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1. Enabling rechargeable Li‐MnO ₂ batteries using ether electrolytes

   https://doi.org/10.1002/smm2.1208  

   Xia, Dawei; Gao, Hongpeng; Li, Mingqian; Holoubek, John; Yan, Qizhang; Yin, Yijie; Xu, Panpan; Chen, Zheng (October 2023, SmartMat)

   Abstract A low‐carbon future demands more affordable batteries utilizing abundant elements with sustainable end‐of‐life battery management. Despite the economic and environmental advantages of Li‐MnO₂batteries, their application so far has been largely constrained to primary batteries. Here, we demonstrate that one of the major limiting factors preventing the stable cycling of Li‐MnO₂batteries, Mn dissolution, can be effectively mitigated by employing a common ether electrolyte, 1 mol/L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,3‐dioxane (DOL)/1,2‐dimethoxyethane (DME). We discover that the suppression of this dissolution enables highly reversible cycling of the MnO₂cathode regardless of the synthesized phase and morphology. Moreover, we find that both the LiPF₆salt and carbonate solvents present in conventional electrolytes are responsible for previous cycling challenges. The ether electrolyte, paired with MnO₂cathodes is able to demonstrate stable cycling performance at various rates, even at elevated temperature such as 60°C. Our discovery not only represents a defining step in Li‐MnO₂batteries with extended life but provides design criteria of electrolytes for vast manganese‐based cathodes in rechargeable batteries. 

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2. A Green, Fire‐Retarding Ether Solvent for Sustainable High‐Voltage Li‐Ion Batteries at Standard Salt Concentration

   https://doi.org/10.1002/aenm.202400773  

   Xia, Dawei; Tao, Lei; Hou, Dong; Hu, Anyang; Sainio, Sami; Nordlund, Dennis; Sun, Chengjun; Xiao, Xianghui; Li, Luxi; Huang, Haibo; et al (October 2024, Advanced Energy Materials)

   Abstract Lithium‐ion batteries (LIBs) are increasingly encouraged to enhance their environmental friendliness and safety while maintaining optimal energy density and cost‐effectiveness. Although various electrolytes using greener and safer glyme solvents have been reported, the low charge voltage (usually lower than 4.0 V vs Li/Li⁺) restricts the energy density of LIBs. Herein, tetraglyme, a less‐toxic, non‐volatile, and non‐flammable ether solvent, is exploited to build safer and greener LIBs. It is demonstrated that ether electrolytes, at a standard salt concentration (1 m), can be reversibly cycled to 4.5 V vs Li/Li⁺. Anchored with Boron‐rich cathode‐electrolyte interphase (CEI) and mitigated current collector corrosion, the LiNi_0.8Mn_0.1Co_0.1O₂(NMC811) cathode delivers competitive cyclability versus commercial carbonate electrolytes when charged to 4.5 V. Synchrotron spectroscopic and imaging analyses show that the tetraglyme electrolyte can sufficiently suppress the overcharge behavior associated with the high‐voltage electrolyte decomposition, which is advantageous over previously reported glyme electrolytes. The new electrolyte also enables minimal transition metal dissolution and deposition. NMC811||hard carbon full cell delivers excellent cycling stability at C/3 with a high average Coulombic efficiency of 99.77%. This work reports an oxidation‐resilient tetraglyme electrolyte with record‐high 4.5 V stability and enlightens further applications of glyme solvents for sustainable LIBs by designing Boron‐rich interphases. 

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3. Cycling Performance and Structure Evolution of Co-Free Lithium- and Manganese-Rich Layered Oxides in Lithium-Ion Batteries

   https://doi.org/10.1149/1945-7111/ae2890  

   Badami, Pavan P; Kwok, Chun Yuen; Gargye, Avi; Trask, Stephen E; Dogan, Fulya; Lopez, Antonio T; Croy, Jason R; Balasubramanian, M; Abraham, Daniel P (December 2025, Journal of The Electrochemical Society)

   Lithium- and manganese-rich (LMR) layered oxides are high-capacity cathode materials that are being considered for electric vehicle (EV) lithium-ion batteries (LIBs). Here, we investigate the electrochemical cycling behavior of cells containing a cobalt-free LMR oxide, 0.3Li₂MnO₃·0.7LiMn_0.5Ni_0.5O₂, paired with either Li or graphite anodes. Two- and three-electrode cells are cycled under varying conditions to examine the effects of oxide activation, upper cutoff voltage, separator type, and electrolyte composition. Post-cycling characterization of harvested electrodes, with electrochemical, X-ray absorption spectroscopy, and solid-state⁶Li nuclear magnetic resonance spectroscopy techniques, are used to correlate cell performance changes with redox state evolution in the oxide and Li inventory shifts in the cell. Our results show that capacity fade and impedance rise primarily originate at the graphite anode and LMR cathode, respectively. Notably, while Ni undergoes reversible redox, Mn shows no evidence of bulk redox activity even in highly-aged electrodes: only relithiated LMR electrodes show some reduction of Mn. Graphite electrodes degrade due to particle isolation and SEI growth, exacerbated by Mn dissolution and deposition on graphite anodes. These findings highlight the coupled structural and electrochemical degradation mechanisms in LMR/graphite cells and underscore lithium inventory retention and electrode interfacial stability as critical factors for enhancing long-term performance. 

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4. Size-Dependent Reaction Mechanism of λ -MnO ₂ Particles as Cathodes in Aqueous Zinc-Ion Batteries

   https://doi.org/10.34133/2022/9765710  

   Tang, Zhichu; Chen, Wenxiang; Lyu, Zhiheng; Chen, Qian (February 2022, Energy Material Advances)

   Manganese dioxide (MnO 2 ) with different crystal structures has been widely investigated as the cathode material for Zn-ion batteries, among which spinel λ -MnO 2 is yet rarely reported because Zn-ion intercalation in spinel lattice is speculated to be limited by the narrow three-dimensional tunnels. In this work, we demonstrate that Zn-ion insertion in spinel lattice can be enhanced by reducing particle size and elucidate an intriguing electrochemical reaction mechanism dependent on particle size. Specifically, λ -MnO 2 nanoparticles (NPs, ~80 nm) deliver a high capacity of 250 mAh/g at 20 mA/g due to large surface area and solid-solution type phase transition pathway. Meanwhile, severe water-induced Mn dissolution leads to the poor cycling stability of NPs. In contrast, micron-sized λ -MnO 2 particles (MPs, ~0.9  μ m) unexpectedly undergo an activation process with the capacity continuously increasing over the first 50 cycles, which can be attributed to the formation of amorphous MnO x nanosheets in the open interstitial space of the MP electrode. By adding MnSO 4 to the electrolyte, Mn dissolution can be suppressed, leading to significant improvement in the cycling performance of NPs, with a capacity of 115 mAh/g retained at 1 A/g for over 500 cycles. This work pinpoints the distinctive impacts of the particle size on the reaction mechanism and cathode performance in aqueous Zn-ion 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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