The sodium storage mechanism of hard carbon, optimization strategies of electrochemical performance, and the scientific challenges towards the commercialization of sodium-ion batteries were systematically summarized and analyzed.
Capacity fading induced by unstable surface chemical properties and intrinsic structural degradation is a critical challenge for the commercial utilization of Ni-rich cathodes. Here, a highly stabilized Ni-rich cathode with enhanced rate capability and cycling life is constructed by coating the molybdenum compound on the surface of LiNi 0.815 Co 0.15 Al 0.035 O 2 secondary particles. The infused Mo ions in the boundaries not only induce the Li 2 MoO 4 layer in the outermost but also form an epitaxially grown outer surface region with a NiO-like phase and an enriched content of Mo 6+ on the bulk phase. The Li 2 MoO 4 layer is expected to reduce residential lithium species and promote the Li + transfer kinetics. The transition NiO-like phase, as a pillaring layer, could maintain the integrity of the crystal structure. With the suppressed electrolyte−cathode interfacial side reactions, structure degradation, and intergranular cracking, the modified cathode with 1% Mo exhibits a superior discharge capacity of 140 mAh g −1 at 10 C, a superior cycling performance with a capacity retention of 95.7% at 5 C after 250 cycles, and a high thermal stability.
A Mn-based NASICON-type Na 4 VMn(PO 4 ) 3 cathode is considered to be one of the most promising substitutions for Na 3 V 2 (PO 4 ) 3 due to the huge abundance and appropriate redox potential from Mn. However, the current Na 4 VMn(PO 4 ) 3 /C cathode still delivers a limited electrochemical performance due to the sluggish kinetics and negative structural degradation caused by the Mn in the structure. Herein, a selective replacement of vanadium rather than manganese in the Na 4 VMn(PO 4 ) 3 system was developed to fully utilize the manganese element and enhance the structural stability. Both experimental and calculation results affirmed that the Al-substituted Na 4 V 0.8 Al 0.2 Mn(PO 4 ) 3 cathode shows favorable Na + kinetics and structure stability. The resulting Na 4 V 0.8 Al 0.2 Mn(PO 4 ) 3 reveals a discharge capacity of ∼84 mA h g −1 at 40 C and renders a capacity retention of 92% after cycling 1000 times at 5 C. Inspired by the availability of Al dopants, we also demonstrated the Al-doped Mn-richer Na 4.2 V 0.6 Al 0.2 Mn 1.2 (PO 4 ) 3 to be a viable candidate for Mn-rich phosphate cathodes.
great significance to develop electrochemical energy-storage technique and take advantage of sustainable and renewable energy. [1][2][3][4][5][6][7] Owing to natural abundance, wide availability, and low cost of sodium resources, sodium-ion batteries (SIBs) have been considered as one of most fascinating alternatives to the well-commercialized lithium-ion batteries for future large-scale stationary energy-storage systems with high adaptability and energy efficiency. [8][9][10][11][12][13] To develop satisfactory electrode materials in the future development of SIBs, continued research efforts have been devoted to screen new cathodes over the past few years. [14][15][16][17][18][19] Among a wide variety of cathode candidates including layered oxides, polyanion compounds, and Prussian blue analogues, layered oxide cathode materials have received significant attention because of the high voltage, low cost, and simple synthesis. Recently, research has made dramatic progress especially on manganese-based layered oxides such as zinc-doped Na 0.833 [Li 0.25 Mn 0.75 ]O 2 , Na 0.7 Mg 0.05 [Mn 0.6 Ni 0.2 Mg 0.15 ]O 2 , and Na 2.3 Cu 1.1 Mn 2 O 7−δ , which open new opportunities for developing high-performance cathode materials. [20][21][22][23][24] However, typical P2-type Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode material As one of the most promising cathode candidates for room-temperature sodium-ion batteries (SIBs), P2-type layered oxides face the challenge of simultaneously realizing high-rate performance while achieving long cycle life. Here, a stable Na 2/3 Ni 1/6 Mn 2/3 Cu 1/9 Mg 1/18 O 2 cathode material is proposed that consists of multiple-layer oriented stacking nanoflakes, in which the nickel sites are partially substituted by copper and magnesium, a characteristic of the material that is confirmed by multiscale scanning transmission electron microscopy and electron energy loss spectroscopy techniques. Owing to the optimal morphology structure modulation and chemical element substitution strategy, the electrode displays remarkable rate performance (73% capacity retention at 30C compared to 0.5C) and outstanding cycling stability in Na half-cell system couple with unprecedented full battery performance. The underlying thermal stability, phase stability, and Na + storage mechanisms are clearly elucidated through the systematical characterizations of electrochemical behaviors, in situ X-ray diffraction at different temperatures, and operando X-ray diffraction upon Na + deintercalation/intercalation. Surprisingly, a quasi-solid-solution reaction is switched to an absolute solid-solution reaction and a capacitive Na + storage mechanism is demonstrated via quantitative electrochemical kinetics calculation during charge/discharge process. Such a simple and effective strategy might reveal a new avenue into the rational design of excellent rate capability and long cycle stability cathode materials for practical SIBs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.