Inactive lithium (Li) formation is the immediate cause of capacity loss and catastrophic failure of Li metal batteries. However, the chemical component and the atomic level structure of inactive Li have rarely been studied due to the lack of effective diagnosis tools to accurately differentiate and quantify Li + in solid electrolyte interphase (SEI) components and the electrically isolated unreacted metallic Li 0 , which together comprise the inactive Li. Here, by introducing a new analytical method, Titration Gas Chromatography (TGC), we can accurately quantify the contribution from metallic Li 0 to the total amount of inactive Li. We uncover that the Li 0 , rather than the electrochemically formed SEI, dominates the inactive Li and capacity loss. Using cryogenic electron microscopies to further study the microstructure and nanostructure of inactive Li, we find that the Li 0 is surrounded by insulating SEI, losing the electronic conductive pathway to the bulk electrode. Coupling the measurements of the Li 0 global content to observations of its local atomic structure, we reveal the formation mechanism of inactive Li in different types of electrolytes, and identify the true underlying cause of low Coulombic efficiency in Li metal deposition and stripping. We ultimately propose strategies to enable the highly efficient Li deposition and stripping to enable Li metal anode for next generation high energy batteries. Main Text:To achieve the energy density of 500 Wh/kg or higher for next-generation battery technologies, Li metal is the ultimate anode, because it is the lightest metal on earth (0.534 g cm -3 ), delivers ultra-high theoretical capacity (3860 mAh g -1 ), and has the lowest negative electrochemical potential (-3.04 V vs. SHE) 1 . Yet, Li metal suffers from dendrite growth and low Coulombic efficiency (CE) which have prevented the extensive adoption of Li metal batteries (LMBs) 2-4 . Since the first demonstration of a Li metal battery in 1976 5 , tremendous effort has been made in preventing dendritic Li growth and improving CE, including electrolyte engineering 6-9 , interface protection 10 and substrate architecture 11 . While dense Li can be achieved without any dendrites during the plating process, the stripping process will eventually dominate the CE thus the reversibility of Li metal anode.The formation of inactive Li, also known as "dead" Li, is the immediate cause of low CE, short cycle life and violent safety hazard of LMBs. It consists of both (electro)chemically formed Li + compounds

Although layered lithium oxides have become the cathode of choice for state‐of‐the‐art Li‐ion batteries, substantial gaps remain between the practical and theoretical energy densities. With the aim of supporting efforts to close this gap, this work reviews the fundamental operating mechanisms and challenges of Li intercalation in layered oxides, contrasts how these challenges play out differently for different materials (with emphasis on Ni–Co–Al (NCA) and Ni–Mn–Co (NMC) alloys), and summarizes the extensive corpus of modifications and extensions to the layered lithium oxides. Particular emphasis is given to the fundamental mechanisms behind the operation and degradation of layered intercalation electrode materials as well as novel modifications and extensions, including Na‐ion and cation‐disordered materials.

CHIP is a dimeric U box E3 ubiquitin ligase that binds Hsp90 and/or Hsp70 via its TPR-domain, facilitating ubiquitylation of chaperone bound client proteins. We have determined the crystal structure of CHIP bound to an Hsp90 C-terminal decapeptide. The structure explains how CHIP associates with either chaperone type and reveals an unusual asymmetric homodimer in which the protomers adopt radically different conformations. Additionally, we identified CHIP as a functional partner of Ubc13-Uev1a in formation of Lys63-linked polyubiquitin chains, extending CHIP's roles into ubiquitin regulation as well as targeted destruction. The structure of Ubc13-Uev1a bound to the CHIP U box domain defines the basis for selective cooperation of CHIP with specific ubiquitin-conjugating enzymes. Remarkably, the asymmetric arrangement of the TPR domains in the CHIP dimer occludes one Ubc binding site, so that CHIP operates with half-of-sites activity, providing an elegant means for coupling a dimeric chaperone to a single ubiquitylation system.

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g−1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g−1 still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

Lithium metal has been considered the "holy grail" anode material for rechargeable batteries despite the fact that its dendritic growth and low Coulombic efficiency (CE) have crippled its practical use for decades. Its high chemical reactivity and low stability make it difficult to explore the intrinsic chemical and physical properties of the electrochemically deposited lithium (EDLi) and its accompanying solid electrolyte interphase (SEI). To prevent the dendritic growth and enhance the electrochemical reversibility, it is crucial to understand the nano- and mesostructures of EDLi. However, Li metal is very sensitive to beam damage and has low contrast for commonly used characterization techniques such as electron microscopy. Inspired by biological imaging techniques, this work demonstrates the power of cryogenic (cryo)-electron microscopy to reveal the detailed structure of EDLi and the SEI composition at the nanoscale while minimizing beam damage during imaging. Surprisingly, the results show that the nucleation-dominated EDLi (5 min at 0.5 mA cm) is amorphous, while there is some crystalline LiF present in the SEI. The EDLi grown from various electrolytes with different additives exhibits distinctive surface properties. Consequently, these results highlight the importance of the SEI and its relationship with the CE. Our findings not only illustrate the capabilities of cryogenic microscopy for beam (thermal)-sensitive materials but also yield crucial structural information on the EDLi evolution with and without electrolyte additives.

Breakthroughs in performance of Li/Cu with Ni-rich cathodes can be achieved via manipulation of anion interfacial chemistry, as uncovered by experiment/modeling.

supported long term operation of a high-voltage (4.85 V) LNMO/graphite full cell, which retained $70% of its original first-cycle discharge capacity after the 1000th cycle. Based on these results, this new carbonate-free electrolyte system, supported by the mechanistic understanding of its behavior, presents a promising new direction toward unlocking the potential of next generation Li-ion battery electrodes.

The Li-excess layered oxide compound is one of the most promising positive electrode materials for next generation batteries exhibiting high capacities of >300 mA h g−1 due to the unconventional participation of the oxygen anion redox in the charge compensation mechanism.