Performance Of Cathode Materials Research Articles

Nanosphere-rod-like Co3O4 as high performance cathode material for aluminium ion batteries

Aluminium ion batteries are considered to be a promising development for large-scale energy storage and conversion applications. In this research, a nanosphere-rod-like Co3O4 has been synthesized after the hydrothermal reaction and the subsequent heat treatment process, which is used for the cathode materials of aluminium ion batteries. The working mechanisms of the Co3O4 are deeply investigated. It is found that the electrochemical deposition and dissolution of aluminum occurs on the surface of pure aluminium anode, and the Al3+ cations are intercalated and de-intercalated in the cathode materials during the discharge and charge processes. The battery exhibits a high discharge specific capacity of 490 mAh g−1 at the first cycle, with the current density of 50 mA g−1. Furthermore, the discharge capacity still maintains a high level of 122.1 mAh g−1 after 100 cycles at the current density of 200 mA g−1, indicating a good cycle performance. Therefore, the nanosphere-rod-like Co3O4 as the cathode for aluminium ion batteries has a promising potential.

Polyaniline-Intercalated MnO2 As a High Performance Cathode Material for Zinc-Ion Battery

Metal-ion batteries based on aqueous electrolyte are attracting widespread attention in the field of large-scale energy storage due to the low cost, high safety and environmental friendliness. However, the development of the most studied aqueous Li+ and Na+ batteries are plagued by the low energy density, which mainly derived from the low capacity of electrode materials (<150 mAh g-1) and the limited voltage window of aqueous electrolyte (<1.8 V). The latter could be conquered by the water-in-salt electrolyte, and the operating voltage > 3V could be obtained1. But the capacity of electrode materials still needs to be enhanced. Due to the high capacity of metal zinc anode (820 mAh g-1), aqueous Zinc-ion battery based on Zn2+ storage cathode and metal Zn anode holds immense potential to achieve high capacity. But the capacity of cathode still has much room for improvement. As the most used cathode materials for zinc-ion battery, manganese oxides exhibit high theoretical capacity (308 mAh g-1), low cost and low toxicity. Various manganese dioxides, including the α-MnO2, β-MnO2, γ-MnO2, δ-MnO2, etc. have been reported as host materials for Zn2+/H+ insertion in the mild aqueous electrolyte. However, all the crystalline form of manganese oxides undergo structure transformation to layered structure with interlaminar water molecules during zinc-ion insertion, leading to capacity fading of the cell. And the cycling stability of manganese oxides decreases dramatically when cycled at high depth of discharge2. In this work, we proposed novel polyaniline-intercalated MnO2 nanolayers as a high performance cathode material for zinc-ion battery, which is prepared by a simple one-step inorganic/organic interface reaction3. With the typical nano-size (approximately 10 nm), expanded interlayer space, uniform meso-structure and polymer-reinforced layered structure, the polyaniline-intercalated MnO2 nanolayers show a high rate performance and excellent cycle stability at high charge/discharge depth (200 stable cycles with capacity of 280 mAh g-1, corresponding 90.9% utilization of theoretical capacity of 308 mAh g-1), which is much superior to previous reports. The polyaniline-reinforced layered structure efficiently eliminate the hydrated H+/Zn2+-insertion-induced phase transformation and the subsequent structure collapse, which is important to achieve long cycle life and high utilization simultaneously. In addition, a H+/Zn2+ co-insertion process in the layered MnO2 was proposed, and a self-regulating mechanism of electrolyte involving generation/dissolution of flake-like zinc hydroxide sulfate was clarified. Reference: 1 C. Yang, J. Chen, T. Qing, X. Fan, W. Sun, A. von Cresce, M.S. Ding, O. Borodin, J. Vatamanu, M.A. Schroeder, N. Eidson, C. Wang, and K. Xu, Joule, 1, 122 (2017). 2 J. Huang, Z. Guo, Y. Ma, D. Bin, Y. Wang, and Y. Xia, Small methods, 1800272 (2018). 3 J. Huang, Z. Wang, M. Hou, X. Dong, Y. Liu, Y. Wang, and Y. Xia, Nature Communications, 9, 2906 (2018).

Co-Free Cathode Material with Simultaneous MgO Coating and Mg Doping for High-Voltage Sodium-Ion Batteries

To simultaneously address the inherent limitations of the capacity and cycling instability of Na[Ni0.5Mn0.5]O2 cathodes, it is necessary to concurrently stabilize particle surfaces and crystal structure. Encouraged by previously conducted research activities in this field, we have adopted an effective strategy for simultaneous MgO coating and Mg doping to produce substantially improved high voltage stability compared to the previously reported results in the literature on Na[Ni0.5Mn0.5]O2 cathodes. The MgO coating layer effectively suppressed the unfavorable side reactions during cycling while the partial Mg doping into the bulk Ni sites improved the structural stability by moderating the extent of the irreversible multiphase transformation. As a result, the combination of a MgO coating with Mg doping provides enhanced electrochemical performance and structural stability of Na[Ni0.5Mn0.5]O2 within the voltage range of 2.0–4.2 V. The practical acceptability of the simultaneous MgO coating and Mg doping of the Na[Ni0.5Mn0.5]O2 cathode was obviously verified using scaled-up pouch-type full cells with hard carbon anodes. Compared with previously reported similar cathode materials, the proposed MgO-NM55 cathode showed great competitiveness for high-voltage stability in SIBs. Moreover, the use of earth's abundant and inexpensive Mg and Na elements, and a simple practical strategy are highly desirable for developing high-energy and low-cost SIBs. Although the practical use of the MgO-NM55 cathode in SIBs will require further work, the methodology used in this study will be helpful in developing an efficient design of high performance cathode materials for SIBs. References J.-Y. Hwang, S.-T. Myung and Y.-K. Sun, Soc. Rev., 2017, 46, 3529–3614. J.-Y. Hwang, C. S. Yoon, I. Belharouak and Y.-K. Sun, J. Mater. Chem. A, 2016, 4, 17952.P.-F. Wang, H.-R. Yao, X.-Y. Liu, J.-N. Zhang, L. Gu, X.-Q. Yu, Y.-X. Yin and Y.-G. Guo, Adv. Mater., 2017, 29, 1700210.S. Komaba, N. Yabuuchi, T. Nakayama, A. Ogata, T. Ishikawa and I. Nakai, Inorg. Chem., 2012, 51, 6211.

F-doped LiFePO4@N/B/F-doped carbon as high performance cathode materials for Li-ion batteries

LiFePO4 (LFP) is widely considered as a practical cathode material for lithium ion batteries, however its applications are still plagued by the low ionic and electronic conductivities. To address this challenge, F-doped LFP coated with N, B, F ternary doped carbon layer (F-LFP@NBFC) was synthesized by hydrothermal method using ionic liquid [BMIM]BF4 as the sole source for C, N, B and F. The F-LFP@NBFC exhibits superior electrochemical performance compared with the pristine LFP. F-LFP@NBFC demonstrates a discharge capacity of 162.2 mAh g−1 at 0.1 C, which is close to its theoretical capacity, and maintains a 100% of discharge capacity after 40 cycles at 0.1 C. F-LFP@NBFC also shows an excellent rate capability and delivers a discharge capacity of 71.3 mAh g−1 at 15 C. The excellent performance is ascribed to the surface coating of LFP and heteroatom doping into the carbon and LFP. On one hand, the N, B, F ternary doped carbon film acts as conductive network for LFP particles, improves the electronic conductivity of electrode particle and consequently enhances the Li+/Li0 reduced/oxidized kinetics. On the other hand, the crystal lattice of LFP is enlarged by the F doping, which facilitates the Li+ intercalation/deintercalation. This study provides a convenient approach to prepare a high performance cathode material for lithium ion batteries.

Ce-doped V2O5 microspheres with improved electrochemical performance for high-power rechargeable lithium ion batteries

The development of high performance cathode materials is of importance for the widespread application of lithium-ion batteries in advanced energy storage devices. V2O5 is an attractive cathode candidate for lithium ion batteries owing to its high capacity as well as abundant source and low cost. In this work, Ce-doped V2O5 microspheres were fabricated by a combine method of one-step solvothermal process and subsequently annealing treatment. The electrochemical performance of V2O5 microspheres was enhanced dramatically by Ce-doping. Ce0.1V2O5 microspheres exhibit a high initial reversible capacity of 280.7 mAhg−1 at 0.5C and an excellent rate capability of 163.1 mAhg−1 at 10C. The discharge capacity of Ce0.1V2O5 microspheres could maintain up to 193.7 mAhg−1 with a capacity retention of about 88.93% even after 200 cycles, displaying a good cycling stability. The improved electrochemical properties of the synthesized Ce-doped V2O5 microspheres can be attributed to the lattice expansion upon Ce ions doping that can enhance the Li+ diffusion coefficient of electrodes. Meanwhile, Ce-doped V2O5 microspheres is constructed with aggregated nanoparticles, which is benefit for superior Li+ transportation and structural stability. The Ce-doped V2O5 microspheres could be utilized as a promising cathode material for lithium-ion batteries.

Optimization of synthesis parameters for uniform sphere-like Li1.2Mn0.54Ni0.13Co0.13O2 as high performance cathode material for lithium ion batteries

Lithium-rich layered oxide materials of Li1.2Mn0.54Ni0.13Co0.13O2 have been successfully synthesized through a facile one-step coprecipitation method without the use of any toxic chelating agent. The structure and morphology of the as-prepared Li1.2Mn0.54Ni0.13Co0.13O2 cathode material were well optimized by tuning synthesis parameters including the co-precipitation pH value, the feeding rate of metal precursors and the reaction temperature. The optimal Li1.2Mn0.54Ni0.13Co0.13O2 spherical particles present well-ordered layer structure and low cation-mixing degree. As a result, Li1.2Mn0.54Ni0.13Co0.13O2 as a cathode material presents excellent reversible capacity, rate capability, and cycling performance, which delivers a high initial discharge capacity of 255 mAh g−1 and 172 mAh g−1 at 0.1 C and 1 C, respectively. Moreover, a discharge capacity of 155 mAh g−1 can be maintained even after 300 cycles at 1 C, corresponding to a capacity retention as high as 81%.

Niobium doped tungsten oxide mesoporous film with enhanced electrochromic and electrochemical energy storage properties

Exploring high performance cathode materials is of great means for the development of bi-functional electrochromic energy storage devices. Herein, Nb-doped WO3 mesoporous films as integrated high-quality cathode are successfully constructed via a facile sol-gel method. Chemical state and crystallinity of the WO3 based films are significantly influenced by doping concentration. Compared with the pure WO3, the optimal Nb-doped film shows improved optical-electrochemical properties with high specific capacity (74.4 mAh g−1 at 2 A g−1), excellent high-rate capability, large optical contrast (61.7% at 633 nm), and ultra-fast switching speed (3.6 s and 2.1 s for coloring and bleaching process, respectively). These positive features suggest the potential application of Nb-doped WO3 mesoporous cathode. Our research paves the way for the development of multifunctional photoelectrochemical energy devices.

Tailoring π-Conjugated Systems: From π-π Stacking to High-Rate-Performance Organic Cathodes

Summary Organic sodium-ion batteries (OSIBs) have numerous promising advantages for foreseeable large-scale applications, particularly including the convenience of performance optimization through molecular design. However, the reported organic cathodes still suffer from limited capacity, low cyclability, and poor rate performance. The tailoring of the π-conjugated system reported here can enhance the π-π intermolecular interactions, leading to insolubility, long-range layer-by-layer π-π stacking, fast-charge transport, and extraordinary stability and ionic conductivity (10−9 cm2 s−1). Consequently, the obtained cathodes delivered high electrochemical performance with high capacity (∼290 mAh g−1), superior fast-charge-discharge ability (∼160 and 100 mAh g−1 at 10 and 50 A g−1, respectively), and ultra-long cycle life (capacity as high as 97 mAh g−1 after 10,000 cycles at 50 A g−1).

Mo-doping for improving the ZrF4 coated-Li[Li0.20Mn0.54Ni0.13Co0.13]O2 as high performance cathode materials in lithium-ion batteries

The different amounts of Mo6+ and the 2 wt% ZrF4 coating layer have been co-modified the Li[Li0.20Mn0.54Ni0.13Co0.13]O2 cathode material via using the carbonate co-precipitation method and wet coating process. And the influences of Mo6+ doping and ZrF4 surface coating on the cathode crystal structure, morphology and electrochemical properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), Transmission Electron Microscope (TEM) and galvanostatic charge–discharge tests. The 2 wt% ZrF4 coated-Li[Li0.20Mn0.52Ni0.13Co0.13Mo0.02]O2 demonstrated the lower cation mixing and a thickness of 15–35 nm film coated on the surface of cathode particles. Compared with the pristine cathode, the samples after ZrF4 coating and Mo6+ doping exhibited the less irreversible capacity loss, better high rate capability and superior cyclic performance owing to the lower impedance for Li+ migration across the SEI film and the faster Li+ migration speed in the cathode bulk. Among all samples, the 2 wt% ZrF4 coated-Li[Li0.20Mn0.52Ni0.13Co0.13Mo0.02]O2 showed the optimum electrochemical properties, with a high capacity retention of 88.7% after 100 cycles at 55 °C, much higher than that (82.9%) of the pristine cathode. Besides, when the electric current increased to 5C high rate, the pristine Li[Li0.20Mn0.54Ni0.13Co0.13]O2 delivered a discharge capacity of 21.9 mAh g−1 lower than that of 2 wt% ZrF4 coated-Li[Li0.20Mn0.52Ni0.13Co0.13Mo0.02]O2.

Structure modulation and performance optimization of P2-Na0.7Mn0.75Fe0.25-x-yNixCoyO2 through a synergistic substitution of Ni and Co for Fe

The poor cycling stability and inferior rate capability of the cathodes critically restrict the application of sodium ion batteries (SIBs). Herein, we propose a strategy to optimize the electrochemical performances of P2-Na0.7Mn0.75Fe0.25-x-yNixCoyO2 cathode materials for SIBs through modulating the crystal structure with a synergistic substitution of Fe by Ni and Co. The structure-performance relationship and the synergistic improvement mechanism have been unraveled by means of x-ray diffraction, neutron diffraction and electrochemical techniques. The synergistic substitution of Fe by Ni and Co leads to the enlargement of the interlayer spacing and the Na-O bond length, and shrinks the TM-O and O-O bonds, which enhances the sodium ion diffusion coefficient, the rate capability and the cycling stability. In addition, Jahn–Teller effect is also alleviated owing to the reduction of Mn3+, which can further enhance the stability of the layered structure. Ni and Co co-doped Na0.7Mn0.75Fe0.15Ni0.05Co0.05O2 (FNC) cathode shows a relatively smooth charge-discharge curve in 1.5–4.2 V and demonstrates a much better rate performance in compared to Na0.7Mn0.75Fe0.25O2 (MF), Na0.7Mn0.75Fe0.15Ni0.1O2 (FN) and Na0.7Mn0.75Fe0.15Co0.1O2 (FC). At a high current density of 1C, 2C, 5C and 10C, FNC can still deliver a reversible capacity of 127, 109, 83 and 58 mAh g−1, respectively. FNC also provides a higher reversible capacity of 181 mAh g−1 at 0.1C with a high cycling stability. This study offers some new insights into designing high performance cathode materials for SIBs through cooperatively modulating the crystal structure with multi-elements doping.

Cr-doped Fe2F5·H2O with open framework structure as a high performance cathode material of sodium-ion batteries

The sphere-like Fe(2-x)CrxF5·H2O (x = 0, 0.03, 0.05, 0.07) composites with open framework structure are prepared via an IL based assisted approach, and served as the cathode material for Na-ion batteries (NIBs). The physicochemical and electrochemical properties of the Cr-doped Fe2F5·H2O cathode materials are systematically characterized. The results indicate that the Cr-doped materials not only reduce the crystalline size, but also remarkably enhance electronic conductivity. Meanwhile, the electrochemical tests further show that Fe1.95Cr0.05F5·H2O as the cathode active material of NIBs exhibits a high initial discharge capacity of 357 mAh g−1 and retains a discharge capacity of 171 mAh g−1 after 100 cycles at 0.1 C (1 C = 200 mAh g−1). Moreover, even at high rate of 1 C, it can still deliver a high discharge capacity of 147 mAh g−1. Compared with the Fe2F5·H2O, the Fe1.95Cr0.05F5·H2O shows higher discharge capacity, excellent cycle stability and better rate capability, which can be attributed to the improvement of structure stability and electronic conductivity due to the appropriate amount (5%) of Cr3+ doping. Therefore, the preparation of Cr-doped Fe2F5·H2O sample provides a unique perspective to enhance the electrochemical performance of Fe2F5·H2O, which is an essential step for the development of high specific energy sodium-ion batteries.

VSe2-reduced graphene oxide as efficient cathode material for field emission

Field emission properties of pristine VSe2 and its hybrid with reduced graphene oxide (RGO) have been investigated in detail. Promising field emission performance were noted with lower values of turn-on and threshold fields of ∼1.3 V μm−1 and 2.12 V μm−1 respectively for the VSe2/RGO hybrid which is much more superior than that of pristine VSe2 emitter and other 2D materials. Density Functional Theory (DFT) simulations have also been performed to qualitatively support our experimental observations through demonstration of Density of States and computation of work function for pristine VSe2 and hybrid VSe2/RGO. The lowering of work function and appearance of additional states near Fermi level from carbon p orbital of RGO is responsible for superior field emission characteristics in hybrid VSe2/RGO compared to pristine VSe2 which supports our experimental observations. Our experimental data and theoretical insight from electronic structure simulations strongly infer that the synthesized hybrid VSe2/RGO has the potential to be tailored as efficient and high performance cathode material in field emission based devices.

Structure tuned Li1.2Mn0.6Ni0.2O2 with low cation mixing and Ni segregation as high performance cathode materials for Li-ion batteries

The sol-freeze-drying method is successfully applied to tune the structure of Co-free Li-rich Mn-based layered material (Li1.2Mn0.6Ni0.2O2). The structure, morphology and electrochemical performances of the tuned materials are compared with its counterpart prepared by traditional sol-gel method. The results confirm that sol-freeze-drying method is an effective approach to homogenize the transition metal distribution in Li1.2Mn0.6Ni0.2O2 without surface segregation of Ni. The specific capacity of Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method is 232 mAh g−1 after 100 cycles at 0.2C with 96% of initial discharge capacity retained. It is much higher than the 182 mAh g−1 of Li1.2Mn0.6Ni0.2O2 prepared by sol-gel method with poor capacity retention of 79%. Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method delivers the capacities of 252, 220, 192, 148, and 84 mAh g−1 at rates of 0.1C, 0.5C, 1C, 2C, and 5C, respectively. Besides, impedance spectroscopy shows that the charge-transfer resistance of Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method after 20 cycles increases from 43 Ω to 51 Ω, which is much lower than that of Li1.2Mn0.6Ni0.2O2 prepared by sol-gel method from 42 Ω to 78 Ω.

Lithium manganese oxyfluoride as a new cathode material exhibiting oxygen redox

A new high performance cathode material for Li-ion batteries with a disordered rocksalt structure powered by manganese and oxygen redox.

Facile pulse elecrodeposition of LixMnO2 nano-structures as high performance cathode materials for lithium ion battery

A one-pot strategy is employed for facile synthesis of mesoporous LixMnO2 (x = 0.19–0.41) by means of pulse electrodeposition technique. LixMnO2 materials with different chemical and physico-chemical properties are synthetized by modulating the pulse parameters. As results demonstrating, the functional properties of LixMnO2 are deeply influenced by varying both independent parameters namely, ton (time of current applying) and toff (time of current switching off) as well as dependent parameters: duty cycle (θ) and pulse frequency (ƒ). The mesoporous Li0.41MnO2 with a hierarchical morphology of nano-walls and a considerably high BET surface area of 137.49 m2 g−1 is achieved by applying the optimized pulse parameters (ton = 5 ms, toff = 45 ms, duty cycle = 10% and pulse frequency = 20 Hz). The Li0.41MnO2 shows superior performance as cathode material of Li-ion batteries, delivering the first discharge capacity of 284.45 mAh g−1, retaining 94.22% of first discharge capacity after 250 charge-discharge cycles and is still able to deliver 204 mAh g−1 after 110 successive charge-discharge cycles at different C-rates. This work proves that applying a lower duty cycles of pulse current, with optimized value of 10%, leads to the unique featured properties of LixMnO2 which giving rise to superior electrochemical performance.

Al2O3 coating on Li1.256Ni0.198Co0.082Mn0.689O2.25 with spinel-structure interface layer for superior performance lithium ion batteries

Li-rich manganese-based layered electrode materials are expected to be superior performance cathode materials for next-generation lithium ion batteries due to high capacity, low cost and environmentally benignity. However, the commercialization of such cathode materials is impeded by severe capacity fading and poor rate performance. To overcome these problems, Al2O3 is coated on the Li1.256Ni0.198Co0.082Mn0.689O2.25, meanwhile, spinel-structure interface layer is formed between the Li1.256Ni0.198Co0.082Mn0.689O2.25 and Al2O3 coating. This modified cathode material has a significant improvement on rate performance with a discharge capacity of 189 mAhg−1 at current density of 1250 mAg−1. In addition, it reveals a discharge capacity of 240 mAhg−1 at current densities of 250 mAg−1 and a retention of 95.2% after 60 cycles. The improved rate performance and cycling stability are benefited from the formation of spinel-structure interface layer and Al2O3 coating.

Nanostructured-VO2(B): A high-capacity magnesium-ion cathode and its electrochemical reaction mechanism

This paper reports the experimental feasibility of using VO2(B) nanomaterial as a high-capacity, high-voltage, and promising performance cathode material for magnesium-ion battery. Recent research on monoclinic VO2(B) material in the prevailing lithium-ion batteries has attracted more and more interest, primarily due to the layered structure and large charge/discharge capacity of the material. We synthesized VO2(B) in both forms of nanorods and nanosheets via a facile hydrothermal method to use as the cathode for an Mg ion battery, and investigated their properties, and electrochemical performance and mechanism with SEM, FT-IR, XRD, XPS, ICP and the electrochemical technique. . An encouraging performance is achieved with VO2(B) in the form of nanorods instead of nanosheets. The VO2(B) nanorods are capable of operation with a high discharge voltage at 2.17 V vs. Mg2+/Mg and a high initial discharge specific capacity of 391 mAh/g at a voltage ranging from −1.00 V to 0.30 V vs. Ag+/Ag, corresponding to 0.61 mol Mg per unit at a current density of 25 mA/g at 20 °C. Even at 12 °C, the first discharge specific capacity of 394 mAh/g is obtained with a capacity retention ratio up to 52.2% after 60 cycles at 50 mA/g, showing a better cyclability and capability. Significantly, the VO2(B) nanorods are confirmed to be a promising cathode material for use in Mg rechargeable batteries of a high capacity and a high voltage.

Facile triethanolamine-assisted combustion synthesized layered LiNi1/3Co1/3Mn1/3O2 cathode materials with enhanced electrochemical performance for lithium-ion batteries

The present study introduces a facile triethanolamine-assisted combustion method, wherein stoichiometric hydrate transition metal acetate with and without the addition of triethanolamine (TEA) were dissolved and mixed uniformly in deionized water and heated to burn. The ashes were then grinded and calcinated to synthesize layered LiNi1/3Co1/3Mn1/3O2 cathode materials. The structure, morphology, and electrochemical performance of two kinds of LiNi1/3Co1/3Mn1/3O2 materials were investigated and compared systematically. The results indicate that the sample with TEA possesses smaller particles and exhibits less aggregation and a better hexagonal layered structure. On the contrary, the sample with TEA exhibits lower polarization, a better cycling ability, a significantly improved rate performance, and better electronic conductivity. The enhanced electronic conductivity and electrochemical performance may be ascribed to a higher combustion enthalpy and better dispersion in the solvent following the introduction of TEA. This simple synthetic strategy presents a promising synthetic model for the enhancement of electrochemical performance cathode materials for lithium-ion batteries.

Improving the electrochemical performances of Li-rich Li1.20Ni0.13Co0.13Mn0.54O2 through a cooperative doping of Na+ and PO43− with Na3PO4

Li-rich layered oxide cathodes suffer from poor rate capability, voltage decay and inferior cycling stability. Herein, we propose a novel synergistic strategy to improve the electrochemical performances of Li-rich Li1.20Ni0.13Co0.13Mn0.54O2 by the co-doping of Na+ and PO43−. The co-doping of Na+ for Li and PO43− for Mn is simultaneously achieved using Na3PO4 as a dopant. The co-doping of Na+ and PO43− not only enhances the high-rate performance (106.4 mAhg−1@10C) and capacity retention (93.8%@1C@100 cycles) but also mitigates the voltage decay owing to the synergistic effect of Na+ and PO43− co-doping. The synergistic mechanism is unraveled based on neutron diffraction, aberration-corrected scanning transmission electron microscope, X-ray photoelectron spectroscopy, ex-situ X-ray absorption spectra, ex-situ X-ray diffraction, electrochemical impedance spectroscopy and electrochemical measurements. The co-doping of Na+ and PO43− enlarges the interlayer spacing and suppresses Li/Ni mixing which increases Li+ diffusivity and enhances the rate capability. Meanwhile, the co-doping of Na+ and PO43− shrinks the thickness of the slabs, weakens the TM-O covalency and alleviates the volume change in the charge/discharge process which improves the layered structure stability and the cycling performances. This study presents some new insights into designing high performance cathode materials through a cooperative modulation of different crystal sites doping.

LiMn0.5Co0.5BO3 solid solution: Towards high performance cathode material for next-generation lithium-ion battery

LiMn0.5Co0.5BO3 solid solution is synthesized by Sol-gel method. The crystal structure, morphology and the electrochemical properties of the LiMn0.5Co0.5BO3 solid solution are analyzed. X-ray diffraction analysis result reveals the existence of monoclinic phase with C2/c space group. Raman spectroscopy result indicates the presence of Co-O and Mn-O stretching vibration. X–ray Photoelectron spectroscopy confirms the surface oxidation of Mn in the LiMn0.5Co0.5BO3 solid solution. Transmission electron microscopy image shows the elongated spherical shaped particle with diameter of 40 nm. Galvanostatic charge – discharge studies indicate that the LiMn0.5Co0.5BO3 solid solution delivers the first discharge capacity of 110 mAh g−1 at C/10 rate with good stability and yield 68 mAh g−1 at 75th cycle. The enhanced electrochemical properties demonstrated in this study will give more attention to borate based cathode material as a potential alternative to current lithium-ion battery cathodes.