Li‐rich cathode materials have attracted increasing attention because of their high reversible discharge capacity (>250 mA h g−1), which originates from transition metal (TM) ion redox reactions and ...unconventional oxygen anion redox reactions. However, many issues need to be addressed before their practical applications, such as their low kinetic properties and inefficient voltage fading. The development of cutting‐edge technologies has led to cognitive advances in theory and offer potential solutions to these problems. Herein, a recent in‐depth understanding of the mechanisms and the frontier electrochemical research progress of Li‐rich cathodes are reviewed. In addition, recent advances associated with various strategies to promote the performance and the development of modification methods are discussed. In particular, excluding Li‐rich Mn‐based (LRM) cathodes, other branches of the Li‐rich cathode materials are also summarized. The consistent pursuit is to obtain energy storage devices with high capacity, reliable practicability, and absolute safety. The recent literature and ongoing efforts in this area are also described, which will create more opportunities and new ideas for the future development of Li‐rich cathode materials.
The practical applications of Li‐rich cathode materials, especially Li‐rich Mn‐based (LRM) cathodes, are hindered by their inherent shortcomings. In this case, the recent understanding of complex reaction mechanisms, the novel modification methods, and the corresponding development trends are comprehensively reviewed. Additionally, other branches and the future opportunities of the Li‐rich cathode materials are also summarized.
Li‐rich Mn‐based cathode materials (LRMs) are potential cathode materials for high energy density lithium‐ion batteries. However, low initial Coulombic efficiency (ICE) severely hinders the ...commercialization of LRM. Herein, a facile oleic acid‐assisted interface engineering is put forward to precisely control the ICE, enhance reversible capacity and rate performance of LRM effectively. As a result, the ICE of LRM can be precisely adjusted from 84.1% to 100.7%, and a very high specific capacity of 330 mAh g−1 at 0.1 C, as well as outstanding rate capability with a fascinating specific capacity of 250 mAh g−1 at 5 C, are harvested. Theoretical calculations reveal that the introduced cation/anion double defects can reduce the diffusion barrier of Li+ ions, and in situ surface reconstruction layer can induce a self‐built‐in electric field to stabilize the surface lattice oxygen. Moreover, this facile interface engineering is universal and can enhance the ICEs of other kinds of LRM effectively. This work provides a valuable new idea for improving the comprehensive electrochemical performance of LRM through multistrategy collaborative interface engineering technology.
Introduced cation/anion double defects can reduce the interface charge transfer resistance and enhance the Li+ ion diffusion coefficient. The induced in situ surface reconstruction layer can increase the electronic conductivity and stabilize the surface lattice oxygen. As a result, the initial Coulombic efficiency of Li‐rich Mn‐based cathode material is controlled precisely.
Revealing the relationship between plants and fungi is very important in understanding biodiversity maintenance, community stability, and ecosystem functioning. However, differences in the community ...and network structures of phyllosphere epiphytic and endophytic fungi are currently poorly documented. In this study, we examined epiphytic and endophytic fungal communities associated with the leaves of six mangrove species using Illumina MiSeq sequencing of internal transcribed spacer 2 (ITS2) sequences.
A total of 635 operational taxonomic units (OTUs) of endophytic and epiphytic fungi were obtained at a 97% sequence similarity level; they were dominated by Dothideomycetes and Tremellomycetes. Plant identity had a significant effect on the OTU richness of endophytic fungi, but not on epiphytic fungi. The community composition of epiphytic and endophytic fungi was significantly different, and plant identity had a greater effect on endophytic fungi than on epiphytic fungi. Network analysis showed that both epiphytic and endophytic network structures were characterized by significantly highly specialized and modular but lowly connected and anti-nested properties. Furthermore, the endophytic network had higher levels of specialization and modularity but lower connectance and stronger anti-nestedness than the epiphytic network.
This study reveals that the phyllosphere epiphytic and endophytic fungal communities differ, and plant identity has a greater effect on the endophytic fungi than on epiphytic fungi. These findings demonstrate the role of host plant identity in driving phyllosphere epiphytic and endophytic community structure.
Summary
There is limited knowledge on how the association of trees with different mycorrhizal types shapes soil microbial communities in the context of changing tree diversity levels. We used ...arbuscular (AM) and ectomycorrhizal (EcM) tree species as con‐ and heterospecific tree species pairs (TSPs), which were established in plots of three tree diversity levels including monocultures, two‐species mixtures and multi‐tree species mixtures in a tree diversity experiment in subtropical China. We found that the tree mycorrhizal type had a significant effect on fungal but not bacterial alpha diversity. Furthermore, only EcM but not AM TSPs fungal alpha diversity increased with tree diversity, and the differences between AM and EcM TSPs disappeared in multi‐species mixtures. Tree mycorrhizal type, tree diversity and their interaction had significant effects on fungal community composition. Neither fungi nor bacteria showed any significant compositional variation in TSPs located in multi‐species mixtures. Accordingly, the most influential taxa driving the tree mycorrhizal differences at low tree diversity were not significant in multi‐tree species mixtures. Collectively, our results indicate that tree mycorrhizal type is an important factor determining the diversity and community composition of soil microbes, and higher tree diversity levels promote convergence of the soil microbial communities.
Significance statement
More than 90% of terrestrial plants have symbiotic associations with mycorrhizal fungi which could influence the coexisting microbiota. Systematic understanding of the individual and interactive effects of tree mycorrhizal type and tree species diversity on the soil microbiota is crucial for the mechanistic comprehension of the role of microbes in forest soil ecological processes. Our tree species pair (TSP) concept coupled with random sampling within and across the plots, allowed us the unbiased assessment of tree mycorrhizal type and tree diversity effects on the tree‐tree interaction zone soil microbiota. Unlike in monocultures and two‐species mixtures, we identified species‐rich and converging fungal and bacterial communities in multi‐tree species mixtures. Consequently, we recommend planting species‐rich mixtures of EcM and AM trees, for afforestation and reforestation regimes. Specifically, our findings highlight the significance of tree mycorrhizal type in studying ‘tree diversity – microbial diversity – ecosystem function’ relationships.
Environmental selection and dispersal limitation are two of the primary processes structuring biotic communities in ecosystems, but little is known about these processes in shaping soil microbial ...communities during secondary forest succession. We examined the communities of ectomycorrhizal (EM) fungi in young, intermediate and old forests in a Chinese subtropical ecosystem, using 454 pyrosequencing. The EM fungal community consisted of 393 operational taxonomic units (OTUs), belonging to 21 EM fungal lineages, in which three EM fungal lineages and 11 EM fungal OTUs showed significantly biased occurrence among the young, intermediate and old forests. The EM fungal community was structured by environmental selection and dispersal limitation in old forest, but only by environmental selection in young, intermediate, and whole forests. Furthermore, the EM fungal community was affected by different factors in the different forest successional stages, and the importance of these factors in structuring EM fungal community dramatically decreased along the secondary forest succession series. This study suggests that different assembly mechanisms operate on the EM fungal community at different stages in secondary subtropical forest succession.
Summary
Elucidating the temporal dynamics of arbuscular mycorrhizal (AM) fungi is critical for understanding their functions. Furthermore, research investigating the temporal dynamics of AM fungi in ...response to agricultural practices remains in its infancy.
We investigated the effect of nitrogen fertilisation and watering reduction on the temporal dynamics of AM fungi, across the lifespan of wheat.
Nitrogen fertilisation decreased AM fungal spore density (SD), extraradical hyphal density (ERHD), and intraradical colonisation rate (IRCR) in both watering conditions. Nitrogen fertilisation affected AM fungal community composition in soil but not in roots, regardless of watering conditions. The temporal analysis revealed that AM fungal ERHD and IRCR were higher under conventional watering and lower under reduced watering in March than in other growth stages at low (≤ 70 kg N ha−1 yr−1) but not at high (≥ 140) nitrogen fertilisation levels. AM fungal SD was lower in June than in other growth stages and community composition varied with plant development at all nitrogen fertilisation levels, regardless of watering conditions.
This study demonstrates that high nitrogen fertilisation levels disrupt the temporal dynamics of AM fungal hyphal growth but not sporulation and community composition.
Insufficient eradication capacity and dysfunction are common occurrences in T cells that characterize cancer immunotherapy failure. De novo DNA methylation promotes T cell exhaustion, whereas ...methylation inhibition enhances T cell rejuvenation in vivo. Decitabine, a DNA methyltransferase inhibitor approved for clinical use, may provide a means of modifying exhaustion-associated DNA methylation programmes. Herein, anti-tumour activities, cytokine production, and proliferation are enhanced in decitabine-treated chimeric antigen receptor T (dCAR T) cells both in vitro and in vivo. Additionally, dCAR T cells can eradicate bulky tumours at a low-dose and establish effective recall responses upon tumour rechallenge. Antigen-expressing tumour cells trigger higher expression levels of memory-, proliferation- and cytokine production-associated genes in dCAR T cells. Tumour-infiltrating dCAR T cells retain a relatively high expression of memory-related genes and low expression of exhaustion-related genes in vivo. In vitro administration of decitabine may represent an option for the generation of CAR T cells with improved anti-tumour properties.
Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior ...cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid–electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g–1 at 100 mA g–1, and excellent cycle performance with a capacity of 708.6 mAh g–1 and 87.1% capacity retention after 820 cycles at 1000 mA g–1, outperforming the reported results of Si/C composite anodes. Furthermore, a low electrode swelling of 18.1% at a high areal capacity of 3.8 mAh cm–2 can be obtained. When assembled into a practical 3.2 Ah cylindrical cell, extraordinary long cycling life with a capacity retention of 81.4% even after 1200 cycles at 1C (3.2 A) and excellent rate performance are achieved, indicating significant advantages for long-life power batteries in electric vehicles.
The construction of a protective layer for stabilizing anion redox reaction is the key to obtaining long cycling stability for Li‐rich Mn‐based cathode materials. However, the protection of the ...exposed surface/interface of the primary particles inside the secondary particles is usually ignored and difficult, let alone the investigation of the impact of the surface engineering of the internal primary particles on the cycling stability. In this work, an efficient method to regulate cycling stability is proposed by simply adjusting the distribution state of the boron nickel complexes coating layer. Theoretical calculation and experimental results display that the full‐surface boron nickel complexes coating layer can not only passivate the activity of interface oxygen and improve its stability but also play the role of sharing voltage and protective layer to gradually activate the oxygen redox reaction during cycling. As a result, the elaborately designed cobalt‐free Li‐rich Mn‐based cathode displays the highest discharge‐specific capacity retentions of 91.1% after 400 cycles at 1 C and 94.3% even after 800 cycles at 5 C. In particular, the regulation strategy has well universality and is suitable for other high‐capacity Li‐rich cathode materials.
An efficient method to regulate the surface structure of Co‐free Li‐rich cathode materials is proposed by simply adjusting the distribution state of the boron nickel complexes coating layer. The full‐surface coating layer plays the role of sharing voltage, protective layer, and passivation of surface lattice oxygen. As a result, the comprehensive electrochemical properties are enhanced effectively.
Li‐rich Mn‐based layered oxides (LRLO) are considered promising cathode candidates for high‐energy‐density lithium‐ion batteries (LIBs). However, severe capacity/voltage fading and poor rate ...performance hinder their practical application. Herein, a microstructure engineering strategy is put forward to design the unique bayberry‐like Li1.2Mn0.54Co0.13Ni0.13O2 (LRLO‐S) cathode material, composed of a spherical core and the shell self‐assembled by radially oriented nanorods with intrinsic rapid electron and ion transport capability, benefiting to increase the electrochemical reaction kinetics during cycling. Meanwhile, the radial texturing of the nanorods in shell layer forms a natural protective interface constituted by thermodynamically stable (003) planes, resisting electrolyte corrosion effectively. Furthermore, the configuration of orderly self‐assembled nanorods can effectively regulate the stress and strain to stabilize the lattice framework, finally improves the cycling stability of LRLO. As a result, the elaborately designed LRLO‐S cathode delivers remarkable high‐rate long‐term cycling stability with high capacity retentions of 91.2% after 500 cycles at 1 C and of 81.3% after 1000 cycles at 5 C. More importantly, the voltage stability is enhanced greatly with a superior retention of 89.6% after cycling 500 times at 1 C. Here a valuable strategy is provided to develop intrinsic mechanically robust high‐performance Li‐rich‐layered cathode materials for advanced LIBs.
Li‐rich layered oxide cathode material Li1.2Mn0.54Ni0.13Co0.13O2 assembled by the radially oriented nanorods is successfully produced. The order radially orientation of nanorods can greatly improve the intrinsic structural stability and electronic and ionic conductivities. In addition, the exposed stable (003) plane can suppress the interfacial side reactions greatly. As a result, the designed bayberry‐like Li‐rich cathode shows greatly enhanced electrochemical performance.
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