ABSTRACT
Polysulfides are easily dissolved in the electrolyte of Li-S batteries after long cycles. Sn atom modification electrodes are beneficial for improving cycling stabilities of Li-S batteries. However, the influence of Sn atoms on the structure and electrochemical performance of SnO2/C composite materials is not explored. Sn/SnO2/C composite materials are developed as sulfur carriers in Li-S batteries in our work. In addition, the cycling stability mechanism of Sn/SnO2/C/S composite electrodes is also elucidated. Results show that introduced Sn/SnO2/C/S composite electrodes display good cycling stability (420.1 mAh·g-1 at 1C after 1000 cycles) in Li-S batteries. The sulfur load of Sn/SnO2/C/S composite electrodes is 80 wt % (2 mg-1·cm-2). The introduction of Sn into Sn/SnO2/C/S composite electrodes plays three roles. The first role is to enhance the structural stability of SnO2. The second role is to help adsorb active sulfur ions. The last role is to promote the electron transportation ability during the initial discharging/charging process. Sn/SnO2/C/S composite electrodes are beneficial for inhibiting the dissolution of polysulfides in electrolytes after long cycles.
ABSTRACT
A four-stage systematic tracking survey of 240 households was conducted from the summer of 2011 to the spring of 2012 in a Chinese city of Suzhou to determine the characteristics of household hazardous waste (HHW) generated by the city. Factor analysis and a regression model were used to study the major driving forces of HHW generation. The results indicate that the rate of HHW generation was 6.16 (0.16-31.74, 95% CI) g/person/day, which accounted for 2.23% of the household solid waste stream. The major waste categories contributing to total HHW were home cleaning products (21.33%), medicines (17.67%) and personal care products (15.19%). Packaging and containers (one-way) and products (single-use) accounted for over 80% of total HHW generation, implying a considerable potential to mitigate HHW generation by changing the packaging design and materials used by manufacturing enterprises. Strong correlations were observed between HHW generation (g/person/day) and the driving forces group of "household structure" and "consumer preferences" (among which the educational level of the household financial manager has the greatest impact). Furthermore, the HHW generation stream in Suzhou suggested the influence of another set of variables, such as local customs and culture, consumption patterns, and urban residential life-style. This study emphasizes that HHW should be categorized at its source (residential households) as an important step toward controlling the HHW hazards of Chinese cities.
