[Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)] (PEDOT:PSS, Baytron P) composite films were prepared under various conditions and their conductivities were studied by the current-sensing atomic force microscopy (CS-AFM) technique. Topographic and current images of pristine and additive-treated PEDOT:PSS as well as electrochemically synthesized PEDOT films were obtained in nanoscale using the CS-AFM. The as-prepared pristine PEDOT:PSS films showed a low population of conductive spots isolated by large insulating regions; both their population and the conductivities increased upon addition of a few additives to the PEDOT:PSS solution before spin-coating. From the current-voltage (I-V) traces recorded at a few representative spots of different electronic states, much improved pathways for charge percolation appeared to have been established in the additive-treated films. Electrochemically prepared PEDOT films showed much better electrical properties compared with spin-casted films of chemically prepared polymers. The conductivity of all these films was shown to be significantly enhanced by the electrochemical doping process.

Durability of high-energy throughput batteries is a prerequisite for electric vehicles to penetrate the market. Despite remarkable progresses in silicon anodes with high energy densities, rapid capacity fading of full cells with silicon–graphite anodes limits their use. In this work, we unveil degradation mechanisms such as Li+ crosstalk between silicon and graphite, consequent Li+ accumulation in silicon, and capacity depression of graphite due to silicon expansion. The active material properties, i.e. silicon particle size and graphite hardness, are then modified based on these results to reduce Li+ accumulation in silicon and the subsequent degradation of the active materials in the anode. Finally, the cycling performance is tailored by designing electrodes to regulate Li+ crosstalk. The resultant full cell with an areal capacity of 6 mAh cm−2 has a cycle life of >750 cycles the volumetric energy density of 800 Wh L−1 in a commercial cell format.

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An extremely strong oxidant, ferrate (Fe(VI) or FeO4(2-), has been produced electrochemically in an acidic aqueous medium for the first time.