Interfacial Superassembly of Grape-Like MnO-Ni@C Frameworks for Superior Lithium Storage

Co-assisted strategy of sacrificial salt-template and nitrogen-doping to promote lithium storage performance of NiO-Ni/N-C frameworks

Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO-Ni/N-C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO-Ni/N-C electrode leads it to exhibit a capacity of 1310.8 mAh g-1 at 0.1 A g-1 for 120 loops and a rate capability of 441.5 mAh g-1 at 20.0 A g-1. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications.

Multifunctional Cr Substitution Modulates Electrochemical Activity of Mn1-xCrxO for High-Performance Lithium-Ion Battery Anodes

Metal oxides are a promising candidate for lithium-ion battery (LIB) anodes due to their high theoretical capacity and long cycle life but also face inherent poor conductivity and volume variation, making them difficult to promote the application. The cation substitution strategy is an important means to facilitate improved rate and cycling performance. However, the effect of cation substitution on electrochemical activity is multivariate and complex, and a comprehensive and systematic analysis is essential for understanding the relationship between components and properties. Herein, the aliovalent heterogeneous Cr-substituted MnO was used as a model to systematically investigate the effects of Cr substitution on the crystal structure, electron distribution, defect construction, and electrochemical reaction processes. Theoretical calculations and experimental results reveal that Cr substitution can effectively modulate the electronic structure, build a built-in electric field, generate cationic defects, and catalyze the electrochemical reaction process, thereby improving the electrode kinetics and electrochemical activity of active materials. When the optimized Mn_0.94Cr_0.06O was used as the anode for LIBs, a reversible capacity of 1547.3 mAh g^-1 was obtained after 450 cycles at a current density of 1 C (1 C = 756 mA g^-1 for half-cells), and a reversible capacity of up to 1126.2 mAh g^-1 could be maintained even after 700 cycles at a current density of 2 C. The assembled Mn_0.94Cr_0.06O//LiCoO₂ full cell further confirms the scalability of the heterogeneous atom substitution strategy.

Heterogeneous Atoms Substituted Rock Salt Phase Mn1 -x Fex O Solid Solution with Rich Defects for Advanced Lithium-Ion Batteries

Heterogeneous atoms substitution is an efficient method for promoting Li⁺ storage of transition metal oxides. Herein, a series of Fe-substituted MnO solid solutions with different Fe contents are synthesized by a feasible solid-phase method. The synergistic effects between heterogeneous atoms and rich vacancies are synchronously obtained, which hold distinctive electronic structures and substantial active sites. When optimized Mn_0.55 Fe_0.45 O solid solution as anodes for lithium-ion batteries, pre-prepared electrodes exhibit reversible lithium storage of 1286.9 mAh g^-1 at 1 A g ^-1 after 400 cycles and even 628.1 mAh g^-1 at 2 A g^-1 after 1000 cycles. The LiCoO₂ //Mn_0.55 Fe_0.45 O full cells are assembled, achieving the reversible capacity of 130.2 and 111.3 mAh g^-1 after 150 cycles at 0.1 and 0.2 A g^-1 , respectively. Density functional theory calculations also authenticate that the electrochemical activity can be markedly boosted by the heterogeneous atoms substituted Mn_{1 -x} Fe_x O solid solution.

Co3O4 Nanoparticles Dotted Hierarchical-Assembled Carbon Nanosheet Frameworks Catalysts with Formation/Decomposition Mechanisms of Li2O2 for Smart Lithium-Oxygen Batteries

The Li-O2 batteries (LOB) have been regarded as a promising candidate for the next generation of electric vehicles owing to their excellent energy density. Nevertheless, the practical application of LOB...

Constructing an interspace in MnO@NC microspheres for superior lithium ion battery anodes

In this work, silica nanospheres were introduced into nitrogen-carbon (NC) coated MnO microspheres and filled the gap between NC and MnO. After etching, an interspace was formed between the coating layer and the MnO microspheres. The structure not only provides a conductive NC layer, but also constructs a space to mitigate the volume effect of MnO. As expected, the specific capacity remained at 1143.93 mA h g^-1 after 200 cycles at a current density of 0.2 A g^-1, and 726.96 mA h g^-1 after 450 cycles at a high current density of 1 A g^-1. The superior performance can be attributed to the unique structure with an internal void space and the excellent protection of MnO microspheres by the surface NC layer.

Super-Assembled Hierarchical CoO Nanosheets-Cu Foam Composites as Multi-Level Hosts for High-Performance Lithium Metal Anodes

Achieving uniform lithium (Li) deposition is the key to tackle uncontrollable dendrite growth, which hinders the application of Li metal anodes. In this study, molten Li is thermally injected into a 3D framework by growing lithiophilic CoO nanosheets on Cu foam (CF). The CoO layer grown on the CF surface physically adsorbs molten Li, which makes it possible to spontaneously wet the framework. The morphology of CoO nanosheets does not change during the Li injection process and formed a multi-level structure with the CF, which is difficult to be achieved previously, as most lithiophilic oxides undergo serious chemical changes due to chemical reaction with Li and cannot provide a stable submicron structure for the subsequent Li stripping/plating process. The super-assembled multi-level structure provides abundant Li nucleation sites and electrolyte/electrode contact areas for rapid charge transfer in the composite anode. Therefore, the prolonged lifespan of symmetrical cells for 300 cycles at 10 and 10 mAh cm^-2 with lower polarization is achieved, which further renders the LiFePO₄ and Li₄ Ti₅ O₁₂ based full cells with improved capacity retention up to 87.3% and 80.1% after 500 cycles at 1 C. These results suggest that the composite anode has a great application prospect.

Surface modification of manganese monoxide through chemical vapor deposition to attain high energy storage performance for aqueous zinc-ion batteries

Surface modification of the manganese-based oxide electrode is considered to be a viable strategy to improve electrochemical property in aqueous zinc-ion batteries (ZIBs). However, the modification method through traditional wet-chemical technology can hardly to satisfy high rate capability for aqueous ZIBs due to unhomogeneous and nonconformal coating originates from surface energy mismatch. Herein, a surface modification strategy based on chemical vapor deposition is developed to enhance the electrochemical property of the inactive MnO in aqueous ZIBs. The constructed carbon coating modified MnO electrode shows excellent reversible capacity and superior rate capability with remarkable energy density of 351 Wh kg^-1 at 625 W kg^-1. The energy storage mechanism of the electrode during the charge and discharge processes is elucidated according to the ex-situ measurements of X-ray diffraction and photoelectron spectroscopy, Fourier transform infrared spectra, and galvanostatic intermittent titration techniques. Moreover, soft-packaged batteries are fabricated with the carbon coating modified MnO, which shows great promises for the practical application of the material. The work paves the way for the exploitation of high performance surface-modified electrode through chemical vapor deposition for aqueous ZIBs.

Straightforward preparation of Na2(TiO)SiO4 hollow nanotubes as anodes for ultralong cycle life lithium ion battery

One-dimensional Na₂(TiO)SiO₄ (SNTO) nanotubes have been successfully synthesized by a straightforward hydrothermal method with the assistance of cetyltetramethyl ammonium bromide (CTAB). Herein, the influence of the Si/Ti ratio on the morphology or composition of SNTO hollow nanotubes has been investigated, and the result shows that the optimum molar ratio of the optimal morphology is 1 : 1. The prepared samples were first applied as anodes in lithium ion batteries (LIBs) for the time being and superior rate capability, ultralong and stable cycling lifespan performance were obtained. The facile and uniquely designed one-dimensional SNTO nanotube electrodes delivered a high reversible capacity of 121.9 mA h g^-1 after 5000 cycles at a high current of 1.0 A g^-1 without significant attenuation. The superior electrochemical properties are attributed to their special nanotube structure with a high specific surface area, which could shorten the ion/electron transport pathway, and increase the number of active sites and the contact area between the electrolyte and active electrodes. Meanwhile, the kinetic analysis of the electrochemical behaviors of SNTO hollow nanotube electrodes was carried out by performing calculations using cyclic voltammograms recorded at different scan rates, and the results showed that the obtained reversible capacity is mainly due to the capacitive contribution. This work expands the types of anode materials for LIBs, which will further promote the development of LIBs.

Polymerization inspired synthesis of MnO@carbon nanowires with long cycling stability for lithium ion battery anodes: growth mechanism and electrochemical performance

Manganese-based transition metal oxides are regarded as one kind of high capacity and low cost anode material for Li-ion batteries. To overcome the challenges of poor electrical conductivity and large volumetric expansion during the charging-discharging process of MnO, we here synthesize MnO@carbon (MnO@C) nanowires via the polymerization inspired in situ growth of [Mn-NTA] (NTA = nitrilotriacetic acid) precursor nanowires with a subsequent heat treatment process. The growth mechanism of [Mn-NTA] precursor nanowires was studied. The morphology of the precursor nanowires depended largely on the molar ratio of MnCl2 to NTA reactants. At a molar ratio of 2, the length of the [Mn-NTA] nanowires reached up to more than 140 μm. Furthermore, the as-synthesized MnO@C nanowires were integrated with a very low content of reduced graphene oxide (rGO) to prepare a self-standing paper-like MnO@C/rGO anode for lithium ion batteries without a binder. The MnO@C/rGO anode showed a unique structure with one-dimensional porous MnO nanowires hierarchically encapsulated by a conductive carbon framework. As a result, the self-standing electrode achieved a high capacity of 1368 mA h g-1 after 100 cycles at a current density of 100 mA g-1 and prominent cycling stability with a capacity of 689.9 mA h g-1 even after 1700 cycles at 2000 mA g-1.

Synthesis of hierarchically porous MnO/C composites via a sol–gel process followed by two-step combustion for lithium-ion batteries

Hierarchically porous MnO/C composites with interconnected macropores and co-continuous skeletons were fabricated via a sol–gel process combined with phase separation, followed by a two-step combustion.

Interfacial superassembly of MoSe2@Ti2N MXene hybrids enabling promising lithium-ion storage

Our work presents an interfacial superassembly by engineering MoSe₂ nanoflowers coupled with ribbon-like Ti₂N MXene frameworks. It can provide a novel synthesis strategy to improve the performance of LIBs.