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1. Solid-state polymer-particle hybrid electrolytes: Structure and electrochemical properties

   https://doi.org/10.1126/sciadv.ado4719  

   Utomo, Nyalaliska W; Hong, Shifeng; Sinha, Ritwick; Kim, Keun-il; Deng, Yue; Ochonma, Prince; Kitahata, Minori G; Garcia-Mendez, Regina; Joo, Yong L; Archer, Lynden A (July 2024, Science Advances)

   Solid-state electrolytes (SSEs) are challenged by complex interfacial chemistry and poor ion transport through the interfaces they form with battery electrodes. Here, we investigate a class of SSE composed of micrometer-sized lithium oxide (Li₂O) particles dispersed in a polymerizable 1,3-dioxolane (DOL) liquid. Ring-opening polymerization (ROP) of the DOL by Lewis acid salts inside a battery cell produces polymer-inorganic hybrid electrolytes with gradient properties on both the particle and battery cell length scales. These electrolytes sustain stable charge-discharge behavior in Li||NCM811 and anode-free Cu||NCM811 electrochemical cells. On the particle length scale, Li₂O retards ROP, facilitating efficient ion transport in a fluid-like region near the particle surface. On battery cell length scales, gravity-assisted settling creates physical and electrochemical gradients in the hybrid electrolytes. By means of electrochemical and spectroscopic analyses, we find that Li₂O particles participate in a reversible redox reaction that increases the effective CE in anode-free cells to values approaching 100%, enhancing battery cycle life. 

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2. Poor Stability of Li ₂ CO ₃ in the Solid Electrolyte Interphase of a Lithium‐Metal Anode Revealed by Cryo‐Electron Microscopy

   https://doi.org/10.1002/adma.202100404  

   Han, Bing; Zhang, Zhen; Zou, Yucheng; Xu, Kang; Xu, Guiyin; Wang, Hong; Meng, Hong; Deng, Yonghong; Li, Ju; Gu, Meng (April 2021, Advanced Materials)

   Abstract The solid electrolyte interphase (SEI) dictates the cycling stability of lithium‐metal batteries. Here, direct atomic imaging of the SEI's phase components and their spatial arrangement is achieved, using ultralow‐dosage cryogenic transmission electron microscopy. The results show that, surprisingly, a lot of the deposited Li metal has amorphous atomic structure, likely due to carbon and oxygen impurities, and that crystalline lithium carbonate is not stable and readily decomposes when contacting the lithium metal. Lithium carbonate distributed in the outer SEI also continuously reacts with the electrolyte to produce gas, resulting in a dynamically evolving and porous SEI. Sulfur‐containing additives cause the SEI to preferentially generate Li₂SO₄and overlithiated lithium sulfate and lithium oxide, which encapsulate lithium carbonate in the middle, limiting SEI thickening and enhancing battery life by a factor of ten. The spatial mapping of the SEI gradient amorphous (polymeric → inorganic → metallic) and crystalline phase components provides guidance for designing electrolyte additives. 

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3. Li–O ₂ /Air Batteries Using Ionic Liquids – A Comprehensive Review

   https://doi.org/10.1002/aenm.202300985  

   Zaidi, Syed Shoaib Hassan; Li, Xianglin (June 2023, Advanced Energy Materials)

   Abstract The remarkable surge in energy demand has compelled the quest for high‐energy‐density battery systems. The Li–O₂battery (LOB) and Li–air battery (LAB), owing to their extremely high theoretical energy density, have attracted extensive research in the past two decades. The commercial development of LOB is hampered due to the numerous challenges its components present. Ionic liquids (ILs) are considered potential electrolyte solvents of LOBs and LABs due to their excellent electrochemical stability, thermal stability, non‐flammability, low flammability, and O₂solubility. In addition to electrolyte solvents, ILs also have other applications in LOB and LAB systems. This review reports the progress of IL‐based LOBs and LABs over the years since treported for the first time in 2005. The impact of the physiochemical properties of ILs on the performance of LOB and LAB at various operating conditions is thoroughly discussed. The various methodologies are also summarized that are employed to tune ILs’ physiochemical properties to render them more favorable for rechargeable lithium batteries. Tunable properties of ILs create the possibility of designing cost‐effective batteries with excellent safety, high energy density and high power density, and long‐term stability. 

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4. Lithium‐Ion Mobility in Layered Oxide Li ₂ (La _0.75 Li _0.25 )(Ta _1.5 Ti _0.5 )O ₇ Containing Lithium on both Intra and Inter‐Stack Positions

   https://doi.org/10.1002/ejic.202100950  

   Fanah, Selorm_Joy; Ramezanipour, Farshid (February 2022, European Journal of Inorganic Chemistry)

   Abstract With the aid of neutron diffraction and electrochemical impedance spectroscopy, we have demonstrated the effect of the increase in lithium concentration and distribution on Li‐ion conductivity. This has been done through the synthesis of a layered oxide Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇, with the so‐called Ruddlesden‐Popper type structure, where bilayer stacks of (Ta/Ti)O₆octahedra are separated by lithium ions, located in inter‐stack spaces. There are also intra‐stack spaces that are occupied by a mixture of La and Li, as confirmed by neutron diffraction. The distribution of lithium over both inter‐ and intra‐stack positions leads to the enhancement of Li‐ion conductivity in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇compared to Li₂La(TaTi)O₇, which has a lower concentration of lithium ions, located only in inter‐stack spaces. The analyses of real and imaginary components of electrochemical impedance data confirm the enhanced mobility of ions in Li₂(La_0.75Li_0.25)(Ta_1.5Ti_0.5)O₇. While the Li‐ion conductivity needs further improvement for practical applications, the success of the strategy implemented in this work offers a useful methodology for the design of layered ionic conductors. 

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5. Ambient‐Pressure Relithiation of Degraded Li _x Ni _0.5 Co _0.2 Mn _0.3 O ₂ (0 < x < 1) via Eutectic Solutions for Direct Regeneration of Lithium‐Ion Battery Cathodes

   https://doi.org/10.1002/aenm.201900454  

   Shi, Yang; Zhang, Minghao; Meng, Ying_Shirley; Chen, Zheng (April 2019, Advanced Energy Materials)

   Abstract With the rapid growth of the lithium‐ion battery (LIBs) market, recycling and re‐use of end‐of‐life LIBs to reclaim lithium (Li) and transition metal (TM) resources (e.g., Co, Ni), as well as eliminating pollution from disposal of waste batteries, has become an urgent task. Here, for the first time the ambient‐pressure relithiation of degraded LiNi_0.5Co_0.2Mn_0.3O₂(NCM523) cathodes via eutectic Li⁺molten‐salt solutions is successfully demonstrated. Combining such a low‐temperature relithiation process with a well‐designed thermal annealing step, NCM523 cathode particles with significant Li loss (≈40%) and capacity degradation (≈50%) can be successfully regenerated to achieve their original composition and crystal structures, leading to effective recovery of their capacity, cycling stability, and rate capability to the levels of the pristine materials. Advanced characterization tools including atomic resolution electron microscopy imaging and electron energy loss spectroscopy are combined to demonstrate that NCM523's original layered crystal structure is recovered. For the first time, it is shown that layer‐to‐rock salt phase change on the surfaces and subsurfaces of the cathode materials can be reversed if lithium can be incorporated back to the material. The result suggests the great promise of using eutectic Li⁺molten–salt solutions for ambient‐pressure relithiation to recycle and remanufacture degraded LIB cathode materials. 

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