Type Of Cathode Research Articles

Graphite Regeneration and NCM Cathode Type Synthesis from Retired LIBs by Closed-Loop Cycle Recycling Technology of Lithium-Ion Batteries

A closed-loop regeneration process for spent LiCoO2 has been successfully designed with prior synthesis of LiNixCoyMnzO2, by the authors. This research applies the methodology to lithium-ion battery anodes, using spent graphite from a decommissioned battery in a leaching process with 1.5 mol∙L−1 malic acid and 3% H2O2 alongside LiCoO2. The filtered graphite was separated, annealed in an argon atmosphere, and the filtrate was used to synthesize NCM cathode material. Characterization involved X-ray diffraction, EDX, and SEM techniques. The regenerated graphite (RG) showed a specific discharge capacity of 340.4 mAh/g at a 0.1C rate in the first cycle, dropping to 338.4 mAh/g after 55 cycles, with a Coulombic efficiency of 99.9%. CV and EIS methods provided further material assessment. In a related study, the SNCM111 synthesized from the leaching solution showed a specific discharge capacity of 131.68 mAh/g initially, decreasing to 115.71 mAh/g after 22 cycles.

The Development and Prospect of Stable Polyanion Compound Cathodes in LIBs and Promising Complementers.

Cathode materials are usually the key to determining battery capacity, suitable cathode materials are an important prerequisite to meet the needs of large-scale energy storage systems in the future. Polyanionic compounds have significant advantages in metal ion storage, such as high operating voltage, excellent structural stability, safety, low cost, and environmental friendliness, and can be excellent cathode options for rechargeable metal-ion batteries. Although some polyanionic compounds have been commercialized, there are still some shortcomings in electronic conductivity, reversible specific capacity, and rate performance, which obviously limits the development of polyanionic compound cathodes in large-scale energy storage systems. Up to now, many strategies including structural design, ion doping, surface coating, and electrolyte optimization have been explored to improve the above defects. Based on the above contents, this paper briefly reviews the research progress and optimization strategies of typical polyanionic compound cathodes in the fields of lithium-ion batteries (LIBs) and other promising metal ion batteries (sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), calcium ion batteries (CIBs), zinc ion batteries (ZIBs), aluminum ion batteries (AIBs), etc.), aiming to provide a valuable reference for accelerating the commercial application of polyanionic compound cathodes in rechargeable battery systems.

Simultaneous structure and surface engineering of metal-organic framework derived LiNi0.5-xFe2xMn1.5-xO4 cathode material for improving high voltage performance of lithium-ion batteries

This study presents a novel material synthesis approach utilizing a terephthalic acid-based metal-organic framework as a precursor and employing an ethanol-assisted hydrothermal treatment to produce high-performance Fe-doped LiNi0.5Mn1.5O4 (LNMO) cathode material. This strategy yields a well-crystallized spinel structure with uniformly distributed transition metal ions. Additionally, the appropriate quantity of Fe dopant can achieve the desired Mn3+/Mn4+ ratio, level of structural disordering, and crystal phase purity for Fe-doped LNMO. The synthesis process also aids in forming an amorphous Li2CO3 surface layer, approximately 1 nm thick, which protects the active material from excessive reaction with electrolyte. The typical Fe-doped LNMO cathode (S-05) exhibits superior performance compared to a commercialized LNMO counterpart. It delivers an initial discharge capacity of 135 mAh g-1 at 1 C with exceptional cycling stability over 500 cycles (capacity retention of 90%) under high voltage (5.0 V vs. Li+/Li). Furthermore, its rate capability significantly improves, with a capacity retention of 85% (5 C/0.2 C). This enhanced performance aligns with evidence of activated Ni2+/Ni3+/Ni4+ redox reactions and suppressed cathode electrolyte interphase resistance, leading to promoted Li+ diffusion. Moreover, it is found the cathode helps alleviate electrolyte degradation at high voltages by inhibiting the formation of singlet oxygen in the electrolyte.

Modulating interfacial Zn2+ deposition mode towards stable Zn anode via bimetallic co-doped coating

Artificial coatings represent the promising means to address the interfacial issues of Zn anode, but it poses a significant challenge to their stability due to the fatigue and resulting cracking of coatings during repeated cycling. Here, a functional coating with the synergistic effect of bimetallic co-doping was developed, which changes the Zn2+ deposition mode to interlayer deposition in coating. The simultaneous doping of Cu2+ and In3+ reduces the pyrrolic N content and enhances the adsorption of Zn2+ in the active sites. Bimetallic co-doping results in an increase in specific surface area and a decrease in pore size, thus providing more active sites. As well as enhanced electrical conductivity, electrons can enter between the coatings, thus promoting redox reactions between the layers. Therefore, it endows surface coating with low polarization and stress buffering simultaneously, which avoids cracking and stripping of coatings during cycling. As a result, the cycle life of CuInZIF-8@Zn||CuInZIF-8@Zn symmetric cell exhibits more than 1200 h at 5 mA cm−2 and 5 mAh cm−2. The CuInZIF-8@Zn anode can match multiple types of cathodes and achieve excellent cycling stability; For instance, it can cycle stably for 3000 cycles when paired with vanadium-based cathode. This work provides a new perspective of artificial coatings towards highly stable Zn anode.

Competition for Ion Intercalation in Prussian Blue Analogues as Cathode Materials for Calcium Ion Batteries

With multivalent ion batteries being considered viable post‐lithium energy storage technologies, the last few years have seen increasing interest in intercalation type cathode materials for Ca‐ion batteries (CIBs). Prussian blue analogues (PBAs) display many positive attributes such as open structural framework, large interstitial sites, and versatile transition metal redox activity. The PBA cathodes reported for CIBs often contain K‐ion or Na‐ion due to the syntheses involving the use of potassium or sodium hexacyanoferrate. It has been long overlooked whether the presence of K‐ion or Na‐ion in pristine PBAs could affect the Ca‐ion storage in the PBAs when assessing their CIB performance. Through a combined experimental and computational investigation, this work reports that when K+/Na+ is present in the pristine PBAs, K/Na intercalation is preferred by the PBA structure over Ca intercalation even in the Ca cells. Ca‐ion intercalation can be increased when the K+/Na+ content in the pristine PBAs is reduced, shifting from a K or Na‐dominated intercalation process to a Ca/K or Ca/Na co‐intercalation process. This work consolidates that PBAs are an interesting and versatile intercalation host for several ions, but investigating PBAs as intercalation cathodes requires careful consideration of all ions present in the battery system.

Na3.5(MnVFeTi)0.5(PO4)3: A Multi‐transition‐metal‐ion‐engineered NASICON‐type Cathodes for Sodium Ion Batteries

Electrochemically active Na‐superconductor (NASICON)‐type cathodes have the structural flexibility to include various transition elements, thus enabling high power outputs benefited by multi‐electron redox reactions. This study amalgamated multiple transition metal ions to construct a new NASICON‐type cathode i.e., carbon coated Na3.5(MnVFeTi)0.5(PO4)3 (NMVFTP/C), for Na‐ion batteries (NIBs). The NMVFTP/C cathode engineered in this study demonstrated stable Na+‐storage capacity, including long‐term cycling stability up to 4000 cycles at 3000 mA g‐1 with 96% capacity retention and a high‐rate output capacity of 86.78 mAh g‐1 at 2500 mA g‐1. To elucidate the ion transport process within the cathode, density functional theory modeling was employed. The low energy barrier for the diffusion of Na+ in the NMVFTP/C materials was proved to be a key factor supporting our material’s superior electrochemical performances.

A Customized Strategy Realizes Stable Cycle of Large‐Capacity and High‐Voltage Layered Cathode for Sodium‐Ion Batteries

High‐voltage P2‐Na0.67Ni0.33Mn0.67O2 layered oxide cathode exhibits significant potential for sodium‐ion batteries, owing to the elevated operating voltage and theoretical energy density beyond lithium iron phosphate, but the large‐volume phase transition is the devil. Currently, this type cathode still suffers from stability–capacity trade‐off dilemma. Herein, a concept of customized strategy via multiple rock‐forming elements trace doping is presented to address the mentioned issue. The customized Mg‐Al‐Ti trace doped cathode maintains a notable capacity of 140.3 mAh g − 1 with an energy density approaching 500 Wh kg − 1, and shows good cycle stability, retaining 89.0% of its capacity after 50 cycles at 0.1C. Additionally, the full cell, paired with a hard carbon anode, achieves an advanced energy density of 303.3 Wh kg−1. The multiple characterizations reveal the failure mechanism of contrast sample involving severe intragranular cracks coupled with layer to rock salt transformation, which reduces active substance and increases charge transfer resistance. The doped sample with increased sliding energy barrier well suppresses this phenomenon. Impressively, the customized strategy can be extended to Mg‐Fe‐Ti system. This research provides a novel concept for the design of high energy sodium‐ion cathode.

A novel hybrid sodium ion capacitor based on Na [Ni0.60Mn0.35Co0.05] O2 battery type cathode and presodiated D-Ti3C2Tx pseudocapacitive anode

The combination of the high-power density of supercapacitors and the high energy density of batteries makes hybrid sodium-ion capacitors (HSICs) a promising device. HSICs can provide better performance characteristics by harnessing both ion adsorption/desorption in the capacitor-type electrode and sodium-ion intercalation in the battery-type electrode. Here, the synthesis of MXene (Ti3C2Tx), a two-dimensional (2D) carbide and nitride is reported. Delaminated MXene (D-Ti3C2Tx) is a promising candidate for anode material in HSIC due to its large surface area (∼ 42 m2/g) and good electronic conductivity. Electrochemical study indicates that D-Ti3C2Tx anode exhibits a high discharge capacity of ∼213 mAh/g at a current rate of 20 mA/g. Further the presodiated D-Ti3C2Tx anode is paired with Na [Ni0.60Mn0.35Co0.05] O2 (P2-NMC) cathode to obtain the configuration of HSIC. The HSIC exhibits good specific capacitance of ∼187 F/g and specific discharge capacity of ∼110 mAh/g at a current density of 10 mA/g, according to the electrochemical analysis. A notable improvement in specific energy density (∼ 256 Wh/kg) and specific power density (∼579 W/kg) is also demonstrated by the HSIC. With P2-NMC being used as the cathode material rather than traditional activated carbon, there has been a rise in specific energy density.

A review of electrodynamic tether missions: Historical trend, dimensionless parameters, and opportunities opening space markets

More than half a century after pioneering theoretical works proposed them, about 27 missions with long orbiting conductors have been carried out on suborbital and orbital flights,. The analysis of this review work organized them based on type of tether (insulated or bare), type of cathode (hollow cathode, expellant-less cathode, and no cathode), and the cross-section of the tether. It shows that, while all the missions in the 20th century used insulated and round tethers, the bare tether concept clearly dominated in the 21st century. Due to the cancellation of the ProSEDS mission and the suborbital character of the T-REX experiment, no tether mission with a bare tether and a hollow cathode has been on-orbit demonstrated. The E.T.PACK mission, planned by 2025/2026, can be the first on-orbit experiment testing such special EDT system, which is the one offering the largest propulsive performance. Therefore it can represent a turning point for the limited support received for the technology in the 21st century, confirmed by the fact that the total tether length used in the missions reduced from more than 40 km to less than 4 km between the 20th and 21st centuries. The study finds and discusses some important dimension-less parameters related to electrodynamic performance, current collection, and dynamic characteristics of the ProSEDS PROX-1, TEPCE, and E.T.PACK missions. Finally, some ideas to promote the opening and support of markets in the space sector by using electrodynamic tethers are provided.

Full Exploitation of Charge Compensation of O3-type Cathode Toward High Energy Sodium-Ion Batteries by High Entropy Strategy.

O3-type cathodes with sufficient Na content are considered as promising candidates for sodium-ion batteries (SIBs). However, these cathodes suffer from insufficient utilization of the active elements, restraining the delivered capacity. In this work, a high entropy strategy is applied to a typical O3 cathode NaLi0.1Ni0.35Mn0.55O2 (NLNM), forming a high entropy oxide NaLi0.1Ni0.15Cu0.1Mg0.1Ti0.2Mn0.35O2 (Na-HE). Results show that the active elements are fully exploited in Na-HE, with a two-electron reaction by Ni2+/4+ (further extended to Cu redox and even oxygen redox), vastly different from a one-electron reaction of Ni2+/3+ in NLNM. The full utilization of the active elements dramatically improves the output capacity of the cathode (122.6 mAh g-1 of Na-HE versus 81 mAh g-1 of NLNM). Moreover, the detrimental phase transition is well suppressed in Na-HE. The cathode exhibits high capacity retention of 88.7% after 100 cycles at 130mA g-1, compared to only 36.4% for NLNM. These findings provide new insight for the design of new cathode materials for SIBs with high energy density and robust stability.

On the Thermal Stability of Selected Electrode Materials and Electrolytes for Na-Ion Batteries

Sodium-ion batteries are a technology rapidly approaching widespread adoption, so studying the thermal stability and safety of their components is a pressing issue. In this work, we employed differential scanning calorimetry (DSC) and ex situ powder X-ray diffraction to study the thermal stability of several types of sodium-ion electrolytes (NaClO4 and NaPF6 solutions in PC, EC, DEC, and their mixtures) and various cathode and anode materials (Na3V2(PO4)3, Na3(VO)2(PO4)2F, β-NaVP2O7, and hard carbon) in combination with electrolytes. The obtained results indicate, first, the satisfactory thermal stability of liquid Na-ion electrolytes, which start to decompose only at 270~300 °C. Second, we observed that charged vanadium-based polyanionic cathodes, which appear to be very stable in the “dry” state, demonstrate an increase in decomposition enthalpy and a shift of the DSC peaks to lower temperatures when in contact with 1 M NaPF6 in the EC:DEC solution. However, the greatest thermal effect from the “electrode–electrolyte” interaction is demonstrated by the anode material: the heat of decomposition of the soaked electrode in the charged state is almost 40% higher than the sum of the decomposition enthalpies of the electrolyte and dry electrode separately.

(General Student Poster Award Winner, 3rd Place) Lithium Niobate Coatings on Lithium Iron Phosphate Cathode Materials for Applications in Lithium-Ion Batteries

Lithium-ion batteries have become a crucial tool in countering global fossil fuel reliance; when paired with electric motors, they provide an alternative to petroleum-based energy storage for internal combustion engines. Typical cathode materials used in lithium-ion batteries present a unique set of challenges. Some of the electrochemical materials that have a relatively high performance also have serious impacts on the environment and human health.1 Other materials that lack these specific drawbacks, such as lithium iron phosphate (LFP), face other issues. For example, LFP suffers from a relatively low electrical conductivity and a relatively slow lithium-ion diffusion, both of which affect the general electrochemical performance of this material. These weaknesses can be addressed using coatings applied to LFP nanoparticles. Carbon coatings have already been shown to improve the performance of LFP nanoparticles, but materials with higher ionic conductivities have remained relatively undeveloped.2 By synthesizing a composite coating of both carbon and lithium niobate, further improvements to LFP nanoparticles were sought to enable a wider range of applications for this cathode material.In this work, lithium niobate coatings on carbon coated LFP nanoparticles were synthesized using a low temperature solvothermal method. Lithium niobate coatings have been shown to improve the specific capacity, rate capability, and durability of other cathode materials for lithium-ion batteries.3 Half-cells were fabricated to examine the effect of adding a lithium niobate coating to the carbon coated LFP cathode materials. Electrochemical testing techniques such as galvanostatic cycling and cyclic voltammetry were used to compare the properties and performance of the composite coated LFP relative to the carbon coated LFP. The composite coatings were also characterized using transmission electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. This coating method has resulted in the successful synthesis of lithium niobate coatings on carbon coated LFP nanoparticles with an observed improvement in durability. Goodenough, J. B.; Kim, Y. Challenges for Rechargeable Li Batteries. Mater. 2010, 22 (3), 587–603.Wang, J.; Sun, X. Understanding and Recent Development of Carbon Coating on LiFePO4 Cathode Materials for Lithium-Ion Batteries. Energy Environ. Sci. 2012, 5 (1), 5163–5185.Kim, J. H.; Kim, H.; Choi, W.; Park, M.-S. Bifunctional Surface Coating of LiNbO3 on High-Ni Layered Cathode Materials for Lithium-Ion Batteries. ACS Appl. Mater. Interfaces 2020, 12 (31), 35098–35104.

Two-Step Atmospheric RF-Microplasma Synthesis of Lithium-Ion Battery Cathode

To address the increasing demand for lithium-ion batteries for use in energy storage applications, such as electric vehicles, there is a need to make the cathode synthesis process less energy intensive, as the current method requires a sintering temperature of 650 – 950 °C for up to 12 hours. Radiofrequency (RF) microplasma setups provide an avenue to approach this problem by providing a tunable system that can be operated under atmospheric conditions, with a more efficient transfer of energy in the plasma setup as compared to a thermal furnace. Through an RF-microplasma setup, nickel, manganese, and cobalt (NMC) particles were produced from a metal acetate solution under a plasma assisted chemical vapor synthesis. These produced particles were then sintered for less time and under a lower temperature than traditional cathode synthesis methods, to produce a lithiated NMC type cathode. The product was examined physiochemically and electrochemically to examine its structure and functionality. The produced product was reversibly cycled over 60 times with a peak specific capacity around 150 mAh/g, and with future process refinement could meet the current capacity standards set by more established synthetic routes

Regulations of Bulk and Interfacial Chemistry of Mn-Based Cathode Materials for Sodium Ion Batteries

Sodium ion batteries (SIBs) show the great potential to achieve large-scale energy storage due to their low cost and good safety as well as abundant resources of sodium. Among the cathode materials for SIBs, manganese-based layered oxides with adjustable structure have been attached great interest for the high energy density and low-cost SIBs. . Particularly, P2-type Mn-based materials exhibit anionic redox during charge and discharge processes, which can not only elevate the battery potential but also provide extra capacity, drastically boosting the energy density of the batteries. However, the irreversible phase transition, Jahn-Teller effect of manganese and interphase degradation at high charge cutoff voltage during anionic redox largely affect the cyclic stability of the cathodes. Therefore, it is essential to develop effective strategies to regulate the structural and interfacial chemistry for suppressing the phase transition and voltage hysteresis as well as increasing the cycle life of cathode materials. In this work, various electrochemical inert/active elements have been introduced into Mn-based P2 type cathode materials for regulating the electronic structure of the cathodes to promote more anionic redox and improve the structural stability. In addition, a new type of ionic liquid is introduced to build a stable interphase and improve the high voltage stability of the cathode material. Multi-model synchrotron-based X-ray characterization techniques combined with first-principles calculation are used to reveal the effectiveness of different strategies on the electrochemical properties of SIBs. The results provide valuable information for the development of high-performance cathode materials. Acknowledgement This work at Shanghai Jiao Tong University was financially supported by the National Natural Science Foundation of China (No. 22209106).

An Active Halide Catholyte Boosts the Extra Capacity for All-Solid-State Batteries.

Replacing flammable organic liquid electrolytes with nonflammable solid electrolytes (SEs) in lithium batteries is crucial for enhancing safety across various applications, including portable electronics, electric vehicles, and scalable energy storage. Since typical cathode materials do not possess superionic conductivity, Li-ion conduction in the cathode predominantly relies on incorporating a significant number of SEs as additives to form a composite cathode, which substantially compromises the energy density of solid-state lithium batteries. Here, a halide SE, Li3VCl6 is demonstrated, which not only exhibits a decent Li+ conductivity, but more importantly, delivers a highly reversible capacity of approximately 80 mAh g-1 with an average voltage of 3V versus Li+/Li. The ionic conductivity of Li3VCl6 experiences marginal fluctuations upon electrochemical lithiation/delithiation, as its prototypical solid-solution reaction results solely in a reduction of lithium vacancy. When combined with the traditional LiFePO4 cathode, the active Li3VCl6 catholyte enables an impressive capacity of 217.1 mAh g-1 LFP and about 50% increase in energy density compared with inactive catholytes. Harnessing the integrated mass of the catholyte-which can serve as an active material-presents an opportunity to boost the extra capacity, rendering it feasible in applications.

Multifunctional-Element doping of NASICON-Structured cathode enables High-Rate and stable sodium storage

The NASICON cathode of sodium ion battery (SIB) exhibits a stable structure and good electrochemical performance. Na3V2(PO4)3 (NVP), as a typical NASICON cathode, has been widely used in SIBs due to its high capacity and long cycle life. However, the high proportion of vanadium in NVP escalates its cost, which deviates from the initial objective of affordable sodium-ion batteries. In this work, a multifunctional-element substitution of vanadium sites in NVP is introduced by the cost-effective transition metals (Mn and Al), which optimizes the host structure, promotes the transmission of sodium ions and improves the cycle stability. The introduction of Mn can enhance its electrochemical activity and increase the reaction potential, and the doping of Al can improve structural support and cycle stability by the enhanced covalent skeleton. It was found that the Na3.7VAl0.3Mn0.7(PO4)3 cathode shows a high capacity of 87.77 mAh g−1 even at 40C (93.2 % retention compared to 1C), and the capacity retention reaches 96.33 % after 1000 cycles at 2C. In-situ XRD analysis demonstrate that the Na3.7VAl0.3Mn0.7(PO4)3 cathode exhibits a solid solution reaction mechanism instead of the previous two-phase transformation process during the Na+ (de)insertion. Furthermore, we conducted assessments on the efficacy of diverse phosphate cathodes within a coin-type full-cell configuration, which initially exhibits a high energy density of 343.9 Wh kg−1 and excellent capacity retention of 91.58 % after 150 cycles at 0.5C. These characteristics position it as a promising candidate for NASICON cathode materials in the field of research and development.

Hybrid process combining ultrafiltration and electro-oxidation for COD and nonylphenol ethoxylate removal from industrial laundry wastewater

Laundry wastewater is a significant source of nonylphenol ethoxylate (NPEO) at wastewater treatment plants, where its breakdown forms persistent nonylphenol (NP). NP poses risks as an endocrine disruptor in wildlife and humans. This study investigates the degradation of NPEO and COD in industrial laundry wastewater (LWW) using a two-stage process combining ultrafiltration (UF) and electro-oxidation (EO). UF was used to remove suspended solids, while soluble COD (COD0 = 239 ± 6 mg.L−1) and NPEO (NPEO0 = 341 ± 8 μg.L−1) were oxidized by the EO process. Different operating parameters were studied such as current density, electrolysis time, type of cathode and supporting electrolyte concentration. Using an experimental design methodology, the optimal conditions for COD and NPEO3-17 degradation were recorded. This included achieving 97% degradation of NPEO3-17 and 61% degradation of COD, with a total operating cost of 3.65 USD·m−3. These optimal conditions were recorded at a current density of 15 mA cm−2 for a 120-min reaction period in the presence of 4 g·Na2SO4 L−1 using a graphite cathode. The EO process allowed for reaching the guidelines required for water reuse (NPEO <200 μg.L−1, COD <100 mg.L−1) in the initial laundry washing cycles. Furthermore, our results demonstrate that both NP and NPEO compounds, including higher and shorter ethoxylate chains (NPEO3-17), were effectively degraded during the EO process, with removal efficiencies between 94% and 98%. This confirms the EO process's capability to effectively degrade NP, the by-product of NPEO breakdown.

Wehnelt photoemission in an ultrafast electron microscope: Stability and usability

We tested and compared the stability and usability of three different cathode materials and configurations in a thermionic-based ultrafast electron microscope: (1) on-axis thermionic and photoemission from a custom 100 μm diameter LaB6 source with a graphite guard ring, (2) off-axis photoemission from the Ni aperture surface of the Wehnelt electrode, and (3) on-axis thermionic and photoemission from a custom 200 μm diameter polycrystalline Ta source. For each cathode type and configuration, including the Ni Wehnelt aperture, we illustrate how the photoelectron beam-current stability is deleteriously impacted by simultaneous cooling of the source following thermionic heating. Furthermore, we demonstrate usability via collection of parallel- and convergent-beam electron diffraction patterns and by formation of the optimum probe size. We find that usability of the off-axis Ni Wehnelt-aperture photoemission is at least comparable to on-axis LaB6 thermionic emission, as well as to on-axis photoemission [the heretofore conventional approach to ultrafast electron microscopy (UEM) in thermionic-based instruments]. However, the stability and achievable beam currents for off-axis photoemission from the Wehnelt aperture were superior to that of the other cathode types and configurations, regardless of the electron-emission mechanism. Beam-current stability for this configuration was found to be ±1% (one standard deviation from the mean) for 70 min (longest duration tested), and steady-state beam current was reached within the sampling-time resolution used here (∼1 s) for 15 pA beam currents (i.e., 460 electrons per packet for a 200 kHz repetition rate). Repeatability and robustness of the steady-state condition were also found to be within ±1% of the mean. We discuss the implications of these findings for UEM imaging and diffraction experiments, for pulsed-beam damage measurements, and for practical switching between optimum conventional TEM and UEM operation within the same instrument.

Suppression of Adverse Phase Transition of Layered Oxide Cathode via Local Electronic Structure Regulation for High-Capacity Sodium-Ion Batteries.

Advancing the high-voltage stability of the O3-type layered cathodes for sodium-ion batteries is critical to boost their progress in energy storage applications. However, this type of cathode often suffers from intricate phase transition and structural degradation at high voltages (i.e., >4.0 V vs Na+/Na), resulting in rapid capacity decay. Here, we present a Li/Ti cosubstitution strategy to modify the electronic configuration of oxygen elements in the O3-type layered oxide cathode. This deliberate modulation simultaneously mitigates the phase transitions and counteracts the weakening of the shielding effect resulting from the extraction of sodium ions, thus enhancing the electrostatic bonding within the TM layer and inducing and optimizing the O3-OP2 phase transition occurring in the voltage range of 2.0-4.3 V. Consequently, the cosubstituted NaLi1/9Ni1/3Mn4/9Ti1/9O2 exhibits an astounding capacity of 161.2 mAh g-1 in the voltage range of 2.0-4.3 V at 1C, and stable cycling up to 100 cycles has been achieved. This work shows the impact mechanism of element substitution on interlayer forces and phase transitions, providing a crucial reference for the optimization of O3-type materials.

Self-Assembled Nanocomposite Based on SrCo0.7Fe0.2Sc0.1O3-δ as an Efficient Intermediate-to-Low-Temperature SOFC Cathode.

The high performance of intermediate-to-low temperature solid oxide fuel cells (ILT-SOFCs) closely depends on the catalytic activity of the cathode material. However, most high-activity perovskite cathodes are rich in Sr and will arise from Sr segregation during the long-term working, resulting in the decay of activity and stability. Herein, by regulating the calcined way and temperature, a type of self-assembled nanocomposite perovskite cathode is developed, the stoichiometric SrCo0.7Fe0.2Sc0.1O3-δ (SCFSc) powder self-separates into a cubic phase (Pm3̅m, Sc-rich) and a tetragonal phase (P4/mmm, Sc-fewer). Meanwhile, a single cubic phase is prepared with the same formula via calcining the SCFSc pellet. It is found that the nanocomposite cathode shows better oxygen reduction reaction catalytic activity than single cubic SCFSc, caused by lower impedance of oxygen surface exchange and bulk diffusion. Particularly, the nanocomposite SCFSc cathode with the self-assembled heterointerfaces mitigates the Sr segregation and shows a peak power density of 1.17 W cm-2 at 700 °C and excellent stability for ∼101 h at 600 °C. This work provides a strategy for the development of nanocomposite cathodes to mitigate cation segregation and improve catalytic activity and stability.