Nonhierarchical Heterostructured Fe₂O₃/Mn₂O₃ Porous Hollow Spheres for Enhanced Lithium Storage

Abstract

High capacity transition-metal oxides play significant roles as battery anodes benefiting from their tunable redox chemistry, low cost, and environmental friendliness. However, the application of these conversion-type electrodes is hampered by inherent large volume variation and poor kinetics. Here, a binary metal oxide prototype, denoted as nonhierarchical heterostructured Fe O /Mn O porous hollow spheres, is proposed through a one-pot self-assembly method. Beyond conventional heteromaterial, Fe O /Mn O based on the interface of (104) and (222) exhibits the nonhierarchical configuration, where nanosized building blocks are integrated into microsized spheres, leading to the enhanced structural stability and boosted reaction kinetics. With this design, the Fe O /Mn O anode shows a high reversible capacity of 1075 mA h g at 0.5 A g , an outstanding rate capability of 638 mA h g at 8 A g , and an excellent cyclability with a capacity retention of 89.3% after 600 cycles.

Optimization of Von Mises Stress Distribution in Mesoporous α‐Fe2O3/C Hollow Bowls Synergistically Boosts Gravimetric/Volumetric Capacity and High‐Rate Stability in Alkali‐Ion Batteries

“…The plots of log( i ) versus log( v ), where i and v are the current density of the five pairs of cathodic/anodic peaks and the scan rate of the CV curves, respectively, are displayed in Figure g. The slope values for the cathodic and anodic reactions are determined to be 0.88 and 0.82, respectively, suggesting that the electrochemical lithium storage is dominated by both ion diffusion and the capacitive effect . The obtained capacitive contributions are 47.9%, 56.6%, 64.8%, 70.9%, and 75.3% at 0.1, 0.2, 0.4, 0.7, and 1.1 mV s −1 , respectively (Figure h), which confirms that surface capacitive behavior has a significant role in the total capacity, especially at high scan rates.…”

Room-temperature solution synthesis of ZnMn2O4 nanoparticles for advanced electrochemical lithium storage

“…Presently, the energy density of lithium-ion batteries (LIBs) needs urgently to be improved to meet the market development, which is principally restricted by the current commercial graphite anode materials (z372 mA h g À1 ). 1,2 Hence, enormous efforts have been implemented to exploit anode materials with high capacity, such as metal oxide/sulde, [3][4][5] phosphide, 6 Sibased compounds. 7 In consideration of their nontoxicity, low cost and high energy density, transition metal oxides (TMOs) have attracted extraordinary attention, owing to their high theoretical reversible capacity, which is twice as high as that of graphite.…”

Biological Metabolism Synthesis of Metal Oxides Nanorods from Bacteria as a Biofactory toward High‐Performance Lithium‐Ion Battery Anodes

“…In addition, these single crystal biometabolic α‐Fe 2 O 3 nanorods are transformed into the polycrystalline nanorods composed of numerous small grains as shown in Figure c. The generated cracks and small iron oxide grains are mainly attributed to the reaction between Fe 2 O 3 and Li + in the first discharge process that results in the destruction of crystal structure accompanied by the formation of Fe 0 and Li 2 O grains . Interestingly, as depicted in Figure d, the morphology and chemical composition of biometabolic α‐Fe 2 O 3 nanorods after 100 cycles are similar to its initial state, implying the superior structural stability during the long‐term cycling.…”

“…Iron‐based oxides (e.g., α‐Fe 2 O 3 , γ‐Fe 2 O 3 , and Fe 3 O 4 ) as promising anode materials for LIBs have deserved soaring attention because of their much higher capacity than that of conventional graphite (372 mAh g −1 ), as well as nontoxicity, abundance, and low cost . Particularly, α‐Fe 2 O 3 electrochemically reacted with Li + ions via the conversion mechanism (Fe 2 O 3 + 6Li + + 6 e − ↔ 2Fe + 3Li 2 O) theoretically delivers an extremely high capacity of 1007 mAh g −1 .…”

“…However, restricted by dramatic volume expansion rate, low electronic conductivity, and unstable solid electrolyte interphase (SEI), α‐Fe 2 O 3 suffers rapid capacity fading during the long‐term cycling and inferior rate capability under high‐current charge–discharge processes . So far, one effective approach to improve the cycle life and rate performance is to rationally design and fabricate delicate nanostructured α‐Fe 2 O 3 that can not only shorten Li + diffusion pathways but also alleviate volume expansion . Although a variety of nanostructured α‐Fe 2 O 3 including nanorods, nanowires, nanotubes, nanosheets, nanospheres, and nanoparticles are widely verified to overcome the aforementioned issues in the past decades, the conventional physical/chemical synthetic methods extensively involve complex chemical reactions, high hazardous and expansive reagents, and high energy and time consumption, which is a huge challenge for the large‐scale application of nanostructured α‐Fe 2 O 3 anodes in LIBs.…”