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The mechanism of oxygen reduction at MnO2-catalyzed air cathode was investigated by measurements of polarization curves in wide OH− concentrations, oxygen pressures and using different crystalline MnO2 catalysts. It is found that the oxygen reduction at MnO2 catalyst is accompanied with the reduction of MnO2 and the catalytic activities of MnO2 is closely related to the electrochemical activities of MnO2. Based on the experimental determination of the reaction orders of OH−, O2 and the intermediate Mn3+ ion, we propose a chemical oxidation mechanism for the catalytic oxygen reduction, in which oxygen reduction proceeds through chemical oxidation of the discharge product of MnO2 rather than through a direct two-electron reduction. The rate expression derived from this mechanism can very well explain the observed polarization properties and the concentration dependence of oxygen reduction. [Copyright &y& Elsevier]

A nanocrystalline Li[Li0.12Ni0.32Mn0.56]O2 powder was synthesized by a pyrolysis method using polyacrylate salts as the precursor compounds. XRD and TEM results demonstrated that the Li[Li0.12Ni0.32Mn0.56]O2 powder has a layered structure as α-NaFeO2 and has an average particle size of 50–70nm. The charge–discharge experiments show that the Li[Li0.12Ni0.32Mn0.56]O2 electrode can deliver a reversible capacity of ∼140mAhg-1 cycling at 2.5–4.5V and can still remain 94% of its initial capacity after 10 cycles, showing a great promise for future applications. [Copyright &y& Elsevier]

A Na-rich poly(diphenylaminesulfonic acid sodium) (PDS) is prepared by oxidative polymerization and tested as an organic Na-host cathode for Na-ion batteries. Due to the highly self-doped benzenesulfonic anions grafted on the polyaniline backbones, this redox-active polymer demonstrates a reversible capacity of 100 mAh g − 1 at an average potential of ~ 3.4 V, reaching its theoretical value of reversible 1 Na insertion/extraction reaction. In addition, this polymer cathode also exhibits considerable rate capability and cycling stability, possibly serving as a low cost and sustainable cathode of Na-ion batteries for widespread electric storage applications. [ABSTRACT FROM AUTHOR]

Abstract: A novel room temperature ionic liquid (N-methyl-N-butyl-piperidinium bis(trifluoromethanesulfonyl) imide (PP14-RTIL) ) was synthesized and tested as electrolyte for Li/S cells. The CV results revealed that this new RTIL electrolyte has a wide potential window of 5.2V∼−0.15 (vs. Li/Li+), and is electrochemically stable and workable for lithium and sulfur electrodes. The charge–discharge experiments of Li/S cells using the PP14- RTIL electrolyte demonstrated that the sulfur cathode can achieve a high initial capacity of 1055mAh/g and maintains a reversible capacity of ca. 750 mAh/g after a few of cycles, showing a greatly improved dischargeability and cycleability as compared with the sulfur cathodes cycled in organic liquid or polymer electrolytes. [Copyright &y& Elsevier]

Abstract: Eu2O3 as a cathodic electrocatalyst was for the first time investigated and found to exhibit not only a high electrocatalytic activity for oxygen reduction, but also a strong tolerance to the attack of BH4 −. Based on these experimental findings, a simple membraneless direct borohydride fuel cell (DBFC) is assembled and exhibits a peak power density of 66.4mWcm−2 at 0.495V under ambient condition by using the Eu2O3-catalyzed cathode and hydrogen storage alloy anode. Since this new configuration of DBFCs can operate very well without the help of expensive cation-exchange membranes, it may provide a simple way to construct cost-effective and high efficient DBFCs for a number of portable applications. [Copyright &y& Elsevier]