Featuring pronounced controllability, versatility, and scalability, electrophoretic deposition (EPD) has been proposed as an efficient method for film assembly and electrode/solid electrolyte fabrication in various energy storage/conversion devices including rechargeable batteries, supercapacitors, and fuel cells. High-quality electrodes and solid electrolytes have been prepared through EPD and exhibit advantageous performances in comparison with those realized with traditional methods. Recent advances in the application of EPD materials in electrochemical energy storage and conversion devices are summarized. In particular, the parameters that influence the efficiency of an EPD process from colloidal preparation to deposition are evaluated with the aim to provide insightful guidance for realizing high-performance electrochemical energy conversion materials and devices.

Olivine-type LiFePO₄, which is an extensively employed cathode material in lithium-ion batteries, has attracted much attention due to its abundance, low cost, low toxicity, and high thermal stability. However, low electronic conductivity and sluggish lithium-ion diffusion in LiFePO₄ result in poor rate capability, which seriously limits its applications in next-generation green and sustainable power systems. Extensive efforts have focused on exploring efficient synthetic approaches to optimize its performance by controlling the particle size and shape. In this Review, we first summarize the typical synthetic methods for LiFePO₄ and follow with a discussion of the correlation between LiFePO₄ crystal size/morphology and the associated electrochemical performance. Our overview seeks to provide insightful guidance for the design of high-performance lithium-ion batteries with highly efficient and cost-effective LiFePO₄ cathode materials.

Impeded gas diffusion causes serious concentration polarization (CP) in fuel cells. The facile and accurate measurement of gas diffusivities in various electrodes facilitates the pre-evaluation of two key parameters in fuel cells, that is, the limiting current density (LCD) and CP. However, previously reported electrochemical devices for this purpose only employ a single oxygen voltage sensor, which induces inevitable voltage errors, owing to the existing oxygen gradient across the measurement tube. In this report, the correlation of such voltage errors with the errors of diffusivity measurement as well as the errors in pre-evaluating LCD and CP is analyzed quantitatively. A dual oxygen-sensing device is then proposed for the first time to eliminate the voltage errors, allowing for accurate diffusivity measurements and reliable pre-evaluation of LCD and CP in fuel cells with both bulk and thin nanostructured electrodes operated at different temperatures.

Lithium–air batteries are considered to be promising electrochemical storage devices, due to their high specific energy density. However, instability limits their cyclic performance and rate capacity and also leads to a high overpotential; lithium–air batteries are typically characterized by capacity degradation and short cycle life. Such challenges prevent lithium–air batteries from entering and competing in the battery market. Electrodes, organic solvents, the interface between electrolyte and cathode, and ambient conditions have all been demonstrated to impact substantially the stability of the lithium–air battery. In this Minireview, we focus on electrode and electrolyte decomposition, side reactions, and physical mass transport in aprotic lithium–air batteries, as well as other types of lithium–air batteries, and aim to understand comprehensively their performance and association with instability factors.

In the field of oriented-attachment crystal growth, one-dimensional nanocrystals are frequently employed as building blocks to synthesize two-dimensional or large-aspect-ratio one-dimensional nanocrystals. Despite recent extensive experimental advances, the underlying inter-particle interaction in the synthesis still remains elusive. In this report, using Ag as a platform, we investigate the van der Waals interactions associated with the side-by-side and end-to-end assemblies of one-dimensional nanorods. The size, aspect ratio, and inter-particle separation of the Ag precursor nanorods are found to have dramatically different impacts on the van der Waals interactions in the two types of assemblies. Our work facilitates the fundamental understanding of the oriented-attachment assembling mechanism based on one-dimensional nanocrystals.

The diffusion rate of oxygen has a significant impact on the power density, rate capacity, discharge capacity, and electrolyte stability of lithium–air batteries (H.-G. Jung, J. Hassoun, J.-B. Park, Y.-K. Sun, B. Scrosati, Nat. Chem. 2012, 4, 579–585; J. Read, K. Mutolo, M. Ervin, W. Behl, J. Wolfenstine, A. Driedger, D. Foster, J. Electrochem. Soc.­ 2003, 150, A1351–A1356; Y. Cui, Z. Wen, X. Liang, Y. Lu, J. Jin, M. Wu, X. Wu, Energy Environ. Sci.­ 2012, 5, 7893–7897). Oxygen diffusivity in the solid porous cathodes of gas-based batteries is typically obtained by employing a few electrochemical models. In addition to the indirect computing characteristic, previous methods of evaluating oxygen diffusivity require multiple voltage–current experiments over intact lithium–air batteries, and can cause unnecessary costs resulting from the waste of materials from other battery components (J. Read, J. Electrochem. Soc. 2006, 153, A96–A100). In this report, through derivation and analytical design, a methodology is proposed for the direct out-of-cell oxygen diffusivity measurement in lithium–air batteries. The proposed electrochemical devices allow for efficient diffusivity measurements in porous solid cathodes, as well as subsequent quantitative pre-evaluation of important battery parameters including electrode porosity, thickness, and tortuosity. The proposed methodology is expected to facilitate the development of low-cost battery systems for a variety of applications, such as large-capacity automobile batteries and electronics.