Enabling High-Voltage Lithium-Metal Batteries under Practical Conditions

Ren, Xiaodi; Zou, Lianfeng; Cao, Xia; Engelhard, Mark H.; Li, Wen; Burton, Sarah D.; Lee, Hongkyung; Niu, Chaojiang; Matthews, Bethany E.; Zhu, Zihua; Wang, Chongmin; Arey, Bruce W.; Xiao, Jie; Li, Jun; Zhang, Ji‐Guang; Xu, Wu

doi:10.1016/j.joule.2019.05.006

Cited by 711 publications

(727 citation statements)

References 45 publications

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“…This is similar to some previous studies on LHCEs that salt anions instead of solvent molecules would preferably form the passivating SEI layers. [ 9b,14 ] The slight amount of C‐F species (Figure 3i; Figure S11c, Supporting Information) found in the LHCEs indicates the participation of TTE in the SEI formation. As indicated by the AIMD simulation results shown in Figure 1, the higher peak of Li‐O EC than that of Li‐Ovc in Figure 1e,f, respectively, confirms the stronger interaction between Li + and EC in AE003 than that of VC in AE002.…”

Section: Resultsmentioning

confidence: 99%

Advanced Electrolytes for Fast‐Charging High‐Voltage Lithium‐Ion Batteries in Wide‐Temperature Range

Zhang

Zou

et al. 2020

Advanced Energy Materials

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190

167

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IntroductionLithium (Li)-ion batteries (LIBs) have now been the indispensable power sources for portable electronic devices, electric vehicles, stationary or grid applications, etc. [1] However, further efforts on extending the cycle life, rate capability, energy density and working temperature range and improving the safety of LIBs are still facing significant challenges for their large-scale applications. Focusing on the increase in energy density of a battery, the possible approach is to use the high capacity electrode (cathode or anode) material and the high voltage cathode material. Ni-rich layered oxides LiNi x Mn y Co 1−x−y O 2 (NMC) with Ni content ≥80% (e.g., NMC811) are regarded as one of the most potential candidates to usher in the new stage of ultra-high energy density LIBs due to their increased specific capacities at higher voltages and the low cost with less Co content. However, the practical applications of these Ni-rich NMC cathode materials are greatly hindered by the poor cathode-electrolyte interface (CEI) layer formed on such cathode surface in the state-of-the-art electrolytes comprised of lithium hexafluorophosphate (LiPF 6 ) in carbonate solvents, especially at voltages higher than 4.3 V versus Li/Li + , [2] causing continuous electrolyte oxidative decomposition and other related side reactions such as transition metal dissolution from the cathode surface, thus leading to poor cycling stability, especially at elevated temperatures and high operating voltages. [3] Therefore, advanced electrolytes with better oxidative protection to Ni-rich NMC cathode materials, especially under high voltages are critically important for enabling application of Ni-rich NMCs in LIBs.Significant efforts have been made to develop novel electrolytes for high voltage cathode materials, mainly through using high anodic solvents to substitute carbonate solvents, the increase of salt concentration and the utilization of film-forming additives. Fan et al. developed an all-fluorinated electrolyte of 1 m LiPF 6 in fluoroethylene carbonate/3,3,3-fluoroethylmethyl carbonate/1,1,2,2-tetrafluoroethyl-2′,2′,2′-trifluoroethyl ether (FEC/FEMC/HFE, 2:6:2 by wt), which significantly enhanced the cycling stability of Li||NMC811 (2.7-4.4 V) and Li||LiCoPO 4 (3.5-5.0 V) in high voltages by effectively inhibiting electrolyte LiNi x Mn y Co 1−x−y O 2 (NMC) cathode materials with Ni ≥ 0.8 have attracted great interest for high energy-density lithium-ion batteries (LIBs) but their practical applications under high charge voltages (e.g., 4.4 V and above) still face significant challenges due to severe capacity fading by the unstable cathode/electrolyte interface. Here, an advanced electrolyte is developed that has a high oxidation potential over 4.9 V and enables NMC811-based LIBs to achieve excellent cycling stability in 2.5-4.4 V at room temperature and 60 °C, good rate capabilities under fast charging and discharging up to 3C rate (1C = 2.8 mA cm −2 ), and superior low-temperature discharge performance down to −30 °C with a ca...

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Section: Resultsmentioning

confidence: 99%

Advanced Electrolytes for Fast‐Charging High‐Voltage Lithium‐Ion Batteries in Wide‐Temperature Range

Zhang

Zou

et al. 2020

Advanced Energy Materials

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190

167

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“…[ 21a,23 ] However, adding TTE into the IL electrolyte significantly increases the wettability to the PE separator, showing a lower contact angle and rapid penetration (Figure 2e), owing to the low viscosity and surface tension of LCIL. [ 9b,11a ] Therefore, comprehensively studying the solution structure and physicochemical properties reveals that the IL electrolyte design with a higher Li concentration and added TTE enables increasing Li‐ion transport and ionic conductivity while decreasing lower viscosity. Furthermore, high‐energy‐density cells with LCIL may be viable by allowing PE separator use.…”

Section: Resultsmentioning

confidence: 99%

“…For instance, newly proposed localized high‐concentration electrolytes (LHCEs) use HFEs as cosolvents to dilute highly concentrated electrolytes (HCEs), suppressing Li dendrites and thereby increase the CE during high‐rate cycling of LMBs. [ 9 ] Furthermore, excellent fire retardancy [ 10 ] and high‐voltage stability [ 11 ] have been demonstrated using LHCEs that synergistically combine a fire‐retardant solvent and well‐tuned formulation engineering. Therefore, cosolvent strategies that choose appropriate HFEs can offer new possibilities to overcome the challenges of IL‐based electrolytes.…”

Section: Introductionmentioning

confidence: 99%

Safe, Stable Cycling of Lithium Metal Batteries with Low‐Viscosity, Fire‐Retardant Locally Concentrated Ionic Liquid Electrolytes

Lee

Park

Koo

et al. 2020

Adv Funct Materials

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Ionic liquid (IL) electrolytes with concentrated Li salt can ensure safe, high‐performance Li metal batteries (LMBs) but suffer from high viscosity and poor ionic transport. A locally concentrated IL (LCIL) electrolyte with a non‐solvating, fire‐retardant hydrofluoroether (HFE) is presented. This rationally designed electrolyte employs lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1‐methyl‐1‐propyl pyrrolidinium bis(fluorosulfonyl)imide (P13FSI) and 1,1,2,2‐tetrafluoroethyl 2,2,3,3‐tetrafluoropropyl ether (TTE) as the IL and HFE, respectively (1:2:2 by mol). Adding TTE enables a Li‐concentrated IL electrolyte with low viscosity and good separator wettability, facilitating Li‐ion transport to the Li metal anode. The non‐flammability of TTE contributes to excellent thermal stability. Furthermore, synergy between the dual (FSI/TFSI) anions in the LCIL electrolyte can help modify the solid electrolyte interphase, increasing Li Coulombic efficiency and decreasing dendritic Li deposition. LMBs (Li||LiCoO2) employing the LCIL electrolyte exhibit good rate capability (≈89 mAh g−1 at 1.8 mA cm−2, room temperature) and long‐term cycling (≈80% retention after 400 cycles).

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“…32 In spite of their promising features, the practical use of HCEs is hindered 8,33 by their high viscosity, poor ability to wet nonpolar polyolefin separators, and the high cost of Li salts. Although a new class of localized high concentration electrolytes (LHCEs) [34][35][36] obtained by diluting HCEs with ''inert'' co-solvents may ultimately overcome these challenges, new highly compatible electrolytes for both LMAs and highvoltage cathodes that do not employ high salt concentrations are still urgently needed. This clearly calls for new organic solvents with excellent LMA-compatibility.…”

Section: Introductionmentioning

confidence: 99%

FSI-inspired solvent and “full fluorosulfonyl” electrolyte for 4 V class lithium-metal batteries

Xue

Shi

Huang

et al. 2020

Energy Environ. Sci.

225

169

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Enabling High-Voltage Lithium-Metal Batteries under Practical Conditions

Cited by 711 publications

References 45 publications

Advanced Electrolytes for Fast‐Charging High‐Voltage Lithium‐Ion Batteries in Wide‐Temperature Range

Advanced Electrolytes for Fast‐Charging High‐Voltage Lithium‐Ion Batteries in Wide‐Temperature Range

Safe, Stable Cycling of Lithium Metal Batteries with Low‐Viscosity, Fire‐Retardant Locally Concentrated Ionic Liquid Electrolytes

FSI-inspired solvent and “full fluorosulfonyl” electrolyte for 4 V class lithium-metal batteries

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