Defective TiO2 hollow nanospheres as photo-electrocatalysts for photo-assisted Li-O2 batteries

Photo-Assisted Rechargeable Metal Batteries: Principles, Progress, and Perspectives

The utilization of diverse energy storage devices is imperative in the contemporary society. Taking advantage of solar power, a significant environmentally friendly and sustainable energy resource, holds great appeal for future storage of energy because it can solve the dilemma of fossil energy depletion and the resulting environmental problems once and for all. Recently, photo-assisted energy storage devices, especially photo-assisted rechargeable metal batteries, are rapidly developed owing to the ability to efficiently convert and store solar energy and the simple configuration, as well as the fact that conventional Li/Zn-ion batteries are widely commercialized. Considering many puzzles arising from the rapid development of photo-assisted rechargeable metal batteries, this review commences by introducing the fundamental concepts of batteries and photo-electrochemistry, followed by an exploration of the current advancements in photo-assisted rechargeable metal batteries. Specifically, it delves into the elucidation of device components, operating principles, types, and practical applications. Furthermore, this paper categorizes, specifies, and summarizes several detailed examples of photo-assisted energy storage devices. Lastly, it addresses the challenges and bottlenecks faced by these energy storage systems while providing future perspectives to facilitate their transition from laboratory research to industrial implementation.

Determinants of the Surface Film during the Discharging Process in Lithium-Oxygen Batteries

Lithium-oxygen batteries have one of the highest theoretical capacities and specific energies, but several challenges remain. One of them is premature death caused by a passivation layer with poor conductivities (both electronic and ionic) on the electrode surface during the discharge process. Once this thin layer forms on the surface of the catalyst and substrate, the overpotential significantly increases and causes early cell death. Therefore, understanding this thin layer is crucial to achieving high specific energy lithium-oxygen batteries. Herein, we quantitatively compared the ratio of lithium carbonate to lithium peroxide during the discharge process in a flow cell at different potentials. We found that the ratio rapidly increased at low potential and high flow rates. The surface route led to significant byproducts on the Au electrodes, and consequently, a 3 nm thick discharge product film passivates the electrode surface in a flow cell.

Improved Lithium Storage Performance of a TiO2 Anode Material Doped by Co

TiO₂ is a promising anode material for lithium-ion batteries (LIBs) due to its low cost, suitable operating voltage, and excellent structural stability. The inherent poor electron conductivity and low ion diffusion coefficient, however, severely limit its application in lithium storage. Here, Co-doped TiO₂ is synthesized by a hydrothermal method as an anode material since Co@TiO₂ possesses a large specific surface area and high electronic conductivity. Thanks to the Co dopants, the ion diffusion and electron transport are both greatly improved, which is very beneficial for cycle stability, coulombic efficiency (CE), reversible capacity, and rate performance. As a result, Co@TiO₂ shows a high reversible capacity of 227 mAh g^-1 at 3 C, excellent rate performance, and cycling stability with a capacity of about 125 mAh g^-1 at 10C after 600 cycles (1 C = 170 mA g^-1).

Chemical Electron Microscopy (CEM) for Heterogeneous Catalysis at Nano: Recent Progress and Challenges

Chemical electron microscopy (CEM), a toolbox that comprises imaging and spectroscopy techniques, provides dynamic morphological, structural, chemical, and electronic information about an object in chemical environment under conditions of observable performance. CEM has experienced a revolutionary improvement in the past years and is becoming an effective characterization method for revealing the mechanism of chemical reactions, such as catalysis. Here, we mainly address the concept of CEM for heterogeneous catalysis in the gas phase and what CEM could uniquely contribute to catalysis, and illustrate what we can know better with CEM and the challenges and future development of CEM.

Photo-Assisted Metal-Air Batteries: Recent Progress, Challenges and Opportunities

To meet the need of high energy density, long durability, safe and cost-efficient energy conversion and storage devices, metal-air batteries like Li-O₂ and Zn-O₂ batteries have received enormous attention and were subject to exciting development in the past decade. Photo-assisted strategies that enable the effective combination of photo/electric energy conversion/storage render a new dimension for the conventional metal-air batteries techniques with mere electric energy utilization. Therefore, tremendous research is ongoing in search of more efficient and durable devices with photo-assisted strategies. This review provides an overview of photo-assisted Li-O₂ batteries, Zn-O₂ batteries, and batteries with various metal/air components. The working mechanism, the basic device architecture and practical performances of various photo-assisted systems are summarized and discussed. Furthermore, certain technical challenges and future opportunities for the photo-assisted metal air batteries are emphasized and discussed in the hope of stimulating further research.