Manganese-based Cathode Materials Research Articles

Hierarchical accordion-like manganese oxide@carbon hybrid with strong interaction heterointerface for high-performance aqueous zinc ion batteries.

Aqueous zinc ion batteries have attracted extensive concern as a promising candidate for large-scale energy storage because of their high theoretical specific capacity, low cost and inherent safety. However, the lacking of applicable cathode materials with outstanding electrochemical performance have severely hindered the further development of aqueous zinc ion batteries. Herein, we report a hierarchical accordion-like manganese oxide@carbon (MnO@C) hybrid with strong interaction heterointerface and comprehensively inquire into its electrochemical performance as cathode materials for aqueous zinc ion batteries. The unique hierarchical accordion-like layered structure coupling with strong interaction heterointerface between small MnO and carbon matrix efficaciously improve the ion/electron transfer process and enhance structure stability of the MnO@C hybrid. Benefitting from these unique advantages, the MnO@C hybrid bestows excellent specific capacity of 456mAhg-1 at 50mAg-1. Impressively, the MnO@C hybrid presents distinguished long-term cycling stability with fairly low decay rates of only 0.0079% per cycle even over 2000 cycles at 2000mAg-1. Moreover, comprehensive characterizations are executed to elucidate the mechanism involved. Therefore, this work affords a new idea for developing outstanding performance manganese-based cathode materials for aqueous zinc ion batteries.

Phase-Transformation-Activated MnCO3 as Cathode Material of Aqueous Zinc-Ion Batteries

The intrinsic high safety of rechargeable aqueous batteries makes them particularly advantageous in the field of large-scale energy storage. Among them, rechargeable Zn–Mn batteries with high energy density, low cost, high discharge voltage, and nontoxicity have been considered as one of the most promising aqueous battery systems. However, exiting research on manganese-based cathode materials mainly focuses on diverse manganese oxides analogs, while reports on other promising manganese-based analogs with high performance are still limited. Herein, we report a MnCO3 cathode material, which can be manufactured on a large scale by a facile coprecipitation method. Interestingly, the MnCO3 can spontaneously be converted into MnO2 material during the charging process. The Zn–MnCO3 battery delivers a highly specific capacity (280 mAh g−1) even at the high current density of 50 mA g−1. It is also noteworthy that the battery with a high loading mass (7.2 mg cm−2) exhibits good reversibility of charge–discharge for 2000 cycles, showing a competitive cycling stability in aqueous systems.

Enhancing cyclic performance of lithium-rich manganese-based cathode via in-situ co-doping of magnesium and fluorine

Lithium-rich manganese-based materials (LRM) are regarded as promising next-generation commercial cathodes due to their exceptionally high capacities and working voltages. However, lithium-rich manganese-based materials are plagued with inferior cyclic stability and voltage fading, which greatly stifled their commercial transitions. In this work, the dopant F and Mg uniformly distributed lithium-rich manganese-based cathode material is firstly prepared via an in-situ co-precipitation and high-temperature calcination method. The F and Mg co-doped sample can demonstrate excellent cyclic stability (88.56%, after 100 cycles at 1 C), and higher initial discharge and coulombic efficiency by reducing the transition metal (TM) loss and structure stabilization. Thus, this work presents crucial findings in the development of lithium-rich manganese-based materials, which provides a novel doping route and a vital method of cation-anion co-doping to prepare high-performing cathodes.

Exploration of Calcium-Doped Manganese Monoxide Cathode for High-Performance Aqueous Zinc-Ion Batteries

Manganese-based cathode materials for rechargeable zinc-ion batteries (ZIBs) have drawn much interest because of their reliable safety, abundant resources, and low cost. Manganese monoxide is not considered a suitable candidate cathode due to the lack of tunneling structure but exhibits a considerable specific capacity. Therefore, investigation of the energy storage mechanism of manganese monoxide is instructive for the development of ZIBs. Here, a one-step solid-phase reaction synthesizes manganese monoxide with calcium doping. The experimental characterization and ex situ X-ray diffraction (XRD) results demonstrate that Ca dopants significantly speed up the formation of Mn defects and prolong the cycling stability. Aqueous ZIBs with Ca-doped MnO cathode can deliver a high specific capacity of 315 mAh g–1 at 0.1 A g–1 and long-term cycling performance with a significant capacity retention rate (74%) at 1 A g–1 after 5000 cycles. This work may provide a new strategy for designing high-performance cathode materials for aqueous ZIBs via heteroatom doping and help to understand its energy storage mechanism.

Enabling stable 4.6 V LiCoO2 cathode through oxygen charge regulation strategy

LiCoO2 is the preferred cathode material for consumer electronic products due to its high volumetric energy density. However, the unfavorable phase transition and surface oxygen release limits the practical application of LiCoO2 at a high-voltage of 4.6 V to achieve a higher energy density demanded by the market. Herein, both bulk and surface structures of LiCoO2 are stabilized at 4.6 V through oxygen charge regulation by Gd-gradient doping. The enrichment of highly electropositive Gd on LiCoO2 surface will increase the effective charge on oxygen and improve the oxygen framework stability against oxygen loss. On the other hand, Gd ions occupy theCo-sites and suppress the unfavorable phase transition and micro-crack. The modified LiCoO2 exhibits superior cycling stability with capacity retention of 90.1% over 200 cycles at 4.6 V, and also obtains a high capacity of 145.7 mAh/g at 5 C. This work shows great promise for developing high-voltage LiCoO2 at 4.6 V and the strategy could also contribute to optimizing other cathode materials with high voltage and large capacity, such as cobalt-free high-nickel and lithium-rich manganese-based cathode materials.

Aluminum doping and lithium tungstate surface coating double effect to improve the cycle stability of lithium-rich manganese-based cathode materials

Al doped lithium-rich manganese-based Li1.2Mn0.54−xAlxNi0.13Co0.13O2 (x = 0, 0.03) cathode materials for lithium-ion batteries were synthesized with sol-gel method, and then Li2WO4 coating was prepared by one-step liquid phase method. The effects of Al doping and Li2WO4 coating on the electrochemical properties of lithium-rich manganese-based cathode materials were systematically studied. The results show that Al doping significantly improves the cycle stability of lithium-rich manganese-based cathode material, and the coating Li2WO4 significantly improves its magnification performance and the voltage attenuation of discharge plateau. The coating amount of Li2WO4 is 5%, and the specific capacity of Li1.2Mn0.51Al0.03Ni0.13Co0.13O2 cathode material is still up to about 110 mAh·g−1 in the charge and discharge voltage range of 2.0-4.8 V and the current density of 1,000 mA·g−1. At the same time, the capacity retention rate of 300 cycles at the current density of 100 mA·g−1 is 78%, and the voltage attenuation of the discharge plateau during the cycle is also significantly reduced. This work provides a new idea for solving the cycle stability and platform voltage attenuation of lithium-ion battery lithium-rich manganese-based cathode materials.

Surface engineering for high stable lithium-rich manganese-based cathode materials

Lithium-rich manganese-based material shows great potential as the high specific cathode materials due to its low cost, environmental friendliness, high operating voltage and simple preparation process. However, the poor capacity retention and cycling performance caused by its unstable structure during cycling restrict the commercialization. In this work, Li1.2Ni0.16Mn0.56Co0.08O2 was synthesized utilizing a Co-precipitation method and different amount of La(PO3)3 (La(PO3)3 = 2 wt%, 4 wt% and 6 wt%) was selected as the coating layer to resolve the above issues. During the calcination process, La(PO3)3 reacts with impurities such as LiOH and Li2CO3 on the lithium-rich surface to reduce the residual lithium on the surface, thus improving the interfacial stability, slowing down the corrosion of the electrolyte, and finally enhancing its electrochemical performance. The cathode materials coated with 4% of La(PO3)3 showed the best electrochemical performance in terms of capacity retention and cycling performance compared to the pristine NCM. The high initial discharge capacity of 214.21 mAh/g and capacity retention of 94.2% after 100 cycles at 0.1 C can be obtained. This work provides an effective strategy to protect the cathode from corrosion and will promote its further practical applications in high specific Li-ion batteries.

PVDF−HFP binder for advanced zinc−manganese batteries

In order to optimize and select the appropriate binder to improve the electrochemical performance of aqueous zinc−manganese batteries, the influences of water-soluble binders and oil-based binders on the zinc storage performance of manganese-based cathode materials were systematically investigated. The results show that the water-soluble binders with large numbers of hydroxyl and carboxyl groups are easily soluble in aqueous electrolytes, leading to poor electrochemical performance. Fortunately, the cathodes with polyvinylidene fluoride− hexafluoropropylene (PVDF−HFP) binder display high specific capacity of 264.9 mA·h/g and good capacity retention of 92% after 90 cycles at 100 mA/g. Meanwhile, PVDF−HFP binder with plenty of hydrophobic groups presents excellent ability in inhibiting cracks on the surface of electrode, reducing voltage polarization and charge transfer resistance, as well as maintaining electrode integrity.

Layered O6/O3 Multi-Phase Composite Derived from the P2/O3 Nanocrystalline Composite for High-Performance Li-Rich Manganese-Based Cathode Material

As a result of the redox reaction of lattice oxygen occurring at 4.5 V, the Li-rich manganese cathode material with an O3 configuration has a theoretically high discharge capacity (>250 mA h/g). However, it also suffers a structural transition from layered structure to spinel structure in the cycling process, leading to severe voltage decay and capacity fading. On contrary, the O6 type material obtained via ion exchange of P2 type material can effectively inhibit the phase transition and stabilize the layered structure. Hence, in this work, we design an O6/O3 multi-phase composite material after ion exchange of the P2/O3 nanocrystalline composite. Compared with the O3 type cathode, the as-obtained cathode composite exhibits a higher initial discharge capacity (≈265 mA h/g at 20 mA/g) and an excellent capacity retention (≈87% after 100 cycles). Moreover, the first cycle Coulombic efficiency increases by nearly 10%, and voltage attenuation is effectively inhibited. Our findings demonstrate that modulating the O6/O3 configuration is a practical and simple methodology to promote the electrochemical performance of lithium-rich layered materials.

A high-performance silver-doped manganese oxide nanowire cathode based on combination displacement/intercalation reaction and deposition-dissolution mechanism

Rechargeable aqueous zinc ion batteries (ZIBs) have attracted increasing interest in large-scale energy storage systems due to their low cost, high safety, and high volumetric energy density. Manganese-based materials are one of most promising aqueous zinc ion battery cathode materials while their practical applications in ZIBs are limited by their low electrical conductivity, poor cycling stability and controversial energy storage mechanism. In this work, Ag0.8Mn8O16, a kind of manganese-based cathode material with combination displacement/intercalation reaction was prepared by using a hydrothermal method. Due to combination displacement/intercalation reaction mechanism, the generation of metallic silver during the discharge process greatly enhances the electronic conductivity of the material and thus the Ag0.8Mn8O16 exhibits excellent rate performance and a reversible capacity of 198 mA h g−1 at 2 A g−1 after 1000 cycles. In addition, Ag0.8Mn8O16 shows an interesting capacity rise at low current density and through a series of comparative experiments, the existence of deposition dissolution mechanism in Zn/Ag0.8Mn8O16 battery was confirmed to be a critical factor of capacity increase.

Cation and polyanion co-doping synergy to improve electrochemical performances of Li-rich manganese-based cathode materials

The redox of anions can be realized by the Li-rich manganese-based (LRM) cathode materials at high voltage, which provides a high specific capacity application prospect for lithium-ion batteries. However, the anion redox reaction brings problems such as poor cycling performance and serious voltage decay, which can be improved by the doping method. Herein, Al3+ cation and (BO3)3-/(BO4)5- polyanion are introduced into the LRM cathode materials to achieve double site occupation and charge regulation of the structure. It results in excellent electrochemical properties, especially in terms of cycling stability. The doped sample shows a discharged capacity of 239 mAh g−1 at 0.01 C after 100 cycles and a capacity retention rate of 92.0 % (higher than 77.9 % of the pristine sample). Through the brand newly-developed in-situ electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy analysis, the joint regulation of Al3+ and (BO3)3-/(BO4)5- inhibits the attack of singlet oxygen on the electrolyte and makes the cathode electrolyte interphases (CEI) film more uniform. First-principles calculations show that the introduction of electron holes and the reduction of the covalency between transition metal and O are key factors in the improvement of electrochemical property and structural stability of the modified materials.

Superstructure Control of Anionic Redox Behavior in Manganese-Based Cathode Materials for Li-Ion Batteries.

Anionic charge compensation creates conditions for realizing high capacity and energy density of Li-ion batteries cathode materials. However, the issues of voltage hysteresis, capacity attenuation, and structure transformation caused by the labile anionic redox are still difficult to solve fundamentally. The superstructure formed by a Li-Mn ordered arrangement is the intrinsic reason to trigger the anionic charge compensation. In this work, manganese-based cathode materials with series of Li-Mn ordered superstructure types have been prepared by an ion exchange method, and superstructure control of the anionic redox behavior has been synthetically investigated. With the dispersion of a LiMn6 superstructure unit, the aggregation of Li vacancies in Mn slab is gradually inhibited, which eliminates the production of O-O dimers and improves the reversibility of oxygen redox. Therefore, the voltage hysteresis and capacity fading have been significantly improved. Meanwhile, the amount of reactive oxygen species and their capacity contribution is reduced, and the sluggish electrochemical reaction kinetics of anion requires a low current density to boost the high-capacity advantage. This paper provides effective ideas for the design of various superstructures and the rational utilization of anionic redox.

Scalable fabrication of NiCoMnO4 yolk-shell microspheres with gradient oxygen vacancies for high-performance aqueous zinc ion batteries

Defect regulation, which enables better charge transfer and capacity retention in manganese-based cathode materials, is the key to the development of rechargeable aqueous zinc-ion batteries. Herein, yolk-shell structured NiCoMnO4-VO with gradient oxygen vacancies are synthesized by spray pyrolysis and ammonia etching. The generation of the yolk-shell structures are regulated by the diffusion rate of ions in the atomized droplets during the nucleation process instead of adding template agent. In addition, the etching effect of ammonia gradually dissolves nickel oxide in the material from the surface to the interior, creating abounding gradient oxygen vacancies and thereby achieving more active sites for zinc storage and faster charge transfer. Therefore, the material exhibits superior electrochemical performances with initial discharge capacities of 277.9 mA h g−1 at 0.2 A g−1, and the long-term capacities retention rate is 89.3% after 2800 cycles at 5 A g−1. Ex-situ XRD demonstrates NiCoMnO4-VO belongs to the embedding-extraction mechanism of H+ and Zn2+. In-situ optical microscopy reveals that the formation of zinc dendrites is suppressed to some extent.

Challenges and Perspectives for Doping Strategy for Manganese-Based Zinc-ion Battery Cathode

As one of the most appealing options for large-scale energy storage systems, the commercialization of aqueous zinc-ion batteries (AZIBs) has received considerable attention due to their cost effectiveness and inherent safety. A potential cathode material for the commercialization of AZIBs is the manganese-based cathode, but it suffers from poor cycle stability, owing to the Jahn–Teller effect, which leads to the dissolution of Mn in the electrolyte, as well as low electron/ion conductivity. In order to solve these problems, various strategies have been adopted to improve the stability of manganese-based cathode materials. Among those, the doping strategy has become popular, where the dopant is inserted into the intrinsic crystal structures of electrode materials, which would stabilize them and tune the electronic state of the redox center to realize high ion/electron transport. Herein, we summarize the ion doping strategy from the following aspects: (1) synthesis strategy of doped manganese-based oxides; (2) valence-dependent dopant ions in manganese-based oxides; (3) optimization mechanism of ion doping in zinc-manganese battery. Lastly, an in-depth understanding and future perspectives of ion doping strategy in electrode materials are provided for the commercialization of manganese-based zinc-ion batteries.

Suppress oxygen evolution of lithium-rich manganese-based cathode materials via an integrated strategy

Improving the reversibility of anionic redox and inhibiting irreversible oxygen evolution are the main challenges in the application of high reversible capacity Li-rich Mn-based cathode materials. A facile synchronous lithiation strategy combining the advantages of yttrium doping and LiYO2 surface coating is proposed. Yttrium doping effectively suppresses the oxygen evolution during the delithiation process by increasing the energy barrier of oxygen evolution reaction through strong Y–O bond energy. LiYO2 nanocoating has the function of structural constraint and protection, that protecting the lattice oxygen exposed to the surface, thus avoiding irreversible oxidation. As an Li+ conductor, LiYO2 nanocoating can provide a fast Li+ transfer channel, which enables the sample to have excellent rate performance. The synergistic effect of Y doping and nano-LiYO2 coating integration suppresses the oxygen release from the surface, accelerates the diffusion of Li+ from electrolyte to electrode and decreases the interfacial side reactions, enabling the lithium ion batteries to obtain good electrochemical performance. The lithium-ion full cell employing the Y-1 sample (cathode) and commercial graphite (anode) exhibit an excellent specific energy density of 442.9 Wh kg−1 at a current density of 0.1C, with very stable safety performance, which can be used in a wide temperature range (60 to −15 °C) stable operation. This result illustrates a new integration strategy for advanced cathode materials to achieve high specific energy density.

Improve the Midpoint Voltage and Structural Stability of Li-Rich Manganese-Based Cathode Material by Increasing the Nickel Content

Lithium-rich manganese is a promising new-generation cathode material for lithium-ion batteries. However, it has the common problems of serious discharge capacity decline, poor rate performance, and faster midpoint voltage decay. In this experiment, a sol-gel method was used to synthesize a high-nickel, lithium-rich layered oxide (1 − x)Li1.2Mn0.54Co0.13Ni0.13O2 − xLiNiO2 (x = 0, 1.0, 2.0, 3.0 and 4.0) that was characterized by XRD, SEM, XPS, TEM, and charge-discharge performance tests. The research results show that increasing Ni content can improve the stability of the material structure and enhance the electrochemical performance of the cathode material. When the LiNiO2 is 0.3, the electrochemical performance is better, the capacity retention rate is 100.3% after 60 cycles at a current density of 0.2 C, and the capacity retention rate for 100 cycles at 0.5 C is 99.0%.

Hydrated ammonium manganese phosphates by electrochemically induced manganese-defect as cathode material for aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) with the merits of low cost, low toxicity, high safety, environmental benignity as well as multi-valence properties as the large-scale energy storage devices demonstrate tremendous application prospect. However, the explorations for the most competitive manganese-based cathode materials of AZIBs have been mainly limited to some known manganese oxides. Herein, we report a new type of cathode material NH4MnPO4·H2O (abbreviated as AMPH) for rechargeable AZIBs synthesized through a simple hydrothermal method. An in-situ electrochemical strategy inducing Mn-defect has been used to unlock the electrochemical activity of AMPH through the initial charge process, which can convert poor electrochemical characteristic of AMPH towards Zn2+ and NH4+ into great electrochemically active cathode for AZIBs. It still delivers a reversible discharge capacity up to 90.0 mAh/g at 0.5 A/g even after 1000th cycles, which indicates a considerable capacity and an impressive cycle stability. Furthermore, this cathode reveals an (de)insertion mechanism of Zn2+ and NH4+ without structural collapse during the charge/discharge process. The work not only supplements a new member for the family of manganese-based compound for AZIBs, but also provides a potential direction for developing novel cathode material for AZIBs by introducing defect chemistry.

Xanthan gum with double-helix structure as a novel aqueous binder to stabilize lithium-rich cathode

Lithium-rich manganese-based cathode materials have the advantages of high specific capacity and operating voltage, but they still pose some problems such as poor cycle performance and serious voltage fading. Here, xanthan gum (XG) with double-helix structure has been investigated as a novel aqueous binder to improve the electrochemical performance of Li[Li0.2Co0.13Ni0.13Mn0.54]O2. When the mass proportion of XG is 5%, the prepared lithium-rich cathode shows the highest specific capacity and best cycle stability. After cycling, the discharge voltage of the lithium-rich cathode decreases by only 273 mV, indicating that XG can effectively inhibit the voltage fading of the lithium-rich material.

Study on La-doped lithium-rich manganese-based cathode materials (Li1.5Mn0.7Co0.15Ni0.15O2.5)

Study on La-doped lithium-rich manganese-based cathode materials (Li1.5Mn0.7Co0.15Ni0.15O2.5)

A facile and high-effective oxygen defect engineering for improving electrochemical performance of lithium-rich manganese-based cathode materials

The irreversible evolution of oxygen for lithium-rich manganese-based cathode (LRMC) is the main challenge which will induce accelerated migration of transition metal ions and structural transformation, thus resulting in serious voltage attenuation and capacity decay. Herein, a facile and high-effective oxygen vacancy engineering of hydrogenation treatment is proposed for introducing oxygen vacancy on the surface of LRMC to suppress the irreversible evolution of oxygen. X-ray diffraction (XRD) Rietveld refinement, X-ray photoelectron spectroscopy and electron paramagnetic spectroscopy demonstrate the successful introduction of oxygen vacancy on the surface of LRMC. The changes of physicochemical properties of LRMC after hydrogenation treatment are investigated through systematical electrochemical performance tests and scanning electron microscopy and transmission electron microscopy. The investigative results reveal that the presence of oxygen vacancy can significantly improve the structural stability, electrical conductivity and Li+ diffusion kinetics of the LRMC materials. Especially, the optimized H500-LRMC shows excellent electrochemical performances including the enhanced cyclic stability with a capacity retention of 221.8 mAh g−1 and a capacity retention rate of 94.11% after 100 cycles. Therefore, the well-designed oxygen vacancy engineering through hydrogenation treatment is a promising strategy for the development and industrialization of the high-performance LRMC.