Cathode Material Research Articles

High-Performance Alluaudite-Type Na2.54(Fe0.97Mg0.03)1.73(SO4)3 Microspheres Cathode for Sodium-Ion Batteries with an Ultrahigh Rate Capability and 9000 Cycle Life.

Na2+2xFe2-x(SO4)3 (NFSO) is a promising cathode material for sodium-ion batteries (SIBs) due to its low cost and high operating potential (≈3.8V). However, poor intrinsic electronic conductivity and sluggish kinetics are major drawbacks to its practical application. Herein, magnesium doped Na2+2xFe2-x(SO4)3 microspheres (Na2.54(Fe0.97Mg0.03)1.73(SO4)3) are synthesized via a designed spray-drying process. The optimized cathode material (NFSO@C-Mg0.02) possesses excellent rate performance up to 50C (50.8mAhg-1 at 50C) and long-cycle stability (capacity retention of 78.3% even after 9000 cycles at 10C). Despite an increase in the mass loading to 10mgcm-2, the electrode continues to represent a reversible capacity of 72.1mAhg-1 at 3C. Furthermore, NFSO@C-Mg0.02║HC full cell demonstrates superior cycling stability (80% capacity retention over 8000 cycles at 5C) and high energy density (≈310Whkg-1, based on the cathode). In situX-ray diffraction (XRD)results reveal that the Mg doping strategy successfully mitigates the variation in lattice volume. The density functional theory (DFT) calculations verify that the prominent rate performance is attributed to the enhanced Na+ diffusion kinetics and low ionic-migration energy barrier. This work provides an effective strategy and a fundamental understanding to enhance the electrochemical performance of cathode materials for SIBs.

La Doping LiNiO2 Cathode to Immobilize the Lattice Oxygen for Highly Stable Lithium-Ion Batteries.

LiNiO2 (LNO) with a high theoretical capacity and entirely free of cobalt has aroused much attention as a promising cathode material for lithium-ion batteries (LIBs). The rapid capacity decay, however, obstructs its commercialization. We first propose a strategy of La lattice-doping in the LNO (La-LNO) as a high-stability cathode for LIBs. Density-functional theory calculations suggest that the La dopant occupies the Ni-sites to stabilize the lattice oxygen due to a strengthening of the transition metal-oxygen bonds and mitigation of the charge compensation. La lattice-doped LNO cathode materials were fabricated successfully and had a specific capacity of 159.6 mAh g-1 after 100 cycles at 1 C with a capacity retention of 94.2% and a voltage retention of 99.9%. Atomic characterization reveals that La-LNO effectively inhibits the oxygen release and phase transformation during the cycling process. Our strategy provides leading guidance for designing practical high-performance LNO cathode materials for advanced LIBs.

Recycling and regeneration of failed layered oxide cathode materials for lithium-ion batteries.

With broad usage of lithium-ion batteries (LIBs) in electronic devices and electric vehicles (EVs), a large number of decommissioned LIBs will be generated, which cause serious environmental pollution and waste of resources. Therefore, to reduce environmental pressure and realize secondary resource utilization of valuable metals, recycling decommissioned LIBs is urgent. At present, although pyrometallurgy, hydrometallurgy, direct regeneration and other methods have been used significantly in the recovery of failed LIB cathode materials, it is still necessary to formulate the best recovery strategy to achieve higher recovery efficiencies and value-added materials from spent cathodes. Thus, in this article, the latest progress in the recycling of retired LIB layered oxide cathode materials is reviewed in detail, and the recycling process, advantages and limits of each recycling method are analyzed. In view of the recycling challenges, the future development is prospected to promote the sustainable, environmentally friendly and efficient reutilization of failed LIB cathodes and contribute to the low-carbon circular economy.

Superior Cycling Stability in Zinc-Ion Batteries with Ca2+-Induced Cathode-Electrolyte Interface and Phytic Acid: Experimental Validation of Theoretical Predictions.

This study investigates the impact of Ca2+ and phytic acid (PA) pre-insertion on the performance of vanadium oxide (V6O13) as a cathode material for aqueous zinc-ion batteries. Ab initio molecular dynamics (AIMD) simulations reveal that the diffusion coefficient of Ca2⁺ is higher than that of Zn2+, leading to the preferential extraction of Ca2⁺. The extracted Ca2⁺ readily forms a dense cathode-electrolyte interphase (CEI) with SO₄2 - on the electrode surface, effectively mitigating electrode dissolution. Furthermore, density functional theory (DFT) calculations indicate that the incorporation of Ca2⁺ lowers the diffusion energy barrier for Zn2⁺, facilitating its diffusion. Additionally, PA insertion stabilizes the interlayer spacing of V6O13, and its strong chelating ability stabilizes the structure by preventing collapse during cycling. Experimental validation through a one-step solvothermal method confirms these theoretical predictions. The CaVO-PA composite exhibits excellent cycling stability, with a capacity retention rate increasing from 60% to 102% after 3000 cycles at 10Ag-¹. Even at 20 Ag-¹, it delivers a specific capacity of 170.2mAhg-¹ with stable Coulombic efficiency. After 10000 cycles, the capacity shows no significant degradation, demonstrating superior cycling stability and high current tolerance, thereby confirming the effectiveness of the CEI and PA in enhancing electrochemical performance.

Strategy Formulation for Mitigating Capacity Fading of Na-Layered Oxides.

The mechanisms underlying capacity fading during cycling in layered oxide cathode materials for sodium-ion batteries remain inadequately understood. It is essential to elucidate the reasons and propose effective strategies. Here, the capacity fading mechanism of commercial NaFe1/3Mn1/3Ni1/3O2 is due to the dissolution of iron ions. Additionally, the extraction of sodium ions (after the Fe3+/Fe4+ reaction) lowers the energy level of NaFe1/3Mn1/3Ni1/3O2 below that of the electrolyte solvent, thereby inducing solvent decomposition. We establish screening criteria for electrolyte additives through theoretical calculations to improve capacity retention. We identified a series of nitrogen-containing Lewis base additives that can kinetically bind efficiently to iron ions in NaFe1/3Mn1/3Ni1/3O2 and thermodynamically exhibit stronger electron-donating abilities than the solvents. A new compound sodium bis(trimethylsilyl)amide (which has not been studied as a Na-ion battery additive before) is selected through the Reaxys database (out of 61 molecules) because it is commercially available at a low price and is relatively stable in the electrochemical process. Such additive is demonstrated to greatly improve the Coulombic efficiency and reduce the dissolution of iron ions of NaFe1/3Mn1/3Ni1/3O2//hard carbon cells.

Physicochemical Properties of a Pressurized Deep Eutectic Solvent and Its Application in Extraction Metallurgy

Deep eutectic solvents are widely employed in the recycling and reuse of spent lithium-ion battery cathode materials because of their non-toxicity, low cost, and recyclability. Although DESs have a high recovery rate for metals and are more environmentally friendly, they typically require a longer time or higher temperatures. High temperature and pressure considerably improve leaching efficiency in traditional aqueous systems; this study investigates whether the same is true in DES systems. The physicochemical properties of a DES composed of choline chloride (ChCl) and malonic acid (MA) (1:1) were measured before and after high-temperature and high-pressure treatments, along with their effects on the leaching efficiency of cathode materials for spent lithium-ion batteries (LIBs). The results show that after treatment, the 632.03 cm−1 twisted vibration peak of C-O was red-shifted to 603 cm−1 and the alkyl chain of the DES was lengthened, whereas the 1150.52 cm−1 C-O peak was blue-shifted to 1219 cm−1 and the hydrogen-bonding effect was weakened. At long reaction times, crystals appeared inside the DES. Over time, the crystals increased in size and became less dense, and the color of the material changed from clear to blue to green. After pressurization treatment, the conductivity of the DES increased considerably over its value at atmospheric pressure. The leaching efficiency of Li, Co, Ni, and Mn were 53.20, 47.24, 26.27, and 48.57%, respectively, at 3 h of leaching at atmospheric pressure. The leaching efficiency increased to 78.20, 79.74, 69.76, and 81.80%, respectively, after being pressurized at 3.3 MPa. On this basis, the reaction time was extended to 6 h, and the leaching efficiency of Li, Co, Ni, and Mn were 96.41, 97.62, 98.13, and 97.34%, respectively, trending towards complete leaching. The leaching efficiency of spent LIB cathode materials in DESs was considerably improved under pressurized conditions, providing an efficient method for recovering spent LIB cathode materials using DESs.

Ion-Docking Effect Enabling Rechargeable High-Voltage Magnesium-Iodine/Chlorine Battery.

Rechargeable magnesium (Mg) batteries represent a promising energy storage system by offering low cost and dendrite-less propensity. However, the limited selection of cathode materials, and often with low voltage and capacity, constrain Mg batteries. Herein, by exploiting the ion-docking effect between two halogen species - iodine cations (I+) and chlorine anions (Cl-) - we activate the cathodic activity of halogens and develop a magnesium-iodine/chlorine (Mg-I/Cl) battery prototype with high energy and power density. The ion-docking effect enables I+ and Cl- to mutually balance and disperse their charges, weakens the coordination strength between Cl- and Mg2+ while enhances the stability of I+, thus facilitating the multi-electron (2+1/3) redox reactions of halogens. We also find the solvation state of iodine species determine the reaction process of the I0/I3-/I- redox couples. The here-developed magnesium-iodine/chlorine battery features an impressively high discharge plateau of up to 3.0 V with a high capacity exceeding 400 mAh g-1, and demonstrates a stable lifespan for 500 cycles, with the ability of ultra-fast charging at 20C and low-temperature cycling under -30 °C. These findings may provide new insights for developing high-energy-density Mg battery systems.

Enhanced Electrochemical Performance of Li‐rich Cathode Materials by Al Doping

AbstractLi‐rich oxides are the most promising of the high‐voltage cathode materials with their high specific capacity. However, Li‐rich cathode materials suffer from structural instability, voltage degradation, and capacity fading upon cycling. Al‐doping can improve electrochemical performance by stabilizing the structure and suppressing the phase transitions for Li‐rich cathodes. In this paper, we investigate the effect of different amounts of Al with the general formula Li1.2Mn0.54‐xNi0.13Co0.13AlxO2 and Li1.2‐xMn0.54Ni0.13Co0.13AlxO2 (x=0.02, 0.05, 0.1) cathode materials. The Li and Mn elements were replaced by Al, and the electrochemical performance was compared to pristine Li1.2Mn0.54Ni0.13Co0.13O2. The Li and Mn elements were replaced by Al, and the electrochemical performance was compared. The impact of substitution of Mn and Li by Al on the structural and morphological properties has been investigated by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The charge and discharge tests show that doping with Al substitution leads to improved electrochemical performance, enhancing both the cycling stability and rate capability of the Li‐rich cathode materials. Along with the improved specific capacities, these materials demonstrate superior rate performance, particularly for the composition with the lowest Al content.

Porous Dodecahedral NiS2/NiSe2 Nanomaterials as Cathode Material for Aluminum Batteries

Porous Dodecahedral NiS₂/NiSe₂ Nanomaterials as Cathode Material for Aluminum Batteries

Optimizing Carbon Coating Process for Lithium-Rich LiFePO4 Cathode Materials.

Li1+xFe1-xPO4 (Li-rich LFP) has been proposed as an alternative to address low ionic and electronic conductivity of stoichiometric LiFePO4 (LFP). However, comprehensive studies investigating the impact of the carbon coating process on crystal structure and electrochemical performance during the synthesis of Li-rich LFP are still lacking. In particular, the characteristics of carbon precursor and calcination atmosphere significantly influence formation of crystal structure and electrochemical properties of the Li-rich LFP, underlining the necessity for further investigation. In this study, we compare two synthesis process: introducing carbon precursor before formation of LFP crystal structure (C/BLF) and adding it an additional calcination step after structure has formed (C/ALF). The C/ALF process sample has a larger unit cell volume and denser coating layer. As a result, the C/ALF sample exhibits a lower overpotential (0.54 V) and a higher discharge capacity (~134.13 mAhg-1) than C/BLF sample. These findings elucidate the influence of carbon coating process sequence on crystal structure and electrochemical performance during the synthesis of Li-rich LFP.

A novel method for selective lithium recovery from end-of-life LiFePO4 automotive batteries via thermal treatment combined with a leaching process.

As the demand for electric vehicles increases, effective solutions for recycling end-of-life lithium-ion batteries become crucial. Since lithium iron phosphate (LFP) batteries represent a significant portion of the automotive battery market, this research introduces an innovative method to produce concentrated lithium solutions by combining a calcination process with a microwave-assisted hydrometallurgical process. The initial steps involve safe collection and disassembly of discarded batteries to preserve components and minimize contamination. The cathode coils are separated and ground to a particle size smaller than 0.25mm, concentrating 96% of the lithium compounds. Afterward, the cathode material undergoes calcination for 1h at temperatures ranging from 300 to 900 °C in air and N₂ atmospheres. For samples treated in an oxidative atmosphere, the complete phase conversion of LiFePO₄ to Li₂Fe₃(PO₄)₃ occurs at 500 °C, whereas in an inert atmosphere, this phase change fully manifests at 700 °C. Different sulfuric acid concentrations (0.5, 1.0, and 1.5mol/L) are subsequently used in the microwave-assisted leaching process for all the calcined and non-calcined cathodic powders. Using leaching with aqua regia as a reference for the complete leaching of metals, the best results in terms of lithium selectivity are achieved with samples calcined at 500 °C and leached with 0.5mol/L sulfuric acid. Under these conditions, 75% of all the lithium and only 2.5% of all the iron are extracted in solution. This result demonstrates that calcination in an air atmosphere prior to a hydrometallurgical process plays a fundamental role in achieving high lithium selectivity without the need for any other additives.

Direct Recycling of Ternary Lithium-Ion Batteries via Solvent-Assisted Separation of Cathode Materials.

Effective separation of cathode active materials from Al foil is a critical step in the recycling of spent lithium-ion batteries (LIBs). Conventional techniques, including thermal treatment, organic solvent dissolution, and alkaline etching, are often associated with challenges such as incomplete separation, high energy demand, and environmental hazards. In this study, a green organophosphonic acid, 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP), was utilized to achieve rapid and effective delamination of LiNi0.55Co0.15Mn0.3O2 cathode materials from Al foil. Complete separation was accomplished in just 4 min under mild conditions, with Al leaching as low as 4.58%. Mechanistic investigations revealed that HEDP reacts with Al foil to form a compact passivation layer on its surface, effectively suppressing further corrosion and reducing binder adhesion. This eco-friendly and cost-effective approach offers a sustainable solution for the recycling of spent LIBs.

Operando Magnetism on Oxygen Redox Process in Li-Rich Cathodes.

Oxide ions in lithium-rich layered oxides can store charge at high voltage and offer a viable route toward the higher energy density batteries. However, the underlying oxygen redox mechanism in such materials still remains elusive at present. In this work, a precise in situ magnetism measurement is employed to monitor real-time magnetization variation associated with unpaired electrons in Li1.2Mn0.6Ni0.2O2 cathode material, enabling the investigation on magnetic/electronic structure evolution in electrochemical cycling. The magnetization gradually decreases except for a weak upturn above 4.6V during the initial charging process. According to the comprehensive analyses of various in/ex situ characterizations and density functional theory (DFT) calculations, the magnetization rebound can be attributed to the interaction evolution of lattice oxygen from π-type delocalized Mn─O coupling to σ-type O─O dimerization bonding. Moreover, the magnetization amplitude attenuation after long-term cycles provides important evidence for the irreversible structure transition and capacity fading. The oxygen redox mechanism concluded by in situ magnetism characterization can be generalized to other electrode materials with an anionic redox process and provide pivotal guidance for designing advanced high-performance cathode materials.

Review on the recovery and reutilization of anode materials and electrolytes from spent lithium-ion batteries.

Review on the recovery and reutilization of anode materials and electrolytes from spent lithium-ion batteries.

CuxO as an ultra-stable voltage plateaus and long-life cathode material in aqueous ammonium-ion batteries

CuxO as an ultra-stable voltage plateaus and long-life cathode material in aqueous ammonium-ion batteries

Unveiling the Over-Lithiation Behavior of NCM523 Cathode Towards Long-Life Anode-Free Li Metal Batteries.

Anode-free lithium metal batteries (AFLMBs) offer the potential for significantly enhanced energy densities. However, their practical application is limited by a shortened cycling life due to inevitable Li loss from parasitic reactions. This study addresses this challenge by incorporating an over-lithiated Li1+ xNi0.5Co0.2Mn0.3O2 (Li1+ xNCM523) cathode as an internal Li reservoir to compensate for lithium loss during extended cycling. A rigorous investigation of the deep discharge behavior of the Li1+ xNCM523 cathode reveals a critical over-lithiation threshold at x=0.7. At this threshold, excess Li+ ions are safely accommodated within the crystal structure by a transformation from the LiO4 octahedron to two tetrahedral sites. Beyond this threshold (x ≥ 0.7), the structural stability of the cathode is significantly compromised due to the irreversible reduction of transition metal (TM) ions. The optimal Li-rich Li1.7NCM523 releases an additional charge capacity of ≈160 mAh g-1 during the first charge. Consequently, the AFLMBs (Li1.7NCM523||Cu) achieve outstanding capacity retention of 93.3% after 100 cycles at 0.5 C and 78.5% after 200 cycles at 1 C. The findings establish a research paradigm for designing superior over-lithiated transition metal oxide cathode materials and underscore the critical role of the lithium reservoir in extending the cycle life of AFLMBs.

Water-Restrained Hydrogel Electrolytes with Repulsion-Driven Cationic Express Pathways for Durable Zinc-Ion Batteries

The development of flexible zinc-ion batteries (ZIBs) faces a three-way trade-off among the ionic conductivity, Zn2+ mobility, and the electrochemical stability of hydrogel electrolytes. To address this challenge, we designed a cationic hydrogel named PAPTMA to holistically improve the reversibility of ZIBs. The long cationic branch chains in the polymeric matrix construct express pathways for rapid Zn2+ transport through an ionic repulsion mechanism, achieving simultaneously high Zn2+ transference number (0.79) and high ionic conductivity (28.7mScm-1). Additionally, the reactivity of water in the PAPTMA hydrogels is significantly inhibited, thus possessing a strong resistance to parasitic reactions. Mechanical characterization further reveals the superior tensile and adhesion strength of PAPTMA. Leveraging these properties, symmetric batteries employing PAPTMA hydrogel deliver exceeding 6000 h of reversible cycling at 1mAcm-2 and maintain stable operation for 1000 h with a discharge of depth of 71%. When applied in 4 × 4cm2 pouch cells with MnO2 as the cathode material, the device demonstrates remarkable operational stability and mechanical robustness through 150 cycles. This work presents an eclectic strategy for designing advanced hydrogels that combine high ionic conductivity, enhanced Zn2+ mobility, and strong resistance to parasitic reactions, paving the way for long-lasting flexible ZIBs.

Surface modification of cathode materials with functional coatings for enhanced lithium-ion battery durability

Surface modification of cathode materials with functional coatings for enhanced lithium-ion battery durability

A High-Rate and Ultrastable Ammonium Ion-Air Battery Enabled by the Synergy of ORR and NH4 + Storage.

Ammonium ion batteries (AIBs) offer cost-effectiveness, nontoxicity, and eco-friendly attributes in energy storage technology. However, the constrained capacity and poor stability of conventional cathode materials have impeded their widespread adoption. Herein, a synergistic approach is introduced to overcome these challenges, by enhancing the air cathode with NH4 + and simultaneously leveraging atmospheric oxygen as a reservoir for NH4 + storage. Notably, NH4 + significantly enhances the oxygen reduction reaction (ORR) performance in neutral environments. Through in situ Raman spectroscopy and quantum density functional theory calculations, it is elucidated how NH4 + can act as a proton donor, replacing H2O in neutral media and reducing energy barriers in the protonation of *O2 - and *O, thereby accelerating ORR kinetics. The resulting ammonium ion-air battery, comprising an air cathode and a polymer (PNP) anode, showcases impressive metrics: high energy density of 78 Wh kg-1 and power density of 9369 W kg-1 at 1 A g-1, an initial capacity of 94.3 mAh g-1 and exceptional cycling stability (70.4% capacity retention after 12500 cycles) at 10 A g-1. This pioneering research highlights the synergistic relationship between ORR and NH4 + storage and opens up new avenues for the design and advancement of innovative, sustainable, and environment-friendly AIBs.

Sustainable Aloe-Emodin as an Advanced Organic Cathode for High-Performance Aluminum-Ion Batteries.

Anthraquinone derivatives, known for their redox properties, are widely recognized as promising cathode materials for aluminum-ion batteries. This study presents an environmentally benign extraction of aloe-emodin from aloe dry powder, a sustainable and economically viable resource, using ferric chloride as an oxidizing agent in an acidic medium. Emodin and its isomer, aloe-emodin, share a symmetrical polycyclic chemical architecture and carbonyl functionalities, but differ in the position of their hydroxyl groups. The shift of a hydroxyl group from the aromatic ring to the methyl moiety in emodin results in aloe-emodin, enhancing its redox potential. As a cathode material in aluminum-ion batteries, aloe-emodin demonstrates enhanced electrochemical performance compared to emodin, showcasing a high reversible specific capacity of 85.9 mAh/g at 50 mA/g, superior rate capability with 42.0 and 32.0 mAh/g at 1000 and 2000 mA/g, respectively, and remarkable long-term cyclability with a capacity retention of 50.3 mAh/g and a Coulombic efficiency of 99.05% after 6000 cycles at 1000 mA/g. These findings contribute to a deeper understanding of the design principles for aluminum-ion batteries that leverage anthraquinone-based cathode materials.