Li-rich disordered rock salt (DRS) oxides are a promising class of cathode materials with the wide chemical space to be explored. The high capacity (>300mAh/g) of this class of material can be explained by the reversible redox chemistry of the oxide anions, which sets it apart from the conventional layered cathode materials that rely only on the transition metal redox. However, these materials suffer from poor ionic and electronic transport properties: Most previous studies report electrochemical performance at low current rate and elevated temperature. Even then, the particle size needs to be reduced to sub-micrometer size, often by high-energy ball milling, to get reasonable capacities. To mitigate this issue, we performed a detailed study of the synthesis of three different Nb-based Li-rich DRS materials - Li3NbO4, Li1.3Fe0.4Nb0.3O2, and Li1.3Mn0.4Nb0.3O2. Systematic evaluation shows that both the synthesis conditions and the reagents used have a large effect on the phase and morphology of the material synthetized, and therefore on its electrochemical performance. Without varying the synthesis method, the extent of cation ordering, the particle morphology, and the degree of elemental segregation can be controlled by a careful choice of the metal oxide precursors. This study helps the community to distinguish important synthesis criteria in order to design Li-rich DRS cathode materials with improved electrochemical performance.

Sulfide-based solid electrolytes are known to have narrow electrochemical windows which limit their practical use in all-solid-state batteries (ASSBs). Specifically, when paired with a high-voltage transition metal oxide (TMO) cathode, the electrolyte will typically undergo unwanted degradation via chemical reactions or electrochemical oxidation, especially upon charging to voltages beyond the electrochemical stability window of the electrolyte. To mitigate these undesired reactions, thin (<10 nm), conformal, ionically-conducting, and electronically-insulating oxide-based protective coating layers have been applied on the cathode, typically via a solution process. In this work, a lithium borate-based (LBO) coating, prepared instead with a dry coating process, was shown to have the same beneficial properties. As evidenced by electrochemical characterization, the developed LBO coating shows good cycling performance and even performs better than the LiNbO3 coating commonly used in the literature. This new solvent-free coating method can thus be used to fabricate longer-lasting ASSBs.

In the past decades, the rapid growth of electric vehicles and consumer electronics market leads battery technology to attract significant attention. In order to further advance battery technology, in-depth understanding on the electrode and interface structure of battery materials are essential. Focused ion beam – scanning electron microscope is an analytical method combines ion beam for materials processing and electron column for imaging. It enables both 2D interface analysis and 3D imaging capability as well as multimodal information collection, which is an effective analytical approach for battery structure analysis. To date, conventional Ga+ FIB-SEM has been widely employed for battery materials development including interface/interphase characterization, 3D quantification and simulation analysis. However, Ga+ FIB materials removal efficiency limits its capability to access representative area and volume in some battery materials systems, e.g. electrode with tens of micron particle size. In addition, the reactive property of Ga+ ion with alkali metals, e.g. Li metal, results in the complex experimental procedure to limit the Ga+ contamination during FIB-SEM characterization. Recently, the emerging Plasma FIB-SEM (PFIB-SEM) technology has been developed with different ion source and high removal efficiency. It promises great potential for battery materials characterization, due to accessing representative 2D area and 3D volume via 40 times faster (than Ga+ system) milling rate as well as enabling Ga+ free sample preparation on advanced battery system with alkali metal electrode through non-reactive ion source (Xe+ and Ar+ ion). In this presentation, PFIB-SEM has been used to perform 2D interfacial structure analysis and 3D imaging on different battery systems. First, to evaluate the performance of plasma ions processing with Ga+ reactive battery system, lithium metal was selected for the study. Furthermore, the interfacial structure between Li-metal and sulfide based solid electrolyte in all solid-state battery system was investigated. In order to demonstrate the capability of accessing large representative 3D volume through PFIB-SEM, the microstructure of thick NMC 811 cathode (>100 µm field of view with > 70 µm thickness) was selected for 3D reconstruction and quantification. The microstructural characteristics extracted from representative 3D volume helps the understanding of correlation between electrode microstructural evolution and performance deterioration. The success demonstration of PFIB-SEM opens up exciting opportunities for exploring both current and future generation advanced battery technologies, which is expected to become a critical analytical approach for battery development.

All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range, and improved safety compared with today's liquid-electrolyte-based batteries. However, of the various solid-state electrolyte (SSE) classes - polymers, sulfides, or oxides - none alone can deliver the combined properties of ionic conductivity, mechanical, and chemical stability needed to address scalability and commercialization challenges. While promising strategies to overcome these include the use of polymer/oxide or sulfide composites, there is still a lack of fundamental understanding between different SSE-polymer-solvent systems and its selection criteria. Here, we isolate various SSE-polymer-solvent systems and study their molecular level interactions by combining various characterization tools. With these findings, we introduce a suitable Li7P3S11SSE-SEBS polymer-xylene solvent combination that significantly reduces SSE thickness (∼50 μm). The SSE-polymer composite displays high room temperature conductivity (0.7 mS cm-1) and good stability with lithium metal by plating and stripping over 2000 h at 1.1 mAh cm-2. This study suggests the importance of understanding fundamental SSE-polymer-solvent interactions and provides a design strategy for scalable production of ASSBs.

The rise of flexible electronics calls for cost-effective and scalable batteries with good mechanical and electrochemical performance. In this work, we developed printable, polymer-based AgO-Zn batteries that feature flexibility, rechargeability, high areal capacity, and low impedance. Using elastomeric substrate and binders, the current collectors, electrodes, and separators can be easily screen-printed layer-by-layer and vacuum-sealed in a stacked configuration. The batteries are customizable in sizes and capacities, with the highest obtained areal capacity of 54 mAh/cm2 for primary applications. Advanced micro-CT and EIS were used to characterize the battery, whose mechanical stability was tested with repeated twisting and bending. The batteries were used to power a flexible E-ink display system that requires a high-current drain and exhibited superior performance than commercial coin-cell batteries. The developed battery presents a practical solution for powering a wide range of electronics and holds major implications for the future development of practical and high-performance flexible batteries.