Constructing a Stable Lithium Metal–Gel Electrolyte Interface for Quasi

Letter Cite This: ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

www.acsami.org

Constructing a Stable Lithium Metal−Gel Electrolyte Interface for Quasi-Solid-State Lithium Batteries Tong-Tong Zuo,†,§ Yang Shi,†,§ Xiong-Wei Wu,‡ Peng-Fei Wang,†,§ Shu-Hua Wang,† Ya-Xia Yin,†,§ Wen-Peng Wang,†,§ Qiang Ma,†,‡ Xian-Xiang Zeng,†,‡ Huan Ye,† Rui Wen,*,†,§ and Yu-Guo Guo*,†,§

Downloaded via UNIV OF SOUTH DAKOTA on September 13, 2018 at 07:42:31 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

†

CAS Key Laboratory of Molecular Nanostructure and Nanotechnology, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, P. R. China ‡ College of Science, Hunan Agricultural University, Changsha 410128, P. R. China § University of Chinese Academy of Sciences, Beijing 100049, P. R. China S Supporting Information *

ABSTRACT: Interfacial problems, including interfacial stability and contact issues, severely plague the practical application of Li metal anodes. Here we report an interfacial regulation strategy that stabilizes the Li metal-gel electrolyte interface through in situ constructing a stable solid electrolyte interphase (SEI) layer. By stabilizing the interface of Li metal anodes, the gel electrolyte enables dendrite-free morphology and high plating/stripping efficiency. A systematic analysis further confirms that the formed SEI layer is responsible for homogeneous deposition and stable cycling performance. Benefiting from the interfacial stability between electrodes and electrolytes, the lifespan of Li metal batteries is extended. KEYWORDS: Li metal batteries, Li metal anode, gel electrolyte, interfacial stability, solid-state batteries, double polymer network

L

SSEs are nonleaking and can block dendrite penetration, which decrease the possibility of short circuiting and thermal runaway.16,17 Unfortunately, owing to poor interfacial contact and huge volume change between SSEs and electrodes, the interfacial issues become more challenging.18,19 Gel electrolytes, which can balance safety concerns and interfacial issues, are a promising candidate for high-performance and safe LMBs.20,21 Currently, extensive efforts have been devoted by designing robust polymer networks and introducing functional fillers to improve mechanical strength and ionic conductivity of gel electrolytes, respectively.22,23 However, there are few studies focusing on the interfacial chemistry between Li metal anodes and gel electrolytes, although the interfacial stability is of great importance for improving deposition behavior, Coulombic efficiency and cycling performance.24,25 In this work, we regulate the interfacial stability by in situ forming a favorable SEI layer to stabilize the Li metal-gel electrolyte interface. The double polymer network gel electrolyte (dpn-GE) was prepared via a one-step photopolymerization method (find more details in Supporting Information).26 This facile and scalable preparation process is schematically shown in Figure 1a, an interpenetrating poly(ether-acrylate) network containing silica microspheres is

i metal batteries (LMBs) with high energy density show great potential in meeting the continuously surging demands for electric vehicles and smart grid storage.1 In LMBs, Li metal plays an irreplaceable role as an anode material, especially in Li-free cathode systems (i.e., Li−sulfur and Li−air batteries). Despite high specific capacity (3860 mA h g−1) and low electrochemical potential (−3.04 V vs standard hydrogen electrode),2−4 Li metal anodes still face great challenges for commercial applications. The high reactivity of Li metal induces side reactions with organic electrolytes, thus forming solid electrolyte interphase (SEI). Because of the huge volume change during Li plating, the brittle and unstable SEI layer cracks, which further exacerbates inhomogeneous deposition and dendrite formation. Moreover, the ceaseless breakage/formation of SEI consumes both Li metal and electrolyte, leading to low Coulombic efficiency and battery failure. As a result, interfacial problems are the root of plaguing the practical applications of Li metal anodes.5 Most recently, a number of approaches have been adopted to address interfacial issues through engineering the composition and structure of SEI,6 including electrolyte additives,7,8 artificial solid electrolyte interphase layers,9−11 and modified electrodes.12−14 Given the safety hazards of electrolyte leakage and the inherent instability between Li metal and liquid electrolyte, replacing liquid electrolytes (LEs) with solid-state electrolytes (SSEs) or gel electrolytes is considered as an effective solution for building safer LMBs.15 © 2018 American Chemical Society

Received: July 31, 2018 Accepted: August 24, 2018 Published: August 24, 2018 30065

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

Letter

ACS Applied Materials & Interfaces

Figure 1. (a) Schematic illustrations of dpn-GE composition and uniform plating/stripping process. (b) TGA curves of PEO, polyacrylate, TEGDME, and dpn-GE. (c) Electrochemical impedance spectra of the dpn-GE at different temperatures ranging from 20 to 80 °C. (d) Current− time plot during polarization of Li|dpn-GE|Li cell at an applied voltage of 10 mV, the inset shows electrochemical impedance spectra before and after polarization.

Figure 2. Top-view SEM images of Li deposit with (a) LE and (d) dpn-GE. Cross-sectional view SEM images of Li deposit with (b) LE and (e) dpn-GE. (c) Galvanostatic charge/discharge profiles of Li|dpn-GE|Cu cell at a current density of 0.5 mA cm−2 with a deposition capacity of 1 mA h cm−2. (f) Coulombic efficiencies of different electrolytes at a current density of 0.5 mA cm−2 with a deposition capacity of 1 mA h cm−2.

Figure 1b shows the thermogravimetric analyses of dpn-GE and its components. The dpn-GE remains stable until 150 °C, implying high tolerable temperature. The weight loss resulting from solvent evaporation is ∼55%, indicating good solvent uptake capability of double polymer network. Sufficient solvent uptake of dpn-GE guarantees enhanced ionic conductivity and better interfacial contact. Considering the thermal safety of electrolytes is of great importance for safe LMBs, combustion experiments were also carried out. As shown in Figure S1, the commercial ether electrolyte with 1,3-dioxolane/1,2-dimethoxyethane (DOL/DME) solvent is flammable. In contrast, the LE and dpn-GE containing TEGDME solvent are hardly ignited when exposed to the flame, corresponding to the nonflammable property of TEGDME solvent. Electrochemical properties of gel electrolytes, such as ionic conductivity, transference number and electrochemical stability, are critical to their practical performance in LMBs. According to electrochemical impedance spectra (Figure 1c), the ionic conductivity of dpn-GE reaches 6.4 × 10−4 S cm−1 at 25 °C, enabling battery operation at room temperature. The amorphous structure of dpn-GE in Figure S2 also suggests improved ionic conductivity. In addition, the low activation

applied as tough scaffold materials, in which lithium bis(trifluoromethane)sulfonamide (LiTFSI) is dissolved in tetraethylene glycol dimethyl ether (TEGDME) solvent. With the aim of regulating SEI components, lithium nitrate (LiNO3) was utilized to generate a stable SEI layer through interfacial reactions. The as-obtained dpn-GE exhibits several advantages: (1) good thermal stability and mechanical property; (2) high room-temperature ionic conductivity and transference number; (3) favorable interfacial contact with electrodes; (4) stable Li metal-gel electrolyte interface. Combining all above merits, dpn-GE enables homogeneous deposition and highly reversible plating/stripping process. A direct visualization of dendrite-free deposition and interface evolution is provided by operando optical microscopy. The combined analysis of electrochemical performance, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) further demonstrates the stable interface is favorable to smooth deposition morphology and superior cycling stability. Moreover, the good cycling performance of different LMBs (Li-LiFePO4 and Li−Se batteries) in this work illustrates the importance of stabilizing Li metal anodes. 30066

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

Letter

ACS Applied Materials & Interfaces

Figure 3. (a) Schematic illustration of the cell device for operando optical microscopy. (b) Galvanostatic plating/stripping profile and the corresponding optical images after cycling (c) 0, (d) 1, (e, f) 2, (g) 3, (h) 4, (i) 6, and (j) 8 h.

LE and dpn-GE, and then measured the Coulombic efficiency based on the ratio of stripping and plating capacity. The Coulombic efficiency of LE starts to decrease after 22 cycles, which may result from inhomogeneous deposition and “dead Li” formation. In contrast, the dpn-GE ensures high Coulombic efficiencies of ∼97% after 100 cycles. These improvements imply that dpn-GE guides homogeneous Li deposition and protects anodes from excess side reactions. To visualize the deposition behavior and interfacial evolution during electrochemical plating, we conducted operando optical microscopy with a special cell device. Operando cells were assembled with symmetric Li metal electrodes and different electrolytes (Figure 3a). For LE, Li electrode displays obvious dendritic morphology after plating 4 mA h cm−2 (Figure S5), corresponding to SEM results. Another cell with dpn-GE was also assembled to elucidate the dendrite suppression of dpn-GE. Li metal was plated and stripped between two electrodes at a current density of ∼2 mA cm−2. Combined with the voltage profile under galvanostatic control (Figure 3b), optical images were in situ monitored at the Li/dpn-GE interface during Li plating/stripping processes, as shown in Figure 3c−j. During Li plating, the interface between Li electrode and dpn-GE remains smooth without dendrite formation. After plating 2 h, the Li deposit layer marked with white dashed lines (Figure 3f) possesses a uniform thickness of about 20 μm, which coincides with the theoretical deposition capacity. As a result, dpn-GE can maintain a uniform interface and prevent dendrite proliferation even plating 4 mA h cm−2 due to its mechanical strength. It should be emphasized that the huge volume change of Li anodes during cycling generally hinders continuous interfacial

energy (0.26 eV) of dpn-GE is calculated from the temperature-dependent impedance spectra (Figure S3), which implies facilitated ion transfer.27 In contrast with low Li+ ion transference number (t+) of commercial LE (∼0.2),28 dpnGE possess a high t+ of 0.54 (Figure 1d), which is beneficial to guarantee effective Li+ ion transportation and prevent space charge formation.26 These results suggest that dpn-GE could provide a favorable interfacial environment for reversible plating/stripping Li. The electrochemical stability of dpn-GE was also investigated in different voltage ranges. As shown in Figure S5a, cyclic voltammetry was performed in a voltage range of −0.5−1 V. The sharp reduction and oxidation peaks are attributed to the reversible Li deposition and dissolution processes, respectively. The linear sweep voltammetry (Figure S5b) indicates that dpn-GE remains stable at 4.8 V versus Li+/ Li, suggesting a broad electrochemical window. The electrochemical stability demonstrates that dpn-GE possesses favorable compatibility with both cathodes and Li metal anodes. The Li plating behaviors with dpn-GE and LE (1 M LiTFSI dissolved in DOL/DME with 1% LiNO3) were compared with SEM. As shown in Figure 2a, the plated Li with LE exhibits dendritic morphology. In contrast, the electrode assembled with dpn-GE displays spherical morphology after plating (Figure 2d). From the inset images, one can clearly observe that Li deposit with dpn-GE is much more uniform than that with LE. The side-view SEM image (Figure 2b, e) further demonstrates that Li metal is densely plated instead of dendrite formation, suggesting that dpn-GE enables the anode to be dendrite-free morphology. In order to evaluate the reversibility of the plating/stripping process, we assembled Li|Cu cells with 30067

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

Letter

ACS Applied Materials & Interfaces

Figure 4. (a) Cycling performance of Li symmetric cell with dpn-GE at a current density of 0.5 mA cm−2. The inset shows enlarged plating/ stripping curves at different stages. SEM images of Li electrodes after cycling (b) 0, (c) 10, (d) 40, (e) 100, and (f) 400 h. XPS spectra of cycled Li electrodes after cycling (g, l) 0, (h, m) 10, (i, n) 40, (j, o) 100, and (k, p) 400 h. The star symbols of different colors represent different cycling stages.

contact between SSEs and Li metal anodes.15,19 In our case, dpn-GE exhibits a self-regulation behavior to mitigate the compressive stress stemming from huge volume change. Video S1 clearly shows that dpn-GE shrinks during deposition and recovers during dissolution, suggesting that flexible gel electrolyte is capable of enduring huge volume variation and maintaining intimate interfacial contact with electrodes. In addition, it can be obviously observed that the morphology at Li electrode/dpn-GE interface remains dendrite-free upon 2 cycles (Figure 3i, j), which indicates reversible plating/ stripping process and promises good cycling performance. Symmetric Li cells were assembled to evaluate the voltage stability of dpn-GE in LMBs, Figure S6 shows the galvanostatic charge/discharge profile at a current density of 0.2 mA cm−2. After 1000 h, the symmetric cell exhibits stable voltage hysteresis, suggesting uniform plating/stripping process and excellent cycling performance. To further explore the detailed interfacial stability at a higher current density of 0.5 mA cm−2, we simultaneously monitored the voltage stability, electrode morphology and SEI components by electrochemical tests, SEM, and XPS analyses, respectively. As shown in Figure 4a, the voltage polarization remains stable over 400 h, and smooth plateaus at different stages illustrate favorable charge transfer kinetic. Note that the voltage fluctuation during first cycles could be attributed to SEI formation, which is further demonstrated with XPS results subsequently. Post-mortem analyses of Li electrodes at different stages were performed via SEM and XPS. The surface of Li electrode maintains dendritefree morphology after cycling 400 h (Figure 4b−f). As shown in Figure 4g−p, the SEI layer containing ROLi, ROCOOLi and LiNxOy species forms during initial cycles and remains stable during continuous deposition/dissolution reactions.

According to previous literature,29,30 the SEI components are derived from organic solvents and LiNO3 additive; the latter provides rapid diffusion through the interface and guarantees uniform plating/stripping and good cycling performance.30 To evaluate the potential applications of dpn-GE in LMBs, we assembled full cells with Li metal anodes and LiFePO4 (LFP) or Se/C cathodes. It also should be noted that these full cell tests were performed at room temperature for these prominent properties of dpn-GE, i.e., high ionic conductivity, tough mechanical strength, favorable interfacial contacts with electrodes and good interfacial stability toward Li metal. As shown in Figure S7, the initial specific capacity of the Li|LFP cell with dpn-GE is 159 mA h g−1 at 0.1 C. At a higher rate of 0.5 C, the cell exhibits an initial capacity of 140 mA h g−1 and maintains 124 mA h g−1 with stable Coulombic efficiencies after 100 cycles. Both high specific capacity and good cycling performance illustrate the practical potential of dpn-GE. To further demonstrate the advantage of stable interphase and high Coulombic efficiency, a thin Li foil with a thickness of ∼50 μm, rather than common Li foils with the thickness around 550 μm, was applied as anode in Li−Se batteries. Li|Se full cell were assembled with Se/C cathodes (∼0.75 mA h cm−2) and Li metal anodes (∼10 mA h cm−2). For the Li|Se cell with ether-based LE, the specific capacity decays after 50 cycles and maintains only 390 mA h g−1 at 0.2 C (Figure S8a), which is attributed to the loss of active materials. In contrast, the full cell with dpn-GE exhibits a high capacity of 580 mA h g−1 after 50 cycles. This result indicates that the stable interface is able to prevent side reactions between Li metal and dissolved polyselenides. Similar enhancement is achieved at a higher rate of 0.5C (Figure S8b, c), the cell with LE shows rapid capacity decay after 62 cycles. The limited lifespan of Li− 30068

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

ACS Applied Materials & Interfaces

■

Se batteries may come from the instable interface of Li metal and incur low Li utilization. However, the cell with dpn-GE maintains high capacity retention of 79% after 100 cycles, implying high plating/stripping reversibility and good cycling performance. Hence, the improved interfacial stability stemming from dpn-GE ensures high Li utilization and cycling stability for future high-energy LMBs. In summary, we stabilize the Li metal-gel electrolyte interface through in situ constructing a stable SEI layer on Li metal anodes. Benefiting from the stable interface endowed by dpn-GE, dendrite-free morphology and impressive plating/ stripping efficiency have been achieved in quasi-solid-state LMBs. Operando optical observation clearly illustrates the uniform deposition of Li metal and self-regulation behaviors of dpn-GE. XPS results further confirms that the favorable interfacial layer is derived from LiNO3 additive, which is beneficial to dendrite-free deposition and cycling stability in symmetric Li cells. By stabilizing the Li metal anodes, the dpnGE dramatically extends the lifespan of Li metal batteries. Hence, this proof-of-concept study inspires the critical role of interfacial stability in building safe and high-performance LMBs.

■

REFERENCES

(1) Armand, M.; Tarascon, J.-M. Building Better Batteries. Nature 2008, 451, 652−657. (2) Zu, C.-X.; Li, H. Thermodynamic Analysis on Energy Densities of Batteries. Energy Environ. Sci. 2011, 4, 2614−2624. (3) Xu, W.; Wang, J.; Ding, F.; Chen, X.; Nasybulin, E.; Zhang, Y.; Zhang, J.-G. Lithium Metal Anodes for Rechargeable Batteries. Energy Environ. Sci. 2014, 7, 513−537. (4) Yin, Y.-X.; Xin, S.; Guo, Y.-G.; Wan, L.-J. Lithium-Sulfur Batteries: Electrochemistry, Materials, and Prospects. Angew. Chem., Int. Ed. 2013, 52, 13186−13200. (5) Goodenough, J. B.; Kim, Y. Challenges for Rechargeable Li Batteries. Chem. Mater. 2010, 22, 587−603. (6) Cheng, X.-B.; Yan, C.; Zhang, X.-Q.; Liu, H.; Zhang, Q. Electronic and Ionic Channels in Working Interfaces of Lithium Metal Anodes. ACS Energy Lett. 2018, 3, 1564−1570. (7) Li, W.; Yao, H.; Yan, K.; Zheng, G.; Liang, Z.; Chiang, Y. M.; Cui, Y. The Synergetic Effect of Lithium Polysulfide and Lithium Nitrate to Prevent Lithium Dendrite Growth. Nat. Commun. 2015, 6, 7436. (8) Wu, M.; Wen, Z.; Jin, J.; Chowdari, B. V. Trimethylsilyl Chloride-Modified Li Anode for Enhanced Performance of Li-S Cells. ACS Appl. Mater. Interfaces 2016, 8, 16386−16395. (9) Li, N.-W.; Yin, Y.-X.; Yang, C.-P.; Guo, Y.-G. An Artificial Solid Electrolyte Interphase Layer for Stable Lithium Metal Anodes. Adv. Mater. 2016, 28, 1853−1858. (10) Cheng, X.-B.; Yan, C.; Chen, X.; Guan, C.; Huang, J.-Q.; Peng, H.-J.; Zhang, R.; Yang, S.-T.; Zhang, Q. Implantable Solid Electrolyte Interphase in Lithium-Metal Batteries. Chem. 2017, 2, 258−270. (11) Zhao, Q.; Tu, Z.; Wei, S.; Zhang, K.; Choudhury, S.; Liu, X.; Archer, L. A. Building Organic/Inorganic Hybrid Interphases for Fast Interfacial Transport in Rechargeable Metal Batteries. Angew. Chem., Int. Ed. 2018, 57, 992−996. (12) Yang, C.-P.; Yin, Y.-X.; Zhang, S.-F.; Li, N.-W.; Guo, Y.-G. Accommodating Lithium into 3D Current Collectors with a Submicron Skeleton towards Long-Life Lithium Metal Anodes. Nat. Commun. 2015, 6, 8058. (13) Zuo, T.-T.; Wu, X.-W.; Yang, C.-P.; Yin, Y.-X.; Ye, H.; Li, N.W.; Guo, Y.-G. Graphitized Carbon Fibers as Multifunctional 3D Current Collectors for High Areal Capacity Li Anodes. Adv. Mater. 2017, 29, 1700389. (14) Zuo, T.-T.; Yin, Y.-X.; Wang, S.-H.; Wang, P.-F.; Yang, X.; Liu, J.; Yang, C.-P.; Guo, Y.-G. Trapping Lithium into Hollow Silica Microspheres with a Carbon Nanotube Core for Dendrite-Free Lithium Metal Anodes. Nano Lett. 2018, 18, 297−301. (15) Yang, C.; Fu, K.; Zhang, Y.; Hitz, E.; Hu, L. Protected LithiumMetal Anodes in Batteries: From Liquid to Solid. Adv. Mater. 2017, 29, 1701169. (16) Cheng, X. B.; Zhang, R.; Zhao, C. Z.; Zhang, Q. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chem. Rev. 2017, 117, 10403−10473. (17) Xin, S.; You, Y.; Wang, S.; Gao, H.-C.; Yin, Y.-X.; Guo, Y.-G. Solid-State Lithium Metal Batteries Promoted by Nanotechnology: Progress and Prospects. ACS Energy Lett. 2017, 2, 1385−1394. (18) Han, X.; Gong, Y.; Fu, K. K.; He, X.; Hitz, G. T.; Dai, J.; Pearse, A.; Liu, B.; Wang, H.; Rubloff, G.; Mo, Y.; Thangadurai, V.; Wachsman, E. D.; Hu, L. Negating Interfacial Impedance in GarnetBased Solid-State Li Metal Batteries. Nat. Mater. 2017, 16, 572−579. (19) Yang, C.; Zhang, L.; Liu, B.; Xu, S.; Hamann, T.; McOwen, D.; Dai, J.; Luo, W.; Gong, Y.; Wachsman, E. D.; Hu, L. Continuous Plating/Stripping Behavior of Solid-State Lithium Metal Anode in a 3D Ion-Conductive Framework. Proc. Natl. Acad. Sci. U. S. A. 2018, 115, 3770−3775. (20) Liu, M.; Zhou, D.; He, Y.-B.; Fu, Y.; Qin, X.; Miao, C.; Du, H.; Li, B.; Yang, Q.-H.; Lin, Z.; Zhao, T. S.; Kang, F. Novel Gel Polymer Electrolyte for High-Performance Lithium−Sulfur Batteries. Nano Energy 2016, 22, 278−289. (21) Lu, Q.; He, Y. B.; Yu, Q.; Li, B.; Kaneti, Y. V.; Yao, Y.; Kang, F.; Yang, Q. H. Dendrite-Free, High-Rate, Long-Life Lithium Metal

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.8b12986.

■

Letter

Combustion tests, XRD patterns, Arrhenius plot, cyclic voltammetry and linear sweep voltammetry, optical images, cycling profile, rate and cycling performance (PDF) Video S1 showing direct observation of interfacial evolution on the electrode−gel electrolyte interface (AVI)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (Y.G.G.). *E-mail: [email protected] (R.W.). ORCID

Tong-Tong Zuo: 0000-0003-3594-7029 Xiong-Wei Wu: 0000-0001-9393-7123 Peng-Fei Wang: 0000-0001-9882-5059 Ya-Xia Yin: 0000-0002-0983-9916 Yu-Guo Guo: 0000-0003-0322-8476 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This work was supported by Basic Science Center Project of National Natural Science Foundation of China (Grant 51788104), National Natural Science Foundation of China (Grant 21773264), the National Key R&D Program of China (Grant 2016YFA0202500), and the “Transformational Technologies for Clean Energy and Demonstration”, Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDA21070300). The authors acknowledged the National Postdoctoral Program for Innovative Talents (Grant BX201600171), and the China Postdoctoral Science Foundation (Grant 2017M611003). 30069

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070

Letter

ACS Applied Materials & Interfaces Batteries with a 3D Cross-Linked Network Polymer Electrolyte. Adv. Mater. 2017, 29, 1604460. (22) Chen, N.; Dai, y.; Xing, Y.; Wang, L.; Guo, C.; Chen, R.; Guo, S.; Wu, F. Biomimetic Ant-Nest Ionogel Electrolyte Boosts the Performance of Dendrite-Free Lithium Batteries. Energy Environ. Sci. 2017, 10, 1660−1667. (23) Shim, J.; Kim, H. J.; Kim, B. G.; Kim, Y. S.; Kim, D.-G.; Lee, J.C. 2D Boron Nitride Nanoflakes as a Multifunctional Additive in Gel Polymer Electrolyte for Safe, Long Cycle Life and High Rate Lithium Metal Batteries. Energy Environ. Sci. 2017, 10, 1911−1916. (24) Choudhury, S.; Mangal, R.; Agrawal, A.; Archer, L. A. A Highly Reversible Room-Temperature Lithium Metal Battery Based on Crosslinked Hairy Nanoparticles. Nat. Commun. 2015, 6, 10101. (25) Wu, H.; Cao, Y.; Su, H.; Wang, C. Tough Gel Electrolyte Using Double Polymer Network Design for the Safe, Stable Cycling of Lithium Metal Anode. Angew. Chem., Int. Ed. 2018, 57, 1361−1365. (26) Zeng, X.-X.; Yin, Y.-X.; Li, N.-W.; Du, W.-C.; Guo, Y.-G.; Wan, L.-J. Reshaping Lithium Plating/Stripping Behavior via Bifunctional Polymer Electrolyte for Room-Temperature Solid Li Metal Batteries. J. Am. Chem. Soc. 2016, 138, 15825−15828. (27) Zhang, X.; Liu, T.; Zhang, S.; Huang, X.; Xu, B.; Lin, Y.; Xu, B.; Li, L.; Nan, C. W.; Shen, Y. Synergistic Coupling between Li6.75La3Zr1.75Ta0.25O12 and Poly(vinylidene fluoride) Induces High Ionic Conductivity, Mechanical Strength, and Thermal Stability of Solid Composite Electrolytes. J. Am. Chem. Soc. 2017, 139, 13779− 13785. (28) Zhao, C. Z.; Zhang, X. Q.; Cheng, X. B.; Zhang, R.; Xu, R.; Chen, P. Y.; Peng, H. J.; Huang, J. Q.; Zhang, Q. An AnionImmobilized Composite Electrolyte for Dendrite-Free Lithium Metal Anodes. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 11069−11074. (29) Xiong, S.; Xie, K.; Diao, Y.; Hong, X. Characterization of the Solid Electrolyte Interphase on Lithium Anode for Preventing the Shuttle Mechanism in Lithium−Sulfur Batteries. J. Power Sources 2014, 246, 840−845. (30) Zhang, X. Q.; Chen, X.; Cheng, X. B.; Li, B. Q.; Shen, X.; Yan, C.; Huang, J. Q.; Zhang, Q. Highly Stable Lithium Metal Batteries Enabled by Regulating the Li+ Solvation in Nonaqueous Electrolyte. Angew. Chem., Int. Ed. 2018, 57, 5301−5305.

30070

DOI: 10.1021/acsami.8b12986 ACS Appl. Mater. Interfaces 2018, 10, 30065−30070