• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.87-103
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• 2019

Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

• Journal of Soil and Groundwater Environment
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• v.28 no.1
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• pp.1-14
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• 2023

In this study, column tests using relatively uniform Jumunjin sand media were conducted to evaluate the feasibility of calcium polysulfide (CaS_x, CPS) in removing high concentration of Zn²⁺ in groundwater. The injected CPS solution reacted rapidly with Zn²⁺ in artificial groundwater and effectively reduced Zn²⁺ by more than 99% through metal sulfide precipitation. Since the density (d = 1.27 g/cm³ ) of CPS solution was greater than that of water, CPS solution settled down rapidly while capturing Zn²⁺ and formed stable CPS layer similar to dense nonaqueous phase liquid. Mass balance analysis on Zn²⁺ in CPS solution suggested that CPS solution effectively reacted with Zn²⁺ to form metal sulfide precipitates except for high groundwater seepage velocity of 400 cm/d. With greater groundwater seepage velocity, injected CPS did not completely dissolve at the CPS-water interface, but a partially-misible CPS layer continuously moved and reacted with Zn²⁺+ in the direction of groundwater flow. Since hydraulic conductivity (K_h) decreased slightly due to the generated metal precipitates in the inter-pores of media, injection of CPS solution should be optimized to prevent clogging. As evidenced by both XRF and SEM/EDS results, ZnS precipitates were clearly observed through the reaction between the CPS solution and Zn²⁺. Further study is warranted to evaluate the feasibility of CPS to remove high-concentration heavy metalcontaminated groundwater in complex and heterogeneous media.