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Because of its high specific capacity and superior rate performance, porous carbon is regarded as a potential anode material for lithium-ion batteries (LIBs). However, porous carbon materials with wide pore diameter distributions suffer from low structural stability and low electrical conductivity during the application process. During this study, the calcium carbonate nanoparticle template method is used to prepare coal tar pitch-derived porous carbon (CTP-X). The coal tar pitch-derived porous carbon has a well-developed macroporous-mesoporous-microporous hierarchical porous network structure, which provides abundant active sites for Li+ storage, significantly reduces polarization and charge transfer resistance, shortens the diffusion path and promotes the rapid transport of Li+. More specifically, the CTP-2 anode shows high charge capacity (496.9â mAh g-1 at 50â mA g-1), excellent rate performance (413.6â mAh g-1 even at 500â mA g-1), and high cycling stability (capacity retention rate of about 100 % after 1,000 cycles at 2â A g-1). The clean and eco-friendly large-scale utilization of coal tar pitch will facilitate the development of high-performance anodes in the field of LIBs.
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The practical use of lithium-sulfur batteries faces the "shuttle effect" and lithium dendrite growth. Employing SiO instead of Li metal can fundamentally solve the above problems. Nevertheless, selecting a convenient prelithiation method is essential for normal operation of the battery system. Hence, this work proposed a novel SiO-sulfur battery with preloaded Li3N in a cathode as a prelithiation reagent, which can thoroughly solve the dendrite problem and the side reaction with polysulfides of lithium anode. The S@KB-Li3N vs SiO full cell can obtain a high specific capacity of 790 mAh g-1 after the activation process and be maintained at 478 mAh g-1 after 100 cycles. Our design will provide a new prelithiation strategy for a high-specific-energy SiO-sulfur battery system.
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High working voltage, large theoretical capacity and cheapness render Mn3O4 promising cathode candidate for aqueous zinc ion batteries (AZIBs). Unfortunately, poor electrochemical activity and bad structural stability lead to low capacity and unsatisfactory cycling performance. Herein, Mn3O4 material was fabricated through a facile precipitation reaction and divalent copper ions were introduced into the crystal framework, and ultra-small Cu-doped Mn3O4 nanocrystalline cathode materials with mixed valence states of Mn2+, Mn3+ and Mn4+ were obtained via post-calcination. The presence of Cu acts as structural stabilizer by partial substitution of Mn, as well as enhance the conductivity and reactivity of Mn3O4. Significantly, based on electrochemical investigations and ex-situ XPS characterization, a synergistic effect between copper and manganese was revealed in the Cu-doped Mn3O4, in which divalent Cu2+ can catalyze the transformation of Mn3+ and Mn4+ to divalent Mn2+, accompanied by the translation of Cu2+ to Cu0 and Cu+. Benefitting from the above advantages, the Mn3O4 cathode doped with moderate copper (abbreviated as CMO-2) delivers large discharge capacity of 352.9 mAh g-1 at 100 mA g-1, which is significantly better than Mn3O4 (only 247.8 mAh g-1). In addition, CMO-2 holds 203.3 mAh g-1 discharge capacity after 1000 cycles at 1 A g-1 with 98.6 % retention, and after 1000 cycles at 5 A g-1, it still performs decent discharge capacity of 104.2 mAh g-1. This work provides new ideas and approaches for constructing manganese-based AZIBs with long lifespan and high capacity.
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Prussian blue analogues (PBAs) are regarded as promising cathode materials for ammonium-ion batteries (AIBs) because of their low cost and superb theoretical capacity. However, its inherently poor conductivity and structural collapse can significantly limit the enhancement of rate property and cycling stability. In this work, Berlin Green (BG) electrode materials with similar wool-like clusters were constructed by direct precipitation method to accelerate the kinetic, which realizes outstanding cycling stability. Berlin Green with the appropriate amount of iron (BG-2) has a fast ion transport channel, enhanced structure stability, highly reversible insertion/extraction of NH4+, and fine electrochemical reaction activity. Benefiting from the unique architecture and component, the BG-2 electrode shows an excellent rate performance with a discharge/charge specific capacity of 60.1/59.3 mAh g-1 at 5 A g-1. Even at 5 A g-1, BG-2 exhibits remarkable cycling stability with an initial discharge capacity of 59.5 mAh g-1 and a capacity retention rate of approximately 76% after 30,000 cycles. The BG-2 reveals exceedingly good electrochemical reversibility during the process of NH4+ (de)insertion. BG materials indicate huge potential as a cathode material for the next generation of high-performance aqueous batteries.
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ZnCo2 O4 has been attracted wide research attention as a promising anode material for lithium-ion batteries (LIBs) in recent years based on its high theoretical specific capacity, low toxicity as well as stable chemical properties. However, the further large-scale application of pristine ZnCo2 O4 anode have been impeded because of its undesirable Li+ ion conductivity, low electronic conductivity, and finite stability of electrolytes at high potentials. Recently, optimizing the micro/nano structure, modification with carbonaceous materials, incorporation with metal oxides and constructing a binder-free structure on conductive substrate for ZnCo2 O4 -based materials have been verified as promising effective routes for solving the above problems. In this review, the recent advances in underlying reaction mechanisms, synthetic methods and strategies for improving the performance of ZnCo2 O4 anodes are comprehensively summarized. The factors affecting the electrochemical properties of ZnCo2 O4 -based materials are mainly discussed, and paths to promote the specific capacity and cyclic stability are proposed. Finally, several insights into the future developments, challenges, and prospects of ZnCo2 O4 -based anode materials of LIBs are proposed.
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Lithium-rich manganese-based cathode has made a subject of intense scrutiny for scientists and application researchers due to their exceptional thermal stability, high specific capacity, high operating voltage, and cost-effectiveness. However, the inclusion of cobalt, as a crucial component in lithium-rich manganese-based cathode materials, has become a cause for concern due to its limited availability and non-renewable nature, which eventually limits the growth of the battery industry and increase costs. Considering the poor stability of cobalt-free cathode, this work proposes a coating strategy of LiF through a simple high-temperature melting method. Directly coating LiF on Li1.2Ni0.2Mn0.6O2 surface is found to be an effective way to protect the cathode material, decrease metal solubility, and inhibit irreversible phase transition processes, thus leading to an improved electrochemical performance. As a result, the battery employing LiF coated Li1.2Ni0.2Mn0.6O2 cathode can be stabilized over 280 cycles and maintain a capacity of 110 mAh g-1 at 1C. What's more, the mechanisms of ion insertion/extraction behavior and ion migration process are also studied systematically. This study will open the avenue to develop a high-energy battery system with cobalt-free cathode.
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Transition metal sulfides with the high theoretical capacity and low cost have been considered as advanced anode candidate for alkali metal ion batteries, but suffered from unsatisfactory electrical conductivity and huge volume expansion. Herein, a multidimensional structure Cu-doped Co1-xS2@MoS2 in-situ-grown on N-doped carbon nanofibers (denoted as Cu-Co1-xS2@MoS2 NCNFs) have been elaborately constructed for the first time. The bimetallic zeolitic imidazolate framework CuCo-ZIFs were encapsulated in the one-dimensional (1D) NCNFs through an electrospinning route and then on which the two-dimensional (2D) MoS2 nanosheets were in-situ grown via a hydrothermal process. The architecture of 1D NCNFs can effectively shorten ion diffusion path and enhance electrical conductivity. Besides, the formed heterointerface between MOF-derived binary metal sulfides and MoS2 can provide extra active centers and accelerate reaction kinetics, which guarantee a superior reversibility. As expected, the resulting Cu-Co1-xS2@MoS2 NCNFs electrode delivers excellent specific capacity of Na-ion batteries (845.6 mAh/g at 0.1 A/g), Li-ion batteries (1145.7 mAh/g at 0.1 A/g), and K-ion batteries (474.3 mAh/g at 0.1 A/g). Therefore, this innovative design strategy will bring a meaningful prospect for developing high-performance multi-component metal sulfides electrode for alkali metal ion batteries.
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Ternary transition metal oxides (TMOs) are deemed as promising anode materials of Li-ion batteries (LIBs) owing to their large theoretical capacity and rich redox reaction. Nevertheless, the inherent semiconductor characteristic and enormous volume variation of TMOs during cycling bring about sluggish reaction kinetics, fast capacity fading, and poor rate capability. In this study, three-dimensional (3D) porous CoNiO2@CTP architectures, i.e., CoNiO2 microspheres combined with coal tar pitch-derived porous carbon, were designed and synthesized through a one-step hydrothermal method followed by a heat treatment process for the first time. The microsphere morphology increases the contact area between the anode and electrolyte, shortens the transport distance of Li+ ions, and reduces the agglomeration. The existence of the CTP layer provides rich charge transmission paths, improves the electronic conductivity of CoNiO2 and provides abundant active sites for Li+ storage. Owing to the synergistic effect of porous carbon and microsphere morphology of CoNiO2, the CoNiO2@CTP (10.0 wt%) anode shows remarkable electrochemical performance with a high charge capacity (1437.5 mA h g-1 at 500 mA g-1), good rate performance (839.76 mA h g-1 even at 1 A g-1), and remarkable cycle durability (741.4 mA h g-1 after 1000 cycles at 1 A g-1), which is significantly better than pristine CoNiO2. This study not only provides a simple strategy for high-value utilization of CTP but also offers cost-effective CoNiO2@CTP architectures for high-performance LIBs.
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Li-rich Mn-based oxides (LRMOs) are considered as one of the most-promising cathode materials for next generation Li-ion batteries (LIBs) because of their high energy density. Nevertheless, the intrinsic shortcomings, such as the low first coulomb efficiency, severe capacity/voltage fade, and poor rate performance seriously limit its commercial application in the future. In this work, we construct successfully g-C3N4 coating layer to modify Li1.2Mn0.54Ni0.13Co0.13O2 (LMNC) via a facile solution. The g-C3N4 layer can alleviate the side-reaction between electrolyte and LMNC materials, and improve electronic conduction of LMNC. In addition, the g-C3N4 layer can suppress the collapse of structure and improve cyclic stability of LMNC materials. Consequently, g-C3N4 (4 wt%)-coated LMNC sample shows the highest initial coulomb efficiency (78.5%), the highest capacity retention ratio (78.8%) and the slightest voltage decay (0.48 V) after 300 loops. Besides, it also can provide high reversible capacity of about 300 and 93 mAh g-1 at 0.1 and 10C, respectively. This work proposes a novel approach to achieve next-generation high-energy density cathode materials, and g-C3N4 (4 wt%)-coated LMNC shows an enormous potential as the cathode materials for next generation LIBs with excellent performance.
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The Li2MoO3 (LMO) material is one promising cathode material for lithium-ion batteries due to its high specific capacity and absence of oxygen release. However, its surface instability in air and poor conductivity have limited its application. To solve these problems, the Ru element has been successfully introduced into the LMO lattice with the aid of the molten salt method. XRD and TEM characterization showed that the introduction of Ru does not change the crystal structure but expands the crystal plane spacing of the {001} facets, which is further evidenced by density functional theory (DFT) calculations. XPS and EDS tests indicated that the introduction of Ru inhibits the oxidation of Mo species and leads to a more uniform distribution of the material. In addition, DFT calculations revealed that covalent interactions are formed between Mo4d/Ru4d and O2p orbitals, leading to a significant reduction of the band gap. Therefore, Ru-doped samples exhibit good electrochemical performances. The initial discharge capacity of an LMRO-2 sample reaches 299.1 mA h g-1 at a 1C rate, and the capacity remains at 125.2 mA h g-1 after 100 cycles. In comparison, the initial discharge capacity of pure phase sample LMO is only 250.5 mA h g-1 under the same conditions, and the capacity remains only at 76.5 mA h g-1 after 100 cycles. The present results confirmed that Ru doping is an effective strategy to improve the performance of the LMO cathode material.
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Platanus fruit-like CuCo2S4 microspheres were fabricated by using a facile hydrothermal method followed by a sulfidation process. As a lithium storage material, they deliver an outstanding initial specific capacity of 1119.3 mA h g-1 at 0.05 A g-1 and a high reversibility of 954 mA h g-1 over 200 cycles even at 1 A g-1. In addition, when applied in supercapacitors they display a superb specific capacitance of 824 F g-1 at 1 A g-1, even over 10 000 cycles and they can also maintain 75% retention at 5 A g-1 and exhibit good reversibility. Furthermore, an advanced asymmetric supercapacitor (ASC) exhibits an advantageous energy density of 36.67 W h kg-1 when the power density increases up to 750 W kg-1. Additionally, the assembled device can easily light a 1.5 V bulb for several minutes. The excellent performance of CuCo2S4 is due to the bimetallic synergistic effect and the unique platanus fruit-like microsphere architecture, which can limit the restacking of the structure and provide suitable voids. This excellent performance confirms that platanus fruit-like CuCo2S4 microspheres are a promising electrode material for energy storge. This work will provide a new strategy to prepare high-performance bimetallic sulfide anode materials by a facile method.
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Na2Li2Ti6O14 particles were prepared by a simple solid-state process, and then g-C3N4-coated Na2Li2Ti6O14 composites were constructed by a facile solution route for the first time. The g-C3N4-coated Na2Li2Ti6O14 multicomponent composites because of their unique architecture as negative materials for Li-ion batteries can be expected to exhibit a significantly improved cycling stability and reversible capacity even at high rates. g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows a discharge (charge) capacity of 184.4 (184.3) mA h g-1 at 500 mA g-1 after 100 cycles, which is larger than that of pristine Na2Li2Ti6O14 with a discharge (charge) capacity of 122.8 (122.0) mA h g-1. The use of g-C3N4 with a carbon framework containing abundant nitrogen provides more active sites and surface defects for redox reactions and Li-ion transport. The g-C3N4 coating decreases the impedance between the electrolyte and Na2Li2Ti6O14 and enhances the charge transfer, ionic conductivity and diffusion ability of Li ions of Na2Li2Ti6O14. This work offers an efficient way to design high-performance Na2Li2Ti6O14-based materials for advanced lithium ion battery, and g-C3N4 (5 wt%)-coated Na2Li2Ti6O14 shows an enormous potential as a negative material for next generation Li-ion batteries with excellent performance.
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The carbon-coated LiMn0.5Fe0.5PO4@Li0.33La0.56TiO3 nanorod composites (denoted as C/LMFP@LLTO) have been successfully obtained according to a common hydrothermal synthesis following a post-calcination treatment. The morphology and particle size of LiMn0.5Fe0.5PO4 (denoted as LMFP) are not changed by the coating. All electrode materials exhibit nanorod morphology; they are 100-200 nm in length and 50-100 nm in width. The Li0.33La0.56TiO3 (denoted as LLTO) coating can facilitate the charge transfer to enhance lithiation/delithiation kinetics, leading to an excellent rate performance and cycle stability of an as-obtained C/LMFP@LLTO electrode material. The reversible discharge capacities of C/LMFP@LLTO (3 wt %) at 0.05 and 5 C are 146 and 131.3 mA h g-1, respectively. After 100 cycles, C/LMFP@LLTO (3 wt %) exhibits an outstanding capacity of 106.4 mA h g-1 with an 81% capacity retention rate at 5 C, indicating an excellent reversible capacity and good cycle capacity. Therefore, it can be considered that LLTO coating is a prospective pathway to exploit the electrochemical performances of C/LMFP.
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ZnTiO3 and ZnTiO3-CeO2 microspheres with particle sizes of about 100-300 nm were synthesized for the first time by a simple solvothermal process followed by calcination. The results indicate that CeO2 modification does not alter the morphology of the microspheres. ZnTiO3-CeO2 (0, 3, 6, and 9 wt%) show an initial charge (discharge) capacity of 171.01 (253.2), 204.6 (507.5), 213.4 (451.6) and 126.2 (367.2) mA h g-1 at 500 mA g-1, respectively. After 500 cycles, the corresponding charge (discharge) capacities were 191.1 (192.3), 298.7 (300.3), 322.4 (328.5) and 211.2 (212.3) mA h g-1, respectively. Obviously, the charge (discharge) capacities of the ZnTiO3-CeO2 composites are superior to those of pristine ZTO, which demonstrates that the Li storage performance of the CeO2-modified ZTO electrodes is improved. The CeO2 shell provides a good electronic contact between ZnTiO3 and CeO2, decreasing charge transfer resistance and facilitating the charge transportation of the ZnTiO3-CeO2 composite. In addition, the formed phase interface between CeO2 and ZnTiO3 may provide more active sites for electrochemical reactions, improving the reversibility of Li-ion intercalation and decreasing the electrochemical polarization during cycling, especially at high current densities. Therefore, such ZnTiO3-CeO2 microspheres can be regarded as hopeful candidates for anode materials for Li-ion batteries.
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In this work, a rational design and construction of porous spherical NiO@NiMoO4 wrapped with PPy was reported for the application of high-performance supercapacitor (SC). The results show that the NiMoO4 modification changes the morphology of NiO, and the hollow internal morphology combined with porous outer shell of NiO@NiMoO4 and NiO@NiMoO4@PPy hybrids shows an increased specific surface area (SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO4 and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of NiO, and then improves the electrochemical kinetics of NiO. At 20Ag-1, the initial capacitances of NiO, NiMoO4, NiO@NiMoO4 and NiO@NiMoO4@PPy are 456.0, 803.2, 764.4 and 941.6Fg-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8Fg-1, respectively. Especially, the initial capacitance of NiO@NiMoO4@PPy is 850.2Fg-1, and remains 655.2Fg-1 with a high retention of 77.1% at 30Ag-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the NiO@NiMoO4 composite, resulting in a good cycling stability of these materials.
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To recycle the waste and meet the demand for anode materials for Li-ion battery, α-Fe2O3/C for use as anode material is successfully prepared via a simple hydrothermal process using acid-pickled iron oxide red as raw material. The techniques of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy are used to characterize the product. The synthesis conditions, including temperature and time, are optimized by orthogonal experimental design. The optimal reaction temperature, reaction time, Fe2O3/SO42- ratio, Fe2O3/glucose ratio are 120 °C, 30 h, 20:2 and 1:1, respectively. The sample prepared at optimal conditions exhibits a high initial specific capacity of 1144/1535 mA h g-1 at 100 mA g-1 and a superior cycling performance of Ë800 mA h g-1 after 200 cycles. Accordingly, this method provides information for the synthesis of α-Fe2O3/C with acid-pickled iron oxide red for the first time, which may help alleviate the problem of energy shortage and environmental pollution through the rational use of resources.
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To improve their electrochemical performance and structural stability, Na2Li2Ti6O14 (NLTO) nanoparticles were synthesized and then coated with a very thin MgF2 layer. Microscopy confirmed that the MgF2-NLTO particles are about 150-250 nm in size, and that the thickness of the MgF2 layer for the MgF2-NLTO-5 sample is â¼5 nm. Electrochemical measurements showed that the charge-discharge specific capacities of the five samples under a current density of 50 mA g-1 after 100 cycles are 110.4/110.7, 150.7/151.3, 181.1/182.1, 205.7/206.9 and 238.9/239.2 mA h g-1, showing that the performance of MgF2-NLTO-5 is the best among all the samples. Thanks to the thin coating layer, the polarization of the anode was reduced significantly, and its reversibility and lithium diffusion dynamics were also improved obviously. The performance improvement can be attributed to the suppression of surface corrosion and the enhancement of structural stability.
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To enable lithium-oxygen batteries for practical applications, the design and efficient synthesis of nonprecious metal catalysts with high activity and stable structural properties are demanded. The objective is to accelerate the sluggish kinetics of both oxygen reduction reaction and oxygen evolution reaction by facilitating electronic/ionic transport and improving oxygen diffusion in a porous structure. In this study, high-surface-area and porous cobalt phosphide (Co2P) nanosheets are synthesized via an environmentally safe hydrothermal method, where red phosphorous is used as the phosphorous source. It was found that the as-prepared Co2P/acetylene black (AB) composite delivered enhanced electrochemical performances, such as high capacities of 2551 mA h g-1 (based on the total weight of Co2P and AB) or 5102 mA h g-1 (based on the weight of Co2P or AB) and a good cycle life of more than 1800 h (132 cycles) in lithium-oxygen battery. The rational design of the Co2P/AB porous oxygen electrode structure provides sufficient accessible reaction sites and a short diffusion path for electrolyte penetration and diffusion of O2.
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A facile strategy was developed to prepare Li5Cr7Ti6O25@CeO2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO2 coating does not alter the structure of Li5Cr7Ti6O25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO2 layer successfully formed a coating layer on a surface of Li5Cr7Ti6O25 particles and supplied a good conductive connection between the Li5Cr7Ti6O25 particles. The electrochemical characterization reveals that Li5Cr7Ti6O25@CeO2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li5Cr7Ti6O25@CeO2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li5Cr7Ti6O25 only delivers an initial delithiation capacity of â¼94.7 mAh g-1, and the delithiation capacity merely achieves 87.4 mAh g-1 even after 100 cycles. However, Li5Cr7Ti6O25@CeO2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g-1, and the delithiation capacity also reaches 100.5 mAh g-1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li5Cr7Ti6O25 at large current densities.
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Pristine LiNi0.5Mn1.5O4 and FePO4-coated one with Fd-3m space groups were prepared by a sol-gel method. The structure and performance were studied by X-ray diffraction (XRD) rietveld refinement, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectrometer (EDS) mapping, electrochemical impedance spectroscopy (EIS) and charge-discharge tests, respectively. The lattice parameters of all samples almost remain the same from the Rietveld refinement, revealing that the crystallographic structure has no obvious difference between pristine LiNi0.5Mn1.5O4 and FePO4-coated one. All materials show similar morphologies with uniform particle distribution with small particle size, and FePO4 coating does not affect the morphology of LiNi0.5Mn1.5O4 material. EDS mapping and HRTEM show that FePO4 may be successfully wrapped around the surfaces of LiNi0.5Mn1.5O4 particles, and provides an effective coating layer between the electrolyte and the surface of LiNi0.5Mn1.5O4 particles. FePO4 (1wt%)-coated LiNi0.5Mn1.5O4 cathode shows the highest discharge capacity at high rate (2C) among all samples. After 80 cycles, the reversible discharge capacity of FePO4 (1wt%) coated LiNi0.5Mn1.5O4 is 117mAhg-1, but the pristine one only has 50mAhg-1. FePO4 coating is an effective and controllable way to stabilize the LiNi0.5Mn1.5O4/electrolyte interface, and avoids the direct contact between LiNi0.5Mn1.5O4 powders and electrolyte, then suppresses the side reactions and enhances the electrochemical performance of the LiNi0.5Mn1.5O4.