Rapid growth of mobile and even wearable electronics is in pursuit of high-energy-density lithium-ion batteries. One simple and facile way to achieve this goal is the elimination of nonelectroactive components of electrodes such as binders and conductive agents. Here, we present a new concept of monocomponent electrodes comprising solely electroactive materials that are wrapped with an insignificant amount (less than 0.4 wt %) of conducting polymer (PEDOT:PSS or poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate)). The PEDOT:PSS as an ultraskinny surface layer on electroactive materials (LiCoO2 (LCO) powders are chosen as a model system to explore feasibility of this new concept) successfully acts as a kind of binder as well as mixed (both electrically and ionically) conductive film, playing a key role in enabling the monocomponent electrode. The electric conductivity of the monocomponent LCO cathode is controlled by simply varying the PSS content and also the structural conformation (benzoid-favoring coil structure and quinoid-favoring linear or extended coil structure) of PEDOT in the PEDOT:PSS skin. Notably, a substantial increase in the mass-loading density of the LCO cathode is realized with the PEDOT:PSS skin without sacrificing electronic/ionic transport pathways. We envisage that the PEDOT:PSS-skinned electrode strategy opens a scalable and versatile route for making practically meaningful binder-/conductive agent-free (monocomponent) electrodes.

Electric conductivity of conducting polymers has been steadily enhanced towards a level worthy of being called its alias, “synthetic metal”. PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate)), as a representative conducting polymer, recently reached around 3,000 S cm−1, the value to open the possibility to replace transparent conductive oxides. The leading strategy to drive the conductivity increase is solvent annealing in which aqueous solution of PEDOT:PSS is treated with an assistant solvent such as DMSO (dimethyl sulfoxide). In addition to the conductivity enhancement, we found that the potential range in which PEDOT:PSS is conductive is tuned wider into a negative potential direction by the DMSO-annealing. Also, the increase in a redox-active fraction of charge carriers is proposed to be responsible for the enhancement of conductivity in the solvent annealing process.

Abstract. As the World Wide Web becomes a large source of digital music, the music recommendation system has got a great demand. There are several music recommendation systems for both commercial and academic areas, which deal with the user preference as fixed. However, since the music preferred by a user may change depending on the contexts, the conventional systems have inherent problems. This paper proposes a context-aware music recommendation system (CA-MRS) that exploits the fuzzy system, Bayesian networks and the utility theory in order to recommend appropriate music with respect to the context. We have analyzed the recommendation process and performed a subjective test to show the usefulness of the proposed system.

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Highly oxygen evolution reaction (OER)-active electrocatalysts often exhibit improved OER durability in the presence of carbon corrosion or oxidation (COR) in the literature. The activity-durability coincidence of OER electrocatalysts was theoretically understood by preferential depolarization in galvanostatic situations. At constant-current conditions for a system involving multiple reactions that are independent and competitive, the overpotential is determined most dominantly by the most facile reaction so that the most facile reaction is responsible for a dominant portion of the overall current. Therefore, higher OER activity improves durability by mitigating the current responsible for COR. The activity-durability coincidence was then proved experimentally by comparing between two catalysts of the same chemical identity (MnCo2O4) in different dimensions (5 and 100 nm in size). Carbon corrosion responsible for inferior durability was suppressed in the smaller-dimension catalyst (MnCo2O4 in 5 nm) having more numbers of active sites per a fixed mass.