Oxide Cathodes For Sodium-Ion Batteries Research Articles

Application and Prospects of Ni–Mn-Based Layered Oxide Cathodes for Sodium-Ion Batteries

Application and Prospects of Ni–Mn-Based Layered Oxide Cathodes for Sodium-Ion Batteries

Toward the High-Voltage Stability of Layered Oxide Cathodes for Sodium-Ion Batteries: Challenges, Progress, and Perspectives.

Sodium-ion batteries (SIBs) have garnered significant attention as ideal candidates for large-scale energy storage due to their notable advantages in terms of resource availability and cost-effectiveness. However, there remains a substantial energy density gap between SIBs and commercially available lithium-ion batteries (LIBs), posing challenges to meeting the requirements of practical applications. The fabrication of high-energy cathodes has emerged as an efficient approach to enhancing the energy density of SIBs, which commonly requires cathodes operating in high-voltage regions. Layered oxide cathodes (LOCs), with low cost, facile synthesis, and high theoretical specific capacity, have emerged as one of the most promising candidates for commercial applications. However, LOCs encounter significant challenges when operated in high-voltage regions such as irreversible phase transitions, migration and dissolution of metal cations, loss of reactive oxygen, and the occurrence of serious interfacial parasitic reactions. These issues ultimately result in severe degradation in battery performance. This review aims to shed light on the key challenges and failure mechanisms encountered by LOCs when operated in high-voltage regions. Additionally, the corresponding strategies for improving the high-voltage stability of LOCs are comprehensively summarized. By providing fundamental insights and valuable perspectives, this review aims to contribute to the advancement of high-energy SIBs.

Advances in layered transition metal oxide cathodes for sodium-ion batteries

The rapid rise of renewable energy technology has greatly promoted the development of energy storage systems. Breaking decades of stagnation, sodium-ion batteries (SIBs) have now regained momentum in the field of energy storage and they are considered as a low-cost alternative to lithium-ion batteries. The search for suitable materials to reversibly host sodium ions has become a focal point in SIB field. Layered transition metal oxide (NaxTMO2) as the cathode material has attracted increasing attention due to its simple structure, facile synthesis, and high operating potential. Nevertheless, NaxTMO2 still faces severe challenges, including irreversible phase transitions, storage instability, insufficient performance, etc. This work provides a comprehensive review of NaxTMO2 as the cathode material for SIBs, analyzes the challenges encountered by NaxTMO2, and summarizes effective improvement strategies. Strategies including doping, composite cathode materials, high-entropy materials and microstructural modulation can effectively guide the design of NaxTMO2 with excellent performance. SIBs are bound to play a positive role in the new round of energy revolution.

Probing the account of phase transition upon electrochemical cycling of the P2-Na0.67Ni0.15Fe0.2Mn0.65O2 layered oxide cathodes for sodium-ion batteries

Layered P2-Na0.67Ni0.15Fe0.2Mn0.65O2 (P2-NFM) cathode material has attracted great attention in sodium-ion batteries due to its high theoretical capacity, low cost, and environmental friendliness. However, P2-NFM exhibits irreversible phase transition and slip of transition metal layers in the high voltage range during charging process, leading to a gradually declined performance of the cathode material. It is therefore necessary to investigate the mechanism of phase transition of P2-NFM as well as the effect of phase transition on its performance. Herein, utilizing ex situ x-ray diffraction spectroscopy and x-ray photoelectron spectroscopy, the crystal structure and TM (transition-metal) bonding changes caused by phase transition are elucidated. It is found that P2-NFM is prone to undergo an irreversible P2-O2 phase transition at high voltage, causing changes in lattice parameters and rapid capacity decay. The irreversible phase transition is mainly due to he dynamic transformation of valence states of Fe and Ni in P2-NFM materials at high voltage. It is this process that results in irreversible fluctuations in the bond lengths between these elements and oxygen, consequently instigating interlayer slip within the material. Besides, the charge compensation mechanism of P2-NFM has been elucidated based on the study of its initial charging process. Results show that the charge compensation is mainly contributed by Ni and Fe in the high voltage range, while by a small amount of Mn in the low voltage range. It reveals the essential cause of the adverse phase transition of P2-NFM materials and points out the direction for improving the cycling stability of these layered oxide materials.

Realizing high initial Coulombic efficiency in manganese-based layered oxide cathodes for sodium-ion batteries via P2/O′3 biphasic structure optimization

Realizing high initial Coulombic efficiency in manganese-based layered oxide cathodes for sodium-ion batteries via P2/O′3 biphasic structure optimization

Phase engineering of Ni-Mn binary layered oxide cathodes for sodium-ion batteries

Nickel-manganese binary layered oxides with high working potential and low cost are potential candidates for sodium-ion batteries, but their electrochemical properties are highly related to compositional diversity. Diverse composite materials with various phase structures of P3, P2/P3, P2, P2/O3, and P2/P3/O3 were synthesized by manipulating the sodium content and calcination conditions, leading to the construction of a synthetic phase diagram for NaxNi0.25Mn0.75O2 (0.45 ≤ x ≤ 1.1). Then, we compared the electrochemical characteristics and structural evolution during the desodiation/sodiation process of P2, P2/P3, P2/O3, and P2/P3/O3-NaxNi0.25Mn0.75O2. Among them, P2/P3-Na0.75Ni0.25Mn0.75O2 exhibits the best rate capability of 90.9 mA h g−1 at 5 C, with an initial discharge capacity of 142.62 mA h g−1 at 0.1 C and a capacity retention rate of 78.25% after 100 cycles at 1 C in the voltage range of 2–4.3 V. The observed superior sodium storage performance of P2/P3 hybrids compared to other composite phases can be attributed to the enhanced Na+ transfer dynamic, reduction of the Jahn-teller effect, and improved reaction reversibility induced by the synergistic effect of P2 and P3 phases. The systematic research and exploration of phases in NaxNi0.25Mn0.75O2 provide new sights into high-performance nickel-manganese binary layered oxide for sodium-ion batteries.

Structural effects of the iron/manganese ratio in Li-doped layered oxide cathodes for sodium-ion batteries

Li-doped layered oxides with different Fe/Mn ratios corresponding to the Na0.67[Li0.07Fe0.3+xMn0.63-x]O2 (x = 0, 0.15, 0.25) series, prepared between 800 and 1000 °C, are evaluated as cathode for sodium-ion batteries. On increasing the iron content and temperature of synthesis, new P3 and O3 phases appear along with the pre-existing P2 phase. Unfortunately, these multiphase systems are detrimental to the kinetic response and eventually electrochemical performance of these cathode materials, also revealing structural degradation on cycling. Only samples with the highest contribution of P2 phase can perform high capacities which can be retained for a long cycling.

Coupling the Electronic Distribution and Oxygen Redox Potential via Cu Substitution of Layered Oxide Cathodes for Sodium-Ion Batteries

Coupling the Electronic Distribution and Oxygen Redox Potential via Cu Substitution of Layered Oxide Cathodes for Sodium-Ion Batteries

Unraveling and suppressing the voltage decay of high-capacity cathode materials for sodium-ion batteries

The steric heterogeneity of Mn redox derived from the oxygen loss is the trigger of voltage decay in high-capacity oxygen-redox sodium-based layered oxides. Moreover, an electron localization strategy is developed to eliminate the voltage decay.

Routes to high-performance layered oxide cathodes for sodium-ion batteries.

Sodium-ion batteries (SIBs) are experiencing a large-scale renaissance to supplement or replace expensive lithium-ion batteries (LIBs) and low energy density lead-acid batteries in electrical energy storage systems and other applications. In this case, layered oxide materials have become one of the most popular cathode candidates for SIBs because of their low cost and comparatively facile synthesis method. However, the intrinsic shortcomings of layered oxide cathodes, which severely limit their commercialization process, urgently need to be addressed. In this review, inherent challenges associated with layered oxide cathodes for SIBs, such as their irreversible multiphase transition, poor air stability, and low energy density, are systematically summarized and discussed, together with strategies to overcome these dilemmas through bulk phase modulation, surface/interface modification, functional structure manipulation, and cationic and anionic redox optimization. Emphasis is placed on investigating variations in the chemical composition and structural configuration of layered oxide cathodes and how they affect the electrochemical behavior of the cathodes to illustrate how these issues can be addressed. The summary of failure mechanisms and corresponding modification strategies of layered oxide cathodes presented herein provides a valuable reference for scientific and practical issues related to the development of SIBs.

Challenges and Strategies toward Practical Application of Layered Transition Metal Oxide Cathodes for Sodium-Ion Batteries

Challenges and Strategies toward Practical Application of Layered Transition Metal Oxide Cathodes for Sodium-Ion Batteries

Realization High-Voltage Stabilization of O3-Type Layered Oxide Cathodes for Sodium-Ion Batteries by Sn Simultaneously Dual Modification

The total global production of lithium-ion batteries (LIBs) used in electric vehicles and stationary energy storage devices has increased sharply to reach the targeted Net Zero by 2050. This leads to concerns about the future and long-term availability and cost of critical raw materials (cobalt, nickel, lithium and copper) employed in LIBs. Therefore, alternative new-generation batteries with comparable performance but using less critical raw materials are needed.Sodium-ion Batteries (NIBs) offer a wealth of possibilities for inexpensive and sustainable energy storage devices. To maximize their potential, new cathode materials with high energy densities and stable structures are required. Cobalt-free sodium transition metal oxides of O3 type are a predominant cathode for NIBs due to their appreciable specific capacity, reduction in the use of critical elements, and the potential to rival LiFePO4 in terms of energy density. However, rapid capacity fading caused by serious structural and interfacial degradation hamper this process.Herein, we provide a novel Sn-modified O3-type NaNi1/3Fe1/3Mn1/3O2 cathode with improved high-voltage stability by bulk Sn doping and surface coating simultaneously. The bulk substitution of Sn4+ stabilizes the crystal structure by alleviating the irreversible high voltage phase transition and lattice structure degradation. In the meantime, the spontaneously formed tin rich surface layer effectively inhibits surface parasitic reactions and improves interfacial stability during cycling. As a result, the Sn-modified NaNi1/3Fe1/3Mn1/3O2 cathode exhibited excellent cycling performance by an almost doubled capacity retention increase after 200 cycles within 2.0-4.1V. The influence of Sn modification on the crystal structure and electrochemical properties has been investigated for the first time, and the mechanism was studied through an extensive analysis by in situ XRD, HRTEM, FIB-SEM, XPS and Mössbauer spectroscopy.This work offers an industrially feasible strategy to simultaneously stabilize the bulk structure and interface for O3-type layered cathodes for SIBs and raises the possibility of similar effective strategies to be employed for other energy storage materials Figure 1

High Voltage Ga-Doped P2-Type Na2/3 Ni0.2 Mn0.8 O2 Cathode for Sodium-Ion Batteries.

Ni/Mn-based oxide cathode materials have drawn great attention due to their high discharge voltage and large capacity, but structural instability at high potential causes rapid capacity decay. How to moderate the capacity loss while maintaining the advantages of high discharge voltage remains challenging. Herein, the replacement of Mn ions by Ga ions is proposed in the P2-Na2/3 Ni0.2 Mn0.8 O2 cathode for improving their cycling performances without sacrificing the high discharge voltage. With the introduction of Ga ions, the relative movement between the transition metal ions is restricted and more Na ions are retained in the lattice at high voltage, leading to an enhanced redox activity of Ni ions, validated by ex situ synchrotron X-ray absorption spectrum and X-ray photoelectron spectroscopy. Additionally, the P2-O2 phase transition is replaced by a P2-OP4 phase transition with a smaller volume change, reducing the lattice strain in the c-axis direction, as detected by operando/ex situ X-ray diffraction. Consequently, the Na2/3 Ni0.21 Mn0.74 Ga0.05 O2 electrode exhibits a high discharge voltage close to that of the undoped materials, while increasing voltage retention from 79% to 93% after 50 cycles. This work offers a new avenue for designing high-energy density Ni/Mn-based oxide cathodes for sodium-ion batteries.

Construction of environmental-stable and high-rate layered oxide cathodes for sodium-ion batteries

Layered manganese oxides, as dynamic cathodes for high energy density sodium ion batteries (SIBs), still suffer from not only rapid capacity decay, but also irreversible phase transition, unsatisfactory rate performance and air instability. In this work, Li/Ni/Ti co-doping Na0.72Li0.16Ni0.12Ti0.1Mn0.62O2 (NLNTMO) cathode was successfully synthesized and it revealed that the structure design not only effectively inhibits Jahn-Teller distortion to improve cycling stability but also enhances its resistance to air and moisture degradation. Besides, density functional theory (DFT) calculations reveal that Ti can slightly adjust the energy level of isolated O 2p and Mn 3d orbitals. The in-situ X-ray diffraction (XRD) analysis reveals the inhibition of the repulsive phase transition from P2–OP4/O2 and the occurrence of a solid solution reaction instead. As a result, NLNTMO cathode presents a high specific capacity of 198.6 mAh g−1 at 0.2C, 70 mAh g−1 at 20C (4 A g−1) and a high capacity retention of 80 % in 2.0–4.4 V after 200 cycles at 1C.

Structural Evolution of Air-Exposed Layered Oxide Cathodes for Sodium-Ion Batteries: An Example of Ni-doped NaxMnO2.

Sodium-ion batteries have recently aroused the interest of industries as possible replacements for lithium-ion batteries in some areas. With their high theoretical capacities and competitive prices, P2-type layered oxides (NaxTMO2) are among the obvious choices in terms of cathode materials. On the other hand, many of these materials are unstable in air due to their reactivity toward water and carbon dioxide. Here, Na0.67Mn0.9Ni0.1O2 (NMNO), one of such materials, has been synthesized by a classic sol-gel method and then exposed to air for several weeks as a way to allow a simple and reproducible transition toward a Na-rich birnessite phase. The transition between the anhydrous P2 to the hydrated birnessite structure has been followed via periodic XRD analyses, as well as neutron diffraction ones. Extensive electrochemical characterizations of both pristine NMNO and the air-exposed one vs sodium in organic medium showed comparable performances, with capacities fading from 140 to 60 mAh g-1 in around 100 cycles. Structural evolution of the air-exposed NMNO has been investigated both with ex situ synchrotron XRD and Raman. Finally, DFT analyses showed similar charge compensation mechanisms between P2 and birnessite phases, providing a reason for the similarities between the electrochemical properties of both materials.

The effect of configurational entropy on acoustic emission of P2-type layered oxide cathodes for sodium-ion batteries

Sodium-ion batteries (SIBs) see intensive research and commercialization efforts, aiming to establish them as an alternative to lithium-ion batteries. Among the reported cathode material families for SIBs, Na-deficient P2-type layered oxides are promising candidates, benefiting from fast sodium diffusion and therefore high charge/discharge rates. However, upon sodium extraction at high potentials, a transition from the P2 to O2 phase occurs, with the corresponding change in cell volume resulting in particle fracture and capacity degradation. A possible solution to this is to increase configurational entropy by introducing more elements into the transition-metal layer (so-called high-entropy concept), leading to some kind of structural stabilization. In this work, the acoustic emission (AE) of a series of P2-type layered oxide cathodes with increasing configurational entropy [Na0.67(Mn0.55Ni0.21Co0.24)O2, Na0.67(Mn0.45Ni0.18Co0.24Ti0.1Mg0.03)O2 and Na0.67(Mn0.45Ni0.18Co0.18Ti0.1Mg0.03Al0.04Fe0.02)O2] is recorded during SIB operation and correlated to the materials properties, namely change in c lattice parameter and cracking behavior. A structure-property relationship between entropy, manifested in the extent of phase transition, and detected AE is derived, supported by the classification of signals by peak frequency. This classification in combination with microscopy imaging allows to distinguish between inter- and intragranular fracture. Relatively more intergranular and less intragranular crack formation is observed with increasing configurational entropy.

Layered oxide cathodes for sodium-ion batteries: microstructure design, local chemistry and structural unit

Layered oxide cathodes for sodium-ion batteries: microstructure design, local chemistry and structural unit

Tailored P2/O3 phase-dependent electrochemical behavior of Mn-based cathode for sodium-ion batteries

The development of mixed structures is increasingly becoming an efficient way to improve the performance of layered oxide cathodes for sodium-ion batteries. Herein, the Na0.8Mn0.6Ni0.3Cu0.1O2 (NMNC) cathodes with varying fractions of P2/O3-type phases are prepared by adjusting the calcination conditions. The Rietveld refinement of X-ray diffraction (XRD) data confirms the increase in O3 phase fraction from 7 % to 27 % with the increase in calcination temperature from 850 °C to 950 °C. The sample prepared at 850 °C (NMNC-850) exhibits the highest specific capacity (139 mAh g−1, 100 mAh g−1, and 80 mAh g−1 at 0.1C, 1C, and 4C, respectively) and best rate performance among all samples in addition to an excellent cyclability with capacity retention of ~85 % after 100 cycles in 1.5–4.2 V range. The increase in the O3 phase fraction leads to a drastic degradation of rate performance. The galvanostatic intermittent titration technique confirms a diffusion coefficient of 5.13 × 10−13–5.25 × 10−10 cm2 s−1 in biphasic NMNC-850 sample. Ex-situ XRD studies confirm a reversible P2/O3 → P2/P3 → P2/O3 transformation in NNMC-850 during cycling. The improved electrochemical performance is attributed to the presence of non-identical neighboring phases in suppressing the phase transformations during cycling.

Annealing in Argon Universally Upgrades the Na‐Storage Performance of Mn‐Based Layered Oxide Cathodes by Creating Bulk Oxygen Vacancies

AbstractManganese‐rich layered oxide cathodes of sodium‐ion batteries (SIBs) are extremely promising for large‐scale energy storage owing to their high capacities and cost effectiveness, while the Jahn–Teller (J–T) distortion and low operating potential of Mn redox largely hinder their practical applications. Herein, we reveal that annealing in argon rather than conventional air is a universal strategy to comprehensively upgrade the Na‐storage performance of Mn‐based oxide cathodes. Bulk oxygen vacancies are introduced via this method, leading to reduced Mn valence, lowered Mn 3d‐orbital energy level, and formation of the new‐concept Mn domains. As a result, the energy density of the model P2‐Na0.75Mg0.25Mn0.75O2cathode increases by ≈50 % benefiting from the improved specific capacity and operating potential of Mn redox. The Mn domains can disrupt the cooperative J–T distortion, greatly promoting the cycling stability. This exciting finding opens a new avenue towards high‐performance Mn‐based oxide cathodes for SIBs.

Layered Oxide Cathodes for Sodium-Ion Batteries: Storage Mechanism, Electrochemistry, and Techno-economics.

ConspectusLithium-ion batteries (LIBs) are ubiquitous in all modern portable electronic devices such as mobile phones and laptops as well as for powering hybrid electric vehicles and other large-scale devices. Sodium-ion batteries (NIBs), which possess a similar cell configuration and working mechanism, have already been proven as ideal alternatives for large-scale energy storage systems. The advantages of NIBs are as follows. First, sodium resources are abundantly distributed in the earth's crust. Second, high-performance NIB cathode materials can be fabricated by using solely inexpensive and noncritical transition metals such as manganese and iron, which further reduces the cost of the required raw materials. Recently, the unprecedented demand for lithium and other critical minerals has driven the cost of these primary raw materials (which are utilized in LIBs) to a historic high and thus triggered the commercialization of NIBs.Sodium layered transition metal oxides (NaxTMO2, TM = transition metal/s), such as Mn-based sodium layered oxides, represent an important family of cathode materials with the potential to reduce costs, increase energy density and cycling stability, and improve the safety of NIBs for large-scale energy storage. However, these layered oxides face several key challenges, including irreversible phase transformations during cycling, poor air stability, complex charge-compensation mechanisms, and relatively high cost of the full cell compared to LiFePO4-based LIBs. Our work has focused on the techno-economic analysis, the degradation mechanism of NaxTMO2 upon cycling and air exposure, and the development of effective strategies to improve their electrochemical performances and air stability. Correlating structure-performance relationships and establishing general design strategies of NaxTMO2 must be considered for the commercialization of NIBs.In this Account, we discuss the recent progress in the development of air-stable, electrochemically stable, and cost-effective NaxTMO2. The favorable redox-active cations for NaxTMO2 are emphasized in terms of abundance, cost, supply, and energy density. Different working mechanisms related to NaxTMO2 are summarized, including the electrochemical reversibility, the main structural transformations during the charge and discharge processes, and the charge-compensation mechanisms that accompany the (de)intercalation of Na+ ions, followed by discussions to improve the stability toward ambient air and upon cycling. Then the techno-economics are presented, with an emphasis on cathodes with different chemical compositions, cost breakdown of battery packs, and Na deficiency, factors that are critical to the large-scale implementation. Finally, this Account concludes with an overview of the remaining challenges and new opportunities concerning the practical applications of NaxTMO2, with an emphasis on the cost, large-scale fabrication capability, and electrochemical performance.