Battery Cathode Research Articles

Outstanding specific capacitance of air plasma exposed MgCoSiO4 cathode in the rechargeable magnesium batteries

Outstanding specific capacitance of air plasma exposed MgCoSiO4 cathode in the rechargeable magnesium batteries

Recyclable Fluorine‐Free Water‐Borne Binders for High‐Energy Lithium‐Ion Battery Cathodes

AbstractThe rapidly increasing demand for lithium‐ion batteries and the fight against climate change call for novel materials that enhance performance, enable eco‐friendly processing, and are designed for efficient recycling. In lithium‐ion batteries, the binder polymer, used for cathode production, constitutes an integral but often overlooked component. The currently used polyvinylidene fluoride is processed with toxic organic solvents and has numerous other disadvantages concerning adhesion, conductivity, and recyclability. A change to aqueous processing using new, multi‐functional, purpose‐built materials that are soluble in water and fluorine‐free would thus constitute an important advance in the battery sector. Herein, four water‐soluble surfactant‐like polymers based on 11‐aminoundecanoic acid, that can be obtained in high purity and at a multigram scale are described. Free radical polymerization allows modification of the polymer with a wide variety of comonomers. The materials presented significantly enhance adhesion, are thermally stable at temperatures up to 350 °C, and are compatible with state‐of‐the‐art high‐energy LiNi0.6Mn0.2Co0.2O2 (NMC 622) cathode materials. It is also shown new recycling pathways made possible by the reversible pH‐dependent water‐solubility of the materials.

Organosulfur Cathodes in Lithium Metal Batteries: Bridging the Gap between Fundamentals and Practical Applications

AbstractHigh‐specific energy sulfur‐based cathodes have attracted considerable interest in lithium batteries. Organosulfur cathodes offer inherent advantages of high element abundance and an extended cycling life, aligning with the evolving requirements of future energy storage devices. Over the past decade, research efforts have been devoted to optimizing electrochemical performance through the rich and tunable molecular structures of organosulfur compounds. To further advance the fundamental research and practical application of lithium‐organosulfur batteries, a systematical analysis of the correlation between the molecular structures and electrochemical mechanisms of organosulfur cathodes is imperative. This involves deriving the key parameters at the cell level and investigating the feasibility. In this review, the thermodynamics, reaction processes, and electrochemical kinetics of organosulfur cathodes, grounded in fundamental theories of electrochemistry and materials science are discussed. Expanding the insights, comparisons among elemental sulfur, organosulfur, and n‐type organic cathodes (e.g., carbonyl cathodes) are drawn. The gap between fundamentals and practical applications targeting 500 Wh kg−1 lithium organosulfur batteries is highlighted through energy density calculations and identification of key factors affecting pouch cells. Finally, potential strategies and prospects for the overall design of advanced lithium‐organosulfur batteries are proposed, considering both theoretical foundations and practical implementations.

Solid-Solution Reaction and Ultrasmall Volume Change in High-Entropy P2-type Layered Oxide Cathode for All-Climate Sodium-Ion Batteries

Solid-Solution Reaction and Ultrasmall Volume Change in High-Entropy P2-type Layered Oxide Cathode for All-Climate Sodium-Ion Batteries

Destabilization of Oxidized Lattice Oxygen in Layered Oxide Cathode.

Integrating anion-redox capacity with orthodox cation-redox capacity is deemed as a promising solution for high-energy-density battery cathodes surmounting the present technical bottlenecks. However, the evolution of oxidized oxygen species during the electrochemical or chemical process easily jeopardizes the reversibility of oxygen redox and remains poorly understood. Herein, we showcase the gradual conversion of the π-interacting oxygen (localized hole states on O) to the σ-interacting oxygen upon resting at a high voltage for P3-type Na0.6Li0.2Mn0.8O2 with nominally stable ribbon-like superstructure, accompanied by the O-O dimerization and the local structural reorganization. We further pinpoint an abnormal Li+ migration process from the alkali-metal layer to the transition-metal layer for desodiated P3-Na0.6Li0.2Mn0.8O2, thereby leading to a partial reconstruction of the ribbon superstructure. The high-voltage plateau of oxygen-redox cathodes is concluded to be exclusively controlled by the oxygen stabilization mechanism rather than the superstructure ordering. In addition, there exists a kinetic competition between π and σ interaction during the uninterrupted electrochemical process.

Manipulating Local Chemistry and Coherent Structures for High-Rate and Long-Life Sodium-Ion Battery Cathodes.

Layered sodium transition-metal (TM) oxides generally suffer from severe capacity decay and poor rate performance during cycling, especially at a high state of charge (SoC). Herein, an insight into failure mechanisms within high-voltage layered cathodes is unveiled, while a two-in-one tactic of charge localization and coherent structures is devised to improve structural integrity and Na+ transport kinetics, elucidated by density functional theory calculations. Elevated Jahn-Teller [Mn3+O6] concentration on the particle surface during sodiation, coupled with intense interlayer repulsion and adverse oxygen instability, leads to irreversible damage to the near-surface structure, as demonstrated by X-ray absorption spectroscopy and in situ characterization techniques. It is further validated that the structural skeleton is substantially strengthened through the electronic structure modulation surrounding oxygen. Furthermore, optimized Na+ diffusion is effectively attainable via regulating intergrown structures, successfully achieved by the Zn2+ inducer. Greatly, good redox reversibility with an initial Coulombic efficiency of 92.6%, impressive rate capability (86.5 mAh g-1 with 70.4% retention at 10C), and enhanced cycling stability (71.6% retention after 300 cycles at 5C) are exhibited in the P2/O3 biphasic cathode. It is believed that a profound comprehension of layered oxides will herald fresh perspectives to develop high-voltage cathode materials for sodium-ion batteries.

Bi2S3 for aqueous copper ion battery based intercalation chemistry

Aqueous multivalent ion batteries have attracted increasing attention due to their high capacity, long cycle life, and impressive output energy. Considering that intercalation electrodes are more suitable for long cycle battery compared to the conversion ones, Cu2+ with appropriate ion radii has been chosen as intercalation carriers and bismuth sulfide with the matched lattice spacing as cathode to achieve long cycle life aqueous battery. We have synthesized the micrometer-scale flower-like Bi2S3 by regulating temperature and it is proved to be a perennial phase during Cu2+ intercalation/deintercalation of the Bi2S3 host when charge/discharge with a capacity of 104.5 mAh g–1 retention at 0.5 A g–1 after 1000 cycles. Lastly, build a hybrid ion battery with Zn and ZnSO4 electrolyte, the Bi2S3 cathode for Cu2+ intercalation can reach a maximum energy of 427.5 Wh Kg–1. The study provides a new intercalation cathode for aqueous multivalent ion batteries and will broaden the energy storage system.

Mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT cathode for sodium-ion batteries: Electrochemical diffusion kinetics and distribution of relaxation time analysis at different temperatures

We report the electrochemical sodium-ion kinetics and distribution of relaxation time (DRT) analysis of a newly designed mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT composite as a cathode. The specific capacity of 104 mAhg−1 is observed at 0.1 C with the average working voltage of ∼3 V. Intriguingly, a remarkable rate capability and reversibility are demonstrated up to very high current rate of 25 C. The long cycling test up to 10 C shows high capacity retention even after 2000 cycles. The detailed analysis of galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) data reveal the diffusion coefficient of 10−8–10−11 cm2s−1. We find excellent stability in the thermal testing between 25–55 °C temperatures and 80% capacity retention up to 100 cycles at 5 C. Further, we analyze the individual electrochemical processes in the time domain using the novel DRT technique at different temperatures. The ex-situ investigation shows the stable and reversible structure, morphology and electronic states of the long cycled cathode material. More importantly, we demonstrate relatively high specific energy of ≈155 Wh kg−1 (considering the total active material loading of both the electrodes) at 0.2 C for full cell battery having excellent rate capability up to 10 C and long cyclic stability at 1 C.

Supramolecular channels via crown ether functionalized polyaniline for proton-self-doped cathode in aqueous zinc-ion battery

Polyaniline (PANI) has been widely used as a cathode in aqueous zinc-ion batteries (AZIBs) because of its attractive conductivity and energy storage capability. However, the extensive application of PANI is limited by spontaneous deprotonation and slow diffusion kinetics. Herein, an 18-crown-6-functionalised PANI pseudorotaxane (18C6@PANI) cathode is successfully developed through a facile template-directed polymerisation reaction. The 18C6@PANI cathode exhibits a high specific capacity of 256 mAh g−1 at 0.2 A/g, excellent rate performance of 134 mAh g−1 at 6 A/g and outstanding cycle stability at a high current density of 3 A/g over 10,000 cycles. Experimental and theoretical analyses demonstrate the formation of the –N–Zn–O– structure. The abundant supramolecular channels in pseudorotaxane, induced by crown ether functional groups, are beneficial for achieving superior cyclability and rate capability. These encouraging results highlight the potential for designing more efficient PANI-based cathodes for high-performance AZIBs.

Improved electrochemical performance of Li-excessive LiMn2O4 cathode for secondary batteries

Improved electrochemical performance of Li-excessive LiMn2O4 cathode for secondary batteries

Revealing the origin of enhanced structural stability for nickel-rich LiNi0.83Co0.11Mn0.06O2 cathodes in situ modified with multifunctional polysiloxane

Multifunctional polysiloxane (MPS) layer is elaborately constructed on the surface of LiNi0.83Co0.11Mn0.06O2 (NCM83) particles via in situ hydrolysis-polycondensation of tetraethyl orthosilicate. Impressively, optimal NCM83 (NCM83-2) electrode covered with average 7 nm-thickness of fresh MPS layer delivers improved capacity retention ratio of 81.8 % after 150 cycles at 25 °C and retains the value of 78.7 % after 200 cycles at 60 °C and 1.0 C. Moreover, NCM83-2 electrode presents lower polarization degree with sluggish growth of the capacity platform. The significant advantages of NCM83-2 can be interpreted by the fact that the MPS layer effectively mitigates microcracks generation by inhibiting phase transition and lattice oxygen loss. Moreover, the MPS protective layer suppresses the thickening of cathode electrolyte interphase film and boosts the structural stability of NCM83 electrode to optimize electrochemical properties. Therefore, this strategy may provide promising enlightenments for preserving structural integrity and improving interfacial stability of nickel-rich cathodes for lithium-ion batteries.

Modulating Valence Electrons and Na Occupancy in Layered Cathodes for High-Performance Na-Ion Batteries.

Na-ion batteries (NIBs) hold promise as a leading option for large-scale energy storage. However, their development faces challenges due to the lack of high-performance cathode materials. P2-type layered oxides are seen as potential cathode materials for NIBs due to higher structure stability, yet their commercialization is hindered by limited capacity and subpar phase transitions during Na extraction and insertion at high voltages. In this study, we introduce a new P2-type cathode material, Na0.76Ni0.23Li0.1Ti0.02Mn0.65O1.998F0.02 (NLTMOF), synthesized with ternary Li/Ti/F substitution. This modification of ternary Li/Ti/F substitution significantly tailors the electronic structures, increasing the number of valence electrons near the Fermi energy level. This facilitates the electronic conductivity and their involvement in charge compensation, thereby enhancing reversible capacity. Additionally, ternary doping synergistically adjusts the Na occupancy at the Na layer for favorable Na extraction without P2-O2 phase transitions even under a high voltage of 4.4 V, boosting cycling stability. As a result, NLTMOF demonstrates a reversible capacity of 110.0 and 132.2 mAh g-1 at 2-4.2 and 2-4.4 V, respectively, and maintains greatly enhanced cycling stability over long cycles. This study sheds light on the design of transition metal oxides for advanced cathode materials through the modulation of electronic structure and Na occupancy in cathode materials, thus promoting the development of NIBs.

Flower-like covalent organic frameworks as host materials for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as a promising alternative energy storage system due to their high energy density and cost-effectiveness. However, practical applications of Li-S batteries are hindered by challenges such as the shuttle effect and sluggish redox kinetics. In this study, a three-dimensional (3D) flower-like diaminoanthraquinone (DAAQ)-covalent organic framework (COF) was developed, featuring nanorod-like petals and enriched with abundant N and O adsorption sites, serving as a host material for the sulfur cathode of Li-S batteries. Through a process of sulfur melting-diffusion, the resulting DAAQ-COF@S cathode material demonstrated a stable 3D cross-linked morphology with a hierarchical pore structure, maximizing the exposure of N/O adsorptive sites and facilitating rapid ion diffusion. This effectively inhibited the shuttling effect of lithium polysulfides (LiPSs) and enhanced rate performance. Consequently, DAAQ-COF@S cathodes exhibited a high initial discharge capacity of 1182.0 mAh g−1 at 0.1 C, with a capacity retention rate of 79.6% after 500 cycles at 2 C. Even at a high current density of 4 C, they maintained a high capacity of 616.8 mAh g−1, surpassing the majority of previously reported COF-based host materials for Li-S batteries. This work underscores the significance of COF micromorphology and advances the development of high-performance cathodes for Li-S batteries.

A Feasible Dual Modification Strategy of Internal Anion Redox Chemistry and Surface Engineering on P2 Layer-Structured Cathodes in Sodium-Ion Batteries.

Boosting the anion redox reaction opens up a possibility of further capacity enhancement on transition-metal-ion redox-only layer-structured cathodes for sodium-ion batteries. To mitigate the deteriorating impact on the internal and surface structure of the cathode caused by the inevitable increase in the operation voltage, probing a solution to promote the bulk-phase crystal structure stability and surface chemistry environment to further facilitate the electrochemical performance enhancement is a key issue. A dual modification strategy of establishing an anion redox hybrid activation trigger agent inside the crystal structure in combination with surface oxide coating is successfully developed. P2-type layer structure cathode materials with Zn/Li (Na-O-Zn@Na-O-Li) anion redox hybrid triggers and a ZnO coating layer possess superior capacity and cycle performance, along with outstanding structural stability, decreased Mn-ion dissolution effect, and less crystal particle cracking during the cycling process. This study represents a facile modification solution to perform structure optimization and property enhancement toward high-performance layered structure cathode materials with anion redox features in sodium-ion batteries.

Lithium-Ion Conductive Coatings for Nickel-Rich Cathodes for Lithium-Ion Batteries.

Nickel (Ni)-rich cathodes are among the most promising cathode materials of lithium batteries, ascribed to their high-power density, cost-effectiveness, and eco-friendliness, having extensive applications from portable electronics to electric vehicles and national grids. They can boost the wide implementation of renewable energies and thereby contribute to carbon neutrality and achieving sustainable prosperity in the modern society. Nevertheless, these cathodes suffer from significant technical challenges, leading to poor cycling performance and safety risks. The underlying mechanisms are residual lithium compounds, uncontrolled lithium/nickel cation mixing, severe interface reactions, irreversible phase transition, anisotropic internal stress, and microcracking. Notably, they have become more serious with increasing Ni content and have been impeding the widespread commercial applications of Ni-rich cathodes. Various strategies have been developed to tackle these issues, such as elemental doping, adding electrolyte additives, and surface coating. Surface coating has been a facile and effective route and has been investigated widely among them. Of numerous surface coating materials, have recently emerged as highly attractive options due to their high lithium-ion conductivity. In this review, a thorough and comprehensive review of lithium-ion conductive coatings (LCCs) are made, aimed at probing their underlying mechanisms for improved cell performance and stimulating new research efforts.

Tuning Electronegativity‐Difference Configuration to Construct Non‐Bonded O 2p Orbitals for Reversible Anionic Redox in O3‐Type Cathode

AbstractHow to tune the activity and reversibility of oxygen anion redox (OAR) is a critical issue for O3‐type sodium‐ion battery (SIB) cathodes. Herein, the key role of electronegativity‐difference configuration on the activation of OAR is find out, and further tune electronegativity‐difference configuration with La incorporation to construct non‐bonded O 2p orbitals and achieve the reversible anionic redox in O3‐type NaMn1/3Fe1/3Ni1/3O2. Owing to the special extranuclear electronic structure of La3+ [Xe], the La electron cloud is difficult to be disturbed by the O electron cloud, and some O electrons do not participate in the formation of ionic bonds, thus retaining the non‐bonded electrons of O 2p and activating OAR. Moreover, La3+ doping also decreases the Coulomb force between Na+ and O2− favoring Na+ migration as well as strengthening the La─O bonds inhibiting the irreversible phase transition. La2O3 coating layer also plays a role on inhibiting the reaction between molecular oxygen and the electrolyte, and making OAR reversible. After modification, the cycling stability is significantly improved (86.9% vs 27.3%@2C@200cycles; 90.8% vs 52.9%@5C@300 cycles). This study presents some insights on OAR activation mechanism and offers a facile strategy to improve the activity and reversibility of OAR for designing high performance SIBs cathodes.

Deep eutectic solvent with acidity, reducibility, and coordination capability for recycling of valuable metals from spent lithium-ion battery cathodes

The substantial increase in spent lithium-ion batteries (SLIB) has resulted in serious environmental impacts that require attention and appropriate intervention. In this study, we designed a DES composed of ethylene glycol (EG) and hydroxylamine hydrochloride (NH2OH·HCl) with appropriate acidity, remarkable reductive property and strong coordination capability for the efficient one-step leaching of cobalt ions and lithium ions from LiCoO2 (LCO). Following leaching at a modest temperature of 80 °C for 8 h, the solubility of LiCoO2 reaches an 83.3 mg g−1 (much higher than previous works), accompanied by remarkably high leaching efficiencies of up to 99.7 % for lithium and 88.0 % for recovery of cobalt. Notably, this approach significantly enhances the solubility of the LiCoO2 while upholding leaching efficiency. Importantly, this study achieves a one-step separation of lithium and cobalt, avoiding metal co-precipitation and simplifying the separation procedure. Furthermore, the residual components within the system can be reclaimed and recycled. This work provides an efficient and sustainable route for the recovery of precious metals from lithium-ion batteries, characterized by its cost-effectiveness and straightforward processing.

High Capacity and Fast Kinetics Enabled by Metal-Doping in Prussian Blue Analogue Cathodes for Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have gained tremendous attention as promising low-cost electrochemically-tunable electrode materials, which can accommodate large Na+ ions with attractive specific capacity and charge-discharge kinetics. However, poor cycling stability caused by lattice strain and volume change remains to be improved. Herein, metal-doping strategy has been demonstrated in FeNiHCF, Na1.40Fe0.90Ni0.10[Fe(CN)6]0.85·1.3H2O, delivering a capacity as high as 148 mAh g‒1 at 10 mA g‒1. At an exceptionally high rate of 25.6 A g‒1, a reversible capacity of ~55 mAh g‒1 still can be obtained with a very small capacity decay rate of 0.02% per cycle for 1000 cycles, considered one of the best among all metal-doped PBAs. This exhibits the stabilizing effect of Ni doping which enhances structural stability and long-term cyclability. In situ synchrotron X-ray diffraction reveals an extremely small (~1%) change in unit cell parameters. The Ni substitution is found to increase the electronic conductivity and redox activity, especially at the low-spin (LS) Fe center due to inductive effect. This larger capacity contribution from LS Fe2+C6/Fe3+C6 redox couple is responsible for stable high-rate capability of FeNiHCF. The insight gained in this work may pave the way for the design of other high-performance electrode materials for sustainable sodium-ion batteries.

Consistent behaviors of KI in heat, light and electric fields towards the inversely vulcanized dicyclopentadiene cathode for lithium-sulfur batteries

The sulfured dicyclopentadiene (S-DCPD) is a promising cathode candidate for Li-S batteries. Enlightened by the function of KI in dye-sensitized solar cells, we employ KI as a catalyst in the preparation of S-DCPD without eliminating it in the assembly of Li-S batteries. As a result, the sulfurizing reaction proceeds more completely at a lower temperature. The as-prepared material exhibits a different light response to the blank sample, changing from a higher energy level to a lower one. And the electrochemistry is greatly elevated as well. Theoretical calculations validate that KI plays the key role by altering the electron transmitting path. We can thus unify the behaviors of KI in the field of heat, light, and electricity, phenomenally. Furthermore, we investigate the morphology changes of the electrode by dipping it in an ordinary solution and subjecting it to a cycle calendar life in the electrolyte, respectively. As a result, we make clear that the difference of the behaviors between ordinary solutions and electrolytes is also in associated with the electronic path of KI.

A Cu/MnOx Composite with Copper-Doping-Induced Oxygen Vacancies as a Cathode for Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries are anticipated to be the next generation of important energy storage devices to replace lithium-ion batteries due to the ongoing use of lithium resources and the safety hazards associated with organic electrolytes in lithium-ion batteries. Manganese-based compounds, including MnOx materials, have prominent places among the many zinc-ion battery cathode materials. Additionally, Cu doping can cause the creation of an oxygen vacancy, which increases the material's internal electric field and enhances cycle stability. MnOx also has great cyclic stability and promotes ion transport. At a current density of 0.2 A g-1, the Cu/MnOx nanocomposite obtained a high specific capacitance of 304.4 mAh g-1. In addition, Cu/MnOx nanocomposites showed A high specific capacity of 198.9 mAh g-1 after 1000 cycles at a current density of 0.5 A g-1. Therefore, Cu/MnOx nanocomposites are expected to be a strong contender for the next generation of zinc-ion battery cathode materials in high energy density storage systems.