Material flow analysis on the critical resources from spent power lithium-ion batteries under the framework of China's recycling policies.

With the rapid growth of electric vehicles in China, the number of spent power lithium-ion batteries is dramatically increased. Considering the environmental risk, security risk, and potential resource value, China has issued a series of laws and regulations to manage the spent power lithium-ion batteries. This work employs the material flow analysis method to evaluate the material flows of Li, Ni, Co, and Mn during the life cycle of power lithium-ion batteries under the framework of China's recycling policy system. The results show that the demand for primary Li, Ni, Co, and Mn can achieve 26.9, 68.1, 20.4, and 21.9 kt in 2021, and a lot of primary critical resources will inburst the in-use stage. Moreover, the number of secondary Li, Ni, Co, and Mn can achieve 6.1, 15.4, 4.6, and 5 kt in 2021, accounting for 22.7%, 22.6%, 22.5%, and 22.8% of their corresponding demand. Based on the economic evaluation under the framework of China's recycling policy system, it is found that the potential recycling values of Li, Ni, Co, and Mn are approximately 966, 523, 414, and 43 million RMB yuan, which are 66.4%, 71%, 59.6%, and 66.4% higher than those in the absence of China's recycling policy system. It is implied that China's recycling policy system could markedly improve the collection rate by reducing losses and indirectly enhancing the recycling and reuse of spent power lithium-ion batteries. This work is expected to provide guidance for policymakers to improve the management of spent power lithium-ion batteries in China.

Quantifying the effect of socio-economic-geo drivers on the change of municipal waste disposal in China by an integrated TWFE-PRF-SDM methodology.

Municipal solid waste management and disposal in China have significantly evolved since 2000. Due to China's vast land area and significant socioeconomic and geographic disparities, nationwide waste management strategies need to be further evaluated. This study quantified the effect of social, economic, and geographic drivers on municipal waste disposal activities in 31 provincial-level administrative regions from 2003 to 2020, by establishing a methodology integrated by two-way fixed effects regression model, panel random forest, and spatial Durbin model. The results showed, in the past two decades, socio-economic-geo indicators significantly co-decided the landfill and incineration activities. In particular, the explanatory ability of GDP per capita was above 45%, while land resources and city size also showed great significance. Spatial autocorrelation analysis showed that the relationship between landfill/incineration rates and socio-economic-geo drivers changed notably from unobvious to significant with economic growth. Furthermore, the local economy and land resources displayed more impact than those of the neighboring regions, while sci-tech and education showed clear spatial spillover effects. Chinese government would carefully assess the full-scale promotion policy of incineration plants, landfill is still hold as a reasonable option for regions with specific socio-economic-geo conditions.

Interfacial Electrochemical Polymerization for Spinning Liquid Metals into Core-Shell Wires.

Metal wires are of great significance in applications such as three-dimensional (3D) printing, soft electronics, optics, and metamaterials. Ga-based liquid metals (e.g., EGaIn), though uniquely combining metallic conductivity, fluidity, and biocompatibility, remain challenging to be spun due to their low viscosity, high surface tension, and Rayleigh-Plateau instability. In this work, we showed that EGaIn as a working electrode could induce the oxidization of EGaIn and interfacial electrochemical polymerization of electroactive monomers (e.g., acrylic acid, dopamine, and pyrrole), thus spinning itself from an opening of a blunt needle. During the spinning process, the high surface tension of EGaIn was reduced by electrowetting and electrocapillarity and stabilized by polymer shells (tunable thickness of ∼0.6-30 µm on wires with a diameter of 90-300 µm), which were chelated with metal ions. The polymeric shells offered EGaIn wires with an enhanced endurance to mechanical force and acidity. By further encapsulating into elastomers through a facile impregnation process, the resultant elastic EGaIn wires showed a combination of high stretchability (up to 800%) and metallic conductivity (1.5 × 106 S m-1). When serving as wearable sensors, they were capable of sensing facial expressions, body movements, voice recognition, and spatial pressure distributions with high sensitivity, good repeatability, and satisfactory durability. Machine-learning algorithms further assisted to detect gestures with high accuracy.