Cathode Material Research Articles

Synthesis Pathway of Layered-Oxide Cathode Materials for Lithium-Ion Batteries by Spray Pyrolysis.

We report the synthesis of LiCoO2 (LCO) cathode materials for lithium-ion batteries via aerosol spray pyrolysis, focusing on the effect of synthesis temperatures from 600 to 1000 °C on the materials' structural and morphological features. Utilizing both nitrate and acetate metal precursors, we conducted a comprehensive analysis of material properties through X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Our findings reveal enhanced crystallinity and significant oxide decomposition within the examined temperature range. Morphologically, nitrate-derived particles exhibited hollow, spherical shapes, whereas acetate-derived particles were irregular. Guided by high-temperature X-ray diffraction (HT-XRD) data, the formation of a layered LCO oxide structure, with distinct spinel Li2Co2O4 and layered oxide LCO phases was shown to emerge at different annealing temperatures. Optimally annealed particles showcased well-defined layered structures, translating to high electrochemical performance. Specifically, nitrate-based particles annealed at 775 °C for 1 h demonstrated initial discharge capacities close to 179 mAh/g, while acetate-based particles, annealed at 750 °C for 3 h, achieved 136 mAh/g at a 0.1C discharge rate. This study elucidates the influence of synthesis conditions on LCO cathode material properties, offering insights that advance high throughput processes for lithium-ion battery materials synthesis.

A novel morphology of high voltage LiMn1.5Ni0.5O4 cathode material with niobium-doping

Spinel LiMn1.5Ni0.5O4 (LMNO) is one of the promising cathode materials for the next generation Li-ion batteries due to its voltage platform. However, the dissolution of the transition metal at high voltage is the biggest obstacle that LMNO suffers from. In this study, we successfully suppressed transition metal dissolution in LMNO by the morphology control from regular octahedron to spherical. Niobium was integrated as a dopant, which restricted the growth of (111) crystal face, and increased the indices of crystal faces by homogenizing the surface energy. By changing to a smaller surface area with spherical morphology, the contact area with the electrolyte was reduced, thus suppressing the dissolution of the Mn ion. Consequently, the niobium-doped LMNOexhibited superior rate performance, capacity retention with 74.1% at 1C after 500 cycles in half-cell, and thermal stability compared to pristine LMNO.

Nonmetal Substitution in Interstitial Site of O3‐NaNi0.5Mn0.5O2 Induces the Generation of a Nearly Zero Strain P2&O3 Biphasic Structure as Ultrastable Sodium‐Ion Cathode

AbstractCo‐free O3‐type NaNi0.5Mn0.5O2 cathode material for sodium‐ion batteries has shown great promise due to its high theoretical capacity and plentiful Na reservoir. However, the rapid capacity recession caused by harmful phase transition and large volume strain severely restricts their practical application. Herein, the obstacle is well addressed by constructing a P2&O3 biphasic structure via a customized boron‐doping strategy. The light‐weight boron doping in the interstitial position reduces the energy gap of the formation energy of P2 and O3 structure, which induces the formation of P2&O3 biphase in high Na state. In addition, the biphasic structure exhibits near zero volume strain due to the lattice interlocking effect of P2&O3, as identified by in situ X‐ray diffraction measurement. As a result, it presents a remarkable cyclability with a capacity retention of 85.2% over 1000 cycles at a high rate of 5 C. More importantly, a pouch‐type full‐cell device can exhibit a long cycling life with 70.8% capacity retention over 150 cycles at 0.1 C. This work can offer a new inspiration for designing advanced high sodium electrode materials via light element doping for future energy storage devices.

Ca-Doping Cobalt-Free Double Perovskite Oxide as a Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cell.

Mixed oxygen ion and electron-conducting materials are viable cathodes for solid oxide fuel cells due to their excellent oxygen transport kinetics and mixed electrical conductivity, which ensure highly efficient operation at low and medium temperatures. However, iron-based double perovskite oxides usually exhibit poor electrocatalytic activity due to low electron and oxygen ion conductivity. In this paper, Ca is doped in PrBaFe2O5+δ A-site to improve the electrochemical performance of PrBaFe2O5+δ. Results show that replacing Pr with Ca does not change the crystal structure, and the Ca doping effectively increases the adsorbed oxygen content and accelerates the migration and diffusion rate of O2- to the electrolyte|cathode interface. The polarization resistance of the symmetric cell PC0.15BF|CGO|PC0.15BF is 0.033 Ω·cm2 at 800 °C, which is about 56% lower than that of PBF, confirming the enhancement of the mixed conduction of oxygen ions and electrons. In addition, the anode-supported single cell has a peak power density of 512 mW·cm-2 at 800 °C.

Electrocatalytic Decomposition of Lithium Oxalate-Based Composite Microspheres as a Prelithiation Additive in Lithium-Ion Batteries.

In conventional lithium-ion batteries (LIBs), the active lithium from the lithium-containing cathode is consumed by the formation of a solid electrolyte interface (SEI) at the anode during the first charge, resulting in irreversible capacity loss. Prelithiation additives can provide additional active lithium to effectively compensate for lithium loss. Lithium oxalate is regarded as a promising ideal cathode prelithiation agent; however, the electrochemical decomposition of lithium oxalate is challenging. In this work, a hollow and porous composite microsphere was prepared using a mixture of lithium oxalate, Ketjen Black and transition metal oxide catalyst, and the formulation was optimized. Owing to the compositional and structural merits, the decomposition voltage of lithium oxalate in the microsphere was reduced to 3.93 V; when being used as an additive, there is no noticeable side effect on the performance of the cathode material. With 4.2% of such an additive, the first discharge capacity of the LiFePO4‖graphite full cell increases from 139.1 to 151.9 mAh g-1, and the coulombic efficiency increases from 88.1% to 96.3%; it also facilitates the formation of a superior SEI, leading to enhanced cycling stability. This work provides an optimized formula for developing an efficient prelithiation agent for LIBs.

Constructing High‐Performance Cobalt‐Based Environmental Catalysts from Spent Lithium‐Ion Batteries: Unveiling Overlooked Roles of Copper and Aluminum from Current Collectors

AbstractConverting spent lithium‐ion batteries (LIBs) cathode materials into environmental catalysts has drawn more and more attention. Herein, we fabricated a Co3O4‐based catalyst from spent LiCoO2 LIBs (Co3O4‐LIBs) and found that the role of Al and Cu from current collectors on its performance is nonnegligible. The density functional theory calculations confirmed that the doping of Al and/or Cu upshifts the d‐band center of Co. A Fenton‐like reaction based on peroxymonosulfate (PMS) activation was adopted to evaluate its activity. Interestingly, Al doping strengthened chemisorption for PMS (from −2.615 eV to −2.623 eV) and shortened Co−O bond length (from 2.540 Å to 2.344 Å) between them, whereas Cu doping reduced interfacial charge‐transfer resistance (from 28.347 kΩ to 6.689 kΩ) excepting for the enhancement of the above characteristics. As expected, the degradation activity toward bisphenol A of Co3O4‐LIBs (0.523 min−1) was superior to that of Co3O4 prepared from commercial CoC2O4 (0.287 min−1). Simultaneously, the reasons for improved activity were further verified by comparing activity with catalysts doped Al and/or Cu into Co3O4. This work reveals the role of elements from current collectors on the performance of functional materials from spent LIBs, which is beneficial to the sustainable utilization of spent LIBs.

N/S co-doped interconnected hierarchical porous carbon cathode for zinc-ion hybrid capacitors with high energy density

Porous carbon materials (PCMs) are regarded as one of the most promising cathode materials for zinc-ion hybrid capacitors (ZIHCs) because of their low cost and abundant resource. Nevertheless, it is still a major challenge to enhance the energy density of PCMs-based ZIHCs. Herein, N/S co-doped interconnected hierarchical porous carbons (NS-IHPCs) are prepared from coal tar pitch (CTP) via a MgO@ZIF-8 double-template, in situ activation and N/S doping strategy to tune the microstructure and chemical composition. The as-prepared NS-IHPC1.5 features high specific surface area of 1273 m2 g−1, hierarchical pore structure and suitable heteroatom doping. Consequently, as a cathode, the NS-IHPC1.5-based ZIHC exhibits a high energy density of 125.3 Wh kg−1 at 134.5 W kg−1 and still remains 85.3 Wh kg−1 at 14096.1 W kg−1. The calculation results of density functional theory (DFT) demonstrate that the combination of pyrrole nitrogen and ortho-oxidized sulfur in samples achieves more negative Zn2+ adsorption energy. Correspondingly, the high capacity (166.5 mAh g−1 at 0.2 A g−1) and long cycle stability (94.0% capacitance retention at 5 A g−1 after 20,000 cycles) are achieved for NS-IHPC1.5. This work offers a reliable way for synthesizing remarkable cathode materials from coal chemical by-products for energy storage.

Emerging Battery Systems with Metal as Active Cathode Material

AbstractThe high‐cost and limited availability of raw materials for lithium‐ion batteries hinder their future development and urge researchers to explore alternative battery systems. Among them, batteries utilizing the electrochemical redox reaction of metals such as Cu, Fe, Sn, etc. as the cathode to reversibly store and release energy are attractive because their raw materials are common and abundant. This review examines this type of novel battery system, introduces its basic mechanism and problems, analyses the strategies that are used to improve its reversibility and cycling stability and also proposes some possible future directions of investigations.

Formation and Detriments of Residual Alkaline Compounds on High-Nickel Layered Oxide Cathodes.

High-nickel layered oxides LiNixM1-xO2 (x≥0.9) have emerged as promising cathode materials for automotive batteries due to their high energy density and lower cost. However, the formation and accumulation of surface alkaline compounds during storage hinder their mass production and commercialization. Here, a validated chemical method is employed to deconvolute and quantify the evolution of each residual lithium compound in four representative cathodes during ambient-air storage, viz., LiNiO2 (LNO), LiNi0.95Co0.05O2 (NC), LiNi0.95Mn0.05O2 (NM), and LiNi0.95Al0.05O2 (NA). Furthermore, the activation energy of the reaction between water and the cathode is determined by measuring the leached LiOH concentration at various temperatures. While residual lithium and time-of-flight secondary-ion mass spectrometry measurements collectively reveal that the air stability overall follows the trend of NM>NA≈NC>LNO, the aged NM exhibits the highest charge-transfer resistance and the worst electrochemical performance among the cathodes. In situ, X-ray diffraction and scanning transmission electron microscopy unveil that the aged NM is plagued by a large area of resistive spinel-like M3-xLixO4 phases, leading to aggravated particle reaction heterogeneity. Finally, a one-step recalcination method is demonstrated effective in fully restoring the degraded cathodes. This work provides insights into overcoming air sensitivity issues of high-Ni cathodes.

A Comprehensive Review on Reductive Recycling of Cathode Materials of Spent Lithium-Ion Batteries.

The prosperity of the lithium-ion battery market is inevitably accompanied by the depletion of corresponding resources and the accumulation of spent batteries in a dialectical manner. Spent lithium-ion batteries are harboring the characteristics of hazardous waste and high-value resources, so efficient recycling is of great significance. The cathode material is considered as an interesting target for repurposing. Despite some important reviews give commendable emphasis to recycling technologies, there is still a dearth of exploration of recycling mechanisms. This deficiency of awareness highlights the need for further research and development in this area. This review aims to systematically review and thoroughly discuss the reduction reaction mechanism of each method regarding different cathode materials. And systematically digest the selection of reducing agent and the effect of reduction reaction on material regeneration are systematically digested, as well as the impact of the reduction reaction on the regeneration of materials. This review emphasizes the importance of balancing efficiency, economic and environmental benefits in reuse technologies. Finally, the review proposes an outlook on the opportunities and challenges facing the reuse of key materials for next-generation spent batteries aimed at promoting the green and sustainable development of lithium-ion batteries, circular economy and ecological balance.

Design of double layer cathode electrode for improving the safety and stability of lithium-ion batteries

LiNi0.8Co0.1Mn0.1O2 (NCM) is a widely used cathode material for lithium-ion batteries (LIBs). However, the poor cycle performance and safety issue remains a huge challenge for its practical applications. Here we show a simple double layer strategy to improve the electrochemical characteristics and safety performance. NCM was coated by LiFePO4 (LFP), a safe cathode material with long cycle stability, exhibited more excellent cycling stability and similar rate properties at room temperature (called NCM/LFP). Under 45 ℃, the NCM/LFP (6:1)||graphite pouch cell shows excellent 83% capacity retention after 600 cycles at 1C, which compared to the sharp attenuation of pristine NCM. Furthermore, NCM/LFP (6:1)||graphite cell could pass the nail penetration tests and the thermal runaway temperature (TTR) delayed by 193℃, which proved the double layer design has better safety performance. The current work might pave an avenue for cathode materials, as a sustainable solution to high energy density LIBs for applications.

WITHDRAWN: Hybrid morphology of fine nanowires encapsulated with nanoparticles in VO2/CuWO4 nanocomposite as Zn-ion battery cathode

Energy crisis due to decaying fossil fuels can be tackled by using electrochemical energy storage devices specially Zn-ion battery for their non-flammability, cost-effectiveness and promising energy density. However, its feasibility requires excellent cathode materials with high Zn2+ intercalation activity. In this regard, vanadium-based compounds at nanoscale regime are very effective. This work presents a profound synthesis of VO2 nanowires and a novel approach to improve its cathodic property by blending it with a multifunctional CuWO4 compound. For the first time VO2/CuWO4 nanocomposite is developed as a cathode material of Zn-ion battery to showcase a promising specific capacity of 479.9 mAh/g at 0.3 A/g. A stable capacity retention of 85% is achieved after 1000 cycles. SEM and TEM analyses confirms a considerable size reduction of VO2 and CuWO4 constituent in the nanocomposite against their pristine counterparts. This size reduction phenomenon could establish a synergistic effect between VO2 and CuWO4 for a favourable pseudo behaviour combining diffusion and capacitive controlled activities.

High-performance flexible zinc-ion battery: Slurry-coated on carbon fiber

Aqueous zinc-ion batteries (ZIBs) have garnered remarkable attention owing to high safety, low price, environmental friendliness, and versatile adaptability. In this paper, we present the fabrication of a fiber-based ZIB using a slurry composed of ZnVOH and carbon black as the cathode material. This battery demonstrates high capacity and a robust bonding interface. Notably, the binding strength and uniformity of the slurry on the fiber surface play a pivotal role in energy-storage capabilities. Carbon black serves the dual purpose of providing a conductive medium and a viscosity adherence to the fiber surface. ZIBs containing 15 % carbon black exhibit a high capacity of 319.8 mAh g−1 at a current density of 0.5 A g−1. In addition, the fully solid-state fiber battery demonstrates superior electrochemical performance under various bending deformations coupled with optimized electrical conductivity. Importantly, its seamless integration with textiles underscores its potential for large-scale industrial production of flexible fiber-shaped ZIBs, providing a compelling solution for flexible energy storage.

Enhancing interfacial kinetics and stability of LiMn2O4 cathode by fabricating an artificial cathode electrolyte interphase of LiNbO3

LiMn2O4 (LMO) cathode material has received continuous attention due to its low price, environmental friendliness, high voltage platform, and high safety. However, the structure distortion is usually caused by the Jahn-Teller effect of Mn3+ in LMO, in which Mn3+ undergoes disproportionation reaction, resulting in the dissolution of Mn element and leading to the problems of fast capacity decay and short cycle life of battery. In this study, a thin (∼3 nm) artificial cathode electrolyte interphase (CEI) of LiNbO3 (LNO) is uniformly covered on the surface of LMO powder (LMO@LNO) by magnetron sputtering method. Compared with the bare LMO, LMO@LNO delivers a higher discharge capacity and better cycling stability. The capacity retention rate of bare LMO/Li cell reaches 80 % in 150 cycles, while LMO@LNO/Li cell can cycle up to 700 cycles, greatly prolonging the cycle life of battery. According to the experimental tests, it is found that the CEI layer of LNO not only improves the interfacial kinetics of electrode, but also inhibits the dissolution of Mn element and side reactions between electrolyte and electrode, thus effectively enhances the rate capability and cycling stability of batteries even at 55 °C and high-voltage of 4.8 V.

Exploring Recent Developments in Graphene-Based Cathode Materials for Fuel Cell Applications: A Comprehensive Overview.

Fuel cells are at the forefront of modern energy research, with graphene-based materials emerging as key enhancers of performance. This overview explores recent advancements in graphene-based cathode materials for fuel cell applications. Graphene's large surface area and excellent electrical conductivity and mechanical strength make it ideal for use in different solid oxide fuel cells (SOFCs) as well as proton exchange membrane fuel cells (PEMFCs). This review covers various forms of graphene, including graphene oxide (GO), reduced graphene oxide (rGO), and doped graphene, highlighting their unique attributes and catalytic contributions. It also examines the effects of structural modifications, doping, and functional group integrations on the electrochemical properties and durability of graphene-based cathodes. Additionally, we address the thermal stability challenges of graphene derivatives at high SOFC operating temperatures, suggesting potential solutions and future research directions. This analysis underscores the transformative potential of graphene-based materials in advancing fuel cell technology, aiming for more efficient, cost-effective, and durable energy systems.

Exploring Phenolphthalein Polyarylethers as High-Performance Alternative Binders for High-Voltage Cathodes in Lithium-Ion Batteries.

Polyvinylidene fluoride (PVDF) has unique electrochemical oxidation resistance and is the only binder for high-voltage cathode materials in the battery industry for a long time. However, PVDF still has some drawbacks, such as environmental limitations on fluorine, strict requirements for environmental humidity, weak adhesion, and poor lithium ion conductivity. Herein, the long-standing issues associated with high-voltage lithium cobalt oxide (LiCoO2; LCO) are successfully addressed by incorporating phenolphthalein polyetherketone (PEK-C) and phenolphthalein polyethersulfone (PES-C) as binder materials. These binders have unexpected electrochemical oxidation resistance and robustness adhesion, ensure uniform coverage on the surface of LCO, and establish an effective and fast ion-conductive CEI/binder composite layer. By leveraging these favorable characteristics, electrodes based on polyarylether binders demonstrate significantly better cycling and rate performance than their counterparts using traditional PVDF binders. The fast ion-conductive CEI/binder composite layer effectively mitigates adverse reactions at the cathode-electrolyte interface. As anticipated, batteries utilizing phenolphthalein polyarylether binders exhibit capacity retention rates of 88.92% and 80.4% after 200 and 500 cycles at 4.5 and 4.6V, respectively. The application of binders, such as polyarylether binders, offers a straightforward and inspiring approach for designing high-energy-density battery materials.

Enhancing the Structural Stability and Electrochemical Performance of High-Nickel Cathode Materials through Ti Doping with an Exothermic Non-oxide Precursor.

The foreseeable global cobalt (Co) crisis has driven the demand for cathode materials with less Co dependence, where high-nickel layered oxides are a promising solution due to their high energy density and low cost. However, these materials suffer from poor cycling stability and rapid voltage decay due to lattice displacement and nanostrain accumulation. Here, we introduced an exothermic TiN dopant via a scalable coating method to stabilize LiNi0.917Co0.056Mn0.026O2 (NCM92) materials. The exothermic reaction of TiN conversion generates extra heat during the calcination process on the cathode surface, promotes the lithiation process, and tunes the morphology of the cathode material, resulting in compact and conformal smaller particle sizes to provide better particle integration and lithium diffusion coefficient. Moreover, the Ti dopant substitutes the Ni3+ site to generate stronger Ti-O bonding, leading to higher structural stability and extended cycle life. The Ti-doped NCM (NCM92_TiN) shows a remarkable cycling stability of maintaining 80% capacity retention for 400 cycles, while bare NCM92 can only reach 88 cycles. Furthermore, the NCM92_TiN cathodes demonstrate an enhanced rate capability and achieve a discharge capacity of over 168 mAh g-1 at 5C.

Ruthenium Nanoclusters and Single Atoms on α-MoC/N-Doped Carbon Achieves Low-Input/Input-Free Hydrogen Evolution via Decoupled/Coupled Hydrazine Oxidation.

The hydrazine oxidation-assisted H2 evolution method promises low-input and input-free hydrogen production. However, developing high-performance catalysts for hydrazine oxidation (HzOR) and hydrogen evolution (HER) is challenging. Here, we introduce a bifunctional electrocatalyst α-MoC/N-C/RuNSA, merging ruthenium (Ru) nanoclusters (NCs) and single atoms (SA) into cubic α-MoC nanoparticles-decorated N-doped carbon (α-MoC/N-C) nanowires, through electrodeposition. The composite showcases exceptional activity for both HzOR and HER, requiring -80 mV and -9 mV respectively to reach 10 mA cm-2. Theoretical and experimental insights confirm the importance of two Ru species for bifunctionality: NCs enhance the conductivity, and its coexistence with SA balances the H ad/desorption for HER and facilitates the initial dehydrogenation during the HzOR. In the overall hydrazine splitting (OHzS) system, α-MoC/N-C/RuNSA excels as both anode and cathode materials, achieving 10 mA cm-2 at just 64 mV. The zinc hydrazine (Zn-Hz) battery assembled with α-MoC/N-C/RuNSA cathode and Zn foil anode can exhibit 97.3 % energy efficiency, as well as temporary separation of hydrogen gas during the discharge process. Therefore, integrating Zn-Hz with OHzS system enables self-powered H2 evolution, even in hydrazine sewage. Overall, the amalgamation of NCs with SA achieves diverse catalytic activities for yielding multifold hydrogen gas through advanced cell-integrated-electrolyzer system.

Sodium iron sulfate cathodes with ultra-long cycle-life and high safety for sodium-ion batteries

The development of low-cost and high-safety cathode materials is critically important to sodium-ion battery (Na-ion) research. Here we report a carbon nanotube (CNT)-percolating Na2Fe(SO4)2 cathode (NFS-CNT) prepared via a rationally designed mechano-chemical method. The material synthesis mechanism is elucidated for the first time by in situ X-ray diffraction and thermogravimetric analysis. It is discovered that Na2Fe(SO4)·4H2O is formed as an intermediate phase during the mechano-chemical process, which is dehydrated to produce the Na2Fe(SO4)2 cathode material upon a mild thermal treatment. The NFS-CNT composite cathode achieves an ultra-long cycle-life of over 13,000 cycles at 10 C at room temperature and over 6000 cycles at 55 °C, demonstrating its exceptional durability. The superior cycling performance is attributed to the small lattice change during Na-ion extraction/insertion and the percolating CNT network. Furthermore, the NFS/CNT cathode exhibits stable cycle performance in Na-ion full cells (93.4 % retention after 700 cycles) and a significantly lower heat release (∼ 229.2 J g−1) at the fully charged state compared to a wide range of Na-ion and Li-ion cathodes. materials. demonstrating its high thermal stability and safety. This work provides a promising path towards developing low-cost, high-performance Na-ion batteries.

Oxygen Release in Ni‐Rich Layered Cathode for Lithium‐Ion Batteries: Mechanisms and Mitigating Strategies

AbstractLiNixCoyAlzO2 (NCA) and LiNixCoyMnzO2 (NCM) have become extensively utilized as cathodes in lithium‐ion batteries for consumer electronics, electric vehicles, and energy storage applications that necessitate consistent power output over prolonged periods and under varying environmental conditions. A crucial structural degradation issue leading to cycling‐induced deterioration, rapid loss of cell capacity/voltage, and the onset of undesirable thermal runaway events involves the decay of cathode materials enriched in nickel. This contribution offers a comprehensive evaluation of cutting‐edge strategies in engineering and material design to enhance the structural stability of cathode materials and reduce detrimental oxygen evolution reactions. It also provides the most recent discoveries regarding oxygen release phenomena and associated mechanisms contributing to structural breakdown in high‐nickel cathodes. The primary source of oxygen depletion and the ensuing structural deterioration caused are thoroughly examined. Additionally, the kinetic mechanisms responsible for oxygen loss are scrutinized, and measures to mitigate resulting electrochemical degradation are elaborated. This overview can guide researchers in the development of oxygen‐containing cathode materials in the future, where oxygen leakage is of lesser concern compared to other forms of deterioration.