A mild and efficient method was developed to prepare a microsized SiO x /C core−shell composite as anode material for lithium ion batteries. By mixing citric acid and ball-milled SiO x and subjecting them to carbonization, we obtained a uniform SiO x /C core−shell composite with a microsized SiO x core and conformal carbon shell. The carbon shell effectively enhanced the electrical conductivity of SiO x and mitigated the volume changes of SiO x during lithiation and delithiation. The SiO x /C composite electrode delivered a reversible specific capacity of 1296.3 mAh g −1 , coulombic efficiency of as high as 99.8%, and capacity retention of 65.1% (843.5 mAh g −1 ), even after 200 cycles. The composite also exhibited excellent rate capability. The approach is mild, mass-productive, and cost-effective and, thus, can be employed in large-scale production of highperformance SiO x /C composite anode material.
Rapid urbanization has sharply increased the pressure of urban water issues (e.g., urban flooding and water pollution) in the Chinese megacities during last three decades. Sustainable urban water management approaches, such as Nature Based Solutions (NBS) and Low Impact Developments (LIDs), have successfully delivered long-term benefits to cities in Europe and North America. Similarly, the Chinese Sponge City Program (SCP) initiated in 2013 and experimented in 30 pilot Chinese cities. This paper reviewed the first stage of the SCP from 2015 to 2020 by using observation, Semi-Structured Interview (SSI) and Focus Group Approach (FGA) in context of Gui'an New Distinct, SW China to investigate the SCP progress and issues: (1). whether it is effectively solving urban water issues; (2). if there are any major challenges and barriers in the SCP practice. The findings of this case study provide potential solutions for improving the SCP and sustainable urban water management and possibly transform to other Sponge Cities in China.
The enhanced room-temperature photoluminescence of porous Si nanowire arrays and its mechanism are investigated. Over 4 orders of magnitude enhancement of light intensity is observed by tuning their nanostructures and surface modification. It is concluded that the localized states related to Si-O bonds and self-trapped excitations in the nanoporous structures are attributed to the strong light emission.
A binder-free anode for lithium ion batteries consisted of micro-sized silicon particle and polyacrylonitrile (PAN) was prepared. By optimizing the size of Si particle and the ratio of Si particle and PAN, the performance of the anode is greatly enhanced. Although its columbic efficiency in the first cycle is comparatively lower than that made by traditional method, it increases to 99% in the 8th cycle, and remains above 99.5% up to 190+ cycles. Due to its adhesivity and conductance, pyrolyzed PAN 10 (PPAN) can be used both as binder and the conductive agent at the same time.
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