The large-scale retirement of electric vehicle traction batteries poses a huge challenge to environmental protection and resource recovery since the batteries are usually replaced well before their end of life. Direct disposal or material recycling of retired batteries does not achieve their maximum economic value. Thus, the second-life use of EV batteries has become the most economical and environmentally friendly solution. However, there are still many issues facing second-life batteries (SLBs). To better understand the current research status, this article reviews the research progress of second-life lithium-ion batteries for stationary energy storage applications, including battery aging mechanisms, repurposing, modeling, battery management, and optimal sizing. Energy management strategies are reviewed to maximize the economic benefits for SLBs, and the less-demanding applications of SLBs are presented. The technical challenges and future development trends of battery reusing technologies are also discussed. Finally, the conclusions and relevant recommendations for future studies are summarized.

Green finance integrates the concept of environmental governance into the financial industry, which is conducive to sustainable development. Applying the mediating effect model, this paper investigates the effect of green finance on urban haze pollution and explores the mediating role of technological innovation of enterprises between them. Based on a sample of 639 enterprises in China over 2016–2019, a significantly negative effect of green finance on urban haze pollution is found. An increase of one standard deviation in green finance decreases PM2.5 concentration by 8.8 μg/m³, ceteris paribus. Further, green finance may improve environmental quality by promoting technological innovation. Considering the heterogeneity of enterprise ownership, this mediating effect exists in non-state-owned enterprises, while it cannot be observed in state-owned enterprises. This study proposes a new solution for pollution: using green financial tools to promote environmentally friendly technological progress.

Rapid development of High-speed railways (HSR) in China has attracted serious research interest. This paper proposes an endogenous economic growth model to explain how and why HSR may lead to faster economic growth and regional convergence in China using data from 285 cities in 2010–2014. TSLS estimation suggests that HSR has a powerful impact on urban economic growth and regional convergence. It suggests that HSR was a potent driver responsible for the sustainable and steady economic expansion of the Chinese regions in the aftermath of the world financial crisis.