A critical review-promises and barriers of conversion electrodes for Li-ion batteries

Conversion-type electrode materials are discussed in this critical review. Most of the conversion materials are significantly less expensive than modern intercalation-type materials, and the materials involved are appreciably abundant in the nature. However, up to now, no practically viable battery with conversion material-based electrodes was reported, as there are several major barriers to a practical employment of these materials. First, material utilization and cell energy performance are seriously compromised by a low conductivity of the most conversion materials and by a substantial electrolyte involvement in the electrochemical process. Second, the conversion reactions usually demonstrate a severe volume effect, and also conversion electrodes interact with electrolyte developing thick and resistant solid electrolyte interphase films; both of these features result in impractically low electrode cyclability. Third, a large lithiation/de-lithiation voltage hysteresis results in impractically low charge/discharge energy efficiency and suggests a severe battery heating in the course of the battery operation. All these problems present serious challenges for the researchers in the field; the approaches for handling these issues are discussed in the review. For the foreseeable future, there are grounds to expect progress in tackling some of these issues. The issue of high voltage hysteresis is a bottleneck, though, and it actually precludes conversion materials from any practical application.     

Slit Holomorphic Stochastic Flows and Gaussian Free Field

It was realized recently that the chordal, radial and dipolar Schramm–Löwner evolution (SLEs) are special cases of a general slit holomorphic stochastic flow. We characterize those slit holomorphic stochastic flows which generate level lines of the Gaussian free field. In particular, we describe the modifications of the Gaussian free field (GFF) corresponding to the chordal and dipolar SLE with drifts. Finally, we develop a version of conformal field theory based on the background charge and Dirichlet boundary condition modifications of GFF and present martingale-observables for these types of SLEs.