钡钨阴极—热子组合件

文章着重介绍钡钨阴极-热子组合件试用于 D1006、D2013、D3024管型中。由于阴极形状和管结构的差异,降低热子加热功率各不相同。组合件正式投入 D2013管型中应用。     

Surface Facet Dependent Cycling Stability of Layered Cathodes

High chemical and mechanical stability of cathode surface are the prerequisites enabling high-performance rechargeable battery. Surface facet is among the surface properties that dictate surface stability and cycling performance, while its underlying mechanism remains elusive. Herein, it is reported that surface stability is closely related to the surface facet for a variety of layered cathodes. The investigation shows that surface structure of P2 layered cathode undergoes sequential transformation upon cycling, which results in severe surface degradation. This study finds that the surface facets perpendicular to the (002) planes experience severe cracking and corrosion, while other surface facets are much more stable. The surface stability difference mainly comes from a geometric effect on strain release, which determines the mechanical stability of surface. Chemically, transition metal condensation forms a passivation layer to effectively prevent the inward propagation of surface degradation. Therefore, the surface facets oblique to the layered-planes are intrinsically more resistant to mechanical cracking and chemical corrosion, which is further verified as a common effect in several O3-type layered cathodes. This work not only deepens the understanding of the mechanism how surface facet affects surface stability, but also validates surface facet regulation can be a promising strategy for optimizing battery materials.     

Liquid-State Cathode Enabling a High-Voltage and Air-Stable Fe-Al Hybrid Battery

Aluminum (Al) is an ideal anode material in low-cost battery system for energy storage, with high theoretical capacities. However, the sluggish Al³⁺-involved kinetics challenges the selection of common cathode materials (Al³⁺ intercalation or conversion). Herein, a redox-active Fe–Cl complex serves as the liquid-state cathode to couple with a low-cost Al anode, which synergizes the advantages of redox flow batteries and Al rechargeable batteries. The interplay of Fe-Cl coordinated formula and electrochemical properties are revealed for the first time. It is found that [Fe₂Cl₇]⁻ molecule has a high voltage versus Al anode (1.3 V), and the novel Fe-Al hybrid battery fulfills a capacity of 1.6 mAh cm⁻² (20 Ah L⁻¹) record high in a coin cell among Al-based batteries. Furthermore, the energy efficiency, which is a vital parameter to evaluate the energy cost of the energy storage technology, reaches 85% (superior to most Al-based batteries) and an average of 70% over ≈900 h cycling. Particularly, the unique air-stable character enables normal operation of the battery assembled in ambient air. This work establishes a new application scenario for Al anode toward low-cost large-scale energy storage.     

Alloyable Viscous Fluid for Interface Welding of Garnet Electrolyte to Enable Highly Reversible Fluoride Conversion Solid State Batteries

The garnet-type solid-state Li-metal batteries are promising to develop into the high-energy-density system when coupled with the high-capacity conversion reaction cathodes. However, the high interfacial resistance and poor contact between garnet electrolyte and Li anode are still a challenge. Here, an alloyable viscous fluid strategy is proposed for Li/garnet interface welding to enable highly reversible fluoride conversion solid-state batteries. The super-assembled phenide polymer with liquid metal property can serve as “oily” interlayer to in situ construct an ionic/electronic mixed conduction network by thermal and electrochemical lithiation. The resultant healing effect of contact voids between garnet and Li enables a dramatic reduction of interfacial resistance to 6 Ω cm². The confinement and compaction of conversion products by garnet electrolyte endow the FeF₃ based batteries with long-cycling and high-rate performance (520 and 330 mAh g⁻¹ at 0.2 and 2 C respectively). This ceramic configuration also endows the CuF₂ conversion battery with much better rechargeability (instead as widely known primary battery).     

Stabilizing High-Nickel Cathodes with High-Voltage Electrolytes

Electrolytes connect the two electrodes in a lithium battery by providing Li⁺ transport channels between them. Advanced electrolytes are being explored with high-nickel cathodes and the lithium-metal anode to meet the high energy density and cycle life goals, but the origin of the performance differences with different electrolytes is not fully understood. Here, the mechanisms involved in protecting the high-capacity, cobalt-free cathode LiNiO₂ with a model high-voltage electrolyte (HVE) are delineated. The kinetic barrier posed by a thick surface degradation layer with poor Li⁺-ion transport is found to be the major contributor to the fast capacity fade of LiNiO₂ with the conventional carbonate electrolyte. In contrast, HVE reduces the side reactions between the electrolyte and the electrodes, leading to a thinner nano-interphase layer comprised of more beneficial species. Crucially, the HVE leads to a different surface reorganization pathway involving the formation of a thinner nanoscale LiNi₂O₄ spinel phase on the LiNiO₂ surface. With a high 3D Li⁺-ion and electronic conductivity, the spinel LiNi₂O₄ reorganization nanolayer preserves fast Li⁺ transport across the cathode–electrolyte interface, reduces reaction heterogeneity in the electrode and alleviates intergranular cracking within secondary particles, resulting in superior long-term cycle life.     

Direct electrochemical reduction of a bromo-propargyloxy ester at vitreous carbon cathodes in dimethylformamide

Cyclic voltammograms for the reduction of ethyl 2-bromo-3-(3^′,4^′-dimethoxyphenyl)-3-(propargyloxy)propanoate (1) at glassy carbon electrodes in dimethylformamide containing tetraalkylammonium salts exhibit three prominent waves corresponding to cleavage of the carbon–bromine bond and to subsequent reduction of ethyl trans-3-(3^′,4^′-dimethoxyphenyl)-prop-2-enoate (4). Controlled-potential electrolyses of 1 at potentials corresponding to reduction of the carbon–bromine bond afford 4 as the major product with an average yield of 56%. In the presence of a proton donor (1,1,1,3,3,3-hexafluoro-2-propanol), the quantity of 4 decreases slightly, and 2-(3^′,4^′-dimethoxyphenyl)-3-(ethoxycarbonyl)-4-methyl-2,5-dihydrofuran (3) is obtained in moderate amount (26%). We propose a mechanistic scheme whereby the major products are formed via a combination of one- and two-electron processes.     

Influence of the PVdF binder on the stability of LiCoO2 electrodes

We report herein on the effect of the PVdF binder on the stability of composite LiCoO₂ electrodes at elevated temperatures in 1 M LiPF₆ EC/EMC solutions at open circuit conditions. The structure and morphology of composite LiCoO₂ electrodes with different combinations of electrode components (LiCoO₂ active material, PVdF binder, carbon black and current collector) were evaluated by Raman spectroscopy, X-ray diffraction and SEM. The content of Co ions in the electrolyte solutions was determined by ICP. A new effect was discovered, namely, a detrimental impact of the contact between PVdF and LiCoO₂ on the stability of the active mass. The formation of surface Co₃O₄ and dissolution of Co ions at elevated temperatures is accelerated at the contact points between the active mass and the binder. The effect of water content in the electrolyte solutions on the stability of LiCoO₂ was also studied. The presence of water (and/or HF) is a necessary condition for the accelerated dissolution of Co ions from the active mass. LiCoO₂ oxidizes the solvents at elevated temperatures thus forming CO₂.     

The Latest Trends in Electric Vehicles Batteries

Global energy demand is rapidly increasing due to population and economic growth, especially in large emerging countries, which will account for 90% of energy demand growth to 2035. Electric vehicles (EVs) play a paramount role in the electrification revolution towards the reduction of the carbon footprint. Here, we review all the major trends in Li-ion batteries technologies used in EVs. We conclude that only five types of cathodes are used and that most of the EV companies use Nickel Manganese Cobalt oxide (NMC). Most of the Li-ion batteries anodes are graphite-based. Positive and negative electrodes are reviewed in detail as well as future trends such as the effort to reduce the Cobalt content. The electrolyte is a liquid/gel flammable solvent usually containing a LiFeP6 salt. The electrolyte makes the battery and battery pack unsafe, which drives the research and development to replace the flammable liquid by a solid electrolyte.     

Novel Insoluble Organic Cathodes for Advanced Organic K‐Ion Batteries

Organic redox‐active molecules are inborn electrodes to store large‐radius potassium (K) ion. High‐performance organic cathodes are important for practical usage of organic potassium‐ion batteries (OPIBs). However, small‐molecule organic cathodes face serious dissolution problems against liquid electrolytes. A novel insoluble small‐molecule organic cathode [N,N′‐bis(2‐anthraquinone)]‐perylene‐3,4,9,10‐tetracarboxydiimide (PTCDI‐DAQ, 200 mAh g^?1) is initially designed for OPIBs. In half cells (1–3.8 V vs K⁺/K) using 1 m KPF₆ in dimethoxyethane (DME), PTCDI‐DAQ delivers a highly stable specific capacity of 216 mAh g^?1 and still holds the value of 133 mAh g^?1 at an ultrahigh current density of 20 A g^?1 (100 C). Using reduced potassium terephthalate (K₄TP) as the organic anode, the resulting K₄TP||PTCDI‐DAQ OPIBs with the electrolyte 1 m KPF₆ in DME realize a high energy density of maximum 295 Wh kg^?1_cathode (213 mAh g^?1_cathode × 1.38 V) and power density of 13 800 W Kg^?1_cathode (94 mAh g^?1 × 1.38 V @ 10 A g^?1) during the working voltage of 0.2–3.2 V. Meanwhile, K₄TP||PTCDI‐DAQ OPIBs fulfill the superlong lifespan with a stable discharge capacity of 62 mAh g^?1_cathode after 10 000 cycles and 40 mAh g^?1_cathode after 30 000 cycles (3 A g^?1). The integrated performance of PTCDI‐DAQ can currently defeat any cathode reported in K‐ion half/full cells.     

A Long Cycle-Life High-Voltage Spinel Lithium-Ion Battery Electrode Achieved by Site-Selective Doping

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) is a promising cathode candidate for the next-generation high energy-density lithium-ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site-selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd m structure. This site-selective doping not only suppresses unfavorable two-phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg-doped LNMOs exhibit extraordinarily stable electrochemical performance in both half-cells and prototype full-batteries with novel TiNb₂O₇ counter-electrodes. This work pioneers an atomic-doping engineering strategy for electrode materials that could be extended to other energy materials to create high-performance devices.