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1. 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)

   Abstract 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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2. Chaotropic Salt‐Aided “Water‐In‐Organic” Electrolyte for Highly Reversible Zinc‐Ion Batteries Across a Wide Temperature Range

   https://doi.org/10.1002/adfm.202311271  

   Wang, Ziqing; Diao, Jiefeng; Burrow, James_N; Brotherton, Zachary_W; Lynd, Nathaniel_A; Henkelman, Graeme; Mullins, Charles_Buddie (November 2023, Advanced Functional Materials)

   Abstract Aqueous zinc‐ion batteries are promising alternatives to lithium‐ion batteries due to their cost‐effectiveness and improved safety. However, several challenges, including corrosion, dendrites, and water decomposition at the Zn anode, hinder their performance. Herein, an approach is proposed, that deviates from the conventional design by adding water into a propylene carbonate‐based organic electrolyte to prepare a non‐flammable “water‐in‐organic” electrolyte. The chaotropic salt Zn(ClO₄)₂exploits the Hofmeister effect to promote the miscibility of immiscible liquid phases. Interactions between propylene carbonate and water restrict water activity and mitigate unfavorable reactions. This electrolyte facilitates preferential Zn (002) deposition and the formation of solid electrolyte interphase. Consequently, the “water‐in‐organic” electrolyte achieves a 99.5% Coulombic efficiency at 1 mA cm⁻²over 1000 cycles in Zn/Cu cells, and constant cycling over 1000 h in Zn/Zn symmetric cells. A Na_0.33V₂O₅/Zn battery exhibits impressive cycling stability with a capacity of 175 mAh g⁻¹for 800 cycles at 2 A g⁻¹. Additionally, this electrolyte enables sustainable cycling across a wide temperature range from −20 to 50 °C. The design of a “water‐in‐organic” electrolyte employing a chaotropic salt presents a potential strategy for high‐performance electrolytes in zinc‐ion batteries with a large stability window and a wide temperature range. 

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3. Fine‐Tuning Li‐Ion Solvation Structure by Enhanced Solvent‐Diluent Interactions for Long‐Cycling Lithium Metal Batteries

   https://doi.org/10.1002/aenm.202405680  

   Li, Guo‐Xing; Lyu, Xingyi; Nguyen, Au; Kou, Rong; George, Christy; Wu, Siyu; Li, Ruipeng; Wang, Ke; Li, Tao; Wang, Donghai (February 2025, Advanced Energy Materials)

   Abstract Achieving durable lithium (Li) metal anodes in liquid electrolytes remains challenging, primarily due to the instability of the formed solid‐electrolyte interphases (SEIs). Modulating the Li‐ion solvation structures is pivotal in forming a stable SEI for stabilizing Li metal anodes. Here a strategy is developed to fine‐tune the Li‐ion solvation structures through enhanced dipole–dipole interactions between the Li‐ion‐coordinated solvent and the non‐Li‐ion‐coordinating diluent, for creating a stable SEI in the developed binary salt electrolyte. The enhanced dipole–dipole interactions weaken the coordination between Li‐ions and the solvents while strengthening the interaction between Li‐ions and dual anions, thereby facilitating the Li‐ion transport and a robust anion‐derived SEI with a distinct bilayer structure. Consequently, the developed electrolyte exhibited exceptional electrochemical performance in high energy‐density Li||LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cells, with long calendar life, stable cyclability at 1 C, and reliable operation between 25 and −20 °C, and it also demonstrat remarkable cycling stability for a Li||NMC811 pouch cell with projected energy density of 402 Wh kg⁻¹, maintaining 80% capacity retention over 606 cycles under practical conditions. 

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4. Prelithiation of Alloy Anodes via Roll Pressing for Solid‐State Batteries

   https://doi.org/10.1002/adma.202508973  

   Wang, Congcheng; Jeong, Won_Joon; Nelson, Douglas_Lars; Sridhara, Hari; Anderson, Sophia_Nicolette; McDowell, Matthew_T (August 2025, Advanced Materials)

   Abstract Solid‐state batteries with alloy‐type negative electrodes can feature enhanced energy density and safety compared to conventional Li‐ion batteries. However, diffusional Li trapping within Li alloys often causes low initial Coulombic efficiency and leads to capacity loss with cycling. Here, a general roll‐pressing prelithiation method compatible with a variety of alloy‐type negative electrodes (silicon, aluminum, tin, and multi‐phase alloys) is introduced, which is shown to improve performance in solid‐state batteries. By warm‐rolling lithium foil of controlled thickness with various alloy‐type electrodes, both slurry‐cast and foil‐type electrodes can be uniformly prelithiated via direct chemical reaction. The prelithiated electrodes exhibit enhanced specific capacity and extended cycle life in batteries with Li₆PS₅Cl solid‐state electrolyte. Prelithiated multi‐phase foil electrodes with a tailored interface are shown to exhibit superior cycling stability down to 2 MPa stack pressure. This prelithiation technique offers a pathway to overcome intrinsic challenges in alloy anodes for solid‐state batteries. 

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5. 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)

   Abstract 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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