Manganese-based Cathode Materials Research Articles

State-of-Charge Estimation of Lithium-Rich Manganese-Based Batteries Based on WOA LSTM and Extended Kalman Filter

Recent years, electric vehicles gradually become popular, but their cruising range has become one of the main problems that plague car companies and users. The lithium-rich manganese-based cathode material batteries with higher energy density stand out. The state of charge is an important parameter. This paper selects a 19Ah lithium-rich manganese-based cathode material battery for research, using extended Kalman filter based on second-order Equivalent circuit model estimate its state of charge. However, the impedance spectrum of lithium-rich manganese battery is different from that of 18650 lithium-ion battery, and the second-order equivalent circuit model will have errors, resulting in the low accuracy of SOC estimation. In order to solve this problem, this paper proposes two schemes: EKF-LSTM and LSTM-EKF. The whale optimization algorithm (WOA) is used to select the preset parameters. The results show that the LSTM-EKF method has the highest estimation accuracy, with a maximum error of 1.46%.

Efficient recovery and utilization of electrolytic manganese anode mud- preparation of high-performance Li1.2Ni0.2Mn0.6O2 cathode material for lithium-ion batteries

The booming electrolytic manganese industry has brought a huge amount of electrolytic manganese anode mud (EMAM). The management and value-added recovery of EMAM were very important for environmental improvement and economic benefits. In this study, EMAM is used as a cost-effective raw material. Firstly, the manganese-containing solution was obtained by reducing acid leaching with EMAM. Then, Li1.2Ni0.2Mn0.6O2 (Z-LNMO) cathode materials were prepared from a manganese-containing solution by co-precipitation process. Finally, to enhance the performance of the Z-LNMO materials, surfactants (C12H25SO4Na, C10H14N2Na2O8, C18H29NaO3S, C19H42BrN) were introduced in the preparation of precursor materials to obtain the material with higher crystallinity. ICP results showed that S/Fe ions of EMAM were retained in Z-LNMO materials. Moreover, the Z-LNMO sample shows a stoichiometric similar element content to Li1.2Ni0.18Fe0.02Mn0.6O1.96S0.04. EDS results show that S/Fe ions were uniformly distributed in Z-LNMO materials. The shift of XRD peak further indicates that the use of EMAM waste is expected to directly obtain S/Fe ions doped lithium-rich manganese-based cathode materials. The first-principle calculation shows that the S/Fe ions as the doping source make the transfer of excited electrons from the valence band to the conduction band easier, thereby enhancing the conductivity of the materials. The CV curve and differential capacity (dQ/dV) curve show that the Z-LNMO material prepared by EMAM inhibits the excessive oxidation of Li2MnO3 to a certain extent, thus providing excellent reversible capacity and stabilizing the material structure. Electrochemical evaluation reveals that the Z-LNMO materials prepared with the EMAM exhibit superior cycling stability (112% after 100 cycles at 0.1C). Moreover, the introduction of C10H14N2Na2O8 (EDTA-2Na) and C12H25SO4Na (SDS) in the preparation of precursor materials can improve the first discharge-specific capacity and stability of materials by modifying the morphology of precursor materials (refine particles). Among them, the materials modified by EDTA-2Na show the best performance, and the particle size is about 200 nm. Compared with the original materials, the improved first discharge-specific capacity (218.6 mAh g−1 at 0.1C) and capacity retention (245.8 mAh g−1 after 100 cycles) of the materials modified with EDTA-2Na were improved. The EIS results also confirm that the introduction of EDTA-2Na effectively decreases the charge transfer resistance and facilitates the Li diffusion of the as-prepared cathode materials. This work confirmed the possibility of extracting manganese from EMAM to prepare lithium-rich manganese-based cathode materials, and provided a new promising way for the efficient value-added utilization of EMAM.

Hierarchical spheroidal MOF-derived MnO@C as cathode components for high-performance aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) have shown great potential as energy storage devices owing to their high energy density, low cost, and low toxicity. Typically, high performance AZIBs incorporate manganese-based cathode materials. Despite their advantages, these cathodes are limited by significant capacity fading and poor rate performance due to the dissolution and disproportionation of manganese. Herein, hierarchical spheroidal MnO@C structures were synthesized from Mn-based metal–organic frameworks, which benefit from a protective carbon layer to prevent manganese dissolution. The spheroidal MnO@C structures were incorporated onto a heterogeneous interface to act as a cathode material for AZIBs, which exhibited excellent cycling stability (160 mAh g−1 after 1000 cycles at 3.0 A g−1), good rate capability (165.9 mAh g−1 at 3.0 A g−1), and appreciable specific capacity (412.4 mAh g−1 at 0.1 A g−1) for AZIBs. Moreover, the Zn2+ storage mechanism in MnO@C was comprehensively investigated using ex-situ XRD and XPS studies. These results demonstrate that hierarchical spheroidal MnO@C is a potential cathode material for high-performing AZIBs.

Sodium-potassium co-doped layered manganese dioxide cathode material for high performance aqueous zinc-ion batteries

Manganese dioxide with high operating voltage and satisfactory energy density have been identified as the promising cathode materials for aqueous zinc-ion batteries (AZIBs). However, the structural instability of manganese-based materials during the (dis)charging process limits their further development. Herein, sodium-potassium co-doped layered K0.37Na0.18MnO2·xH2O (KNMOH) are synthesized by a liquid-phase synthesis method at room temperature. The co-doping of Na+ and K+ stabilizes the layered structure, widens the layer spacing and has the effect of electrostatic shielding to facilitate the (de)intercalation of Zn2+. Benefiting from the stable structure and nanoscale size, the flower-like KNMOH cathode maintained a high specific capacity of 239.1 mAh·g−1 after 700 cycles at 500 mA·g−1. Simultaneously, this work firstly reveals that the presence of K8(SO4)(SO3OH)6 suppressed the generation of Zn4SO4(OH)6·0.5H2O, resulting in more free Zn2+ and high reversibility. This co-doped design of bimetallic ions insertion enhances the electrochemical performance and provides a new idea for the improvement of the manganese-based cathode materials for AZIBs.

Artificial phosphate solid electrolyte interphase enables stable MnO2 cathode for zinc ion batteries

Rechargeable aqueous zinc-ion batteries based on manganese-based cathode materials are promising energy storage devices, but the low conductivity and dissolution issues of manganese-based cathode materials lead to instability. In order to address these issues, this work proposes an in situ reaction between hydroxyethylene-1,1,-diphosphonic acid and manganese dioxide to create a phosphorylated manganese dioxide (PMO) cathode on which a phosphate solid electrolyte interphase was built. This artificial organic electrolyte interface improves the stability of the cathode during cycling, allowing it to deliver capacities of 250 mAh g−1 and 105 mAh g−1 at current densities of 0.1 A g−1 and 1.0 A g−1, respectively. The intrinsic mechanism of this phosphate retards the side reactions caused by water attack. This strategy provides a general design strategy for manganese-based cathode materials for aqueous zinc ion batteries.

Air-stable manganese based cathode material enabled by organic protection layer for Na-ion batteries

Layered manganese oxide represents one most potential cathode for sodium-ion batteries thanks to high theoretical specific capacity, low cost and environmental friendliness. Nevertheless, its surface structure degrades owing to the hydration reaction when being stored in the humid air. Herein, Na0.67Mn0.92Cu0.04Fe0.04O2 (NMCFO) cathode material is functionalized by tetradecylphosphonic acid (TPA) on the surface to enhance the air stability. It is demonstrated that the TPA protection layer could improve the surface hydrophobicity, and further inhibit the hydration reaction to produce residual alkali, effectively maintaining modified material’s crystal structure and electrochemical performance. After 28 days of placement in the humid air, the modified material delivers a specific capacity of 94.0 mAh g−1 at 5C, and exhibits a capacity retention of 92.22% after 100 cycles at 1C. In summary, we provide an effective pathway to protect layered manganese oxide and other moisture-sensitive materials without sacrificing cell performance.

Boosting the kinetic properties and suppressing the irreversible oxygen redox of lithium-rich manganese-based cathode materials through combined strategies of fast ionic conductor and oxygen vacancy

Oxygen-anion charge compensation facilitates lithium-rich manganese-based cathode materials (LRMCs) to possess higher specific capacity than other conventional layered oxide cathode materials. Nevertheless, irreversible oxygen redox makes LRMCs suffer from oxygen loss, structure degradation, and interfacial side reactions and thus resulting in low initial coulombic efficiency (ICE), poor cyclic stability and rate capacity. To inhibit the irreversible anionic redox and improve the kinetic properties of Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO), herein, an interfacial engineering with sodium hypophosphite (NaH2PO2) is used to modify the LMNCO. The results demonstrate that the Na2HPO4 and reducing gas PH3 that are produced by NaH2PO2 decomposition can react with the residual lithium and unstable surface oxygen to form a stable Li3PO4 protective layer and generate oxygen vacancies on the LMNCO surface. It has been found that the optimum content of NaH2PO2 is 5 wt%, and the electrochemical performance of LMNCO-NP 5% is significantly improved. The ICE of LMNCO-NP 5% is 82.79%, which is much higher than the LMNCO (73.76%). Meanwhile, the capacity retentions of LMNCO-NP 5% are 94.85% and 78.45% at 1 C and 5 C after 100 cycles, respectively. Therefore, the modification strategy based on the formation of Li3PO4 protective layer and generation of oxygen vacancies can play effectively promote the electrochemical performances of LMNCO.

Rationally designed Mn2O3@ZnMn2O4/C core-shell hollow microspheres for aqueous zinc-ion batteries.

Manganese-based oxides are common cathode materials for aqueous zinc ion batteries (AZIBs) because of their great capacity and high working voltage. However, the sharp decline of capacity caused by the dissolution of manganese-based cathode materials and the low-rate performance restrict their development. To address these problems, unique core-shell structured Mn2O3@ZnMn2O4/C hollow microspheres are reported as an ideal cathode material for AZIBs. Benefiting from the hollow structure, the zeolitic imidazolate framework (ZIF)-derived carbon and ZnMn2O4. Its application in AZIBs as the cathode demonstrates its satisfactory rate performance, high cycle stability, and excellent reversibility. Its high reversible capacity is remarkable, which reaches its maximum of 289.9 mA h g-1 at 200 mA g-1 and maintains a capacity of 203.5 mA h g-1 after cycling for 700 times at 1000 mA g-1. These excellent performances indicate that this material is a potential cathode material of AZIBs.

Understanding mechanism of voltage decay and temperature sensitivity of Li-rich manganese-based cathode materials

Li-rich manganese-based (LRM) cathode materials are known as one of the most promising cathode materials for new-generation lithium-ion batteries. At present, exploring the complex voltage decay mechanism of LRM is the main task to promote its commercialization. Herein, the structural evolution and transition metal valence state change of LRM during different reaction stages under different temperatures are discussed, and the mechanism of voltage decay is finally determined based on the electrochemical properties. The results show the evolution of irreversible thermodynamic structure is the fundamental cause leading to voltage decay of LRM cathode, and it worsens with increasing temperature. The early activation of inert Mn, multiple phase transitions, migration of transition metals to the surface, anisotropy of internal valence states caused by partial valence failure and severe interfacial reactions are all strong proofs of the above views. In summary, the reason for voltage decay is revealed by investigating the sensitivity of the LRM cathode materials to temperature. This work not only provides strong evidence for the mechanism of the voltage decay, but also points out the direction to modification design for achieving future commercialization of LRM cathode materials.

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.