Recent development of manganese dioxide-based materials as zinc-ion battery cathode.

The development of advanced cathode materials for zinc-ion batteries (ZIBs) is a critical step in building large-scale green energy conversion and storage systems in the future. Manganese dioxide is one of the most well-studied cathode materials for zinc-ion batteries due to its wide range of crystal forms, cost-effectiveness, and well-established synthesis processes. This review describes the recent research progress of manganese dioxide-based ZIBs, and the reaction mechanism, electrochemical performance, and challenges of manganese dioxide-based ZIBs materials are systematically introduced. Optimization strategies for high-performance manganese dioxide-based materials for ZIBs with different crystal forms, nanostructures, morphologies, and compositions are discussed. Finally, the current challenges and future research directions of manganese dioxide-based cathodes in ZIBs are envisaged.

Recent Advances in Graphene-Based Materials for Zinc-Ion Batteries.

Zinc-ion batteries (ZIBs) are a promising alternative for large-scale energy storage due to their advantages of environmental protection, low cost, and intrinsic safety. However, the utilization of their full potential is still hindered by the sluggish electrode reaction kinetics, poor structural stability, severe Zn dendrite growth, and narrow electrochemical stability window of the whole battery. Graphene-based materials with excellent physicochemical properties hold great promise for addressing the above challenges foe ZIBs. In this review, the energy storage mechanisms and challenges faced by ZIBs are first discussed. Key issues and recent progress in design strategies for graphene-based materials in optimizing the electrochemical performance of ZIBs (anode, cathode, electrolyte, separator and current collector) are then discussed. Finally, some potential challenges and future research directions of graphene-based materials in high-performance ZIBs are proposed for practical applications.

Recent Research Progress into Zinc Ion Battery Solid-Electrolyte Interfaces.

Aqueous zinc ion batteries (ZIBs) are prospective next-generation energy storage device candidates owing to resource abundance, affordability, eco-friendliness, and safety. The solid-electrolyte interface (SEI) produced in a ZIB by electrolyte/electrode interactions significantly impacts battery performance. The SEI is known to promote dendrite growth, determine the electrochemical stability window, passivate zinc-metal-anodic corrosion, and mutate the electrolyte. Accordingly, the SEI is closely related to the overall property of a ZIB device. This review provides an overview of the impact of SEIs on ZIB performance recently and provides an SEI design strategy based on the formation mechanism, type, and characteristics of the SEI. Finally, future investigational directions for SEIs in ZIBs are expected to lead to a deep understanding of the SEI, enhance ZIB performance, and facilitate their extensive implementation.

Improved strategies for ammonium vanadate-based zinc ion batteries.

Aqueous zinc ion batteries (ZIBs) are becoming increasingly popular as a new form of resource for electrochemical energy storage due to their high safety, affordability, availability of natural zinc resources, and high gravimetric energy density. However, the development of high-performance ZIB cathode materials remains a great challenge because current ZIB cathode materials tend to have low conductivity and relatively complex energy storage mechanisms. Compared with other cathode materials, ammonium vanadate-based materials have been extensively investigated as cathode materials for ZIBs due to their plentiful availability and high potential capacity. In this review, we highlight the mechanisms and challenges of ammonium vanadate-based materials and summarize the progress in improved strategies including the design of different morphologies, doping with different impurities, the introduction of different intercalators, and combination with other materials for high-performance ZIBs. Finally, the paper also provides an outlook on the future challenges and development prospects of ammonium vanadate-based cathode materials in ZIBs.

Improved Strategies for Separators in Zinc-Ion Batteries.

The demand for energy storage is growing, and the disadvantages of lithium-ion batteries are being explored to overcome them. Accordingly, aqueous zinc-ion batteries (ZIBs) are developing very rapidly, owing to their high safety, environmental friendliness, high abundance of resources, and high cost performance. Over the last decade, ZIBs have made remarkable progress through extensive efforts in the field of electrode materials and through fundamental understanding of non-electrode components, such as solid-electrolyte interphase, electrolytes, separators, binders, and current collectors. In particular, the breakthrough in using separators on non-electrode elements should not be overlooked as such separators have proven key to conferring ZIBs with high energy and power density. In this Review, recent progress in the development of separators in ZIBs is comprehensively summarized based on their functions and roles in ZIBs, including the modification of conventional separators and the development of novel separators. Finally, the prospects and future challenges of separators are also discussed to facilitate ZIBs development.

A global gridded municipal water withdrawal estimation method using aggregated data and artificial neural network.

Municipal water withdrawal (MWW) information is of great significance for water supply planning, including water supply pipeline networks planning, optimization and management. Currently most MWW data are reported as spatially aggregated over large-area survey regions or even lack of data, which is unable to meet the growing demand for spatially detailed data in many applications. In this paper, six different models are constructed and evaluated in estimating global MWW using aggregated MWW data and gridded raster covariates. Among the models, the artificial neural network-based indirect model (NNM) shows the best accuracy with higher R2 and lower NMAE and NRMSE in different spatial scales. The estimates achieved from the NNM model are consistent with census and survey data, and outperforms the existing global gridded MWW dataset. At last, the NNM model is applied to mapping global gridded MWW for the year 2015 at 0.1 × 0.1° resolution. The proposed method can be applied to a wider aggregated output learning problem and the high-resolution global gridded MWW data can be used in hydrological models and water resources management.

Physiological responses of Goji berry (Lycium barbarum L.) to saline-alkaline soil from Qinghai region, China.

Recently, Goji berry (Lycium barbarum L.) has been extensively cultivated to improve the fragile ecological environment and increase the income of residents in Qinghai Province, northwestern China. However, few studies have focused on the physiological responses of Goji berry under salt stress and alkali stress. Gas exchange, photosynthetic pigments, and chlorophyll fluorescence were evaluated in response to neutral (NaCl) and alkali (NaHCO3) salt stresses. Nine irrigation treatments were applied over 30 days and included 0(Control group), 50, 100, 200, and 300 mM NaCl and NaHCO3. The results showed that salt and alkali stress reduced all the indicators and that alkali stress was more harmful to Goji berry than salt stress under the same solution concentrations. The salt tolerance and alkali resistance thresholds were identified when the index value exceeded the 50% standard of the control group, and threshold values of 246.3 ± 2.9 mM and 108.4.7 ± 2.1 mM, respectively, were determined by regression analysis. These results were used to identify the optimal water content for Goji berry. The minimum soil water content to cultivate Goji berry should be 16.22% and 23.37% under mild and moderate salt stress soils, respectively, and 29.10% and 42.68% under mild and moderate alkali stress soil, respectively.

Observed and simulated hydro-climatic data for the lake Chad basin, Africa.

Lake Chad is one of the largest lakes in the world, but extremely vulnerable to the changing climate and human activities in the basin. The Lake Chad basin is one of the largest endorheic basins in the world and straddles the borders of Central African Republic, Chad, Libya, Niger, Nigeria, Algeria, Cameroon, and Sudan. In the last 40-50 years, the lake has shrunk from a surface area of 25,000 km2 to 2000 km2. However, the availability and quality of hydro-climatic data for researchers are major barriers to research. Since observed station data is highly sparse in the basin and difficult to collect, monthly climatic data was extracted from the gridded Climate Research Unit (CRU) dataset. The gridded CRU temperature and rainfall data was extracted at 81 points, and monthly temperature and rainfall data was converted into daily data for hydrologic modelling in Mahmood and Jia [1]. This data article also includes observed streamflow data of 3 hydrometric stations and rainfall data of 11 stations, which was obtained from the Lake Chad Basin Commission. Natural streamflow data simulated with hydrologic model at N'Djamena station on the Chari-Logone River is also included in this data article.

Assessment of hydro-climatic trends and causes of dramatically declining stream flow to Lake Chad, Africa, using a hydrological approach.

In the 1960s, Lake Chad (LC) was one of the largest inland water body on the earth and since then, it has extremely shrunk from a surface area of 25,000 km2 to 2000 km2. The present study determines hydro-climatic changes in the active parts of the Lake Chad basin by using trend analysis and the causes of declining stream flow to LC due to human interventions and climate variability by using a hydrological approach. One approach, which is used to estimate changes in stream flow due to climate variability, is also modified in this study. Trend results showed that mean temperature exhibited very strong increasing trends, with a mean rise of 1.4 °C for 1951-2015, while precipitation presented very weak to strong declining trends, with an overall decline of 15%. Regarding stream flow, all major rivers showed very strong downward trends, resulting in 67% decline. The northern and eastern regions were the most impacted areas in the basin regarding decreasing precipitation and increasing temperature. The hydrological approach showed that decreasing stream flow to LC varied between 34% and 45% in different decades. In general, human activities attributed a 66% decline in stream flow and climate variability 34% for the impacted period (1972-2013) relative to 1951-1971. Only during 1982-1991, climate variability caused most reduction (59% of total) in stream flow because of devastating drought during this period. Since stream flow to LC was mostly affected by human activities, proper water resources planning and sustainable management are necessary but under the umbrella of considering changing climate.

Analysis of climate variability, trends, and prediction in the most active parts of the Lake Chad basin, Africa.

An understanding of climate variability, trends, and prediction for better water resource management and planning in a basin is very important. Since the water resources of the Lake Chad basin (LCB) are highly vulnerable to changing climate, in the present study, a combination of trend analysis methods was used to examine the climate variability and trends for the period of 1951-2015 using observed and Climate Research Unit (CRU) data, and a combination of spectral analysis techniques was used for the prediction of temperature and precipitation using CRU data. Eighty-four percent of the temperature time series indicated extremely strong signals of increasing trends (α = 0.001) and 25-38% of the precipitation time series indicated strong decreasing trends (α = 0.05). Temperature is expected to increase and precipitation is expected to decrease in the future. However, surprisingly, in some regions located in the South, the temperature was predicted to decrease slightly in 2021-2030 relative to 2006-2015. This decrease might occur because these regions are highly protected natural resource areas and forests are frequently present. On the whole, the temperature was predicted to increase by 0.65-1.6 °C and precipitation was predicted to decrease by 13-11% in the next two decades (i.e., 2016-2025 and 2026-2035) relative to 1961-1990. Periodic analysis showed a 20- to 25-year cycle in precipitation in all basins and a 40- to 45-year cycle in temperature but only in the Chari-Logone basin.

Groundwater Level Analysis Using Regional Kendall Test for Trend with Spatial Autocorrelation.

Assessment of historical evolution of groundwater levels is essential for understanding the anthropogenic impact on groundwater exploitation and developing response policies. In this study, regional groundwater level trend was addressed based on the regional Kendall test with correlated spatial data. With a limited number of data at one location, an exponential relation was proposed to be used to approximate covariances of a variable as a function of distances between locations. The effectiveness of the method was demonstrated using synthetic data experiments. The regional Kendall method was applied to assess evolution of groundwater levels and their annual decline rates in Beijing, Tianjin, and Hebei in China based on county-level data in 1959, 1984, 2005, and 2013. Results indicated that a continuing declining regional trend was shown in groundwater levels, revealing generally higher groundwater recharge rates than withdrawal rates in the study region. The annual groundwater decline rates presented a firstly increasing then decreasing regional trend, which is consistent with the environmental Kuznets curve. The earlier accelerating groundwater decline rate was attributed to supply-driven water resources management, whereas the reversed trend in accelerating groundwater decline rate in the latter period was due to many measures implemented to relieve local water stresses.

Addressing China's grand challenge of achieving food security while ensuring environmental sustainability.

China's increasingly urbanized and wealthy population is driving a growing and changing demand for food, which might not be met without significant increase in agricultural productivity and sustainable use of natural resources. Given the past relationship between lack of access to affordable food and political instability, food security has to be given a high priority on national political agendas in the context of globalization. The drive for increased food production has had a significant impact on the environment, and the deterioration in ecosystem quality due to historic and current levels of pollution will potentially compromise the food production system in China. We discuss the grand challenges of not only producing more food but also producing it sustainably and without environmental degradation. In addressing these challenges, food production should be considered as part of an environmental system (soil, air, water, and biodiversity) and not independent from it. It is imperative that new ways of meeting the demand for food are developed while safeguarding the natural resources upon which food production is based. We present a holistic approach to both science and policy to ensure future food security while embracing the ambition of achieving environmental sustainability in China. It is a unique opportunity for China to be a role model as a new global player, especially for other emerging economies.