New water-soluble CdSeTe/ZnS core-shell quantum dots with excellent near-infrared emission were synthesized via an aqueous solution method; they showed strong electrogenerated chemiluminescence and favorable biocompatibility.

Understanding the key factors that affects overall performances of a battery is crucial to the lithium-ion battery industry. To this end characterisation methods must be specific, reproducible and representative. As such, an interference free and reproducible analytical method with a low detection limit (50 ppb) to evaluate manganese dissolution from lithium-ion battery positive electrodes is presented. Two different electrolytes (1.0 M LiClO4 and 1.0 M LiPF6 in EC:DMC (1:1)), LiFePO4, two nominally similar LiFe0.3Mn0.7PO4 samples and spinel LiMn2O4 are used for proof of concept. Mn and Fe quantification is performed on material ageing in solely in electrolyte, as well as, in a battery system with and without forced oxidation. It is demonstrated that water and free acid content in the electrolyte, as well as, imposing an oxidative electrochemical potential has a profound effect on manganese based material dissolution and battery performance.

No abstract

The pristine LiNi0.5Co0.2Mn0.3O2cathode material particles were successfully coated with Al2O3via a heterogeneous nucleation process and subsequent heat-treatment. The structure and electrochemical properties of Al2O3-coated LiNi0.5Co0.2Mn0.3O2were characterized by XRD and constant-current charge/discharge cycling tests. It was found that the Al2O3coating did not alter the crystal structure of the cathode material. The Al2O3coating layer had a negative influence on the dicharge specific capacity and a positive effect on the cycling performance. The decreased discharge capacity of the coated sample can be attributed to the poor clectronic and ionic conductivity of Al2O3layer, which interfered the Li+intercaltion/deintercaltion into/from the cathode material. The enhanced cycling performance can be ascribed to the suppression of the dissolution of transition metal ions by the HF acid in the eletrolyte and the side reations between electrode and electrolyte by the Al2O3coating layer. The 2wt.% Al2O3-coated sample exhibits the optimal overall electrochemical performance, with discharge specific capacities of 157.0, 137.1 mAh/g at 0.2C and 3C rate, and capacity cycling retention rates of 97.34, 93.53% after 20 & 50 cycles, respectively.

No abstract