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Lithium (Li) metal is regarded as a promising anode for high-energy-density Li-ion batteries because of its high theoretical specific capacity and low potential. Unfortunately, the safety issues derived from Li dendrite formation have hindered their commercialization. Thus, fabricating a flexible, three-dimensional (3D) composite Li anode is an effective strategy to suppress Li dendrite growth. Lithiophilic nanoarrays are commonly constructed on a 3D skeleton to increase its surface area and lithiophilicity. However, the lithiophilic nanoarrays are unstable due to the conversion reaction during Li plating/stripping. Therefore, designing composite nanoarrays with an electrochemically stable inner core and a lithiophilic outer shell is conducive to providing a large surface area and promoting uniform Li deposition. Herein, CoS2 shell–Co(OH)F core composite nanowire arrays were prepared on carbon cloth (CoS2–Co(OH)F/CC) to fabricate a flexible 3D composite Li anode (Li@CoS2–Co(OH)F/CC), in which the electrochemically stable Co(OH)F core ensures the stability of the nanoarray and the lithiophilic CoS2 shell facilitates uniform Li adsorption. Moreover, the Co/Li2S configuration derived from the lithiation of CoS2 could promote homogeneous Li deposition, in which the lithiophilic Li2S phase and electron-conductive Co phase jointly facilitate uniform Li nucleation and charge transfer. Consequently, the symmetric cells and full cells paired with a LiFePO4 (LFP) cathode based on the flexible Li@CoS2–Co(OH)F/CC anode presented superior cycling stability. [ABSTRACT FROM AUTHOR]

The climate in the source region of the Yangtze River, Yellow River, and Mekong River is of great research interest because of its sensitivity to global change and its importance in regulating water resources to densely populated and vast areas downstream. A five-century long record of spring (May–June) for the Palmer Drought Severity Index (PDSI) was reconstructed for this region using tree-ring width chronologies of Qilian juniper (Juniperus przewalskii Kom.) from five high-elevation sites. The reconstruction explained 46% variance in the PDSI during the instrumental period 1955–2005. The reconstructed PDSI showed that the occurrence of dry extremes became frequent during the last century relative to the previous four centuries. The standard deviation of the reconstructed PDSI in the 100-year window showed that the recent century held apparent high values of standard deviation in the long-term context. Sustained droughts occurred in periods 1582–1631, 1737–1757, 1772–1791, 1869–1891, 1916–1939, and 1952–1982, whereas relatively wet intervals were observed in 1505–1527, 1543–1564, 1712–1736, 1792–1816, 1852–1868, 1892–1915, and 1983–2008. Notably, in the context of the past five centuries, the study region showed an increased inter-annual variability in the recent century, suggesting an intensified hydroclimatic activity possibly associated with global warming. Moreover, through diagnostic analysis of atmospheric circulation, we found that the negative phase East Asian–Pacific teleconnection pattern may be likely to trigger drought in the study region. [ABSTRACT FROM AUTHOR]