High Current Enabled Stable Lithium Anode for Ultralong Cycling Life of Lithium-Oxygen Batteries

Engineering Triple-Phase Interfaces around the Anode toward Practical Alkali Metal-Air Batteries

Alkali metal-air batteries (AMABs) promise ultrahigh gravimetric energy densities, while the inherent poor cycle stability hinders their practical application. To address this challenge, most previous efforts are devoted to advancing the air cathodes with high electrocatalytic activity. Recent studies have underlined the solid-liquid-gas triple-phase interface around the anode can play far more significant roles than previously acknowledged by the scientific community. Besides the bottlenecks of uncontrollable dendrite growth and gas evolution in conventional alkali metal batteries, the corrosive gases, intermediate oxygen species, and redox mediators in AMABs cause more severe anode corrosion and structural collapse, posing greater challenges to the stabilization of the anode triple-phase interface. This work aims to provide a timely perspective on the anode interface engineering for durable AMABs. Taking the Li-air battery as a typical example, this critical review shows the latest developed anode stabilization strategies, including formulating electrolytes to build protective interphases, fabricating advanced anodes to improve their anti-corrosion capability, and designing functional separator to shield the corrosive species. Finally, the remaining scientific and technical issues from the prospects of anode interface engineering are highlighted, particularly materials system engineering, for the practical use of AMABs.

Evolving aprotic Li-air batteries

Lithium-air batteries (LABs) have attracted tremendous attention since the proposal of the LAB concept in 1996 because LABs have a super high theoretical/practical specific energy and an infinite supply of redox-active materials, and are environment-friendly. However, due to the lack of critical electrode materials and a thorough understanding of the chemistry of LABs, the development of LABs entered a germination period before 2010, when LABs research mainly focused on the development of air cathodes and carbonate-based electrolytes. In the growing period, i.e., from 2010 to the present, the investigation focused more on systematic electrode design, fabrication, and modification, as well as the comprehensive selection of electrolyte components. Nevertheless, over the past 25 years, the development of LABs has been full of retrospective steps and breakthroughs. In this review, the evolution of LABs is illustrated along with the constantly emerging design, fabrication, modification, and optimization strategies. At the end, perspectives and strategies are put forward for the development of future LABs and even other metal-air batteries.

A novel strategy for improving performance of lithium-oxygen batteries

Although the theoretical energy density of lithium-oxygen batteries is extremely high, pulverization of lithium metal anode obviously influences batteries cycling performance. In this work, the cathode was coated with a membrane to protect the lithium anode from moisture attacking and avoid the pulverization. The membrane is composed of polyethylene oxide and poly tetra fluoroethylene, which improves the cycle life of the lithium-oxygen batteries cycles to 230 times, with a limited specific capacity of 1000 mAh·g^-1, at a current density of 100 mA·g^-1. Furthermore, the batteries perform stable charge and discharge cycles for 55 times in the air atmosphere, with the relative humidity greater than 50%. It demonstrates this strategy provides a new direction for the development of high-performance lithium-oxygen batteries.

Identifying the Degradation Mechanism in Commercial Lithium Rechargeable Batteries via High-Energy X-ray Compton Scattering Imaging

Synchrotron-based high-energy X-ray Compton scattering imaging is a promising technique for non-destructively and quantitatively investigating commercialized lithium rechargeable batteries. We apply the Compton scattering imaging technique to commercial coin-type lithium rechargeable cells (VL2020) to non-destructively identify the degradation mechanism of the cell. The correlations between the Compton scattering intensity and line-shape of the Compton scattering X-ray energy spectrum (S-parameter) obtained from this technique produce unique distributions that characterize the aged cell. These distributions in the aged cell indicate that the stable phase of the anode formed through the overvoltage charge–discharge cycle. This stable phase prevents lithium reactions, producing microbubbles with the decomposition of the electrolyte.

Recent advances in research on anodes for safe and efficient lithium-metal batteries

The revival of lithium metal anodes (LMAs) makes it a potent influence on the battery research community in the recent years after the popularity of Li-ion batteries with graphite anodes. The main reason is due to the over ten-fold increase in the capacity of LMAs when compared with that obtained when using graphite, as well as the low redox potential of Li/Li⁺. However, the full potential of LMAs is heavily inhibited by several factors, such as dendrite growth, pulverization, side reactions, and volume changes. These adversities lower the cell's Coulombic efficiency dramatically if operated without massively excessive Li usage. In this review, we first introduce some of the most significant progresses made in the understandings of the charging/discharging processes at the anode. The importance of combining advanced characterization techniques with classical methods is highlighted. In particular, we aim to explore the hidden links between those studies for obtaining deeper insights. Two main categories of solutions to address common problems, namely, lithium-electrolyte interfacial engineering and three-dimensional hosting of Li, are subsequently illustrated, where each subsection takes a different methodological perspective to demonstrate the relevant state-of-the-art studies. Some interesting approaches to stop dendrites and a brief note on the practical aspects of lithium-metal batteries are provided, too. This review concludes with our essential discoveries from the current literature and valuable suggestions for future LMA research.