High-performance Cathode Materials Research Articles

Two-step electrodeposition synthesis of lamellar Ni@NiCo phosphate heterostructures as cathodes for high-performance hybrid supercapacitors

Porous structures grown in situ increase the electrode contact area with the electrolyte, reduce ion diffusion distance, and enhance electrode material electrochemical properties. In this paper, we have adopted a dual-channel electrodeposition strategy with simultaneous electrodeposition and phosphorylation to construct metal-semiconductor contact heterostructures by depositing Ni@NiCo phosphate microspherical nanostructures directly on a copper foam (CF) (Ni@NiCoP/CF) framework at room temperature. The results show that Ni@NiCoP/CF has excellent electrochemical performance with a high specific capacity of 200 mAh g–1 at 1 A g–1, 147.2 mAh g–1 at 20 A g–1 and 93.6 % after 5000 cycles, showing excellent ration performances and cycling stability. In addition, the hybrid supercapacitor composed of Ni@NiCoP/CF as the positive electrode and activated carbon as the negative electrode achieves a high energy density of 48.7 Wh kg−1 at 874 W kg−1 and has excellent cycling stability with 113.23 % capacity retention after 30,000 charge/discharge cycles at a high current density of 10 A g–1. This study serves as a guide for the development of high-performance capacitor cathode materials with high electrochemical activity and capacity.

Optimizing solution combustion method fuel ratios for enhanced electrochemical performance of LiNi0.5Mn1.5O4 cathode materials

LiNi0.5Mn1.5O4 (LNMO) is a promising high-performance lithium-ion battery cathode material. We synthesized various structures of LNMO precursors based on two calculations, using the solution combustion method with different fuel ratios. The precursors were annealed for a short time under ambient atmospheric conditions, and various polyhedral structures of LNMO samples were formed through natural oxygen absorption. The results reveal that lower fuel ratios (0.2) cause the samples having incomplete crystal structures and severe particle aggregation, resulting in higher polarization and poorer electrochemical performance. Samples with higher fuel ratios (0.8) exhibit complete crystal structures, lower polarization, and excellent rate performance. At 20 C, the electrochemical capacity of sample with fuel ratios (0.8) can reach 90.47 mAh/g. Samples with theoretical fuel ratios (0.5) show the best electrochemical cycling performance, capacity retention, and cycling stability. After 200 cycles at 1 C, the electrochemical capacity still maintains 123.08 mAh/g, with a capacity retention rate of 96.5%. The results indicate that the formation of the precursor, oxygen absorption during annealing, polyhedral structures, different redox couples, and stability of the electrode/electrolyte interface have significant effects on the electrochemical performance. In summary, our research provides insights into the solution combustion synthesis of high-performance LNMO cathode materials, emphasizing the importance of accurate calculation of synthesis parameters to achieve optimal electrochemical performance.

Carbon nanofiber-coated MnO composite as high-performance cathode material for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) are a promising next-generation energy storage technology owing to their intrinsic safety, low cost, and sustainability. However, typical AZIB cathode materials, such as manganese oxides, have poor conductivity and structural stability, leading to low energy storage capacity and poor cycle life, thus, limiting practical applications. In this work, manganese oxide coated with carbon nanofibers (MnO@CNFs) was developed as an AZIB cathode. A facile synthetic strategy based on electrospinning was employed to obtain these composites, which showed dramatically improved electrochemical activity and structural stability. The MnO@CNFs cathode, exhibited a high specific capacity (430 mAh g−1 at 0.1 A g−1), excellent rate capability, and long cycling durability (81% retained after 2500 cycles at 1.0 A g−1). The electrochemical reaction mechanism with complex phase evolution was explored by ex-situ characterization after charging/discharging, indicating the high reversibility and good cycling stability of the co-insertion process of H+/Zn2+ in the MnO@CNFs electrode. This study provides a facile and versatile strategy for fabricating high-performance Mn-based cathode materials and offers a deeper understanding of the energy storage mechanism in AZIBs.

Mg-doped LiMn0.8Fe0.2PO4/C nano-plate as a high-performance cathode material for lithium-ion batteries

Lithium-ion battery cathode materials with the high-voltage platform have turned into research highlights. Manganese-based olivine material LiMn0.8Fe0.2PO4 (LMFP), which is synthesized by cheap and environmentally friendly raw materials as precursors, has received high attention due to the higher energy density than commercial lithium iron phosphate products. However, similar to the low conductivity of olivine-structured lithium iron phosphate (LiFePO4), the defect of low conductivity of LMFP has also become the obstacle of LMFP further application. To improve the kinetic properties of LMFP, Mg-doped LMFP/C nano-plate are forearmed by a straightforward and controllable solvothermal approach. The results demonstrate that Mg2+ can be validly doped into the sample, and can partially displace Li+ position in LMFP. It has been found that the Mg-doped LMFP/C material Li0.97Mg0.015Mn0.8Fe0.2PO4 (LMFP-2) presents excellent electrochemical performances and more sustainable application prospect in the fields of electric vehicle and grid energy storage batteries, which can provide a high initial discharge capacity of 156.9 mAh g−1 at 0.1C. In addition, even at high rates of 10 and 20C, the discharge capacity of LMFP-2 can still maintain 120.7 and 104.8 mAh g−1, where the discharge process can be completed in only 255 and 110 s. These results indicate that the introduction of Mg2+ at Li+ site can validly upgradation the electron conductivity and Li+ mobility in the material, thus promoting the electrochemical performances. The rapid discharge ability and cyclic performance of the as-prepared materials make them have great application potential in high-performance lithium-ion batteries.

Constructing Nitrogen-Doped Carbon Hierarchy Structure Derived from Metal-Organic Framework as High-Performance ORR Cathode Material for Zn-Air Battery.

The development of efficient and low-cost catalysts for cathodic oxygen reduction reaction (ORR) in Zn-air battery (ZAB) is a key factor in reducing costs and achieving industrialization. Here, a novel segregated CoNiPt alloy embedded in N-doped porous carbon with a nanoflowers (NFs)-like hierarchy structure is synthesized through pyrolyzing Hofmann-type metal-organic frameworks (MOFs). The unique hierarchical NFs structure exposes more active sites and facilitates the transportation of reaction intermediates, thus accelerating the reaction kinetics. Impressively, the resulting 15% CoNiPt@C NFs catalyst exhibits outstanding alkaline ORR activity with a half-wave potential of 0.93V, and its mass activity is 7.5 times higher than that of commercial Pt/C catalyst, surpassing state-of-the-art noble metal-based catalysts. Furthermore, the assembled CoNiPt@C+RuO2 ZAB demonstrates a maximum power density of 172mW cm-2 , which is superior to that of commercial Pt/C+RuO2 ZAB. Experimental results reveal that the intrinsic ORR mass activity is attributed to the synergistic interaction between oxygen defects and pyrrolic/graphitic N species, which optimizes the adsorption energy of the intermediate species in the ORR process and greatly enhances catalytic activity. This work provides a practical and feasible strategy for synthesizing cost-effective alkaline ORR catalysts by optimizing the electronic structure of MOF-derived catalysts.

Excellent cycling performance of high-nickel single-crystal cathode material by a well-tailored binary molten-salt method

Nickel-rich LiNixCoyMnzO2 (x + y + z = 1) cathode materials have been extensively studied due to their improved energy density and reduced cost in comparison to conventional layered oxides (LiCoO2) and perovskite-type compounds (LiFePO4). However, the further commercialization of polycrystalline nickel-rich layered cathodes are severely hampered by entrenched particle microcracking that evolves mainly from the randomly oriented grain boundaries in the primary particles. Herein, an environmental-friendly LiOH⋅H2O/Li2CO3 binary molten-salt method is introduced to synthesize single-crystal LiNi0.88Co0.09Mn0.03O2 with good crystallinity and dispersion, and the possible growth mechanism of the particles is inferred. The sample prepared at a lithium ratio of 1.7 (SC1.7) shows a lower degree of cation mixing and larger lithium layer spacing compared to control polycrystalline sample (PC), and the residual alkali is effectively removed from the surface of single crystal particles. These features enable SC1.7 to maintain robust structural stability during cycling, with the cycle retention at 1C rate and a voltage of 4.5 V to be 86.73% after 100 cycles. The desirable performance is rationally derived from the significant inhibition of microcracks in particles, and reduction of parasitic reactions. The unique binary molten-salt strategy provides a new avenue for the design of high-performance high-nickel cathode materials in lithium-ion batteries.

Boosting zinc-ion storage performance by interlayer chemistry modulation on an organic-inorganic hybrid cathode

Aqueous zinc-ion batteries (AZIBs) have triggered a surge of scientific research due to the unique merits of high safety, volumetric specific capacity, and environmental benignity. However, the implementation of this technology is still plagued by the lack of high-performance cathodes that can output high energy density and exceptional cycle life and inadequate Zn reversibility. Here, an organic-inorganic hybrid cathode based on a poly(3,4-ethylenedioxythiophene) (PEDOT) intercalated hydrated vanadium oxide (denoted PVO), which delivers an ultrahigh discharge capacity of 513.1 mAh g−1 (0.5 A g−1) and an ultra-stable cycle with 95.3 % capacity retention and approximately 100 % Coulombic efficiency over 2000 cycles (20 A g−1), is developed. Combining substantive measurements and theoretical calculations, it is demonstrated that favorable structural features with expanded interlayer galleries and robust architecture are believed to be responsible for the enhanced electrochemical performance, which can be further boosted by the improved Zn reversibility because of the introduction of maltitol electrolyte additive. This work provides a new attempt to achieve organic-inorganic composites for high-performance cathode materials of AZIBs and new insights into the charge storage behavior under the synergistic regulation of bilateral interfaces.

First-Principles Studies on the Structural and Electronic Properties of α-Na2FePO4F with Strong Antisite Disorder.

Polyanionic Na2FePO4F is one of the most important cathode materials for sodium-ion batteries. The orthorhombic β-Na2FePO4F material has been studied extensively and intensively since it was proposed. In this article, a novel monoclinic sodium phosphate fluoride α-Na2FePO4F is concerned. Kirsanova's experiment showed that Na and Fe ions in α-Na2FePO4F are prone to antisite, leading to strong antisite disorder. Through first-principle calculations, we show that the steric effect, the magnetic exchange and superexchange interactions between transition-metal cations are shown to be the main driving forces for Na+/Fe2+ antisite disorder. We first calculated the crystal structures, electronic properties, and cohesive energies of all the 10 antisite phases of α-Na2FePO4F and β-Na2FePO4F. Then, we compared the difference charge densities, magnetism, binding energies, and electrostatic potentials of α-Na2FePO4F and β-Na2FePO4F materials in the antisite and pristine phases. In α-Na2FePO4F, the binding energy of the antisite phase with the lowest binding energy is almost degenerate with that of the pristine phase. Moreover, only small differences of the electrostatic potential and the charge density distribution are found between the antisite (with lowest energy) and the pristine phases of α-Na2FePO4F, which also helped elaborate the facile formation of Na+/Fe2+ antisite in the α-Na2FePO4F material. Our research contributes to the understanding of the mechanism of Na+/Fe2+ antisite and the development of high-performance polyanionic cathode materials.

Nano-Ni/Co-PBA as high-performance cathode material for aqueous sodium-ion batteries

Prussian blue analogues (PBAs) are reliable and promising cathode materials for aqueous sodium-ion batteries (ASIBs) owing to their open three-dimensional frameworks, outstanding stability, and low production costs. However, PBAs containing only a single type of transition-metal ion often have limited charge-storage capacities in aqueous systems. This study reports the first example of K0.11Ni0.39Co0.79[Fe(CN)6]·2.04H2O nanoparticles (Ni/Co-PBA) being used as a high-capacity cathode material for ASIBs. Owing to multi-electron redox reactions involving Co and Fe ions, Ni/Co-PBA has an initial capacity of 65 mAh g−1 and a capacity retention rate of 80% after 1000 cycles at 1.0 A g−1, indicating its outstanding cycle performance and capacity retention. Ex-situ x-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and the galvanostatic intermittent titration technique were used to analyze the redox mechanisms and kinetics of Ni/Co-PBA. Ni/Co-PBA-based ASIBs are among the most promising energy-storage technologies for large-scale fixed energy-storage systems because of their outstanding electrochemical performance, low costs, and high efficiency.

Two-dimensional V4C3@NiSe2 (Mxene) as high-energy and long-life cathode materials for sustainable aluminum batteries

In this context, we successfully synthesized a nickel diselenide-doped two-dimensional vanadium carbide composite V4C3@NiSe2, which was achieved by etching the V4AlC3 phase using the Louis acid molten salt etching process and subsequently calcining it with selenium. The chemical groups on the V4C3 layer are replaced by selenium, allowing selenium to integrate into the process, thereby increasing energy density and facilitating smoother intercalation of [AlCl4]− ions between these layers, which will reduce material losses during charge and discharge. Due to the interface modification of selenium, the V4C3@NiSe2 battery exhibits excellent conductivity, faster ion diffusion rate, and superior cycling stability. At 1 A g−1, the V4C3@NiSe2 cathode exhibits an impressive initial capacity of up to 636.8 mAh g−1, maintaining a stable capacity of 95 mAh g−1 after about 2700 cycles. In summary, this work proposes a simple synthesis method for high-performance cathode materials such as V4C3@NiSe2, which paves the way for the industrialization of high-performance rechargeable aluminum batteries.

A critical review of inorganic cathode materials for rechargeable magnesium ion batteries

Rechargeable magnesium ion batteries (RMIBs) have received growing attention due to their advantages of abundant resources, low price, environmental friendliness, and high volumetric capacities. However, the highly polarized Mg2+ ions tend to interact with cathode materials, resulting in the sluggish diffusion kinetics. Therefore, design and synthesis high-performance cathode materials are crucial to the development of RMIBs. Most organic cathode materials for RMIBs not only face the problems of poor intrinsic conductivity and low density of the active material, but also are easily soluble in organic electrolytes and have complex redox mechanisms. At present, most of the research on cathodes for RMIBs is inorganic materials. In recent years, researchers have devoted great effort to the design of efficient cathode materials for RMIBs and the reported cathode materials mainly include transition metal oxides, transition metal sulfides, transition metal selenides, polyanionic compounds, and so on. In this review, we provide an extensive overview of different types of inorganic cathodes for RMIBs, with emphasis on describing the structural characteristics, the charge storage mechanisms, electrochemical properties and optimization ideas of different types of cathodes, highlighting some common strategies currently used to improve the electrochemical magnesium storage performance of cathodes. The aim of this widely covered review is to present important research works on different types of inorganic materials when used as cathodes for RMIBs, to summarize the challenges they face and the future directions. This is a departure from articles with an in-depth study of a particular branch. We hope to promote more research efforts on RMIBs in the future.

First-Principles Simulations for the Effect of Zinc Ions on MnO2/water system

The aqueous zinc-ion battery (AZIB), with its excellent power density, high energy density, safety, and sustainability, is a potential energy storage device. Manganese dioxide (MnO2), as the cathode material of AZIB, has shown exceptional electrochemical performance due to its multiple valence states and outstanding ion storage performance. Nevertheless, the energy storage process of MnO2 remains controversial. In order to explain the energy storage process of MnO2 in AZIB, it is necessary to explore the effect of Zinc ions (Zn2+) on the structure of the MnO2/water interface at the atomic scale. The effect of Zn2+ on the structure of MnO2/water interface systems was examined in this work using molecular dynamics simulation. Two representative crystal phases of MnO2, including α-MnO2 and δ-MnO2, were considered. The results revealed that Zn2+ will affect the structural stability of the MnO2/water interface system, and the degree of structural deformation in MnO2 varies with its crystal phase. Moreover, Zn2+ for both the α-MnO2/water and δ-MnO2/water systems prefer to be stabilized at the interface near MnO2 and the water, forming a spinel-like product. These results offer a fresh understanding of the MnO2 energy storage process in AZIBs and can help in the development of high-performance cathode materials.

Two-Dimensional Conjugated Metal-Organic Frameworks Embedded with Iodine for High-Performance Ammonium-Ion Hybrid Supercapacitors.

Ammonium ions (NH4 + ) are emerging non-metallic charge carriers for advanced electrochemical energy storage devices, due to their low cost, elemental abundance, and environmental benignity. However, finding suitable electrode materials to achieve rapid diffusion kinetics for NH4 + storage remains a great challenge. Herein, we report a two-dimensional conjugated metal-organic framework (2D c-MOF) for immobilizing iodine as a high-performance cathode material for NH4 + hybrid supercapacitors. Cu-HHB (HHB = hexahydroxybenzene) MOF embedded with iodine (Cu-HHB/I2 ) features excellent electrical conductivity, highly porous structure, and rich accessible active sites of copper-bis(dihydroxy) (Cu-O4 ) and iodide species, resulting in a remarkable areal capacitance of 111.7 mF cm-2 at 0.4mA cm-2 . Experimental results and theoretical calculations indicate that Cu-O4 species in Cu-HHB play a critical role in binding polyiodide and suppressing its dissolution, as well as contributing to a large pseudocapacitance with adsorbed iodide. In combination with porous MXene anode, the full NH4 + hybrid supercapacitors deliver an excellent energy density of 31.5 mWh cm-2 and long-term cycling stability with 89.5% capacitance retention after 10,000 cycles, superior to those of the state-of-the-art NH4 + hybrid supercapacitors. This study sheds light on the material design for NH4 + storage, enabling the development of novel high-performance energy storage devices. This article is protected by copyright. All rights reserved.

Lithium Sulfide –Carbon Composite Use as Positive Electrode in Post Lithium Ion Batteries Technology

Li‐ion batteries (LIBs) are the powerhouse for the electronic devices in this modern mobile society, and enabler of the current communication revolution. Consumers demands advanced electronics and sustainable industries in general. To satisfy these demands, the new generation of rechargeable batteries need to provide much higher energy and power density than the actual technology. Commercial LIBs consist of lithium cobalt oxide as positive electrodes and graphite as a negative electrode, this system has energy density values ca. 250 WhL-1.Lithium-sulfur is commonly considered as one of the most promising chemistries for improve traditional lithium-ion batteries in weight sensitive applications due to high theoretical capacity of lithium sulfide (Li2S) and high gravimetric energy density of such cells. Li2S provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g−1). This positive electrode material can be coupled with lithium-free negative electrode to develop high-energy-density batteries; this can improve the safety of the devices. Li2S is significantly more thermally stable, and offer greater mechanical stability as no further volumetric expansion occurs upon cycling.Li2S particles must be handled only in inert atmospheres (making production of high-performance cathode materials, on a commercial scale, quite difficult) and suffer from rapid degradation in cells during cycling. There are still challenges with it (e.g., low conductivity, high over potential and irreversible polysulfide diffusion), which have prevented the S utilization and stability. The dissolved polysulfides deposit on the surface of both electrodes resulting in a rapid impedance growth, loss in active material and ultimately battery failure.The complex synthesis method of Li2S–carbon composites restrains the large-scale productivity. We propose an easy and time saving method to synthesize a Li2S based nanocomposite cathode material by wet milling.This work may shed fresh insight into bridging the huge gap between high energy and safety of rechargeable cells for feasible applications. Figure 1

Polypyrrole-Doped NH4 V3 O8 with Oxygen Vacancies as High-Performance Cathode Material for Aqueous Zinc-Ion Batteries.

The inherent slow diffusion dynamics of aqueous zinc-ion batteries (AZIBs) act as a significant hindrance to their universal utilization as energy storage systems, largely attributed to the scarcity of superior cathode materials. In this study, a novel method that amalgamates oxygen defect engineering and polymer intercalation, guided by theoretical computations, to confront this challenge, is introduced. Thisapproach begins with density functional theory calculations, demonstrating that the shielding effect rendered by polypyrrole (PPy) between NH4 V3 O8 (NVO) layers, along with the cooperative influence of oxygen defects (Od ), optimizes the kinetic transport of Zn2+ . Leveraging these theoretical outcomes, a two-step hydrothermal synthesis procedure is devised to fabricate PPy-intercalated NVO embedded with Od (NVO-Od @PPy). Theempirical findings corroborate the theoretical predictions, showcasing that the NVO-Od @PPy//Zn system manifests exceptional cycling stability. Specifically, the NVO-Od @PPy electrode delivers an optimal reversible capacity, yielding 421 mAh g-1 at a current density of 0.1 A g-1 . Remarkably, even at an elevated current density of 10 A g-1 , it sustains a capacity of 175.7 mAh g-1 , while maintaining a capacity retention of 99% over 1000 cycles. This research provides pivotal insights for the engineering of high-performing cathode materials for AZIBs, paving the way for their future advancements.

Construction of CoS2 Reduction Accelerator-Modified Sulfurized Polyacrylonitrile Nanofibers as High-Performance Cathode Materials for Practical Lithium–Sulfur Batteries

Construction of CoS₂ Reduction Accelerator-Modified Sulfurized Polyacrylonitrile Nanofibers as High-Performance Cathode Materials for Practical Lithium–Sulfur Batteries

Preparation and electrochemical properties of Li3V2(PO4)3 glass-ceramic materials

The monoclinic lithium vanadium phosphate (Li3V2(PO4)3, LVP) is a promising cathode material for lithium-ion batteries due to its high theoretical specific capacitance, high operating voltage, good ionic conductivity, and thermal stability. However, synthesizing the pure LVP phase requires complicated procedures, expensive equipment, and long processing times. Moreover, the pure LVP phase has poor electrical conductivity, limiting its electrochemical properties and application. This study investigated the effect of glass preparation methods (single-crucible and double-crucible) and carbon coating on the crystalline phase, surface morphology, electrical conductivity, and electrochemical properties. A highly crystalline pure LVP phase can be synthesized effectively through heat treatment of the glass powder produced using the double crucible method at 700°C under a 5% H2-95% Ar atmosphere for 2 h. Adding C6H12O6 as a carbon source could increase the reducing atmosphere, preventing the oxidation of V3+ to V4+ and inhibiting the formation of the LiVOPO4 phase. This is beneficial for the synthesis of the pure LVP phase.Furthermore, the formation of an amorphous, uniform carbon coating on the surface of the LVP inhibits grain growth and increases the specific surface area. The CR2032 coin cell made with the LVP added with 10 wt% C6H12O6 had the highest initial discharge specific capacitance of 159.07 mAh g-1, with a specific capacitance retention rate of 77.31% even after 50 cycles. These findings suggest that LVP powder prepared using the double crucible method with carbon coating has the potential as a high-performance cathode material for lithium-ion batteries.

NiCo2Al-LDH@P-Ni(OH)2 cathode material with high power density and super long life for aqueous Ni-Zn battery

Owing to its economic cost, abundant raw materials and intrinsic safety, zinc-based aqueous batteries are coming to be the research hotspot of worldwide. A high-performance cathode material is one of the key factors for Zn-based aqueous batteries. Herein, we report a new cathode material, denoted as NiCo2Al-LDH@P-Ni(OH)2, that the phosphorus-doped Ni(OH)2 (P-Ni(OH)2) microrods are grown on nickel foam (NF) and the NiCo2Al-layered double-hydroxide (NiCo2Al-LDH) nanoflakes are grown on the P-Ni(OH)2 microrods. The NiCo2Al-LDH@P-Ni(OH)2 cathode material demonstrated excellent electrochemical properties with a high specific capacity of 2.95 mAh cm−2 at 4 mA cm−2 (surprisingly 368.7 mAh g−1), a sturdy rate ability of 64.78 % at about 67.8 C, (200 mA cm−2) as well as without any significant capacity degeneration after 10,000 cycles. The NiCo2Al-LDH@P-Ni(OH)2//Zn battery achieves an impressive peak energy density of 5.02 mWh cm−2, a maximum power density of 306.6 mW cm−2 together with a long lifespan of 97.1 % capacity retention after 10,000 cycles, exceeding majority of the aqueous batteries and supercapacitors reported recently. A homemade NiCo2Al-LDH@P-Ni(OH)2//Zn soft-package battery with a voltage of 3 V，which is formed by connecting two Ni-Zn batteries in series, can work even under puncturing, indicating that NiCo2Al-LDH@P-Ni(OH)2 hybrid cathodes have great potential for practical applications in high-performance Ni-Zn batteries.

High-performance Na-doped LiFePO4 cathode material derived from acid-washed iron red for the simultaneous immobilization of multi-metals

High-performance Na-doped LiFePO4 cathode material derived from acid-washed iron red for the simultaneous immobilization of multi-metals

Cu/Ti co-doping boosting P2-type Fe/Mn-based layered oxide cathodes for high-performance sodium storage

Environmentally friendly P2-type layered iron manganese oxides appear to be one of the most potential cathode materials for sodium-ion batteries (SIBs). However, their practical application is hindered by the unfavorable phase transitions, dissolution of transition metals, and poor air stability. One effective strategy by either single-cation doping or high-cost Li involved co-doping is used to alleviate the problems. Here, low-cost Cu/Ti co-doping is introduced to boost P2-Na0.7Cu0.2Fe0.2Mn0.5Ti0.1O2 as an air and electrochemical stable cathode material for SIBs. The resulting electrode delivers an initial capacity of 130 mAh g−1 at 0.1C within 2.0–4.2 V, a reversible discharge capacity of 61.0 mAh g−1 at a high rate of 5C and a capacity retention ratio exceeding 71.1% after 300 cycles. In particular, the co-doped crystal structure is well-maintained after 1 month of exposure to air, and even 3 days of soaking in water. Furthermore, the enhancement is elucidated by the effectively mitigated P2–Z and the completely suppressed P2–P′2 phase transitions, the decreased volume variation proved by in-situ X-ray diffraction (XRD), as well as the lowered transition-metal dissolution evidenced by inductively coupled plasma optical emission spectrometer (ICP-OES) and X-ray photoelectron spectroscopy (XPS). The low-lost Cu/Ti doping strategy could thus be effective for designing and preparing environmentally friendly and high-performance cathode materials for SIBs.