Development of High Performance Cathodes: From Liquid to Solid-State Batteries

Lithium-ion batteries (LIBs) are critical for the development of electric vehicles (EVs) because of their higher operating voltages compared to other energy storage technologies. However, the development of start-of-the-art LIBs touched the ceiling because of three main challenges: safety risks, limited energy density, and high cost. Accordingly, all-solid-state lithium-ion batteries (ASSLIBs) have recently emerged as promising alternative batteries for next-generation EVs because of their ability to overcome the drawbacks of conventional LIBs. Whether in conventional liquid LIBs or ASSLIBs, cathode materials are crucial in determining the overall performance. Hence, this thesis focuses on understanding the degradation mechanism of cathode interfaces and developing novel interfacial strategies in both liquid LIBs and ASSLIBs. The first work in this thesis develops a hybrid Li3PO4-TiO2 coating layer by atomic layer deposition (ALD) to improve both interfacial ionic/electronic conductivities and stability for high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode in liquid LIBs. In the second work, a dual-functional Li3PO4 (LPO) modification is designed for Ni-rich layered oxide cathodes, aiming to address both the interfacial side reactions and the microstructural cracks in sulfide-based ASSLIBs. In the third work, the origin of cathode interface degradation in sulfide-based ASSLIBs is unveiled by the X-ray and electrochemical analyses. Residual lithium compounds on the surface of Ni-rich layered cathodes are proved as the main reason that triggers the oxidation of sulfide solid-state electrolytes (SSEs), therefore inducing severe side reactions at cathode interface and structural degradation of Ni-rich cathodes. The fourth wok for the first time reports a controllable semi-conductive additive, poly(3,4-ethylenedioxythiophene) (PEDOT), in sulfide-based ASSLIBs, therefore realizing effective electron transfer at the cathode/SSE/additive three-phase interface along with a competitive rate capacity. To realize fast-charging ASSLIBs, the fifth work investigates the interfacial evolution of Al foil current collector in all-climate environment. At room temperature, side reactions are the main challenge for interfacial stability. At low temperature, the low Li+ and electron transfer kinetics along with side reactions are the key limitations for rate capability. The challenges at both room temperature and low temperature can be addressed by the graphene modification on Al foil

Design principles for sodium superionic conductors

Partial funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.Motivated by the high-performance solid-state lithium batteries enabled by lithium superionic conductors, sodium superionic conductor materials have great potential to empower sodium batteries with high energy, low cost, and sustainability. A critical challenge lies in designing and discovering sodium superionic conductors with high ionic conductivities to enable the development of solid-state sodium batteries. Here, by studying the structures and diffusion mechanisms of Li-ion versus Na-ion conducting solids, we reveal the structural feature of face-sharing high-coordination sites for fast sodium-ion conductors. By applying this feature as a design principle, we discover a number of Na-ion conductors in oxides, sulfides, and halides. Notably, we discover a chloride-based family of Na-ion conductors NaxMyCl6 (M = La–Sm) with UCl3-type structure and experimentally validate with the highest reported ionic conductivity. Our findings not only pave the way for the future development of sodium-ion conductors for sodium batteries, but also consolidate design principles of fast ion-conducting materials for a variety of energy applications.https://doi.org/10.1038/s41467-023-43436-

Design principles for sodium superionic conductors

Abstract Motivated by the high-performance solid-state lithium batteries enabled by lithium superionic conductors, sodium superionic conductor materials have great potential to empower sodium batteries with high energy, low cost, and sustainability. A critical challenge lies in designing and discovering sodium superionic conductors with high ionic conductivities to enable the development of solid-state sodium batteries. Here, by studying the structures and diffusion mechanisms of Li-ion versus Na-ion conducting solids, we reveal the structural feature of face-sharing high-coordination sites for fast sodium-ion conductors. By applying this feature as a design principle, we discover a number of Na-ion conductors in oxides, sulfides, and halides. Notably, we discover a chloride-based family of Na-ion conductors NaxMyCl6 (M = La–Sm) with UCl3-type structure and experimentally validate with the highest reported ionic conductivity. Our findings not only pave the way for the future development of sodium-ion conductors for sodium batteries, but also consolidate design principles of fast ion-conducting materials for a variety of energy applications

Giant electric field-induced second harmonic generation in polar skyrmions

Abstract Electric field-induced second harmonic generation allows electrically controlling nonlinear light-matter interactions crucial for emerging integrated photonics applications. Despite its wide presence in materials, the figures-of-merit of electric field-induced second harmonic generation are yet to be elevated to enable novel device functionalities. Here, we show that the polar skyrmions, a topological phase spontaneously formed in PbTiO3/SrTiO3 ferroelectric superlattices, exhibit a high comprehensive electric field-induced second harmonic generation performance. The second-order nonlinear susceptibility and modulation depth, measured under non-resonant 800 nm excitation, reach ~54.2 pm V−1 and ~664% V−1, respectively, and high response bandwidth (higher than 10 MHz), wide operating temperature range (up to ~400 K) and good fatigue resistance (>1010 cycles) are also demonstrated. Through combined in-situ experiments and phase-field simulations, we establish the microscopic links between the exotic polarization configuration and field-induced transition paths of the skyrmions and their electric field-induced second harmonic generation response. Our study not only presents a highly competitive thin-film material ready for constructing on-chip devices, but opens up new avenues of utilizing topological polar structures in the fields of photonics and optoelectronics

A gradient oxy-thiophosphate-coated Ni-rich layered oxide cathode for stable all-solid-state Li-ion batteries

Layered oxide cathode active materials suffer from interfacial structural instability when coupled with sulfide solid-state electrolytes. Here, the authors propose a gradient coating with a lithium oxythiophosphate layer that can stabilize the cathode|solid-state electrolyte interface

A Cullin 5-based complex serves as an essential modulator of ORF9b stability in SARS-CoV-2 replication

Abstract The ORF9b protein, derived from the nucleocapsid’s open-reading frame in both SARS-CoV and SARS-CoV-2, serves as an accessory protein crucial for viral immune evasion by inhibiting the innate immune response. Despite its significance, the precise regulatory mechanisms underlying its function remain elusive. In the present study, we unveil that the ORF9b protein of SARS-CoV-2, including emerging mutant strains like Delta and Omicron, can undergo ubiquitination at the K67 site and subsequent degradation via the proteasome pathway, despite certain mutations present among these strains. Moreover, our investigation further uncovers the pivotal role of the translocase of the outer mitochondrial membrane 70 (TOM70) as a substrate receptor, bridging ORF9b with heat shock protein 90 alpha (HSP90α) and Cullin 5 (CUL5) to form a complex. Within this complex, CUL5 triggers the ubiquitination and degradation of ORF9b, acting as a host antiviral factor, while HSP90α functions to stabilize it. Notably, treatment with HSP90 inhibitors such as GA or 17-AAG accelerates the degradation of ORF9b, leading to a pronounced inhibition of SARS-CoV-2 replication. Single-cell sequencing data revealed an up-regulation of HSP90α in lung epithelial cells from COVID-19 patients, suggesting a potential mechanism by which SARS-CoV-2 may exploit HSP90α to evade the host immunity. Our study identifies the CUL5-TOM70-HSP90α complex as a critical regulator of ORF9b protein stability, shedding light on the intricate host–virus immune response dynamics and offering promising avenues for drug development against SARS-CoV-2 in clinical settings