Raising the Intrinsic Safety of Layered Oxide Cathodes by Surface Re-Lithiation with LLZTO Garnet-Type Solid Electrolytes.

Battery safety concerns are becoming more and more prominent with the increasing demands of lithium-ion batteries (LIBs) with higher energy density. The greatest threat to battery safety derives from the easy release of oxygen from the high-capacity layered oxide cathodes at highly delithiated states and subsequent exothermic reactions with reductive agents in batteries. Herein, it is demonstrated that solid electrolyte Li6.5 La3 Zr1.5 Ta0.5 O12 (LLZTO) can supply lithium ions to re-lithiate the charged LiCoO2 at elevated temperatures. Such a re-lithiation process can lower the state-of-charge of LiCoO2 , and thus, inherently postpones its structural decomposition and the associated release of oxygen during the heating process. The LiCoO2 /graphite full cell with 1 wt% addition of LLZTO demonstrates remarkably enhanced safety performances. This work proposes a strategy that through the adoption of solid electrolytes to solve safety issues raised from both flammable liquid electrolytes and high capacity cathodes, to achieve intrinsically safe LIBs or solid-state batteries.

Fast Li Plating Behavior Probed by X-ray Computed Tomography.

Uneven lithium plating/stripping is an essential issue that inhibits stable cycling of a lithium metal anode and thus hinders its practical applications. The investigation of this process is challenging because it is difficult to observe lithium in an operating device. Here, we demonstrate that the microscopic lithium plating behavior can be observed in situ in a close-to-practical cell setup using X-ray computed tomography. The results reveal the formation of porous structure and its progressive evolution in space over the charging process with a large current. The elaborated analysis indicates that the microstructure of deposited lithium makes a significant impact on the subsequent lithium plating, and the impact of structural inhomogeneity, further exaggerated by the large-current charging, can lead to severely uneven lithium plating and eventually cell failure. Therefore, a codesign strategy involving delicate controls of microstructure and electrochemical conditions could be a necessity for the next-generation battery with lithium metal anode.

Enhancing the Thermal Stability of NASICON Solid Electrolyte Pellets against Metallic Lithium by Defect Modification.

All-solid-state batteries (ASSBs) are expected to address the battery safety issues fundamentally by replacing the flammable electrolyte with solid electrolytes (SEs). However, recent studies report that the thermal runaway happened for NASICON-type SEs when they contact with Li metal at high temperature and indicate that the ASSBs may not be totally safe. Here, the thermal stability of a NASICON-type Li1.4Al0.4Ti1.6(PO4)3 (LATP) SE pellet against metallic lithium is quantified in a quasi-practical situation. Accelerated thermal runaway of the LATP pellet compared to LATP powder is observed when they contact with lithium. Combining electrochemical impedance spectroscopy and X-ray computed tomography analysis, lithium penetration into the pellet at high temperature has been observed. The penetrated lithium without surface impurities and the high reactivity of LATP at defect sites (atomic structural defects, cracks, voids, etc.) lead to higher interfacial reactivity and earlier thermal runaway. By adding LiPO2F2 to modify those defect sites of the LATP pellet and impede the lithium/SE interfacial reactions, the thermal runaway can be remarkably delayed. This work elucidates the thermal runaway behaviors of Li/LATP pellets in a quasi-practical environment, provides new information about safety issues of ASSBs, and inspires future investigations into this urgent-needed area.

Approaching Practically Accessible Solid-State Batteries: Stability Issues Related to Solid Electrolytes and Interfaces.

Solid-state batteries have been attracting wide attention for next generation energy storage devices due to the probability to realize higher energy density and superior safety performance compared with the state-of-the-art lithium ion batteries. However, there are still intimidating challenges for developing low cost and industrially scalable solid-state batteries with high energy density and stable cycling life for large-scale energy storage and electric vehicle applications. This review presents an overview on the scientific challenges, fundamental mechanisms, and design strategies for solid-state batteries, specifically focusing on the stability issues of solid-state electrolytes and the associated interfaces with both cathode and anode electrodes. First, we give a brief overview on the history of solid-state battery technologies, followed by introduction and discussion on different types of solid-state electrolytes. Then, the associated stability issues, from phenomena to fundamental understandings, are intensively discussed, including chemical, electrochemical, mechanical, and thermal stability issues; effective optimization strategies are also summarized. State-of-the-art characterization techniques and in situ and operando measurement methods deployed and developed to study the aforementioned issues are summarized as well. Following the obtained insights, perspectives are given in the end on how to design practically accessible solid-state batteries in the future.

Element contents in organs and tissues of Chinese adult men.

This study was undertaken to provide reference values for relevant parameters of Chinese Reference Man. Eighteen kinds of major organ or tissue samples, including muscle, rib, liver, and so on, were obtained from autopsies of 68 healthy adult men living in four areas of China with different dietary patterns (Hebei, Shanxi, Sichuan, Jiangxi or Jiangsu provinces, including Shanghai City) who had just encountered sudden deaths. At the same time, whole blood samples were collected from 10 volunteers living in each of these areas. The concentrations of 60 elements in these samples were detected by using inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), neutron activation analysis (NAA), fluorometry (FL), graphite furnace atomic absorption spectrometry (GF-AAS) techniques and necessary quality control (QC) measures. Based on obtained concentrations and reference values of these organ or tissue weights for Chinese Reference Man, the elemental burdens in these organs or tissues were estimated. As a summary report of a series of research studies for Chinese Reference Man, which included three steps (from 1996 to 2006), the concentrations of 60 elements in 18 main organs or tissues were determined and their elemental burdens in the organs or tissues and whole body were estimated. Furthermore, the organ or tissue distributions of some important elements for radiation protection were discussed. These results may provide more reliable and better representative bases than before for establishing related reference values of Chinese Reference Man and revising current reference values of International Commission on Radiological Protection (ICRP) Reference Man. These basic data will also be very valuable for many other applications in radiation protection and other scientific fields.

Study in China on ingestion and organ content of trace elements of importance in radiological protection.

To improve knowledge of the ingestion and organ content of calcium, cesium, iodine, potassium, strontium, thorium, and uranium that have a high priority in radiological protection, a total diet and organ content studies was conducted. The total diet study used the market basket sample method with representative sampling. For the organ content specimens of muscle, skeleton, liver, kidney, lung, and thyroid were collected during autopsies of normal, healthy adult accidental death victims. The concentration of above stated elements in the diet and organs were analyzed by nuclear and nuclear-related techniques with strict quality assurance measures. The results are presented in the paper and compared with previous national and international data and the parameters of current International Commission on Radiological Protection (ICRP) Reference Man. The study provided a new and reliable database for setting the parameters for the Chinese reference man and the reference Asian man. It also facilitated the study on biokinetics behavior of their radiation counterparts in human body and helped in the realistic assessment of their internal radiation doses.