New lithium salts in electrolytes for lithium-ion batteries (Review)

The properties of electrolyte systems based on standard nonaqueous solvent composed of a mixture of dialkyl and alkylene carbonates and new commercially available lithium salts potentially capable of being an alternative to thermally unstable and chemically active lithium hexafluorophosphate LiPF₆ in the mass production of lithium-ion rechargeable batteries are surveyed. The advantages and drawbacks of electrolytes containing lithium salts alternative to LiPF₆ are discussed. The real prospects of substitution for LiPF₆ in electrolyte solutions aimed at improving the functional characteristics of lithium-ion batteries are assessed. Special attention is drawn to the efficient use of new lithium salts in the cells with electrodes based on materials predominantly used in the current mass production of lithium-ion batteries: grafitic carbon (negative electrode), LiCoO₂, LiMn₂O₄, LiFePO₄, and also solid solutions isostructural to lithium cobaltate with the general composition LiMO₂ (M = Co, Mn, Ni, Al) (positive electrode).     

Preparation and characterization on the carbon nanotube chemically modified electrode grown in situ

Carbon nanotube chemically modified electrode (CNT-CME) was prepared by growing carbon nanotube (CNT) in situ on the pretreated graphite electrode (GE) via the catalytic chemical vapor deposition. The pretreated GE was prepared by ultrasonic immersion method using Ni(NO₃)₂ as the catalyst. The CNT growing on the CNT-CME was characterized by transmission electron microscope and scanning electron microscope. The obtained electrode electrochemical performance was characterized by cyclic voltammetry with the Na₂SO₄ solution and [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ solution. The results showed that the obtained electrode has good current responsive sensitivity and good testing result accuracy, indicating that the obtained electrode may have great application in electrochemical testing field.     

Development of a new in situ cell for the X–ray Absorption Fine Structure analysis of the electrochemical reaction in a rechargeable battery and its application to the Lithium Battery Material,Li1+yMn2−yO4

An electrochemical cell was developed for the in situ transmission X–ray Absorption Fine Structure measurements of the charge/discharge process of the cathode materials of lithium secondary batteries, from which Li can be electrochemically deintercalated or intercalated. The dynamical structural behavior of Mn in Li(Mn_1.93Li_0.07)O₄, and Li(Mn_1.85Li_0.15)O₄ as a function of both excess Li content and the Li deintercalation was revealed using the in situ cell. The analysis disclosed the coexistence of two MnO₆–coordination polyhedra with different Mn–O distances for the Mn³⁺ and Mn⁴⁺ ions at the 16d site of the spinel structure. Because the charge–discharge process accompanies the oxidation–reduction of the Mn ions, this size difference causes an unfavorable lattice distortion for the electrode materials which can cause a loss of cell capacity after cyclic use of the cell. A partial substitution of Li for Mn will diminish this effect and will be favorable for the battery material.     

A novel bacterial cellulose-based carbon paste electrode and its polyoxometalate-modified properties

A novel bacterial cellulose nanofiber-based carbon paste electrode (BCPE) was fabricated. It was characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Compared with traditional carbon paste electrode, BCPE exhibited better electrochemical reversibility with the enhancement of the redox currents and decrease of peak potential separation as well as lower charge transfer resistance in Fe(CN)₆^3?/4? redox system. Keggin-type sodium phosphopolyoxomolybdate, PMo₁₂, was successfully assembled on BCPE via cyclic voltametric scan, and the obtained PMo₁₂/BCPE possessed not only a good electrochemical behavior but also an excellent electrocatalytic activity toward the reduction of nitrite. Because of its nano-dimension, lower cost and prominent electrochemical properties, bacterial cellulose-based carbonaceous materials would be a candidate of graphite for the preparation of novel carbon paste electrode.     

Carbon Electrode Materials for Advanced Potassium-Ion Storage

Tremendous progress has been made in the field of electrochemical energy storage devices that rely on potassium-ions as charge carriers due to their abundant resources and excellent ion transport properties. Nevertheless, future practical developments not only count on advanced electrode materials with superior electrochemical performance, but also on competitive costs of electrodes for scalable production. In the past few decades, advanced carbon materials have attracted great interest due to their low cost, high selectivity, and structural suitability and have been widely investigated as functional materials for potassium-ion storage. This article provides an up-to-date overview of this rapidly developing field, focusing on recent advanced and mechanistic understanding of carbon-based electrode materials for potassium-ion batteries. In addition, we also discuss recent achievements of dual-ion batteries and conversion-type K−X (X=O₂, CO₂, S, Se, I₂) batteries towards potential practical applications as high-voltage and high-power devices, and summarize carbon-based materials as the host for K-metal protection and possible directions for the development of potassium energy-related devices as well. Based on this, we bridge the gaps between various carbon-based functional materials structure and the related potassium-ion storage performance, especially provide guidance on carbon material design principles for next-generation potassium-ion storage devices.     

Monitoring electrode/electrolyte interfaces of Li-ion batteries under working conditions: A surface-enhanced Raman spectroscopic study on LiCoO2 composite cathodes

Lithium-ion batteries are commonly used for electrical energy storage in portable devices and are promising systems for large-scale energy storage. However, their application is still limited due to electrode degradation and stability issues. To enhance the fundamental understanding of electrode degradation, we report on the Raman spectroscopic characterization of LiCoO₂ cathode materials of working Li-ion batteries. To facilitate the spectroscopic analysis of the solid electrolyte interface (SEI), we apply in situ surface-enhanced Raman spectroscopy under battery working conditions by using Au nanoparticles coated with a thin SiO₂ layer (Au@SiO₂). We observe a surface-enhanced Raman signal of Li₂CO₃ at 1090 cm⁻¹ during electrochemical cycling as an intermediate. Its formation/decomposition highlights the role of Li₂CO₃ as a component of the SEI on LiCoO₂ composite cathodes. Our results demonstrate the potential of Raman spectroscopy to monitor electrode/electrolyte interfaces of lithium-ion batteries under working conditions thus allowing relations between electrochemical performance and structural changes to be established.     

纳米级锂离子电池正极材料LiFePO4

LiFePO₄以其价格便宜,稳定性好,无毒等优点而倍受关注。但是非纳米LiFePO₄的电子导电率低及扩散系数小限制了其在锂离子电池领域的大规模应用。而纳米电极材料以其特有的优点很好的解决了这些问题。本文主要综述了国内外合成纳米级LiFePO₄ 的不同方法及所得材料的对电化学性能和相关机理,以及纳米LiFePO₄作为锂离子正极材料存在的问题。     

Quasi in situ XPS investigations on intercalation mechanisms in Li-ion battery materials

New concepts for Li-ion batteries are of growing interest for high-performance applications. One aim is the search for new electrode materials with superior properties and their detailed characterization. We demonstrate the application of X-ray photoelectron spectroscopy (XPS) to investigate electrode materials (LiCoO₂, LiCrMnO₄) during electrochemical cycling. The optimization of a “quasi in situ” analysis, by transferring the samples with a transport chamber from the glove box to the XPS chamber, and the reliability of the experiments performed are shown. The behavior of characteristic chemical species at the electrodes and the changes in oxidation states of LiCrMnO₄ during cycling is discussed. The formation of Cr⁶⁺ is suspected as a possible reason for irreversible capacity loss during charging up to complete Li deintercalation (approximately 5.2 V). Figure Scheme of a quasi in situ XPS experiment on Li-ion battery electrode material     

Review and prospect of layered lithium nickel manganese oxide as cathode materials for Li-ion batteries

Layered structural lithium metal oxides with rhombohedral α-NaFeO₂ crystal structure have been proven to be particularly suitable for application as cathode materials in lithium-ion batteries. Compared with LiCoO₂, lithium nickel manganese oxides are promising, inexpensive, nontoxic, and have high thermal stability; thus, they are extensively studied as alternative cathode electrode materials to the commercial LiCoO₂ electrode. However, a lot of work needs to be done to reduce cost and extend the effective lifetime. In this paper, the development of the layered lithium nickel manganese oxide cathode materials is reviewed from synthesis method, coating, doping to modification, lithium-rich materials, nanostructured materials, and so on, which can make electrochemical performance better. The prospects of lithium nickel manganese oxides as cathode materials for lithium-ion batteries are also looked forward to.     

Ammonium Ion Batteries: Material,Electrochemistry and Strategy

Ammonium-ion batteries (AIBs) have recently attracted increasing attention in the field of aqueous batteries owing to their high safety and fast diffusion kinetics. The NH₄⁺ storage mechanism is quite different from that of spherical metal ions (e.g. Li⁺, Na⁺, K⁺, Mg²⁺, and Zn²⁺) because of the formation of hydrogen bonds between NH₄⁺ and host materials. Although many materials have been proposed as electrode materials for AIBs, their performances hardly meet the requirement of future electrochemical energy storage devices. It is thus urgent to design and exploit advanced materials for AIBs. This review highlights the state-of-the-art research on AIBs. The insights into the basic configuration, operating mechanism and recent progress of electrode materials and corresponding electrolytes for AIBs have been comprehensively outlined. The electrode materials are classified and compared according to different NH₄⁺ storage behaviour in the structure. The challenges, design strategies and perspectives are also discussed for the future development of AIBs.     

On the use of the reverse micelles synthesis of nanomaterials for lithium-ion batteries

The reverse micelles procedure is a convenient route for the preparation of nanomaterials. Chemical reactions in aqueous media are carried out within a restricted volume, limited by the array of surfactant molecules. The versatility of this technique allows its use in the preparation of different electrode materials for lithium-ion batteries. The thermolysis of the reagents in aqueous solution in the micellar volume by contact with hot kerosene allows the preparation of LiCoO₂, LiMn₂O₄, and LiNi_0.5Mn_1.5O₄ fine powders with good electrochemical behavior. The conversion electrode material Co₃O₄ was prepared with controlled particle size and microstructure by a precipitation reaction in the micellar volume. The electrochemical response found in lithium cells was excellent after optimizing the annealing procedure. Cobalt and iron oxalate nanoribbons and submicrometric rhombic particles of manganese carbonate have been prepared by the reverse micelles procedure and partially behave as conversion oxide electrodes. The electrochemical reaction with lithium of these new oxysalt materials takes place by a different conversion reaction than the corresponding oxide, and a surface capacitive contribution has also been detected.     

Diffusion aspects of lithium intercalation as applied to the development of electrode materials for lithium-ion batteries

The creation of new electrode materials and the modification of existing ones are important trends in the development of lithium-ion batteries. Of special significance is to evaluate their diffusivity, i.e., the ability of providing transfer of the electroactive component. Such electrochemical techniques as cyclic voltammetry, electrochemical impedance spectroscopy, potentiostatic intermittent titration technique, and galvanostatic intermittent titration technique are used for this purpose. The values of chemical diffusion coefficient D estimated in similar electrode materials are shown to scatter by several orders of magnitude. Principal causes of this rather considerable scattering are discussed, including the uncertainty of diffusion area estimations and the use of various approaches to deriving equations to calculate D. Our conclusions are illustrated by examples of D estimations in the electrode materials Li _x C₆, Li _x Sn, Li _x TiO₂, Li _x WO₃, LiM _y Mn_2?y O₄, and LiFePO₄.     

Lithium Ferrocyanide Catholyte for High-Energy and Low-cost Aqueous Redox Flow Batteries**

Aqueous redox flow batteries (ARFBs) are a promising technology for grid-scale energy storage, however, their commercial success relies on redox-active materials (RAM) with high electron storage capacity and cost competitiveness. Herein, a redox-active material lithium ferrocyanide (Li₄[Fe(CN)₆]) is designed. Li⁺ ions not only greatly boost the solubility of [Fe(CN)₆]⁴⁻ to 2.32 M at room temperature due to weak intermolecular interactions, but also improves the electrochemical performance of [Fe(CN)₆]^4−/3−. By coupling with Zn, ZIRFBs were built, and the capacity of the batteries was as high as 61.64 Ah L⁻¹ (pH-neutral) and 56.28 Ah L⁻¹ (alkaline) at a [Fe(CN)₆]⁴⁻ concentration of 2.30 M and 2.10 M. These represent unprecedentedly high [Fe(CN)₆]⁴⁻ concentrations and battery energy densities reported to date. Moreover, benefiting from the low cost of Li₄[Fe(CN)₆], the overall chemical cost of alkaline ZIRFB is as low as $11 per kWh, which is one-twentieth that of the state-of-the-art VFB ($211.54 per kWh). This work breaks through the limitations of traditional electrolyte composition optimization and will strongly promote the development of economical [Fe(CN)₆]^4−/3−-based RFBs in the future.     

钴基双金属氧化物的制备及其在电化学储能领域的应

钴基双金属氧化物MCo₂O₄（M=Ni、Zn、Mn等）既继承了单一钴金属氧化物（Co₃O₄、CoO等）高比容量的优点,又引入了新的改性金属元素用于改善其导电性差、倍率性能不佳等缺点,是一种潜在的新型电化学储能材料。本文分类介绍了NiCo₂O₄、ZnCo₂O₄、MnCo₂O₄等钴基双金属氧化物及其复合物的现有研究（包括制备方法、形貌结构、颗粒尺寸及其电化学性能）,阐述了改性手段的可能性机理,并对钴基双金属氧化物后续研究提出了一些看法。     

Atomic Insights into Aluminium-Ion Insertion in Defective Anatase for Batteries

Aluminium batteries constitute a safe and sustainable high-energy-density electrochemical energy-storage solution. Viable Al-ion batteries require suitable electrode materials that can readily intercalate high-charge Al³⁺ ions. Here, we investigate the Al³⁺ intercalation chemistry of anatase TiO₂ and how chemical modifications influence the accommodation of Al³⁺ ions. We use fluoride- and hydroxide-doping to generate high concentrations of titanium vacancies. The coexistence of these hetero-anions and titanium vacancies leads to a complex insertion mechanism, attributed to three distinct types of host sites: native interstitial sites, single vacancy sites, and paired vacancy sites. We demonstrate that Al³⁺ induces a strong local distortion within the modified TiO₂ structure, which affects the insertion properties of the neighbouring host sites. Overall, specific structural features induced by the intercalation of highly polarising Al³⁺ ions should be considered when designing new electrode materials for polyvalent batteries.     

钴基双金属氧化物的制备及其在电化学储能领域的应用

钴基双金属氧化物MCo₂O₄（M=Ni、Zn、Mn等）既继承了单一钴金属氧化物（Co₃O₄、CoO等）高比容量的优点,又引入了新的改性金属元素用于改善其导电性差、倍率性能不佳等缺点,是一种潜在的新型电化学储能材料。本文分类介绍了NiCo₂O₄、ZnCo₂O₄、MnCo₂O₄等钴基双金属氧化物及其复合物的现有研究（包括制备方法、形貌结构、颗粒尺寸及其电化学性能）,阐述了改性手段的可能性机理,并对钴基双金属氧化物后续研究提出了一些看法。     

3d-Transition metal doped spinels as high-voltage cathode materials for rechargeable lithium-ion batteries

Finding appropriate positive electrode materials for Li-ion batteries is the next big step for their application in emerging fields like stationary energy storage and electromobility. Among the potential materials 3d-transition metal doped spinels exhibit a high operating voltage and, therefore, are highly promising cathode materials which could meet the requirements regarding energy and power density to make Li-ion batteries the system of choice for the above mentioned applications. The compounds considered here include substituted Mn-based spinels such as LiM_0.5Mn_1.5O₄ (M = Ni, Co, Fe), LiCrMnO₄ and LiCrTiO₄. In this review, the recent researches conducted on these spinel materials are summarized. These include different routes of synthesis, structural studies, electrode preparation, electrochemical performance and mechanism of Li-extraction/insertion, thermal stability as well as degradation mechanisms. Note that even though the Ni-, Co-, and Fe-doped materials share the same chemical formula, the oxidation state distributions as well as the operating voltages are different among them. Furthermore, apart from the initial structural similarity, the Li-intercalation takes place through different mechanisms in different materials. In addition, this difference in mechanism is found to have considerable influence on the long-term cycling stability of the material. The routes to improve the electrochemical performance of some of the above candidates are discussed. Further emphasis is given to the parameters that limit their application in current technology, and strategies to overcome them are addressed.     

Recent advances of transition metal oxalate-based micro- and nanomaterials for electrochemical energy storage: a review

A key challenge in the development of electrochemical energy storage (EES) is the design and engineering of electrode materials for electrochemical reactions. Transition metal oxalates (TMOxs) have been widely used in various EES applications due to their low cost, simple synthesis, and excellent electrochemical performance. In this review, the recent advances in the design and engineering of transition metal oxalate-based micro- and nanomaterials for EES are summarized. Specifically, the survey will focus on three types of micro- and nano-scale TMOxs (monometallic, bimetallic, and trimetallic TMOxs), their composites (TMOx-metal oxide, TMOx-hydroxide, TMOx-GO, and TMOx-MOFs composites), and derivatives, including transition metal oxides (TiO₂, V₂O₅, Mn_xO_y, Co₃O₄, NiO, CuO, and Nb₂O₅), multi-transition metal oxides (MCo₂O₄ (M = Ni, Cu, and Zn), NiMn₂O₄, and N_xO_y-M_xO_y), transition metal sulfide (NiS₂), and carbon materials (ordinary carbon, GO and their composites), within the context of their intrinsic structure and corresponding electrochemical performance. A range of experimental variables will be carefully analyzed, such as sample synthesis, crystal structure, and electrochemical reaction mechanism. The applications of these materials as EES electrodes are then featured for supercapacitors (SCs) and lithium-ion batteries (LIBs). We conclude the review with a perspective of future research prospects and challenges.     

Determination of Paracetamol Based on 3-Amino-4H-1,2,4-triazole Coated Glassy Carbon Surface in Pharmaceutical Sample

In this present study, to determine paracetamol, an electroanalytical method is presented using differential pulse voltammetry (DPV) at 3-amino-4H-1,2,4-triazole (3AT) coated glassy carbon (GC) electrode. The electrochemical characterization and electron transfer behavior of this prepared electrode in the mixture of K₄[Fe(CN)₆]/K₃[Fe(CN)₆] contains 0.1 M KCl was confirmed by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. Furthermore, scanning electron microscopy (SEM) was used to observe morphological structures of the bare and modified surfaces. The effect of pH was studied on the redox reaction of paracetamol in phosphate buffer in the range of pH 3.0–9.0. The limit of detection was 0.043 μM (3 s/m) for 3AT-GC electrode. The developed electrode was successfully utilized in pharmaceutical samples.     

Molybdenum Disulfide Based Nanomaterials for Rechargeable Batteries

The rapid development of electrochemical energy storage systems requires new electrode materials with high performance. As a two-dimensional material, molybdenum disulfide (MoS₂) has attracted increasing interest in energy storage applications due to its layered structure, tunable physical and chemical properties, and high capacity. In this review, the atomic structures and properties of different phases of MoS₂ are first introduced. Then, typical synthetic methods for MoS₂ and MoS₂-based composites are presented. Furthermore, the recent progress in the design of diverse MoS₂-based micro/nanostructures for rechargeable batteries, including lithium-ion, lithium-sulfur, sodium-ion, potassium-ion, and multivalent-ion batteries, is overviewed. Additionally, the roles of advanced in situ/operando techniques and theoretical calculations in elucidating fundamental insights into the structural and electrochemical processes taking place in these materials during battery operation are illustrated. Finally, a perspective is given on how the properties of MoS₂-based electrode materials are further improved and how they can find widespread application in the next-generation electrochemical energy-storage systems.