The capacity of transition metal oxide cathode for Li‐ion batteries can be further enhanced by increasing the charging potential. However, these high voltage cathodes suffer from fast capacity decay ...because the large volume change of cathode breaks the active materials and cathode‐electrolyte interphase (CEI), resulting in electrolyte penetration into broken active materials and continuous side reactions between cathode and electrolytes. Herein, a robust LiF‐rich CEI was formed by potentiostatic reduction of fluorinated electrolyte at a low potential of 1.7 V. By taking LiCoO2 as a model cathode, we demonstrate that the LiF‐rich CEI maintains the structural integrity and suppresses electrolyte penetration at a high cut‐off potential of 4.6 V. The LiCoO2 with LiF‐rich CEI exhibited a capacity of 198 mAh g−1 at 0.5C and an enhanced capacity retention of 63.5 % over 400 cycles as compared to the LiF‐free LiCoO2 with only 17.4 % of capacity retention.
A robust LiF‐rich cathode‐electrolyte interphase (CEI) is successfully constructed on LiCoO2 cathode by potentiostatic reduction of fluorinated electrolyte at 1.7 V. LiF‐rich CEI maintains the structural integrity and suppresses electrolyte penetration and Co dissolution during cycling at a high cut‐off voltage of 4.6 V, demonstrating an excellent cyclability with high capacity retention of 63.5 % over 400 cycles at 0.5C.
Design strategy for high-performance bifunctional electrode materials with a multilevel structure formed by hydrothermal sulfur etching.
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The synthesis of efficient, stable, and green ...multifunctional electrode materials is a long-standing challenge for modern society in the field of energy storage and conversion. To this end, we successfully synthesized five bimetallic precursor materials with excellent performance by hydrothermal reaction with the assistance of a high concentration of polyvinylpyrrolidone (PVP), and then, sulfide etched the lamellar precursor materials among them to obtain the one-dimensional heterostructured samples. Benefiting from the synergistic effect of the bimetal and the continuous electron/ion transport structure, the samples displayed excellent bifunctional activity in supercapacitor and oxygen evolution reaction (OER). Regarding supercapacitors, the exceptional performance of 2817.2 F g−1 at 1 A g−1 was demonstrated, while the asymmetric supercapacitors made showed an extraordinary energy density of 150.2 Wh kg−1 at a power density of 618.5 W kg−1 and outstanding cycling performance (94.74% capacity retention after 20,000 cycles at 10 A g−1). Simultaneously, a wearable flexible electrode that can be wrapped around a finger was coated on a carbon cloth and was found to light up a 0.5-m-long strip of light. Moreover, it exhibited an ultralow oxygen reduction overpotential of 249 mV at 10 mA cm−2. Hence, our work provides a facile strategy to modulate the synthesis of heterogeneous structured sulfides with a continuous electron/ion transport pathway, which possesses excellent oxygen reduction electrocatalytic performance while meeting superior supercapacitor performance. Such work provides an effective approach for the construction of multifunctional electrochemical energy materials.
•Examined the performance of an ammonia EC compressor stack under steady state.•Back diffusion of ammonia reduced the flow rate of the effluent fluid by up to 67%.•A maximum observed isentropic ...efficiency was 40%.•Compressing the working fluid over several stages is recommended.
Electrochemical (EC) energy conversion has a critical role to play in the future of clean energy. As the world transitions away from fossil fuel energy sources, EC compression emerges as a promising technique for energy storage, specifically energy stored in the form of pressurized ammonia. The present study examines the performance of an ammonia EC compressor stack under steady-state operating conditions to demonstrate the technology's utility in such applications. Using hydrogen as a carrier gas, we examined the effect of pressure and current on the operation of an EC ammonia compressor stack. We found the total voltage increased significantly with increasing current but increased marginally with increasing pressure. We measured the flow rate leaving the cell and analyzed the composition of the effluent gas stream with gas chromatography. While the device provided useful compression work in all observed cases, back diffusion of ammonia hampered the performance, reducing the flow rate of the effluent fluid by as much as 67%. The maximum observed single-cell efficiency was 40% with respect to ideal isentropic compression. The ohmic losses associated with high current and the back diffusion effect are likely responsible for the low cell efficiency.
Aqueous Zn batteries promise high energy density but suffer from Zn dendritic growth and poor low‐temperature performance. Here, we overcome both challenges by using an eutectic 7.6 m ZnCl2 aqueous ...electrolyte with 0.05 m SnCl2 additive, which in situ forms a zincophilic/zincophobic Sn/Zn5(OH)8Cl2⋅H2O bilayer interphase and enables low temperature operation. Zincophilic Sn decreases Zn plating/stripping overpotential and promotes uniform Zn plating, while zincophobic Zn5(OH)8Cl2⋅H2O top‐layer suppresses Zn dendrite growth. The eutectic electrolyte has a high ionic conductivity of ≈0.8 mS cm−1 even at −70 °C due to the distortion of hydrogen bond network by solvated Zn2+ and Cl−. The eutectic electrolyte enables Zn∥Ti half‐cell a high Coulombic efficiency (CE) of >99.7 % for 200 cycles and Zn∥Zn cell steady charge/discharge for 500 h with a low overpotential of 8 mV at 3 mA cm−2. Practically, Zn∥VOPO4 batteries maintain >95 % capacity with a CE of >99.9 % for 200 cycles at −50 °C, and retain ≈30 % capacity at −70 °C of that at 20 °C.
A highly reversible Zn anode working at low temperature is achieved by introducing SnCl2 into eutectic ZnCl2 aqueous electrolyte to form a zincophilic–zincophobic interfacial layer on the Zn anode in situ. The bottom layer of Sn facilitates uniform Zn deposition, while the top layer of zincophobic Zn5(OH)8Cl2 H2O facilitates Zn2+ diffusion and avoids Zn dendrites. The eutectic composition enhances the low temperature conductivity.
Water electrolysis is one of the most promising green hydrogen production technologies. However, using precious metal materials as electrodes for these electrolyzers incurs high costs. To address ...these challenges and simultaneously retain the catalytic activity of precious metals, we synthesize a low-iridium catalyst, Nd–IrO2. At 10 and -10 mA/cm2, this catalyst exhibits 233 and 36 mV overpotentials. Nd–IrO2 maintains stability over prolonged operation in acidic environments, as evidenced by its consistent overpotential. Advanced calculations using density functional theory (DFT) have demonstrated that incorporating Nd and an ample amount of oxygen vacancies can modulate the d-band center of Ir and reduce the adsorption energy of electrochemical reaction intermediates. In summary, we present the synthesis of a low-iridium catalyst, which provides valuable insights for the design and development of catalysts with improved electrocatalytic performance.
•Simple and efficient hydrothermal reaction combined with low temperature annealing.•Abundant oxygen vacancy improves electrochemical performance.•Reduce precious metal costs and improve electrocatalytic performance.
Owing to the advantages of high safety, low cost, high theoretical volumetric capacities, and environmental friendliness, magnesium‐ion batteries (MIBs) have more feasibility for large‐scale energy ...storage compared to lithium‐ion batteries. However, lack of suitable cathode materials due to sluggish kinetics of magnesium ion is one of the biggest challenges. Herein, water‐pillared sodium vanadium bronze nanowires (Na2V6O16·1.63H2O) are reported as cathode material for MIBs, which display high performance in magnesium storage. The hydrated sodium ions provide excellent structural stability. The charge shielding effect of lattice water enables fast Mg2+ diffusion. It exhibits high specific capacity of 175 mAh g−1, long cycle life (450 cycles), and high coulombic efficiency (≈100%). At high current density of 200 mA g−1, the capacity retention is up to 71% even after 450 cycles (compared to the highest capacity), demonstrating excellent long‐term cycling performance. The nature of charge storage kinetics is explored. Furthermore, a highly reversible structure change during the electrochemical process is proved by comprehensive electrochemical analysis. The remarkable electrochemical performance makes Na2V6O16·1.63H2O a promising cathode material for low‐cost and safe MIBs.
Magnesium‐ion batteries with high safety, low cost, and high volumetric capacity have been extensively investigated. However, lack of suitable cathode is the biggest challenge. Here, water‐pillared layered Na2V6O16·1.63H2O nanowires are reported, which show great electrochemical performance and reversibility of Mg2+ insertion. This work aims at bringing new insights to develop Mg battery cathodes for large‐scale energy storage.
Catalysts for zinc-air batteries (ZABs) must be stable over long-term charging-discharging cycles and exhibit bifunctional catalytic activity. In this study, by doping nitrogen-doped carbon (NC) ...materials with three metal atoms (Fe, Ni, and Cu), a single-atom-distributed FeNiCu-NC bifunctional catalyst is prepared. The catalyst includes Fe(Ni-doped)-N
for the oxygen evolution reaction (OER), Fe(Cu-doped)-N
for the oxygen reduction reaction (ORR), and the NiCu-NC catalytic structure for the oxygen reduction reaction (ORR) in the nitrogen-doped carbon nanoparticles. This single-atom distribution catalyst structure enhances the bifunctional catalytic activity. If a trimetallic single-atom catalyst is designed, it will surpass the typical bimetallic single-atom catcalyst. FeNiCu-NC exhibits outstanding performance as an electrocatalyst, with a half-wave potential (E
) of 0.876 V versus RHE, overpotential (E
) of 253 mV versus RHE at 10 mA cm
, and a small potential gap (ΔE = 0.61 V). As the anode in a ZAB, FeNiCu-NC can undergo continuous charge-discharged cycles for 575 h without significant attenuation. This study presents a new method for achieving high-performance, low-cost ZABs via trimetallic single-atom doping.
•The excellent tolerance to SO2 and ORR activity of the PtFe@FeNC/C-10 catalyst was verified.•The introduction of Fe negatively shifts the 4f7/2 binding energy of Pt by 0.2 eV, weakening the ...adsorption strength of Pt for O2.•This dual protection mechanism, involving steric hindrance and electronic effects, ensures excellent resistance to sulfur dioxide.•This stability advantage benefits from the protective carbon shell, inhibiting the dissolution and agglomeration of Pt nanoparticles.
SO2, one of the considerable air pollutants, exhibits a stronger binding affinity with Pt when compared to O2, thereby inducing irreversible degradation of the Oxygen Reduction Reaction (ORR) catalyzed by Pt-based catalysts. Despite this detrimental phenomenon, scarce investigations have delved into the realm of contaminant-tolerant catalysts, and so far, no effective SO2-tolerant catalysts have been proposed. To meet this challenge, we designed and synthesized a core–shell structure catalyst equipped with a dual protection mechanism. This was achieved through the in-situ polymerization of aniline monomers, concomitantly reducing Pt2+. The resulting shell effectively hinders the transmission of SO2 to the active sites of Pt, while permitting the unimpeded transmission of O2. Simultaneously, the intermetallic core inhibits the adsorption of SO2. Therefore, this catalyst exhibits exemplary ORR activity coupled with exceptional resistance to SO2 resistance. In particular, the PtFe@FeNC/C-10 catalyst, optimized in terms of the quantity of added aniline, demonstrates a mass activity 1.84 times greater and a specific activity 4.03 times higher than that of commercial Pt/C catalysts. Following exposure to SO2-induced poisoning, the E1/2 value of the PtFe@FeNC/C-10 catalyst undergoes a decrease of only 51.7 mV, lower than that observed for the commercial Pt/C catalyst (92.0 mV). Moreover, the results of an accelerated durability test affirm the superior stability of PtFe@FeNC/C-10 in comparison to commercial Pt/C. This stability advantage is attributed to the protective carbon shell, which effectively prevents the detachment and agglomeration of Pt nanoparticles.
High performance and excellent durability are essential for the practical application of solid oxide electrolysis cell (SOEC). Here we have demonstrated efficient and durable solid oxide steam ...electrolysis by constructing active La0.8Sr0.2CoO3-δ/Gd0.2Ce0.8O2-δ (LSC/GDC) heterointerface in air electrode using a simple co-impregnation method. The heterostructured air electrode exhibits the outstanding activity for oxygen evolution reaction, and its exchange current density (557 mA cm−2) is 69 times higher than that of the traditional LSM-YSZ. The resulting cell reaches −1.86 A cm−2 @1.3 V and −2.30 A cm−2 @1.5 V at 800 °C and 50% absolute humidity (A.H), and the polarization resistance from the oxygen electrode only is 0.02 Ω cm2. Most importantly, the heterostructured cell presents excellent long-term stability for the 1035 h steam electrolysis operation and excellent durability for 100 times charge-discharge cycles. In the heterostructured air electrode, the problem of electrode delamination is avoided due to the reduced oxygen partial pressure at anode/electrolyte resulting from easy diffusion of O2− at the interphase, and the coarsening of LSC and GDC nanoparticles is limited because of the LSC/GDC percolative interfaces from phase segregation process. This work proposes a simple and effective strategy to design heterointerface for efficient and durable solid oxide steam electrolysis.
•Heterostructured La0.8Sr0.2CoO3-δ/Gd0.2Ce0.8O1.9 air electrode is developed using a simple co-impregnation method.•The heterostructured cell reaches −1.86 A cm−2 @1.3 V and −2.30 A cm−2 @1.5 V under 50% absolute humidity.•The heterostructured cell shows an excellent durability during 1035 h steam electrolysis operation.•OER mechanism on the heterostructured La0.8Sr0.2CoO3-δ/Gd0.2Ce0.8O1.9 electrode is analyzed.•The stabilization mechanism of the heterostructured electrode is proposed.
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