The unstable zinc (Zn)/electrolyte interfaces formed by undesired dendrites and parasitic side reactions greatly hinder the development of aqueous zinc ion batteries. Herein, the hydroxy-rich sorbitol was used as an additive to reshape the solvation structure and modulate the interface chemistry. The strong interactions among sorbitol and both water molecules and Zn electrode can reduce the free water activity, optimize the solvation shell of water and Zn2+ ions, and regulate the formation of local water (H2O)-poor environment on the surface of Zn electrode, which effectively inhibit the decomposition of water molecules, and thus, achieve the thermodynamically stable and highly reversible Zn electrochemistry. As a result, the assembled Zn/Zn symmetric cells with the sorbitol additive realized an excellent cycling life of 2000 h at 1 mA·cm-2 and 1 mAh·cm-2, and over 250 h at 5 mA·cm-2 and 5 mAh·cm-2. Moreover, the Zn/Cu asymmetric cells with the sorbitol additive achieved a high Coulombic efficiency of 99.6%, obtaining a better performance than that with a pure 2 mol·L-1 ZnSO4 electrolyte. And the constructed Zn/poly1, 5-naphthalenediamine (PNDA) batteries could be stably discharged for 2300 cycles at 1 A·g-1 with an excellent capacity retention rate. This result indicates that the addition of 1 mol·L-1 non-toxic sorbitol into a conventional ZnSO4 electrolyte can successfully protect the Zn anode interface by improving the electrochemical properties of Zn reversible deposition/decomposition, which greatly promotes its cycle performance, providing a new approach in future development of high performance aqueous Zn ion batteries.
Two major challenges, high cost and short lifespan, have been hindering the commercialization process of low-temperature fuel cells. Professor Wei’s group has been focusing on decreasing cathode Pt loadings without losses of activity and durability, and their research advances in this area over the past three decades are briefly reviewed herein. Regarding the Pt-based catalysts and the low Pt usage, they have firstly tried to clarify the degradation mechanism of Pt/C catalysts, and then demonstrated that the activity and stability could be improved by three strategies: regulating the nanostructures of the active sites, enhancing the effects of support materials, and optimizing structures of the three-phase boundary. For Pt-free catalysts, especially carbon-based ones, several strategies that they proposed to enhance the activity of nitrogen-/heteroatom-doped carbon catalysts are firstly presented. Then, an in-depth understanding of the degradation mechanism for carbon-based catalysts is discussed, and followed by the corresponding stability enhancement strategies. Also, the carbon-based electrode at the micrometer-scale, faces the challenges such as low active-site density, thick catalytic layer, and the effect of hydrogen peroxide, which require rational structure design for the integral cathodic electrode. This review finally gives a brief conclusion and outlook about the low cost and long lifespan of cathodic oxygen reduction catalysts.
Magnesium (Mg) is a promising alternative to lithium (Li) as an anode material in solid-state batteries due to its abundance and high theoretical volumetric capacity. However, the sluggish Mg-ion conduction in the lattice of solid-state electrolytes (SSEs) is one of the key challenges that hamper the development of Mg-ion solid-state batteries. Though various Mg-ion SSEs have been reported in recent years, key insights are hard to be derived from a single literature report. Besides, the structure-performance relationships of Mg-ion SSEs need to be further unraveled to provide a more precise design guideline for SSEs. In this Viewpoint article, we analyze the structural characteristics of the Mg-based SSEs with high ionic conductivity reported in the last four decades based upon data mining - we provide big-data-derived insights into the challenges and opportunities in developing next-generation Mg-ion SSEs.