RESUMEN
An innovative method to improve the oxidation efficiency of benzyl alcohol utilizes Ni-Co hexacyanoferrate hollow nanoprisms. Synthesized via a gentle self-sacrificial template method, this catalyst exhibits substantial catalytic activity and selectivity towards benzyl alcohol oxidation, facilitated by the strategic incorporation of Co to modulate CN vacancy density. Impressively, it achieves a current density of 10 mA cm-2 at 1.33 V and a remarkable 98% efficiency in benzyl alcohol conversion at 1.4 V.
RESUMEN
Boron doping significantly reduces the Li/Ni cation mixing of LiNi0.8Co0.1Mn0.1O2, decreases the charge transfer resistance, and improves the reversibility of the H2-H3 phase transition at 4.2 V. Among similar materials, the cathode material with 1.0 mol% boron doping shows excellent cycling performance, with capacity retention of 96% after 200 cycles at 50 °C.
RESUMEN
High-capacity O3-type layered sodium oxides are considered one of the most promising cathode materials for the next generation of Na-ion batteries (NIBs). However, these cathodes usually suffer from low high-rate capacity and poor cycling stability due to structure deformation, native air sensitivity, and interfacial side reactions. Herein, a multi-site substituted strategy is employed to enhance the stability of O3-type NaNi0.5 Mn0.5 O2 . Simulations indicate that the Ti substitution decreases the charge density of Ni ions and improves the antioxidative capability of the material. In addition, the synergistic effect of K+ and Ti4+ significantly reduces the formation energy of Na+ vacancy and delivers an ultra-low lattice strain during the repeated Na+ extraction/insertion. In situ characterizations verify that the complicated phase transformation is mitigated during the charge/discharge process, resulting in greatly improved structure stability. The co-substituted cathode delivers a high-rate capacity of 97 mAh g-1 at 5 C and excellent capacity retention of 81% after 400 cycles at 0.5 C. The full cell paired with commercial hard carbon anode also exhibits high capacity and long cycling life. This dual-ion substitution strategy will provide a universal approach for the new rational design of high-capacity cathode materials for NIBs.
RESUMEN
Sodium ion batteries (SIBs) attract most of the attention as alterative secondary battery systems for future large-scale energy storage and power batteries due to abundance resource and low cost. However, the lack of anode materials with high-rate performance and high cycling-stability has limited the commercial application of SIBs. In this paper, Cu7.2S4@N, S co-doped carbon (Cu7.2S4@NSC) honeycomb-like composite structure was designed and prepared by a one-step high-temperature chemical blowing process. As an anode material for SIBs, Cu7.2S4@NSC electrode exhibited an ultra-high initial Coulomb efficiency (94.9%) and an excellent electrochemical property including a high reversible capacity of 441.3 mAh g-1 after 100 cycles at 0.2 A g-1, an excellent rate performance of 380.4 mAh g-1 even at 5 A g-1, and a superior long-cycle stability with a capacity retention rate of approximately 100% after 700 cycles at 1A g-1.
RESUMEN
Ammonium phosphate ((NH4)3PO4) has been first used as a surface treatment reagent for Li-rich cathode materials. Compared to the conventional surface treatment, the samples treated with (NH4)3PO4 exhibit an ultra-high initial Coulomb efficiency of 98.0% and excellent cycling stability. This is mainly attributed to the simultaneous construction of surface integrated structures, including oxygen vacancies, spinel phases, and Li3PO4 coating. This study demonstrates the effectiveness of ammonium phosphate surface treatment and provides a new idea for designing other cathode materials.
RESUMEN
Considering the abundance of iron and manganese within the Earth's crust, the cathode O3-NaFe0.5Mn0.5O2 has shown great potential for large-scale energy storage. Following the strategy of introducing specific heteroelements to optimize the structural stability for energy storage, the work has obtained an O3-type NaFe0.4Mn0.49Cu0.1Zr0.01O2 that exhibits enhanced electrochemical performance and air stability. It displays an initial reversible capacity of 147.5 mAh g-1 at 0.1C between 2 and 4.1 V, a capacity retention ratio exceeding 69.6% after 100 cycles at 0.2C, and a discharge capacity of 70.8 mAh g-1 at a high rate of 5C, which is superior to that of O3-NaFe0.5Mn0.5O2. The codoping of Cu/Zr reserves the layered O3 structure and enlarges the interlayer spacing, promoting the diffusion of Na+. In addition, the structural stability and air stability observed by Cu-doping is well maintained via the incorporation of extra Zr favoring a highly reversible phase conversion process. Thus, this work has demonstrated an efficient strategy for developing cobalt/nickel-free high-capacity and air-stable cathodes for sodium-ion batteries.
RESUMEN
Tremendous effort has been devoted to develop durable electrode materials for sodium ion batteries. This work focuses on enhancing the reversibility of a cathode material Na0.5Ni0.25Mn0.75O2 by adopting the titanium cation doping strategy. The obtained P2-Na0.5Ni0.25Mn0.60Ti0.15O2 material shows smooth charge-discharge curves upon suppressing the Na+/vacancy ordering effect via the partial substitution of Mn4+ for Ti4+, and enhanced cycling performance. It exhibits a reversible capacity of 138 mA h g-1 at 0.5C, as well as a high rate capacity of 81 mA h g-1 at 5C between a cut-off voltage of 2 and 4 V, while long-term cycling stability is demonstrated with a capacity retention of 84% over 200 cycles. An enhanced cycling stability is also observed when the voltage is between 2 and 4.2 V. The feasibility of constructing a symmetrical Na-ion full cell with Na0.5Ni0.25Mn0.60Ti0.15O2 as cathode and anode electrodes is also demonstrated. The titanium cation doping results in reduced charge transfer impedance and an enhanced sodium cation diffusion coefficient, thus suggesting an efficient strategy to obtain a durable cathode material for sodium ion batteries.
RESUMEN
Sodium-ion batteries (SIBs) are recognized as attractive alternatives for grid-scale electrochemical energy storage applications. Transition metal oxide cathodes represent one of the most dynamic materials for industrialization among the various cathodes for SIBs. Here, a cation-doped cathode Na0.44Mn0.89Ti0.11O2 with a tunnel structure is introduced, which undergoes a lowered volume change of only 5.26% during the Na+ insertion/extraction process. Moreover, the average Na+ diffusion coefficients are enhanced by more than 3-fold upon the doping of the Ti cation. The obtained cathode delivers a practically usable capacity of 119 mAh g-1 at 0.1 C as well as an enhanced discharge capacity of 96 mAh g-1 at 5 C. Durability is demonstrated by the retained 71 mAh g-1 after 1000 cycles, corresponding to a capacity retention of 74%. This work demonstrates that the reticular Na0.44Mn0.89Ti0.11O2 is a promising ultrastable cathode material for the development of long-life sodium-ion batteries.
RESUMEN
The development of suitable cathode materials for sodium-ion batteries is the key issue to realize their large-scale applications owing to the lack of appropriate materials with adequate electrochemical capacity and reversibility for Na-ion insertion reaction. Here, a string of nickel hexacyanoferrate (NiHCF) nanocubes is coaxially grown on a CNT@bipolar conducting polymer (BCP) by a facile electrochemical route, and used as a high-performance cathode material for sodium-ion batteries. The obtained cathode shows a surprisingly high specific capacity of 194 mA h g-1 upon the initial discharge, a good cycling performance and excellent rate performance. It is considered that the unique nanostructure not only effectively facilitates the electrode/electrolyte interaction and the electronic and ionic transportation but also exerts a synergistic effect between the BCP and NiHCF nanocubes to trigger the kinetics of the electron and ion transport. It is expected that such a promising environmentally friendly alternative cathode material can be widely applied for sodium-ion batteries (SIBs).
