Mn-based Oxides Research Articles

Constructing stable surface structures enabling fast charging for Li-rich layered oxide cathodes

Li-rich Mn-based layered oxides (LLOs) exhibiting ultrahigh specific capacity larger than 250 mAh g−1 have become the most promising cathode candidate for high energy density lithium-ions batteries (LIBs). Fast charging capability and cycling stability are highly desirable for LIBs so as to satisfy specific application scenarios such as electric vehicles. However, stable cycling and fast charging properties are severely hindered by obstacles including irreversible oxygen release, structural degradation and poor reaction kinetics. In this work, an integrative and facile surface structures constructing strategy to achieve stable cycling and fast charging in LLOs was provided. Oxygen vacancies and double coating layers including lithium phosphate layer and spinel layer were constructed on the surface through ammonium dihydrogen phosphate (NH4H2PO4) pretreatment. The designed material with induced stable bi-phase coating layers delivers a high discharge specific capacity of 284.6 mAh g−1 at 0.1 C with an ultrahigh initial coulombic efficiency of 95.3% and excellent rate performance of 132.2 mAh g−1 at 10 C. Even after 100 cycles, it can display a remarkable capacity of 215.8 mAh g−1 under 1 C/1 C and 205.1 mAh g−1 under 3 C/1 C. The excellent fast charging performance and cycling stability can be attributed to accelerated Li+ transportation rate due to its surface ion conductive layer and surface spinel phase layer, as well as suppressed oxygen release, transition metals dissolution and electrolyte attack resulting from surface oxygen vacancies and dual protective layers.

Enhanced Activity and Reversibility of Anionic Redox by Tuning Lithium Vacancies in Li-Rich Cathode Materials.

Li-rich Mn-based layered oxide cathodes (LLOs) are considered to be the most promising cathode candidates for lithium-ion batteries owing to their high-voltage platform and ultrahigh specific capacity originating from anionic redox. However, anionic redox results in many problems including irreversible oxygen release, voltage hysteresis, and so on. Although many efforts have been made to regulate anionic redox, a fundamental issue, the effect of lithium vacancies on anionic redox, is still unclear. Herein, we synthesized a series of LLO materials with different lithium vacancy contents by controlling the amount of lithium salt. Specifically, lithium-vacancy-type LLOs Li1.11Ni0.18Co0.18Mn0.53O2 with a pompon morphology exhibit an ultrahigh specific capacity (293.9 mA h g-1 at 0.1 C), an outstanding long-term cycling stability (173.5 mA h g-1 after 300 cycles at 1 C), and an excellent rate performance (106 mA h g-1 at 10 C). It reveals that lithium vacancy is a key factor to enhance anionic redox activity and reversibility. Lithium vacancies exhibit different inductive effects on the structure of the surface and bulk. Abundant surface oxygen vacancies and a surface spinel phase layer induced by lithium vacancies suppress irreversible oxygen release, while the bulk phase transformation and cation disorder combined with sufficient lithium vacancies in the bulk stabilize structure and improve anionic redox kinetic. The findings offer a significant theoretical guidance for the practical application of LLO materials.

MnxOy embedded within CNT supporting porous carbon for enhanced lithium storage

Achievement of improved structural stability and conductivity for Mn-based oxides is the crucial premise for them to be high-performance anodes of lithium-ion batteries due to their large volume effect and poor intrinsic conductivity. Herein, the lithium storage performance of the MnxOy nanoparticles containing dominant MnO and slight MnO2 and Mn3O4 has been significantly improved by embedding them into a CNT supporting porous carbon. This composite is therefore denoted as CNT/MnxOy/C. The comparison results of the electrochemical performance of thus CNT/MnxOy/C with CNT/Mn3O4 and pure Mn3O4 nanoparticles demonstrate that the well-designed synergistic effect of high conductive CNT support and flexible spongy porous carbon is responsible for its improved performance, which efficiently enhances not only the structural stability but also the electrochemical kinetics of the CNT/MnxOy/C. As a result, this CNT/MnxOy/C anode shows outstanding performance, obtaining high capacities of 936.5 and 410.5 mAh g-1 at 200 and 1000 mA g-1 after 260 and 800 cycles, respectively. Moreover, this strategy proposed here will be hopefully instructive in constructing other advanced metal oxide nanomaterials toward improved performance of lithium-ion battery anodes.

Insights of the Electrochemical Reversibility of P2-Type Sodium Manganese Oxide Cathodes via Modulation of Transition Metal Vacancies.

Among cathode materials for sodium-ion batteries, Mn-based layered oxides have attracted enormous attention owing to their high capacity, cost-effectiveness, and fast transport channels. However, their practical application is hindered by the unsatisfied structural stability and the deficient understanding of electrochemical reaction mechanisms. Among these issues, the research of transition metal (TM) vacancy remains highly active due to their modulation roles on the anionic redox reactions, but their effects on structural and electrochemical stability remain obscure. Herein, based on Al-substituted P2-type Na2/3MnO2, we comprehensively investigate the effects of TM vacancies on the corresponding layered oxides. With several characterization techniques such as neutron diffraction, superconducting quantum interferometry, in situ X-ray diffraction, ex situ solid-state nuclear magnetic resonance techniques, and X-ray photoelectron spectroscopy, we determined the TM vacancy content and further revealed that higher content of TM vacancies (7.8%) in the transition layer is beneficial to mitigate the structure evolutions and maintain the P2 structure during cycling in voltage range 1.5-4.5 V, while the oxides with lower content of TM vacancies (1.6%) deliver higher discharge capacity but experience complicated phase transition, including stacking faults and P2-P2' transitions. It is demonstrated that regulating the contents of TM vacancies can be utilized as an effective strategy to tune the structure stability and electrochemical performances of layered sodium oxide cathodes.

Ultrahigh rate and durable sodium-ion storage at a wide potential window via lanthanide doping and perovskite surface decoration on layered manganese oxides

P2-type layered manganese oxides are recognized as one of the most compelling cathode candidates for sodium-ion batteries, but these materials suffer from the intrinsic structural Jahn-Teller distortion and oxygen loss, which causes limited rate capability and long-cycle fading under a wide potential window. Here we demonstrate a new approach to realize a simultaneous enhancement on both rate performance and long-term duration over a wide potential window through dilute La lattice doping and perovskite surface modification. We reveal for the first time through both DFT calculations and experimental results, that the La-doping and perovskite LCM surface decoration can efficiently suppress oxygen loss by providing O 2p holes and oxygen vacancies, and meanwhile enhance the electronic and ionic conductivity. The as achieved LNCM/LCM (LaNa0.06Co0.06Mn0.88O3/ Na0.56Co0.17Mn0.8La0.03O2) demonstrates a record high rate performance of 20C (1C=180 mA g−1) and outstanding cycling performance of 300 cycles (70% capacity retention) at a wide potential range (1.5-4.4V), which outperform the state-of-the-art Mn-based layered oxides. We confirm the reversible solid solution reaction during the charge/discharge process using the operando synchrotron XRD analysis. This work demonstrates an applicable approach to realize significant improvement on both rate capability and cycle stability without sacrificing the potential window.

Stabilizing voltage and prolonged cycling life of Li-rich Mn-based oxides through spinel “lithium ion pump” heteroepitaxial coating strategy

The practical application of Li-rich layered oxides is impeded by its cycle instability, poor rate capability and serious voltage decay. Here, nano-sized spinel Li4Ti5O12 (LTO) is constructed on Li1.2Ni0.13Co0.13Mn0.54O2 (LLNCMO). The distinctly heteroepitaxial structure of LTO nanocoating on LLNCMO is corroborated by HAADF-STEM. The LTO coating with fast lithium ion diffusion kinetics acts as “lithium ion pump” when Li+-ions cross over it. The integrated structure can effectively retard oxygen evolution and phase transformation engendering higher capacity and voltage retention. LTO heteroepitaxially coated LLNCMO (LTO@LLNCMO) shows an improvement of initial coulombic efficiency to 74.3% and more stable life with a high capacity retention up to 96.9% at 2C after 500 cycles (40.5% for LLNCMO). LTO@LLNCMO demonstrates minimal voltage fading of 1.33 mV per cycle suggesting suppression of phase conversion to spinel-like structure. The epitaxial spinel modification strategy can be applied to control the surface stability of cathodes.

A novel surface modification strategy for Li-rich Mn-based layered oxide cathodes of high-capacity and high-cyclic stability by an additive of LiBH4 to the electrolyte

Li-rich Mn-based layered oxide (LMLO) cathode materials have high-capacity and high-energy density, which are highly potential for next generation Li-ion batteries; however, their disadvantages of low initial coulombic efficiency, poor cyclic stability, large voltage fading during cycling and poor rate capability hinder their practical applications. In this work, a novel surface modification strategy to improve the electrochemical properties of LMLO cathodes is developed, where a highly reductive compound of LiBH4 is adopted as an additive to a conventional electrolyte. Examined by a conventional LMLO material of Li[Formula: see text]Ni[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2- (L[Formula: see text]M[Formula: see text]LO), the cyclic stability and rate capability of the cathode are significantly improved when 0.3 wt.% LiBH4 is added. The cathode has an initial reversible discharge capacity of 280 mAh g[Formula: see text] at 20 mA g[Formula: see text], showing the capacity retention of 94.3% after 100 cycles. A capacity of 193 mAh g[Formula: see text] maintains after 300 cycles at 200 mA g[Formula: see text], corresponding to the capacity retention of 86.2%, and the capacity reaches as high as 138 mAh g[Formula: see text] at 2000 mA g[Formula: see text]. It is found that partial transition metals (TMs) at the surface of the L[Formula: see text]M[Formula: see text]LO particles are reduced by LiBH4 during the initial several cycles of activation, resulting in an in situ formation of a stable and lithium-diffusion feasible spinel structure surface coating in thickness of several nanometers with atomic match to the bulk particle. The surface coating not only retards the dissolution of the TMs from L[Formula: see text]M[Formula: see text]LO to the electrolyte, stabilizing the crystal structure during cycling, but also facilitates the lithium diffusion. As a result, the cyclic stability and rate capability of the cathode are evidently improved. The method is facile, scalable, and low cost, which has potential for commercial utilization.

Tuning oxygen redox chemistry of P2-type manganese-based oxide cathode via dual Cu and Co substitution for sodium-ion batteries

High-voltage layered Mn-based oxide is promising high-capacity cathode via exploiting the oxygen redox chemistry. But such redox often suffer from irreversible oxygen loss, leading to severe voltage hysteresis, particle cracking and capacity decay. Hence, the complementary strategy of dual Cu and Co substitution is revealed to stabilizing the anion redox chemistry of P2-Na2/3(Mn-Ni-Cu-Co)O2 cathode under upper cut-off voltage. Dual substitution with Cu for Mn and Co for Ni forms stable Cu-O and Co-O octahedrons, which modulate the lattice structure with the shrinkage of TMO2 sheets and expansion of Na layer spacing to enhance the Na+ diffusion kinetics. Co substitution can raise high voltage region to tune the cut-off voltage up to 4.3 V and activate oxygen redox to weaken irreversible O2 loss. And Cu substitution can inhibit the O2 loss and suppress the voltage decay via the interaction between Cu 3d and O 2p orbitals. The P2-type Na0.67Mn0.6Ni0.2Cu0.1Co0.1O2 cathode induced by the complementary effect can boost long cycling life (82.07% capacity retention after 500 cycles) and remarkable rate capability under high upper cut-off voltage in half-cell. Furthermore, the full cells also exhibit outstanding rate capability with a high discharge capacity of 62.6 mAh g–1 at 20 C.

Enhanced Electrochemical Property of Li1.2−xNaxMn0.54Ni0.13Co0.13O2 Cathode Material for the New Optoelectronic Devices

The Li-rich Mn-based oxide Li1.2Mn0.54Ni0.13Co0.13O2 has been extensively studied as a cathode material of the battery module for new optoelectronic devices. To improve and enhance the electrochemical performance, sodium doping is one of the effective approaches. According to the density functional theory of first-principles, the band gap, partial density of states, lithiation formation energy, electron density difference, and potential energy of electrons for Li1.2−xNaxMn0.54Ni0.13Co0.13O2 were simulated with Materials Studio, Nanodcal, and Matlab. When the sodium doping amount x = 0.10 mol, simulations show that Li1.2−xNaxMn0.54Ni0.13Co0.13O2 has a better conductivity. The potential maps of Li1.2−xNaxMn0.54Ni0.13Co0.13O2 obtained in Matlab demonstrate that the potential barrier is lower and the rate capability is enhanced after sodium doping. Results of analyses and calculations agree with the experimental result of Chaofan Yang’s group. This theoretical method could be a great avenue for the investigation of the battery application of new optoelectronic devices. Also, our findings could give some theoretical guidance for the subsequent electrochemical performance study on doping in the field of lithium-ion batteries.

Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

The catalytic oxidation of biomass-derived 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising route to produce bioplastic monomers. Developing budget non-noble-metal catalysts for the efficient air-oxidation of HMF to FDCA is highly demanded but challenging. In this contribution, we present a facile and green vitamin C (VC)-assisted solid-state grinding method for synthesizing mesoporous Mn–Co spinel oxides with improved oxygen vacancy (Ov) concentration, which could offer a satisfactory FDCA yield of 96% using air as the oxygen source (130 °C, 1.5 MPa air, 3 h). Remarkably, Mn3Co2Ox–0.3VC offered an outstanding FDCA formation rate of 2611 μmolFDCA·gcat–1·h–1, which is the highest value achieved so far among ever-described Mn-based catalysts. Based on experimental studies, the catalytic performance of Mn–Co oxides for the oxidation of HMF corresponds well with their Mn–O bond intensities. The catalyst with a higher Ov concentration exhibits a weaker Mn–O bond intensity, which brings about a higher lattice oxygen (OL) reactivity. More importantly, density functional theory (DFT) calculations also demonstrate that increasing the Ov amount not only boosts the OL reactivity of the catalyst by reducing the formation energy of Ov but also contributes to the adsorption and activation of O2 over the catalyst by significantly cutting down the O2 adsorption energy, thus leading to an enhanced catalytic activity for the oxidation of HMF. Besides, the catalyst with a higher Ov concentration provides a stronger substrate adsorption ability, which may also promote the HMF oxidation reactions. This work provides insights into the role of Ov over Mn-based oxides in oxidation catalysis by a Mars–van Krevelen mechanism.

A P3-Type K1/2Mn5/6Mg1/12Ni1/12O2 Cathode Material for Potassium-Ion Batteries with High Structural Reversibility Secured by the Mg-Ni Pinning Effect.

Mn-based layered oxides are very attractive as cathodes for potassium-ion batteries (PIBs) due to their low-cost and environmentally friendly precursors. Their transfer to practical application, however, is inhibited by some issues including consecutive phase transitions, sluggish K+ deintercalation/intercalation, and serious capacity loss. Herein, Mg-Ni co-substituted K1/2Mn5/6Mg1/12Ni1/12O2 is designed as a promising cathode material for PIBs, with suppressed phase transitions that occurred in K1/2MnO2 and improved K+ storage performance. Part of Mg2+ and Ni2+ occupies the K+ layer, playing the role of a "nailed pillar", which restrains metal oxide layer gliding during the K+ (de)intercalation. The "Mg-Ni pinning effect" not only suppresses the phase transitions but also reduces the cell volume variation, leading to the improved cycle performance. Moreover, K1/2Mn5/6Mg1/12Ni1/12O2 has low activation barrier energy for K+ diffusion and high electron conductivity as demonstrated by first-principles calculations, resulting in better rate capability. In addition, K1/2Mn5/6Mg1/12Ni1/12O2 also delivers a higher reversible capacity owing to the participation of the Ni element in electrochemical reactions and the pseudocapacitive contribution. This study provides a basic understanding of structural evolution in layered Mn-based oxides and broadens the strategic design of cathode materials for PIBs.

Boosting oxygen reduction activity and enhancing stability through structural transformation of layered lithium manganese oxide

Structural degradation in manganese oxides leads to unstable electrocatalytic activity during long-term cycles. Herein, we overcome this obstacle by using proton exchange on well-defined layered Li2MnO3 with an O3-type structure to construct protonated Li2-xHxMnO3-n with a P3-type structure. The protonated catalyst exhibits high oxygen reduction reaction activity and excellent stability compared to previously reported cost-effective Mn-based oxides. Configuration interaction and density functional theory calculations indicate that Li2-xHxMnO3-n has fewer unstable O 2p holes with a Mn3.7+ valence state and a reduced interlayer distance, originating from the replacement of Li by H. The former is responsible for the structural stability, while the latter is responsible for the high transport property favorable for boosting activity. The optimization of both charge states to reduce unstable O 2p holes and crystalline structure to reduce the reaction pathway is an effective strategy for the rational design of electrocatalysts, with a likely extension to a broad variety of layered alkali-containing metal oxides.

Achieving high initial coulombic efficiency and low voltage dropping in Li-rich Mn-based cathode materials by Metal-Organic frameworks-derived coating

Li-rich Mn-based oxides (LRMOs) are promising cathode materials for next-generation Li-ion batteries because of their high voltage, high capacity, and low cost. However, the low initial Coulombic efficiency (ICE), severe capacity fading and voltage dropping during cycling hinder their large-scale application of LRMOs. Hence, we propose a facile Metal-Organic Frameworks (MOF)-self-assembly coating strategy to modify LRMOs with CoxOy/C coating (LRMO@CoxOy/C). The CoxOy/C layer can alleviate the side-reaction between the electrolyte and cathode materials, and enhance both ion-diffusion and electrons-transportation speed throughout the surface of the electrode materials. In addition, the CoxOy/C layer suppresses the lattice oxygen release and improve structural stability of LRMOs during long-term cycling. Consequently, the LRMO@CoxOy/C cathode shows a high ICE of 91.5% and slow voltage dropping of only 2 mV/cycle at 0.2 C. After 300 cycles, it still delivers a high discharge capacity of 210.7 mAh·g−1 at 0.5 C with a capacity retention of ~80%. This work provides a novel approach to achieve next-generation high-energy density cathode materials.

Toward functional units constructing Mn-based oxide cathodes for rechargeable batteries

Toward functional units constructing Mn-based oxide cathodes for rechargeable batteries

Superior Oxidative Dehydrogenation Performance toward NH3 Determines the Excellent Low-Temperature NH3-SCR Activity of Mn-Based Catalysts.

Mn-based oxides exhibit outstanding low-temperature activity for the selective catalytic reduction of NOx with NH3 (NH3-SCR) compared with other catalysts. However, the underlying principle responsible for the excellent low-temperature activity is not yet clear. Here, the atomic-level mechanism and activity-limiting factor in the NH3-SCR process over Mn-, Fe-, and Ce-based oxide catalysts are elucidated by a combination of first-principles calculations and experimental measurements. We found that the superior oxidative dehydrogenation performance toward NH3 of Mn-based catalysts reduces the energy barriers for the activation of NH3 and the formation of the key intermediate NH2NO, which is the rate-determining step in NH3-SCR over these oxide catalysts. The findings of this study advance the understanding of the working principle of Mn-based SCR catalysts and provide a fundamental basis for the development of future generation SCR catalysts with excellent low-temperature activity.

Evolution mechanism of transition metal in NH3-SCR reaction over Mn-based bimetallic oxide catalysts: Structure-activity relationships

The unexpected phenomenon in which different transition metals (Co, Ni and Cu) presented significant variation of participation levels as the auxiliaries in Mn-based bimetallic oxide catalysts were reported here. It is found that the Co element more easily to form Mn enriched surface bimetallic oxides with Mn than Ni and Cu, resulting in Co-MnOx exhibited the best deNOx activity and SO2 tolerance, followed by Ni-MnOx and Cu-MnOx. The role of different transition metal and structure-activity relationships were systematically investigated by advanced techniques including Synchrotron XAFS and in situ DRIFTs analysis. The excellent activity of Co-MnOx was related to its unique Mn-enriched surface (Co2+)tet(Mn3+ Co3+)octO4 structure with Mn cations occupying the octahedral sites, which is superior to the Ni-MnOx and Cu-MnOx with Mn-lean surface. In addition, the reaction energy barrier of Co-MnOx is weakened due to the lower electron cloud density around the Mn atom as compared to Ni-MnOx and Cu-MnOx. Moreover, Co-MnOx benefiting from the rapid electron migration between Mn and Co, more active bidentate/bridged nitrates could react with adsorbed NH3 in faster reaction rates following the L-H mechanism.

Recent Development of Mn-based Oxides as Zinc-Ion Battery Cathode.

Manganese-based oxide is arguably one of the most well-studied cathode materials for zinc-ion battery (ZIB) due to its wide oxidation states, cost-effectiveness, and matured synthesis process. As a result, there are numerous reports that show significant strides in the progress of Mn-based oxides as ZIB cathode. However, ironically, due to the sheer number of Mn-based oxides that have been published in recent years, there remain certain contemplations with regards to the electrochemical performance of each type of Mn-based oxides and their performance comparison among various Mn polymorphs and oxidation states. Thus, to provide a clearer indication of the development of Mn-based oxides, the recent progress in Mn-based oxides as ZIB cathode was summarized systematically in this Review. More specifically, (1) the classification of Mn-based oxides based on the oxidation states (i. e., MnO2 , Mn3 O4 , Mn2 O3 , and MnO), (2) their respective polymorphs (i. e., α-MnO2 and δ-MnO2 ) as ZIB cathode, (3) the modification strategies commonly employed to enhance the performance, and (4) the effects of these modification strategies on the performance enhancement were reviewed. Lastly, perspectives and outlook of Mn-based oxides as ZIB cathode were discussed at the end of this Review.

Insight of reaction mechanism and anionic redox behavior for Li-rich and Mn-based oxide materials from local structure

Li-rich and Mn-based oxides (LRMO) have been an obvious choice of high specific energy batteries owing to their unique anion redox behavior based on the main component Li 2 MnO 3 . However, there are still electrochemical behaviors that cannot perfectly match the theoretical structure. So far, most theoretical research on LRMO has been carried out around the ideal Li 2 MnO 3 structure. Nevertheless, there are a great number of non-ideal local configurations in the pristine materials under the case of practical situations. Herein, the ubiquitous complex local structures (defect-like) in the interior of Li 2 MnO 3 particle, some of which have not been observed in the past, are directly presented through the atomic-level observation. We summarized these structures and proposed for the first time the great influence of these local structures on the electrochemical and the oxygen redox behavior of LRMO by combining observation, DFT calculation, XAS, XPS and electrochemical experiments. These micro-structures have been roughly divided into four categories by the advanced AC-STEM, including the so-called stacking faults caused by the slip of the adjacent TM layer, the local multi-Li or multi-Mn arrangement due to the combination of different stacking type along a–b plane, the expansion of the interlayer spacing, and even the distribution of polycrystalline domains, of which the second and third configurations were observed for the first time. These types of local structures dominate the electrochemical reaction of electrodes in some aspects by improving the activity of oxygen non-bonding 2p states, along with the improvement of (de)intercalation ability for Li ions in the bulk through reducing the energy barrier, and they are even one of the sources of voltage hysteresis by affecting the energy level distribution of oxygen unoccupied 2p states after delithiation. This research has perfected a more comprehensive and practical understanding of LRMO under the case of practical situations, laying a key foundation for the further modification and application of LRMO cathode materials. • The new revelation of complex local structures in the practical Li-rich and Mn-based oxides. • The decisive influence of these local structures on the electrochemical behavior of anion redox and materials. • Perfection of the theoretical system by combining DFT calculation with atomic-level observation and XAS. • A new perspective for the future modification of Li-rich and Mn-based cathode materials.

A Queue-Ordered Layered Mn-Based Oxides with Al Substitution as High-Rate and High-Stabilized Cathode for Sodium-Ion Batteries.

Development of highly stabilized and reversible cathode materials has become a great challenge for sodium-ion batteries. O'3-type layered Mn-based oxides have deserved much attention as one of largely reversible-capacity cathodes featured by the resource-rich and low-toxic elements. However, the fragile slabs structure of typical layered oxides, low Mn-ion migration barriers, and Jahn-Teller distortion of Mn3+ have easily resulted in the severe degradation of cyclability and rate performances. Herein, a new queue-ordered superstructure is built up in the O'3-NaMn0.6 Al0.4 O2 cathode material. Through the light-metal Al substitution in O'3-NaMnO2 , the MnO6 and AlO6 octahedrons display the queue-ordered arrangements in the transition metal (TM) slabs. Interestingly, the presence of this superstructure can strengthen the layered structure, reduce the influence from Jahn-Teller effect, and suppress the TM-ions migrations during long-terms cycles. These characteristics results in O'3-NaMn0.6 Al0.4 O2 cathode deliver a high capacity of 160 mAh g-1 , an enhanced rate capability and the excellent cycling performance. This research strategy can provide the broaden insight for future electrode materials with high-performance sodium-ions storage.

Mn-based oxides for aqueous rechargeable metal ion batteries

Mn-based oxides as promising materials for aqueous energy storage are desirable in view of their low-cost, eco-friendliness and high theoretical capacity.