding the Effect of Polymer Surface Layers on Magnesium Insertion in PEDOT/MnO2 Coaxial Nanowires

Rechargeable magnesium batteries are a possible alternative technology to lithium-ion batteries. However, there are challenges associated with all parts of magnesium battery systems – anode, cathode, and electrolyte. Regarding cathodes, the divalent Mg ion has slow insertion kinetics in many common metal oxide materials due to strong electrostatic interactions with the host ionic lattice. These materials are desirable due to their high voltage and thus the potential to contribute to a high energy density battery, therefore strategies to aid Mg2+ insertion in metal oxides are an important research focus. Two strategies to improve Mg2+ insertion include utilizing nanostructured cathode materials as well as introducing water, either in the electrolyte or crystal water within the metal oxide structure. Previous work demonstrated that manganese dioxide (MnO2) nanowires deposited via anodic electrodeposition effectively intercalated Mg ions when water was present in a ratio of 6:1 (H2O:Mg2+) in Mg(ClO4)2/propylene carbonate electrolyte (1). Without water in the electrolyte to solvate the Mg2+ and shield the charge, Mg2+ does not insert into the MnO2. Further, an investigation of the charge storage mechanism for this process determined that a conversion reaction on the MnO2 surface in addition to Mg insertion into the bulk both were dependent on the presence of water (2). Following this work, there were two additional characteristics of interest regarding MnO2 cathodes cycled in water-containing organic electrolyte: manganese dissolution and electronic conductivity. A previously published one-step co-electrodeposition process of MnO2 and poly(3,4-ethylenedioxythiophene)(PEDOT) provided a tunable structure to test both effects (3). With the PEDOT surface layer, there are two possible advantages: first is confining the MnO2 layer to minimize Mn dissolution, and second is addition of the more electronically conductive PEDOT layer for fast electron transport along the comparatively resistive MnO2 material. Here, coaxial PEDOT/MnO2 nanowires served as a test structure to investigate how a PEDOT surface layer affected Mg ion insertion into the MnO2 at the core and to develop additional understanding of the properties of MnO2 and how structural alterations could influence the electrochemical reactions. By altering the voltage of electrodeposition, the thickness of the PEDOT layer was varied. Cyclic voltammetry and galvanostatic charge/discharge tests were done to evaluate the Mg insertion capabilities, power performance, and cyclability of coaxial nanowires with PEDOT thicknesses ranging from 10-90 nm. Transmission electron microscopy and scanning electron microscopy were used to monitor structural properties and changes. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to monitor changes in manganese content. This work will address how PEDOT thickness influences the ability of Mg2+ to insert into MnO2, how it affects Mn dissolution, and how the increased electronic conductivity of PEDOT impacts performance when cycling at higher current densities. These results could help inform better design of future cathode materials for rechargeable Mg battery systems. 1. J. Song, M. Noked, E. Gillette, J. Duay, G. Rubloff and S. B. Lee, Physical Chemistry Chemical Physics, 17, 5256 (2015).2. E. Sahadeo, J. Song, K. Gaskell, N. Kim, G. Rubloff and S. B. Lee, Physical Chemistry Chemical Physics, 20, 2517 (2018).3. R. Liu and S. B. Lee, Journal of the American Chemical Society, 130, 2942 (2008).

New Tetraazapentacene-Based Redox-Active Material As a Promising High-Capacity Organic Cathode for Potassium Batteries

Following the Paris agreement signed in 2015 to address the problem of global climate change, many countries are aiming to decrease CO2 emissions particularly by using renewable sources of energy, e.g. solar, wind, geothermal, etc. However, any massive implementation of renewables requires cheap and efficient solutions for bulk energy storage. There are limited examples of application of lithium-ion batteries (LIBs) for peak shaving in electric grids and for storage of the energy produced by solar plants. The main obstacle for implementation of LIBs on a large scale is related to their high cost dictated by both low abundance of lithium resources and use of expensive nanostructured inorganic cathode materials. It should be emphasized that the total amount of lithium available on the planet is insufficient even for replacing all cars currently used in the world with electric vehicles while leaving unsatisfied all other demands for energy storage. Therefore, it is imperative to develop alternative post-lithium battery technologies. Potassium-ion batteries (KIBs) have recently attracted a particular attention since there are abundant resources of potassium in both Earth’s crust and oceans, which make this element almost an order of magnitude cheaper than lithium. Moreover, KIBs usually show higher discharge voltages in comparison with lithium-ion and, especially, sodium-ion batteries thus featuring a potential for reaching high energy densities [1]. However, the current progress in the development of KIBs is strongly limited by scarce number of suitable inorganic cathodes, which can deliver decent capacities and charge-discharge cycling stabilities. Organic redox-active materials represent a promising alternative since they are based on abundant elements, can be cheap and environment friendly [2]. In this work we present a new organic cathode for metal-ion batteries based on octahydroxytetraazapentacene (OHTAP) possessing a theoretical capacity of ~ 520 mAh g-1. To evaluate the K-ion storage properties of OHTAP, we assembled K//OHTAP cells using either the tape or the spray coating of the slurry (OHTAP+Super-P+PVDF in NMP) on Al or Al/C current collectors. A 1 M potassium bis(trifluoromethane sulfonyl) imide (KTFSI) solution in dimethoxyethane and dioxolane mixture (DOL : DME = 1:1 v/v) was used as the electrolyte. The fabricated cells delivered stabilized capacities of >220 mAh g-1 after 10 cycles, which are among the best values reported so far for both organic and inorganic cathode materials in potassium-ion batteries. The obtained results pave a way to the development of a new family of organic cathodes for advanced potassium-ion batteries.

Carbon coating nanostructured-LiNi1/3Co1/3Mn1/3O2 cathode material synthesized by chemical vapor deposition method for high performance lithium-ion batteries

Efficient energy storage of lithium-ion batteries plays a significant role across lots of sectors including consumer electronics, electric and hybrid electric vehicles and a smart grid accommodating intermittent renewable energy sources. Nanostructured cathode materials present fascinating opportunities for high-performance lithium-ion batteries, but intrinsic problems linked with the high surface area to volume ratios in the nanometer-range have restricted their adoption for practical applications. We demonstrate processing platform that realize high-performance nanostructured-LiNi1/3Co1/3Mn1/3O2 (NCM) layer cathode with carbon coating as a conductive additive. In this paper, we first presented a green, novel, economic and controllable chemical vapor deposition (CVD) method with sucrose as carbon source to coating NCM. Sol-gel synthesized NCM of carbon coated with optimized thickness by this formula are shown to have outstanding rate performance and robust cycle lifetime. The thickness - optimized sample of discharge capacity is as high as 104.5 mAh g−1 for 10 C (6s). High capacity retentions of 94.29% and 94.78% after 100 cycles for 0.1 C, respectively. Compared with the heat evaporation method, with the CVD method has better uniformity and higher quality. This approach further improves evidently the NCM of electrochemical performance and thus promotes lithium-ion battery development technology into unprecedented regimes of operation.

Solution-combustion synthesis of nanomaterials for lithium storage

Solution-combustion synthesis (SCS) is an effective method for mass production of electrode materials, in particular metal oxides, for electrochemical energy storage owing to its simplicity and energy/time effectiveness. The present mini-review aims at summarizing the recent data on the SCS of nano-structured anode and cathode materials for lithium-ion batteries. The advantages of electrode materials prepared by SCS are discussed in detail, with special emphasis on morphology control during the SCS process.

Nanostructured cathode materials for lithium–sulfur batteries: progress, challenges and perspectives

This review article summarises the progress, challenges and prospects of nanostructured cathode materials for lithium–sulfur batteries.

A Brief Review on Integrated (Layered and Spinel) and Olivine Nanostructured Cathode Materials for Lithium Ion Battery Applications

A Brief Review on Integrated (Layered and Spinel) and Olivine Nanostructured Cathode Materials for Lithium Ion Battery Applications

Nanoparticle Synthesis and Oxygen Anion Diffusion in Double Perovskite GdBaCo2-xFexO5+δ Electrodes for SOFC

Development of an intermediate temperature solid oxide fuel cell essentially require the synthesis of electrocatalytically active nanostructured cathode materials with fast oxygen anion transport and surface exchange properties. Double perovskite structured GaBaCo2O5+δ (GBCO) electrode showing an average particle size of less than 20 nm was synthesized by a bio-milling approach. In parallel, molecular dynamics (MD) simulations were utilised to calculate the effect of Fe doping at the B-site on the oxygen anion diffusivity of GdBaFexCo2-xO5.5 double perovskites. The oxygen diffusion was observed to be preferential in the a-b plane of GBCO with a value of D=2.8 x 10-7 cm2 s-1, calculated at 1173 K. The change in diffusion coefficient (D=1.95 x 10-7 cm2 s-1 at 1173 K) was negligible on doping 50% Fe in the structure. However, in 100% Fe substituted structure, GdBaFe2O5.5 (GBFO5.5), the diffusivity was significantly reduced (D=2 x 10-8 cm2 s-1 at 1173 K).

The effect of LiBF4 salt concentration in EC-DMC based electrolyte on the stability of nanostructured LiMn2O4 cathode

Electrolytes which have different LiBF4 salt concentrations (0.8 m, 1.0 m, 1.2 m and 1.4 m) in the ratio of 2:1 (w/w) Ethylene Carbonate (EC): Dimethyl Carbonate (DMC) solvents were prepared. Obtained electrolytes were used to assemble half-cells containing metallic Li anode and nanostructured LiMn2O4 cathode material. In order to investigate the effect of LiBF4 salt concentration on the stability of LiMn2O4 cathode material after electrochemical tests with 100 cycles, the cells were disassembled and the cathode materials were taken out to examine the effect of electrolyte solutions on the stability of nanostructured LiMn2O4 cathode materials via Raman, XRD and FEG-SEM methods. The optimum LiBF4 salt concentration was found for LiBF4-EC-DMC based electrolyte solutions and results showed that higher salt concentration contributes to the stability of the bare nanostructured LiMn2O4 cathode material even after 100 cycles charge–discharge test. In addition, the electrode degradation arising from the lower LiBF4 salt concentration is compatible with the electrochemical capacity fading for the cathode materials compared with our previous work.