Robust Cathode Research Articles

Edge-Site-Free and Topological-Defect-Rich Carbon Cathode for High-Performance Lithium-Oxygen Batteries.

The rational design of a stable and catalytic carbon cathode is crucial for the development of rechargeable lithium-oxygen (LiO2 ) batteries. An edge-site-free and topological-defect-rich graphene-based material is proposed as a pure carbon cathode that drastically improves LiO2 battery performance, even in the absence of extra catalysts and mediators. The proposed graphene-based material is synthesized using the advanced template technique coupled with high-temperature annealing at 1800°C. The material possesses an edge-site-free framework and mesoporosity, which is crucial to achieve excellent electrochemical stability and an ultra-large capacity (>6700 mAh g-1 ). Moreover, both experimental and theoretical structural characterization demonstrates the presence of a significant number of topological defects, which are non-hexagonal carbon rings in the graphene framework. In situ isotopic electrochemical mass spectrometry and theoretical calculations reveal the unique catalysis of topological defects in the formation of amorphous Li2 O2 , which may be decomposed at low potential (∼ 3.6V versus Li/Li+ ) and leads to improved cycle performance. Furthermore, a flexible electrode sheet that excludes organic binders exhibits an extremely long lifetime of up to 307 cycles (>1535h), in the absence of solid or soluble catalysts. These findings may be used to design robust carbon cathodes for LiO2 batteries.

Flower-like K1+δVOPO4F crystallite with a layered framework structure as a robust cathode for potassium-ion batteries

Flower-like K1+δVOPO4F crystallite with a layered framework structure as a robust cathode for potassium-ion batteries

Field emission cathodes made from knitted carbon nanotube fiber fabrics

Field electron emission cathodes were constructed from knitted fabrics comprised entirely of carbon nanotube (CNT) fibers. The fabrics consisted of a top layer array of ∼2 mm high looped structures and a bottom layer that was 1 mm thick with a flat underlying surface. Field emission (FE) experiments were performed on 25.4 mm diameter CNT fabric cathodes in both direct current (DC) and pulsed voltage (PV) modes, and the results were compared to those obtained from a CNT film cathode. The DC measurements were performed at a maximum voltage of 1.5 kV. The CNT fabric cathode emitted 20 mA, which was an 8× increase over the emission current from the CNT film cathode. The DC results were analyzed using the corrected form of the Fowler–Nordheim FE theory initially developed by Murphy and Good, which allows for the determination of the formal emission area and effective gap-field enhancement factor. The PV experiments resulted in Ampere level emission currents from both CNT fabric and CNT film cathodes. For a 25 kV, 500 ns voltage pulse, the CNT fabric cathode emitted 4 A, which was 2× more current than the CNT film cathode. Scanning electron microscopy imaging after PV testing revealed that the fibers remained intact after >5000 pulses. These results indicate that knitted CNT fabrics offer a promising approach for developing large area, conformable, robust FE cathodes for vacuum electronic devices.

Mn-Fe Prussian blue analogue as low-cost robust cathode for non-aqueous Zn-ion batteries

Mn-Fe Prussian blue analogue as low-cost robust cathode for non-aqueous Zn-ion batteries

Tailoring solvation chemistry in carbonate electrolytes for all-climate, high-voltage lithium-rich batteries

High-voltage Li-rich layered oxide materials (LLOs) are considered as the promising next-generation cathode materials because of their high energy density and low cost. However, their electrochemical performance continues to deteriorate under high voltages when using traditional lithium hexafluorophosphate (LiPF6)-based carbonate electrolytes, mostly due to the detrimental reactions with free anions, unstable electrode interface and limited Li+ kinetic process. Here, we demonstrate a highly oxidation-resistant carbonate electrolyte by incorporating multifunctional lithium difluoro(oxalato)borate (LiDFOB) and Tris(trimethylsilyl) Phosphite (TMSPi) additives. It is discovered that the introduction of LiDFOB and TMSPi can manipulate the electrolyte solvation structure by reducing the number of coordinated solvent molecules and free PF6−anions at the electrolyte-electrode interface, thus promoting the desolvation process of Li+, suppressing the generation of harmful HF species and conducive to forming a thin and robust cathode electrolyte interphase (CEI) layer. As a result, the Li||LLO cells with dual additives show excellent cycle stability and improved rate capability in a wide temperature ranged from -20 °C to 55 °C, and the retention rate of LLO||graphite pouch cell (2.5 Ah) using EEDB-TMSPi electrolyte is up to 91.1% after 200 cycles. It is anticipated that the work provides a promising strategy for realizing long-cycle stability of layered cathode materials under high-voltage and wide-temperature conditions.

Highly adaptable SEI/CEI interfacial layers enabling remarkable performance of high-nickel solid-state batteries

Designing a robust cathode electrolyte interphase (CEI) on a high-voltage cathode and stable solid electrolyte interphase (SEI) on a Li anode is the key to success in developing solid-state Li metal batteries (SSLMBs). In this work, we design an inorganic compound-intensive CEI layer and a LiF-rich gradient SEI layer in SSLMBs through the in-situ polymerization of a novel multi-functional electrolyte. The inorganic compound-intensive CEI offers excellent electrochemical compatibility with high-voltage layered cathode LiNi0.8Co0.1Mn0.1O2 (NCM), while the LiF-rich gradient SEI successfully suppresses Li dendrite formation and harmful interfacial parasite reactions. As a result, SSLMBs present a remarkable rate performance of 182 mAh g−1 at 1 C and a long cycling stability of 88.6% capacity retention after 300 cycles at room temperature. The fundamental insights into interface chemistry and facile strategy demonstrated in this work could assist the rapid development of SSLMBs toward remarkable performance.

Non-polar ether-based electrolyte solutions for stable high-voltage non-aqueous lithium metal batteries

The electrochemical instability of ether-based electrolyte solutions hinders their practical applications in high-voltage Li metal batteries. To circumvent this issue, here, we propose a dilution strategy to lose the Li+/solvent interaction and use the dilute non-aqueous electrolyte solution in high-voltage lithium metal batteries. We demonstrate that in a non-polar dipropyl ether (DPE)-based electrolyte solution with lithium bis(fluorosulfonyl) imide salt, the decomposition order of solvated species can be adjusted to promote the Li+/salt-derived anion clusters decomposition over free ether solvent molecules. This selective mechanism favors the formation of a robust cathode electrolyte interphase (CEI) and a solvent-deficient electric double-layer structure at the positive electrode interface. When the DPE-based electrolyte is tested in combination with a Li metal negative electrode (50 μm thick) and a LiNi0.8Co0.1Mn0.1O2-based positive electrode (3.3 mAh/cm2) in pouch cell configuration at 25 °C, a specific discharge capacity retention of about 74% after 150 cycles (0.33 and 1 mA/cm2 charge and discharge, respectively) is obtained.

High-Voltage Cyclic Ether-Based Electrolytes for Low-Temperature Sodium-Ion Batteries.

Cyclic ethers are promising solvents for low-temperature electrolytes, but they still suffer from intrinsic poor antioxidant abilities. Until now, ether-based electrolytes have been rarely reported for high-voltage sodium-ion batteries (SIBs) operated under a low-temperature range. Herein, a novel ether-based electrolyte consisting of tetrahydrofuran as the main solvent is proposed and it could be utilized for a high-voltage Na2/3Mn2/3Ni1/3O2 (MN) cathode in a wide-temperature range from -40 to 25 °C. Meanwhile, a thin and robust inorganic component-rich cathode electrolyte interface layer is elaborately introduced on the MN cathode by this tailored electrolyte, resulting in excellent cycle life of MN cathode. Specifically, a capacity retention of 97.2% after 140 cycles could be delivered by MN at 0.3 C at room temperature (RT). Especially at an ultra-low temperature of -40 °C, the initial discharge capacity of MN could still approach 89.3% of that at RT, and the capacity retention is 94.1% at 0.2 C after 100 cycles. This work provides a new insight into the rational design of ether-based electrolytes for high-voltage and stable SIBs operated in a wide-temperature range.

Insights into the enhanced performance of NiCo-LDH modified Pd/NF cathode for electrocatalytic hydrodechlorination

To obtain an electrocatalytic hydrodechlorination (ECH) cathode with low noble metal content, low energy consumption and high catalytic activity, a novel electrode that arming Pd with NiCo-layered double hydroxide (Pd/NiCo-LDH/NF) was prepared. The Pd/NiCo-LDH/NF electrode shows excellent ECH activity, having a mass activity of 32.80 min−1 gPd−1 for dechlorination of 2,4-dichlorophenol (2,4-DCP), which is 5 ∼ 10 times higher than other reports on ECH cathodes. The higher ECH activity is due to the synergistic effect between NiCo-LDH interlayer and Pd2+. The influence of preparation parameters on morphology, composition, conductivity and hydrogen evolution performance of the NiCo-LDH was investigated by means of scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectrometer, cyclic voltammetry, electrochemical impedance spectroscopy, and linear scanning voltammetry. Density functional theory (DFT) analysis results showed that the NiCo-LDH containing OH− vacancies enhanced the generation of Hads*, weakened the toxicity of phenol to the electrode, and improved the ECH activity of the electrode. This work designed a robust electrocatalytic cathode with low energy consumption, low cost and high efficiency for the ECH of chlorinated phenols.

Long-Lasting Ni-Rich NCMA Cathodes via Simultaneous Microstructural Refinement and Surface Modification

Li[Ni1–x–y–zCoxMnyAlz]O2 (NCMA) cathodes have attracted public attention owing to their improved durability by leveraging the advantages of NCM and NCA cathodes. As the Ni content approaches 90%, however, it is challenging to realize high-energy Ni-rich NCMA cathodes without sacrificing durability. Herein, we improve the cycling stability of a Ni-rich Li[Ni0.93Co0.03Mn0.03Al0.01]O2 (NCMA93) cathode using a combination strategy involving microstructural refinement and surface modification. The F-coating-induced protective layer of the F-coated, Sb-doped NCMA93 cathode combined with its engineered microstructure enables the formation of a robust cathode–electrolyte interphase (CEI) layer on the cathode surface, which suppresses surface degradation to afford a long battery life. However, the F coating alone does not significantly improve the cycling stability of cathode because it suffers severe microcracking during cycling owing to its suboptimal microstructure. To realize a cathode with a long lifespan, a robust CEI layer should be generated and maintained on the cathode without severe microcracking.

Boosting Li-O2 Battery Performance via Coupling of P-N Site-Rich N, P Co-Doped Graphene-Like Carbon Nanosheets with Nano-CePO4.

Development of efficient and robust cathode catalysts is critical for the commercialization of Li-O2 batteries (LOBs). Herein, a well-designed CePO4 @N-P-CNSs cathode catalyst for LOBs via coupling P-N site-rich N, P co-doped graphene-like carbon nanosheets (N-P-CNSs) with nano-CePO4 via a novel "in situ derivation" coupling strategy by in situ transforming the P atoms of P-C sites in N-P-CNSs to CePO4 is reported. The CePO4 @N-P-CNSs exhibit superior bifunctional ORR/OER activity relative to commercial Pt/C-RuO2 with an overall overpotential of 0.64V (vs RHE). Moreover, the LOB with CePO4 @N-P-CNSs as the cathode catalyst delivers a low charge overpotential of 0.67V (vs Li/Li+ ), high discharge capacity of 29774 mAh g-1 at 100mA g-1 and long cycling stability of 415 cycles, respectively. The remarkably enhanced LOB performance is attributable to the in situ derived CePO4 nanoparticles and the P-N sites in N-P-CNSs, which facilitate increased bifunctional ORR/OER activity, promote the rapid and effective decomposition of Li2 O2 and inhibit the formation of Li2 CO3 . This work may provide new inspiration for designing efficient, durable, and cost-effective cathode catalysts for LOBs.

High-entropy hexacyanoferrates as robust cathode active materials for sodium storage

In a recent study published in <i>Advanced Functional Materials</i>, Ma and colleagues reported a high-entropy Mn-based hexacyanoferrate of composition Na_x(MnFeNiCuCo)[Fe(CN)₆] for reversible sodium storage, showing improved performance over lower configurational entropy cathode counterparts. Systematic comparisons of the properties of high-, medium-, and low-entropy hexacyanoferrates helped to identify the origin of the enhanced cyclability: entropy-mediated suppression of phase transitions.

Manganese ion batteries: LiV3O8 nanorods as a robust and long-life cathode module

Aqueous rechargeable batteries (ARBs) are the most dependable energy storage devices (ESDs) due to their tremendous safety and cost-efficiency. The recent invention of the usage of extremely cheaper and high-capacity metallic Mn to construct aqueous manganese ion batteries (AMIBs) shows great promise for the eco-friendly society. However, AMIBs are still in the early stages and their practical utilities need significant achievements on the Mn2+ storing modules. This study demonstrates the competence of a layered-type LiV3O8 (LVO) as cathode material for AMIBs and its reversible electrochemical storage properties of Mn2+ ions. The preliminary electrochemical results (65 mAh g−1 at 5 A g−1 with 88% capacity retention after 9990 cycles and 45 mAh g−1 at 6 A g−1 with 85% capacity retention after 30,000 cycles) are highly encouraging that the layered type materials are the first-choice cathode for AMIBs.

Wet-chemical assisted synthesis of MnSe/ZnO nanostructures as low-resistance robust novel cathode material for advanced hybrid supercapacitors

We proposed a novel MnSe–ZnO-based binary nanocomposite synthesized via a wet-chemical assisted method which deliver high power and energy densities, suppressing previous reports on MnSe and ZnO with decent cycling durability with good rate performance.

A robust and thickness-insensitive hybrid cathode interlayer for high-efficiency and stable inverted organic solar cells

A robust and thickness-insensitive cathode interlayer (PFOPy-N) consisting of a cross-linkable interfacial polymer (PFOPy) and n-type self-doped interfacial molecule (PDINN) is developed for high-efficiency and stable inverted organic solar cells.

A closed-shell phenalenyl-based dinuclear iron(III) complex as a robust cathode for a one-compartment H2O2 fuel cell.

Closed-shell phenalenyl (PLY) systems are increasingly becoming more attractive as building blocks for developing promising catalysts and electroactive cathode materials, as they have tremendous potential to accept electrons and participate in redox reactions. Herein, we report a PLY-based dinuclear [FeIII2(hmbh-PLY)3] complex, 1, and its utility as a cathode material in a H2O2 fuel cell. Complex 1 was synthesized from a new Schiff base ligand, (E)-9-(2-(2-hydroxy-3-methoxybenzylidene)hydrazineyl)-1H-phenalen-1-one, hmbh-PLYH2, designed using a PLY precursor, Hz-PLY. The newly derived ligand and complex 1 were characterized by various analytical techniques, including single-crystal X-ray diffraction (SCXRD). The cyclic voltammetry (CV) study revealed that complex 1 undergoes five electron reductions under an applied electric potential. When the electroactive complex 1 was employed as a cathode in a membrane-less one-compartment H2O2 fuel cell, with Ni foam as the corresponding anode, the designed fuel cell exhibited an exceptionally high peak power density (PPD) of 2.41 mW cm-2, in comparison with those of all the previously reported Fe-based molecular complexes. DFT studies were performed to gain reasonable insights into the two-electron catalytic reduction (pathway I) of H2O2 by the Fe-center of complex 1 and to explore the geometries, energetics of the electrocatalyst, reactive intermediates and transition states.

A medium entropy cathode with enhanced chromium resistance for solid oxide fuel cells

Perovskite type SrCo0.9Ta0.1O3-δ (SCT91) cathode exhibits high activity for oxygen reduction reactions, but the instability in Cr-containing atmosphere restricts its application in intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, a B-site medium-entropy SrCo0.5Fe0.2Ti0.1Ta0.1Nb0.1O3-δ (SCFTTN52111) cathode is proposed and investigated as a potential Cr-tolerance cathode. The electrochemical activity of pristine SCT91 cathode degrades rapidly in the presence of volatile chromium species. In contrast, SCFTTN52111 performs very stable. Chromium vapors prefer to react with segregated SrO species rather than Co3O4 precipitates. Significant secondary phases of SrCrO4 and Co3O4 are detected on SCT91 electrode, while only trace by-products are found on medium-entropy cathode. The better Cr tolerance is closely related to the enhanced structural stability by medium-entropy engineering and reduced surface Sr segregations. This work sheds light on the development of robust cathodes for IT-SOFCs through rational design of configuration entropy.

Enhanced cycling performance of surface-amorphized Co3S4 as robust cathode for supercapacitors

The interfacial engineering via surface amorphization is an effective strategy to regulate the structure and character of material. Herein, a facile hydrothermal method followed by NaBH4 treatment is proposed to fabricate surface-amorphized Co3S4 (SA-Co3S4). XRD and SEM characterization implies the micro flower structure of Co3S4. TEM test further demonstrates the heterointerface between crystal Co3S4 core and defect-rich amorphous Co3S4 surface, which can reduce electron/ion transport path and accelerate internal charge transfer rate, thus enhancing the integral electrical conductivity. Electrochemical measurements imply that the SA-Co3S4 displays satisfying specific capacitance of 1043.9 F g−1 at 0.5 A g−1 and good rate performance. By employing SA-Co3S4 as a cathode, and active carbon as an anode, the asymmetric supercapacitor exhibits a high energy density of 41.9 Wh kg−1 at a power density of 162 W kg−1 and good cycling durability (above 90 % retention rate after 10,000 cycles). This work offers a novel structure design strategy for fabricating cobalt sulfide materials with high conductivity and electrochemical performances.

Rational design of boron-nitrogen coordinated active sites towards oxygen reduction reaction in aluminum-air batteries with robust integrated air cathode

Rational design of cost-effective electrocatalysts for oxygen reduction reaction (ORR) is essential for developing metal-air batteries. In this work, we propose a pre-self-assembled strategy to prepare controllable B–N coordinated active sites anchored on carbon supports as an efficient electrocatalyst for ORR. The precisely coordinated B–N coordination from the pre-self-assembled boronate-amino ligands are sealed on the in-situ formed carbon dots (CDs) for preservation and further converted into B–N coordinated active sites on the carbon support. The B–N coordinated active sites anchored on the graphene aerogel (denoted as B–N-G) exhibit Pt/C competitive ORR catalytic activity in both alkaline and neutral media, which are attributed to the high content of efficient B–N coordinated active sites with expanded lattice spacing. The operando Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations explain the catalytic mechanism and identify the active sites of the B–N coordination. Furthermore, the B–N-G is directly processed into an integrated air cathode, and the Al-air batteries with the B–N-G integrated air cathode exhibit superior discharge performance and good stability in both NaOH and NaCl electrolytes. This study demonstrates a feasible pre-self-assembled approach to achieve designed B–N coordination in carbon-based electrocatalysts for metal-air batteries.

Surface iodine modification inducing robust CEI enables ultra-stable Li-Se batteries

Lithium-selenium batteries (LSeBs) have attracted increasing attention due to their excellent electronic conductivity and high theoretical specific capacity. However, there are still difficult problems such as low utilization rate and fast capacity decay in the actual application process. Herein, a surface iodine modified three-dimensional (3D) nano hollow carbon fiber (I-NHCF) network is designed and synthesized as Se host (Se@I-NHCF) for highly stable LSeBs. The surface iodine species induce the formation of robust cathode electrolyte interface (CEI), thus preventing the transformation of amorphous selenium to low-activity crystalline selenium and enabling stable electrochemical performance. Moreover, the surface iodine species promote rapid charge transfer, enhancing the chemical reaction kinetics and improving the utilization of the active Se species. As a result, the Se@I-NHCF cathode exhibits superior specific capacity of 581.8 mAh g−1 with a high stability (0.0054% capacity decay per cycle) after 500 cycles at 1C, and an excellent rate performance of 567.6 mAh g−1 at 2C. This work addresses the problem of rapid capacity decay by the formation of uniform and robust CEI to conserve highly reactive amorphous Se species, improve Se utilization, and achieve ultra-stable Li-Se batteries with high energy and long cycle life.