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The solid-state Li-ion battery (SSB) is regarded as one of the most promising next-generation batteries due to its intrinsic safety and high energy density. Unfortunately, its development is plagued by the poor interface compatibility between the electrode and solid-state electrolyte. Herein, flame-retardant trimethyl phosphate (TMP) solvent along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and fuoroethylene carbonate (FEC) additive is utilized as a smart wetting agent to improve the interface compatibility between the Li-metal anode and the Li1.5Al0.5Ge1.5(PO4)3(LAGP) solid electrolyte. By taking advantage of such wetting agent, highly stable anodic and cathodic interfaces with improved physical contact and chemical stability are realized. As a result, the solid-state Li/LAGP/Li symmetrical cell with such wetting agent exhibits superior cycling performance over 1000 h with small polarization voltages. When adding such wetting agent to the solid-state Li/LAGP/LiFePO4battery, we achieved a favorable initial capacity of about 140 mAh g–1at 0.5 C and can retain 80% of its initial capacity even after 700 cycles. Additionally, the solid-state Li–air battery with such wetting agent also shows stable cycling performance over 100 h. The strategy demonstrated here will encourage more research works on developing functional and safe wetting agents for solid-state batteries.

The cycling performance of Li–O2batteries (LOBs), which is an important parameter determining the practical use of this advanced energy technology with ultrahigh energy density, is strongly affected by the nature of the oxygen electrocatalyst. As a good oxygen electrode, it should possess good activity for both the oxygen evolution reaction and the oxygen reduction reaction and superior stability under operating conditions. During the past, oxygen electrodes for LOBs were generally fabricated by loading noble metal nanoparticles on the surface of a porous carbon support. However, the nanoparticles could easily lose contact with the carbon support during the reversible liquid–gas–solid reactions that involve lithium ions, oxygen gas, and Li2O2. Herein, we reported a novel Ru-metal–organic framework (MOF)-derived carbon composite, characterized by stereoscopic Ru nanoparticle distribution within the carbon matrix, as an alternative oxygen catalyst of LOBs, enabling superior operational stability and favorable activity. More specifically, the battery demonstrated stable charge–discharge cycling for up to 800 times (∼107 days) at a current density of 500 mA g–1with low discharge/charge overpotentials (∼0.2/0.7 V vs Li). A mechanism of regenerative surface was further proposed to explain the excellent cycling stability of the LOBs through the use of the Ru-MOF–C catalyst. These encouraging results imply an accessible solution to address issues related to the oxygen catalyst for the realization of practical LOBs.

Rechargeable Zn-air batteries are considered the next-generation energy storage devices for renewable energy due to their high energy density, high safety, low cost, and eco-friendliness. However, rechargeable Zn-air batteries are still far from practical applications for existing many issues, including low energy efficiency, inferior cycling stability, poor depth of discharge, etc. Therefore, understanding the relationship between issues of each component and performance is requested to construct practical rechargeable Zn-air batteries. Herein, we provide an in-depth discussion about the challenge of engineering future rechargeable Zn-air batteries. First, the performance evaluation index and the configuration of rechargeable Zn-air batteries are first introduced. Then we introduce the issues of each component in rechargeable Zn-air batteries and the corresponding solution based on recently reported works. Simultaneously, the impact of each component on performance is discussed. Finally, some personal perspectives, including key component design, performance evaluation index, test conditions, etc., on future development, are presented. This review may afford a direction for the future development of rechargeable Zn-air batteries and inspires more research work under industrial testing conditions.

Redox mediators (RMs) have become a significant point in the now-established Li–O2battery system to reduce the charging overpotential in the oxygen evolution process. Nevertheless, a major inherent barrier of the RM is the redox shuttling between the Li metal anode and mobile RM, resulting in the corrosion of Li and depletion of RM. In this study, taking iodide/triiodide as a model RM, we propose an effective strategy by immersing the Li metal anode in I2steam to create a 1.5 μm thick surface protective layer. The resultant ionic conductive LiI layer on the Li metal anode can not only suppress Li dendrite growth but also act as a buffer layer between the RM and bare Li. By combining the iodide/triiodide RM with the LiI protective layer, the Li–O2battery shows low and steady charge voltage plateaus of ∼3.6 V over 70 cycles. Importantly, the symmetrical cell using the LiI-protected Li electrode exhibited small Li plating/stripping overpotentials (∼20 mV, 480 h), far superior to that of the bare Li electrode (∼70 mV, 300 h). The in situinterfacial observation shows that dendrite growth on the Li metal can be effectively suppressed by optimizing the LiI protective layer.

Ni3Fe oxide, with an average size of 3.5 ± 1.5 nm, was successfully deposited onto polyaniline (PANI) support through a solvothermal strategy followed by calcination.The catalyst–support interaction between Ni3Fe oxide and PANI can enhance the Ni-O covalency via the interfacial Ni-N bond.Ni3Fe oxide/PANI-assembled Zn-air batteries achieve superior cycling life for over 400 h at 10 mA cm−2and a low charge potential of around 1.95 V.