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Li-rich oxide cathodes are drawing increasing attention as next-generation cathode materials for the development of high-energy-density Li-ion batteries due to their strikingly high capacities. However, transition-metal migration, irreversible structural phase transformations, and the irreversible release of oxygen are responsible for rapid capacity and voltage decay. This study reports a Li-rich cation-ordered rock-salt oxide LixV0.4Ti0.4O2(LVTO, x = 0.97/1.2) with space group Fd3¯ m that delivers a high capacity of over 250 mAh g-1and capacity retention up to 89% after 50 cycles. A comprehensive experimental analysis confirms that the capacity can be attributed to the reversible V3+/V5+multielectron cationic redox reactions and a minor contribution from reversible anionic redox reactions. Importantly, LVTO exhibits nearly zero-strain behavior upon (dis)charge cycling cycles, which is associated with reversible V migration from octahedral to tetrahedral sites. Our results demonstrate that Li-rich rock-salt oxide LVTO could be a promising cobalt-free cathode material for Li-ion batteries.

Although the two active redox centers in Li-rich cathodes, including the anionic and cationic contributions, can enable Li-ion batteries to achieve outstanding specific energy, their behaviors at different current densities have not been clarified. Here, we provide a comparative study of transition metals (TMs) and oxygen redox activities by directly accessing their oxidation states in Li-rich materials operated at very different current rates. Our data reveal that the oxidation of oxygen in the near-surface region is at the same level for electrodes cycled with a wide range of current rates, indicating a reaction gradient of lattice oxygen redox reactions. The oxidation process of lattice oxygen is found to be dynamically compatible with that of the TMs. Combining the results of first principles calculations and complementary experimental findings, we propose a detailed mechanism of structural distortion from octahedral Li to tetrahedral Li and the role of oxygen vacancy in Li+ diffusion. It is found that fast delithiation occurring at high current densities can easily cause local structural transformation, leading to a limited Li+ diffusion rate and consequently suppressing rate capability.

All-climate temperature operation capability and increased energy density have been recognized as two crucial targets, but they are rarely achieved together in rechargeable lithium (Li) batteries. Herein, we demonstrate an electrolyte system by using monodentate dibutyl ether with both low melting and high boiling points as the sole solvent. Its weak solvation endows an aggregate solvation structure and low solubility toward polysulfide species in a relatively low electrolyte concentration (2 mol L-1). These features were found to be vital in avoiding dendrite growth and enabling Li metal Coulombic efficiencies of 99.0%, 98.2%, and 98.7% at 23 °C, -40 °C, and 50 °C, respectively. Pouch cells employing thin Li metal (50 μm) and high-loading sulfurized polyacrylonitrile (3.3 mAh cm-2) cathodes (negative-to-positive capacity ratio = 2) output 87.5% and 115.9% of their room temperature capacity at -40 °C and 50 °C, respectively. This work provides solvent-based design criteria for a wide temperature range Li-sulfur pouch cells.

3D hosts are promising to extend the cycle life of lithium metal anodes but have rarely been implemented with lean electrolytes thus impacting the practical cell energy density. To overcome this challenge, a 3D host that is lightweight and easy to fabricate with optimum pore size that enables full utilization of its pore volume, essential for lean electrolyte operations, is reported. The host is fabricated by casting a VGCF (vapor-grown carbon fiber)-based slurry loaded with a sparingly soluble rubidium nitrate salt as an additive. The network of fibers generates uniform pores of ≈3 µm in diameter with a porosity of 80%, while the nitrate additive enhances lithiophilicity. This 3D host delivers an average coulombic efficiency of 99.36% at 1 mA cm-2 and 1 mAh cm-2 for over 860 cycles in half-cell tests. Full cells containing an anode with 1.35-fold excess lithium paired with LiNi0.8 Mn0.1 Co0.1 O2 (NMC811) cathodes exhibit capacity retention of 80% over 176 cycles at C/2 under a lean electrolyte condition of 3 g Ah-1 . This work provides a facile and scalable method to advance 3D lithium hosts closer to practical lithium-metal batteries.

Protective Polymer Coatings (PPCs) have been proposed to protect lithium metal anodes in rechargeable batteries to stabilize the Li/electrolyte interface and to extend the cycle life by reducing parasitic reactions and improving the lithium deposition morphology. However, the ion transport mechanism in PPCs remains unclear. Specifically, the degree of polymer swelling in the electrolyte and the influence of polymer/solvent/ion interactions are never quantified. Here we use poly(acrylonitrile-co-butadiene) (PAN-PBD) with controlled cross-link densities to quantify how the swelling ratio of the PPC affects conductivity, Li+ ion selectivity, activation energy, and rheological properties. The large difference in polarities between PAN (polar) and PBD (non-polar) segments allows the comparison of PPC properties when swollen in carbonate (high polarity) and ether (low polarity) electrolytes, which are the two most common classes of electrolytes. We find that a low swelling ratio of the PPC increases the transference number of Li+ ions while decreasing the conductivity. The activation energy only increases when the PPC is swollen in the carbonate electrolyte because of the strong ion-dipole interaction in the PAN phase, which is absent in the non-polar PBD phase. Theoretical models using Hansen solubility parameters and a percolation model have been shown to be effective in predicting the swelling behavior of PPCs in organic solvents and to estimate the conductivity. The trade-off between conductivity and the transference number is the primary challenge for PPCs. Our study provides general guidelines for PPC design, which favors the use of non-polar polymers with low polarity organic electrolytes.

Aiming at the problems of high temperature and high humidity in coal mining facing, this paper studies the heat distribution law of coal mining facing, compares and analyzes the enthalpy difference method and Sigma thermal difference method to calculate the air supply volume. Based on this, mechanical cooling scheme is scientifically formulated, and the cooling effect is verified by numerical simulation method. The results show that: the air supply calculated by Sigma heat is more accurate than that by traditional enthalpy difference method, and the air supply is 22.4 kg/s, that is, 1 041.6 m3/min. It can be seen from the simulation results that the RWK350 air cooler can achieve effective cooling below the Coal Mine Safety Regulations at both the common 10 m and 15 m air duct outlet locations, thus achieving effective cooling of the driving roadway.

Restructuring of plant proteins by extrusion can form plant-based meat products with similar quality characteristics to animal meat. As a beneficial complement to animal meat, plant-based meat products are of great significance to realize high-value utilization of proteins and guarantee efficient supply. However, the current plant-based meat products still have some prominent problems such as insufficient elasticity, loose structure and poor juiciness, and are mostly used in the form of minced meat in meatballs, meat patties, dumplings and other meat products, which cannot fully meet the demands of Chinese consumers yet. Enzymatic modification technology, which is safe, efficient, green and useful to modify protein structure and improve product texture and flavor, has been widely used in the research and development of meat products, and is also promising for application to plant-based meat products. This paper summarizes the differences in chemical structure and functional properties between animal and plant proteins, analyzes the mechanism and application in meat products of enzymatic modification of protein structure, and reviews the latest progress in the application of enzymatic modification combined with extrusion to plant-based meat products. We anticipate that this review will provide a reference for the development and quality improvement of new plant-based meat products in China.

Evapotranspiration is an important mechanism connecting earth surface and the atmosphere. One of the factors that affect regional transpiration include land cover type. With the speeding up of urbanization around the world, urban land cover change and its impact on surface evaporation have attracted extensive attention from academia. The change in land cover in Guangzhou China, which occupies the central area of the Pearl River Delta Urban Agglomeration, is more diverse and complex during a certain period. This can be attributed to the rapid urbanization of Guagnzhou since the reform and opening up of China. The urbanization process of Guangzhou is typical, and research findings from this study can be referred to ensure rational allocation of water resources and construction of sponge cities during the urbanization process of other large cities. The present study investigated the changes in land cover and urban green space structure in Guangzhou over the last two decades; this was based on the remote sensing interpretation of Landsat datasets for 2000, 2005, 2009, 2015, and 2020. Data were obtained from 38 meteorological stations in Guangzhou and its surrounding areas; thereafter, spatial interpolation of the data was conducted to assess the change in trends of precipitation, temperature, air pressure, wind speed, and relative humidity over the past 20 years. After the above two steps, the change of surface evapotranspiration in Guangzhou was investigated. The obtained results suggested are given below:1) The total area of urban green space in Guangzhou decreased during 2000-2020. The change in land cover was mainly characterized by a significant conversion of non-forest vegetation into construction land or unused land, such as urban residential, industrial, and commercial land. Some of the vegetation had also been converted into forest land. In the past 21 years, the proportion of forest land in the urban greenspace ecosystem of Guangzhou has shown an upward trend. 2) The proportion of forest land and annual average evapotranspiration in Guangzhou showed an overall upward trend during 2000-2020. The annual average evapotranspiration and proportion of forest land were positively correlated. Moreover, high spatial consistency was observed between the increase and decrease in evapotranspiration and the mutual transformation between land cover types with different evapotranspiration capacities. 3) During the study period, evapotranspiration in Guangzhou was positively correlated with precipitation, relative humidity, and temperature and negatively correlated with air pressure, sunshine hours, and wind speed. However, the area proportion of regions with significant or higher correlation between meteorological factors and surface evapotranspiration was too low to indicate that meteorological factors were the main driving factor behind increasing regional evapotranspiration. 4) The increase in surface evapotranspiration in Guangzhou from during the study period did not occur synchronously with the spatial changes of the urban green space ecosystem and showed a lag owing to different reasons, including forest growth cycle and climate conditions. In conclusion, the study summarized the land cover changes and achievements of urban green space ecological construction under the process of urbanization in Guangzhou and explored the comprehensive impact of land cover change on regional surface evapotranspiration in Guangzhou over the last 20 years. This study provides a theoretical basis and data reference for urban ecosystem management in Guangzhou.