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1. (Digital Presentation) Ultrathin Stabilized Zn Metal Anode for Highly Reversible Aqueous Zn-Ion Batteries

   https://doi.org/10.1149/MA2022-024439mtgabs  

   Zhang, Yuxuan ; Song, Han Wook ; Lee, Sunghwan ( October 2022 , ECS Meeting Abstracts)

   Ever-increasing demands for energy, particularly being environmentally friendly have promoted the transition from fossil fuels to renewable energy.¹Lithium-ion batteries (LIBs), arguably the most well-studied energy storage system, have dominated the energy market since their advent in the 1990s.²However, challenging issues regarding safety, supply of lithium, and high price of lithium resources limit the further advancement of LIBs for large-scale energy storage applications.³Therefore, attention is being concentrated on an alternative electrochemical energy storage device that features high safety, low cost, and long cycle life. Rechargeable aqueous zinc-ion batteries (ZIBs) is considered one of the most promising alternative energy storage systems due to the high theoretical energy and power densities where the multiple electrons (Zn²⁺) . In addition, aqueous ZIBs are safer due to non-flammable electrolyte (e.g., typically aqueous solution) and can be manufactured since they can be assembled in ambient air conditions.⁴As an essential component in aqueous Zn-based batteries, the Zn metal anode generally suffers from the growth of dendrites, which would affect battery performance in several ways. Second, the led by the loose structure of Zn dendrite may reduce the coulombic efficiency and shorten the battery lifespan.⁵

   Several approaches were suggested to improve the electrochemical stability of ZIBs, such as implementing an interfacial buffer layer that separates the active Zn from the bulk electrolyte.⁶However, the and thick thickness of the conventional Zn metal foils remain a critical challenge in this field, which may diminish the energy density of the battery drastically. According to a theretical calculation, the thickness of a Zn metal anode with an areal capacity of 1 mAh cm^-2is about 1.7 μm. However, existing extrusion-based fabrication technologies are not capable of downscaling the thickness Zn metal foils below 20 μm.

   Herein, we demonstrate a thickness controllable coating approach to fabricate an ultrathin Zn metal anode as well as a thin dielectric oxide separator. First, a 1.7 μm Zn layer was uniformly thermally evaporated onto a Cu foil. Then, Al₂O₃, the separator was deposited through sputtering on the Zn layer to a thickness of 10 nm. The inert and high hardness Al₂O₃layer is expected to lower the polarization and restrain the growth of Zn dendrites. Atomic force microscopy was employed to evaluate the roughness of the surface of the deposited Zn and Al₂O₃/Zn anode structures. Long-term cycling stability was gauged under the symmetrical cells at 0.5 mA cm^-2for 1 mAh cm^-2. Then the fabricated Zn anode was paired with MnO₂as a full cell for further electrochemical performance testing. To investigate the evolution of the interface between the Zn anode and the electrolyte, a home-developed in-situ optical observation battery cage was employed to record and compare the process of Zn deposition on the anodes of the Al₂O₃/Zn (demonstrated in this study) and the procured thick Zn anode. The surface morphology of the two Zn anodes after circulation was characterized and compared through scanning electron microscopy. The tunable ultrathin Zn metal anode with enhanced anode stability provides a pathway for future high-energy-density Zn-ion batteries.

   Obama, B., The irreversible momentum of clean energy.Science2017,355(6321), 126-129.

   Goodenough, J. B.; Park, K. S., The Li-ion rechargeable battery: a perspective.J Am Chem Soc2013,135(4), 1167-76.

   Li, C.; Xie, X.; Liang, S.; Zhou, J., Issues and Future Perspective on Zinc Metal Anode for Rechargeable Aqueous Zinc‐ion Batteries.Energy & Environmental Materials2020,3(2), 146-159.

   Jia, H.; Wang, Z.; Tawiah, B.; Wang, Y.; Chan, C.-Y.; Fei, B.; Pan, F., Recent advances in zinc anodes for high-performance aqueous Zn-ion batteries.Nano Energy2020,70.

   Yang, J.; Yin, B.; Sun, Y.; Pan, H.; Sun, W.; Jia, B.; Zhang, S.; Ma, T., Zinc Anode for Mild Aqueous Zinc-Ion Batteries: Challenges, Strategies, and Perspectives.Nanomicro Lett2022,14(1), 42.

   Yang, Q.; Li, Q.; Liu, Z.; Wang, D.; Guo, Y.; Li, X.; Tang, Y.; Li, H.; Dong, B.; Zhi, C., Dendrites in Zn-Based Batteries.Adv Mater2020,32(48), e2001854.

   Acknowledgment

   This work was partially supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 22011044) by KRISS.

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2. In Situ Engineering of Inorganic‐Rich Solid Electrolyte Interphases via Anion Choice Enables Stable, Lithium Anodes

   https://doi.org/10.1002/adma.202305645  

   Weeks, Jason A. ; Burrow, James N. ; Diao, Jiefeng ; Paul‐Orecchio, Austin G. ; Srinivasan, Hrishikesh S. ; Vaidyula, Rinish Reddy ; Dolocan, Andrei ; Henkelman, Graeme ; Mullins, C. Buddie ( December 2023 , Advanced Materials)

   The discovery of liquid battery electrolytes that facilitate the formation of stable solid electrolyte interphases (SEIs) to mitigate dendrite formation is imperative to enable lithium anodes in next‐generation energy‐dense batteries. Compared to traditional electrolyte solvents, tetrahydrofuran (THF)‐based electrolyte systems have demonstrated great success in enabling high‐stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic‐rich SEIs. Herein, by employing a variety of different lithium salts (i.e., LiPF_6,LiTFSI, LiFSI, and LiDFOB), it is demonstrated that electrolyte anions modulate the inorganic composition and resulting properties of the SEI. Through novel analytical time‐of‐flight secondary‐ion mass spectrometry methods, such as hierarchical clustering of depth profiles and compositional analysis using integrated yields, the chemical composition and morphology of the SEIs generated from each electrolyte system are examined. Notably, the LiDFOB electrolyte provides an exceptionally stable system to enable lithium anodes, delivering >1500 cycles at a current density of 0.5 mAh g⁻¹and a capacity of 0.5 mAh g⁻¹in symmetrical cells. Furthermore, Li//LFP cells using this electrolyte demonstrate high‐rate, reversible lithium storage, supplying 139 mAh g_(LFP)⁻¹at C/2 (≈0.991 mAh cm⁻², @ 0.61 mA cm⁻²) with 87.5% capacity retention over 300 cycles (average Coulombic efficiency >99.86%).

    

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3. Concentrated ternary ether electrolyte allows for stable cycling of a lithium metal battery with commercial mass loading high‐nickel NMC and thin anodes

   https://doi.org/10.1002/cey2.275  

   Yang, Jun ; Li, Xing ; Qu, Ke ; Wang, Yixian ; Shen, Kangqi ; Jiang, Changhuan ; Yu, Bo ; Luo, Pan ; Li, Zhuangzhi ; Chen, Mingyang ; et al ( March 2023 , Carbon Energy)

   A new concentrated ternary salt ether‐based electrolyte enables stable cycling of lithium metal battery (LMB) cells with high‐mass‐loading (13.8 mg cm⁻², 2.5 mAh cm⁻²) NMC622 (LiNi_0.6Co_0.2Mn_0.2O₂) cathodes and 50 μm Li anodes. Termed “CETHER‐3,” this electrolyte is based on LiTFSI, LiDFOB, and LiBF₄with 5 vol% fluorinated ethylene carbonate in 1,2‐dimethoxyethane. Commercial carbonate and state‐of‐the‐art binary salt ether electrolytes were also tested as baselines. With CETHER‐3, the electrochemical performance of the full‐cell battery is among the most favorably reported in terms of high‐voltage cycling stability. For example, LiNi_xMn_yCo_1–x–yO₂(NMC)‐Li metal cells retain 80% capacity at 430 cycles with a 4.4 V cut‐off and 83% capacity at 100 cycles with a 4.5 V cut‐off (charge at C/5, discharge at C/2). According to simulation by density functional theory and molecular dynamics, this favorable performance is an outcome of enhanced coordination between Li⁺and the solvent/salt molecules. Combining advanced microscopy (high‐resolution transmission electron microscopy, scanning electron microscopy) and surface science (X‐ray photoelectron spectroscopy, time‐of‐fight secondary ion mass spectroscopy, Fourier‐transform infrared spectroscopy, Raman spectroscopy), it is demonstrated that a thinner and more stable cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are formed. The CEI is rich in lithium sulfide (Li₂SO₃), while the SEI is rich in Li₃N and LiF. During cycling, the CEI/SEI suppresses both the deleterious transformation of the cathode R‐3m layered near‐surface structure into disordered rock salt and the growth of lithium metal dendrites.

    

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4. A Highly Reversible, Dendrite‐Free Lithium Metal Anode Enabled by a Lithium‐Fluoride‐Enriched Interphase

   https://doi.org/10.1002/adma.201906427  

   Cui, Chunyu ; Yang, Chongyin ; Eidson, Nico ; Chen, Ji ; Han, Fudong ; Chen, Long ; Luo, Chao ; Wang, Peng‐Fei ; Fan, Xiulin ; Wang, Chunsheng ( February 2020 , Advanced Materials)

   Metallic lithium is the most competitive anode material for next‐generation lithium (Li)‐ion batteries. However, one of its major issues is Li dendrite growth and detachment, which not only causes safety issues, but also continuously consumes electrolyte and Li, leading to low coulombic efficiency (CE) and short cycle life for Li metal batteries. Herein, the Li dendrite growth of metallic lithium anode is suppressed by forming a lithium fluoride (LiF)‐enriched solid electrolyte interphase (SEI) through the lithiation of surface‐fluorinated mesocarbon microbeads (MCMB‐F) anodes. The robust LiF‐enriched SEI with high interfacial energy to Li metal effectively promotes planar growth of Li metal on the Li surface and meanwhile prevents its vertical penetration into the LiF‐enriched SEI from forming Li dendrites. At a discharge capacity of 1.2 mAh cm⁻², a high CE of >99.2% for Li plating/stripping in FEC‐based electrolyte is achieved within 25 cycles. Coupling the pre‐lithiated MCMB‐F (Li@MCMB‐F) anode with a commercial LiFePO₄cathode at the positive/negative (P/N) capacity ratio of 1:1, the LiFePO₄//Li@MCMB‐F cells can be charged/discharged at a high areal capacity of 2.4 mAh cm⁻²for 110 times at a negligible capacity decay of 0.01% per cycle.

    

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5. Natural protein as novel additive of a commercial electrolyte for Long-Cycling lithium metal batteries

   https://doi.org/10.1016/j.cej.2022.135283  

   Wang, Chenxu ; Fu, Xuewei ; Ying, Chunhua ; Liu, Jin ; Zhong, Wei-Hong ( February 2022 , Chemical engineering journal)

   Suffering from critical instability of lithium (Li) anode, the most commercial electrolytes, carbonate-ester electrolytes, have been restrictedly used in high-energy Li metal batteries (LMBs) despite of their broad implementation in lithium-ion batteries. Here, abundant, natural corn protein, zein, is exploited as a novel additive to stabilize Li anode and effectively prolong the cycling life of LMBs based on carbonate-ester electrolyte. It is discovered that the denatured zein is involved in the formation of solid electrolyte interphase (SEI), guides Li+ deposition and repairs the cracked SEI. In specific, the zein-rich SEI benefits the anion immobilization, enabling uniform Li+ deposition to diminish dendrite growth; the preferential zein-Li reaction effectively repairs the cracked SEI, protecting Li from parasite reactions. The resulting symmetrical Li cell exhibits a prolonged cycling life to over 350 h from <200 h for pristine cell at 1 mA cm􀀀 2 with a capacity of 1 mAh cm^ 2. Paired with LiFePO4 cathode, zein additive markedly improves the electrochemical performance including a higher capacity of 130.1 mAh g^ 1 and a higher capacity retention of ~ 80 % after 200 cycles at 1 C. This study demonstrates a natural protein to be an effective additive for the most commercial electrolytes for advancing performance of LMBs. 

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