Designing the Binder-Free Conversion-Based Manganese Oxide Nanofibers as Highly Stable and Rate-Capable Anode for Next-Generation Li-Ion Batteries

Abstract

Recently, manganese (Mn)-based oxides have attracted more attention as a promising anode material for the next-generation lithium-ion batteries (LIBs) because of their higher experimental capacity, abundance, cost-effectiveness, and environmental-friendly nature. However, the poor rate capability and rapid capacity fading caused by the volume fluctuations during cycling hamper their usage in practical applications. To address these concerns, we report one-dimensional, high-aspect ratio MgMn2O4 (MMO) nanofibers with morphological voids/gaps as a binder-free negative electrode for LIBs. Herein, the binder-free electrodes of MMO nanofibers are fabricated via facile electrophoretic deposition technique. They can provide a well-designed network between the active materials and current collector, which enhances the electrical conductivity and Li-ion diffusion by avoiding binders as “dead mass”, which in turn helps to increase the energy density of LIBs. Furthermore, the morphological voids in between the individual nanoparticles of MMO nanofibers and the inactive MgO matrix element act as a buffering space that effectively accommodates the volume variation during lithiation and delithiation processes. The MMO nanofibers as LIB anodes exhibit a high reversible specific capacity of 776 mA h g–1 at 0.1 C after 125 cycles and good cyclic stability (609 mA h g–1 at 2 C after 600 cycles) with ∼99.3% capacity retention. Moreover, the binder-free MMO nanofiber anode also exhibits an ultrahigh rate capability (215 mA h g–1 at 9 C) that is generally difficult to attain in conversion-based materials. The excellent electrochemical performances can be ascribed to the 3D microstructure of the fabricated electrode and one-dimensional porous nanofabric morphology of MMO, which can ensure fast ion and electron transportation. Considering the excellent Li storage performance, the binder-free MMO nanofiber-based electrodes are expected to be promising anodes for next-generation LIBs.

In Situ Electrophoretic Decorated Cactus-Type Metallic-Phase MoS2 on CaMn2O4 Nanofibers for Binder-Free Next-Generation LIBs

“…14 The detection of Mn 2+ in CMO nanofibers suggests the existence of oxygen vacancies, a phenomenon previously observed in oxygen-deficient materials. 14,22 Further, three distinct peaks are observed in the high-resolution XPS spectra of O 1s, as shown in Figure 2i. The peaks detected at binding energies of 532.67, 531.13, and 529.23 eV are ascribed to the presence of oxygen atoms originating from surface-adsorbed water molecules (O W ), lattice oxygen (O L ), and the oxygen defect/vacancy sites (O d ), respectively.…”

“…In the low-frequency region, an inclined line represents the Warburg impedance (W), which describes the process of lithium-ion diffusion. 22,43 The Nyquist plots of the fresh electrodes (Figure 5f) indicate that the bare MS electrode exhibits the lowest charge transfer resistance value of 42 Ω. This value is approximately 70% smaller than the charge transfer resistance (138 Ω) observed for the bare CM electrode.…”

“…By utilizing the EPD process, the CMO nanofibers and MoS 2 nanoflowers were successfully bonded together, forming a uniform co-deposited film with a 3D porous structure. This 3D porous structure plays a crucial role in providing buffer spaces, effectively mitigating the mechanical stress that arises during cycling as a result of volume changes. , Further, the porous structure also amplifies the flow of electrolytes within the electrode, leading to an enhanced interfacial contact area between the electrolyte and active materials. This, in turn, enables a more efficient ion-conducting pathway and shortens the ion diffusion length. ,− With further increments in the concentration of MoS 2 (10 wt %), aggregation between the MoS 2 layers and CMO nanofibers is observed (Figure e).…”

Morphological control of CaxMn1−xNb2O6 columbites for use as lithium hosts in batteries

“…Only 25% of Ca 2+ can be introduced into the structure, which has the effect of giving an ordered structure, compared to the parent niobate and further affects the behaviour towards Li uptake. Conversion reaction occurs upon lithiation for the reported samples, as described for Mn 27,28 and Mo 29–31 -based oxides.…”

“…Only 25% of Ca 2+ can be introduced into the structure, which has the effect of giving an ordered structure, compared to the parent niobate and further affects the behaviour towards Li uptake. Conversion reaction occurs upon lithiation for the reported samples, as described for Mn 27,28 and Mo [29][30][31] -based oxides. (Alfa Aesar, 98.5%), NaOH (Fisher Scientific, 99.4%) or KOH (Fisher Scientific, 85%) was added, and the resulting mixture was stirred at room temperature for 15 min.…”