Guidelines for Air-Stable Lithium/Sodium Layered Oxide Cathodes

The rational design of intercalation materials plays an indispensable role in continuously improving the performance of rechargeable batteries. The capability of some very promising layered oxide materials for positive electrodes (cathodes), such as sodium layered oxides and Ni-rich lithium layered oxides, are limited by several key challenges. Air stability is one of the issues that should be tackled appropriately. In this Perspective, we present the reaction mechanisms of layered oxides when exposed to moist atmospheres, the critical factors that affect the air stability of layered oxides, and the practical strategies toward air-stable electrodes. Based on the above understandings, we highlighted several pivotal research directions for further investigations of air stability of layered oxides. We expect that continued exploration in understanding the air stability of layered oxides will help to advance the design and lower the expense of cost-effective and high-energy cathodes for Li- and Na-ion battery technologies

P2-Na0.67 Alx Mn1-x O2 : Cost-Effective, Stable and High-Rate Sodium Electrodes by Suppressing Phase Transitions and Enhancing Sodium Cation Mobility.

Sodium layered P2-stacking Na0.67 MnO2 materials have shown great promise for sodium-ion batteries. However, the undesired Jahn-Teller effect of the Mn4+ /Mn3+ redox couple and multiple biphasic structural transitions during charge/discharge of the materials lead to anisotropic structure expansion and rapid capacity decay. Herein, by introducing abundant Al into the transition-metal layers to decrease the number of Mn3+ , we obtain the low cost pure P2-type Na0.67 Alx Mn1-x O2 (x=0.05, 0.1 and 0.2) materials with high structural stability and promising performance. The Al-doping effect on the long/short range structural evolutions and electrochemical performances is further investigated by combining in situ synchrotron XRD and solid-state NMR techniques. Our results reveal that Al-doping alleviates the phase transformations thus giving rise to better cycling life, and leads to a larger spacing of Na+ layer thus producing a remarkable rate capability of 96 mAh g-1 at 1200 mA g-1

Highly-stable P2-Na 0.67 MnO 2 electrode enabled by lattice tailoring and surface engineering

Abstract(#br)One of the key challenges of sodium ion batteries is to develop sustainable, low-cost and high capacity cathodes, and this is the reason that layered sodium manganese oxides have attracted so much attention. However, the undesired phase transitions and poor electrolyte-electrode interfacial stability facilitate their capacity decay and limit their practical applications. Herein, we design a novel Al 2 O 3 @Na 0.67 Zn 0.1 Mn 0.9 O 2 electrode to mitigate these problems, by taking the advantages of both structural stabilization and surface passivation via Zn 2+ substitution and Al 2 O 3 atomic layered deposition (ALD), respectively. Long-range and local structural analyses during charging/discharging processes indicate that P2-P2’ phase transformation can be suppressed by substituting proper amount of Mn 3+ Jahn-Teller centers with Zn 2+ , whereas excessive Zn 2+ leads to P2-OP4 structure transition at low sodium contents and facilitates the electrode degradations. Furthermore, the homogeneous and robust cathode electrolyte interphase (CEI) layers formed on the Al 2 O 3 -coated electrodes effectively hinder the organic electrolytes from further decomposition. Therefore, our synergetic strategy of Zn 2+ substitution and ALD surface engineering remarkably boosts the cycling performance of P2-Na 0.67 MnO 2 and provides some new insights into the designing of highly stable cathode electrodes for sustainable sodium ion batteries

Ultrastructure of antennal sensilla of three fruit borers (Lepidoptera: Crambidae or Tortricidae).

Three fruit borers Conogethes punctiferalis (Guenée) (Crambidae), Grapholita molesta Busck (Tortricidae), and Spilonota albicana Motschulsky (Tortricidae) are serious pests of fruit trees. In this study, their antennal morphology, types of sensilla, and distributions were observed by using SEM (Scanning Electron Microscope). Nine types of sensilla were found on the antennae of C. punctiferalis, while eight types of sensilla were presented on each of G. molesta and S. albicana. The sensilla trichodea with two subtypes were the most abundant sensilla among three fruit borers. Two subtypes of sensillum coeloconica (type I with spines and type II without spines) were observed on the antennae of C. punctiferalis and G. molesta. However, sensilla coeloconica (type I) were only found in S. albicana. Although the sensilla campaniformia were only found on the antennae of C. punctiferalis, our observations confirm sensilla campaniformia presence in the moths. In addition, the functions of these sensilla were discussed based on previously reported lepidopteran insects. As a result, our study may provide useful information for advanced electrophysiological and behavioral experiments to better understand the mechanisms related to pests control

Longitudinal development of children's sharing behaviour: Only children versus children with siblings from rural China

This study examined the development of children's sharing behaviour towards friends and strangers using dictator games with a longitudinal design in a sample of rural Chinese children (n = 589, 47.0% girls) at 3-4 years old and 2 years later (n = 453, 44.2% girls). Results showed that the willingness to share and the amount of sharing changed over time and were affected by family structure. Only children shared fewer stickers than non-only children at ages 3-4, but the amount they shared did not differ at ages 5-6. Only children may develop reciprocal friendships at an older age due to their lack of experience with siblings. Children shared more stickers with friends than strangers at ages 3-4, and such ingroup bias became stronger at ages 5-6

The Dark Septate Endophytes and Ectomycorrhizal Fungi Effect on <i>Pinus tabulaeformis</i> Carr. Seedling Growth and their Potential Effects to Pine Wilt Disease Resistance

Pine wilt disease (PWD), a worldwide threat to pine forests, has caused tremendous damage to conifer forest in the world. However, little research has been conducted on the relationship between symbiosis functions of root associated fungi and pine wilt disease. In this study, we assessed the influence of seven ectomycorrhizal fungi (ECMF) and five dark septate endophytic fungi (DSE) on the growth traits and root morphology as well as the correlation of these parameters to the cumulative mortality and the morbidity rates in Pinus tabulaeformis Carr.showed the lowest cumulative mortality rates. We propose that the ECMF/DSE symbiosis enhanced the resistance of pine wilt disease via mitigation the dysfunction of water caused by PWN infection. Our research provided evidence that inoculation of ECMF/DSE could be a potential way for pine wilt disease prevention. To find highly efficient fungi for pine wilt disease management, more ECMF and DSE species should be tested

Engineering Na+-layer spacings to stabilize Mnbased layered cathodes for sodium-ion batteries

钠离子电池（NIBs）具有原料储量丰富、成本低廉等优势，更有望应用于大规模储能器件，如静态储能基站和智能电网等。层状过渡金属氧化物（LiTmO2和NaxTmO2）材料目前仍然是锂离子电池（LIBs）和NIBs的主要正极材料，其晶体结构由碱金属(Li+/Na+)层和过渡金属(TmO2)层的有序堆叠组成。然而，LiTmO2和NaxTmO2材料在充放电过程中，Li+/Na+的嵌入和脱出会引起结构相变，导致电极材料容量快速衰退。杨勇课题组提出了一种简单而有效的水介导改性策略，即在Na0.67MnO2材料的Na+层中插入水分子，再通过高温脱水获得页岩状钠氧化物。该策略有效地扩大了P2型Na0.67MnO2的Na+层间距，并将颗粒转变为页岩状形态。课题组在钠离子电池层状氧化物正极材料构效关系的研究中取得重要进展。该研究工作得到美国国家强磁场实验室傅日强教授、厦门大学王鸣生教授（共同通讯）以及吴顺情教授的支持和帮助。论文第一作者为化学化工学院2017级博士研究生左文华（已毕业）。Layered transition metal oxides are the most important cathode materials for Li/Na/K ion batteries. Suppressing undesirable phase transformations during charge-discharge processes is a critical and fundamental challenge towards the rational design of high-performance layered oxide cathodes. Here we report a shale-like NaxMnO2 (S-NMO) electrode that is derived from a simple but effective water-mediated strategy. This strategy expands the Na+ layer spacings of P2-type Na0.67MnO2 and transforms the particles into accordion-like morphology. Therefore, the S-NMO electrode exhibits improved Na+ mobility and near-zerostrain property during charge-discharge processes, which leads to outstanding rate capability (100 mAh g−1 at the operation time of 6 min) and cycling stability (>3000 cycles). In addition, the water-mediated strategy is feasible to other layered sodium oxides and the obtained S-NMO electrode has an excellent tolerance to humidity. This work demonstrates that engineering the spacings of alkali-metal layer is an effective strategy to stabilize the structure of layered transition metal oxides.This work was financially supported by the National Key Research and Development Program of China (grant nos 2018YFB0905400, 2016YFB0901502), National Natural Science Foundation of China (grant nos 21761132030, 21935009, U1932201), the Fundamental Research Funds for the Central Universities (grant no. 20720200075), and the “Double-First Class” Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University. The authors thank Dr. Dong Su for the kind help and insightful discussions. W.Z. acknowledges the research fellowship from the Alexander von Humboldt Foundation. G.F.O. acknowledges the financial support from Spanish ministry of science and innovation (project nº MAT2017-84002-C2-1-R). R.F. acknowledges the support from the National High Magnetic Field Laboratory which is supported by NSF Cooperative Agreement DMR-1644779 and the State of Florida. The authors gratefully acknowledge the valuable beamtime from beamline BL14B1 of the SSRF.研究工作得到了国家自然科学基金（21761132030、21935009、 U1932201）和国家重点研发计划（2016YFB0901502）的资助