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Enhancing the High-Voltage Cycling Performance of LiNi1/3Co1/3Mn1/3O2/Graphite Batteries Using Alkyl 3,3,3Trifluoropropanoate as an Electrolyte Additive Xiangzhen Zheng,† Tao Huang,† Ying Pan,† Wenguo Wang,† Guihuang Fang,† Kaining Ding,‡ and Maoxiang Wu*,† †

Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, P.R. China ‡ College of Chemistry, Fuzhou University, Fuzhou 350002, P.R. China S Supporting Information *

ABSTRACT: The present study demonstrates that the use of alkyl 3,3,3-trifluoropropanoate, including methyl 3,3,3trifluoropropanoate (TFPM) and ethyl 3,3,3-trifluoropropanoate (TFPE), as new electrolyte additive can dramatically enhance the high-voltage performance of LiNi1/3Co1/3Mn1/3O2/graphite lithium-ion batteries (3.0−4.6 V, vs Li/Li+). The capacity retention was significantly increased from 45.6% to 75.4% after 100 charge−discharge cycles due to the addition of 0.2 wt % TFPM in the electrolyte, and significantly increased from 45.6% to 76.1% after 100 charge−discharge cycles due to the addition of 0.5 wt % TFPE in the electrolyte, verifying their suitability in this application. Electrochemical impedance spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy were employed to study the effect of TFPM and TFPE on cell performance. The data indicates that the improved cycling activity can be ascribed to the participation of TFPM or TFPE in the formation of a thinner cathode/electrolyte interfacial film, thereby enhancing the cell cycling performance owing to a reduced interfacial resistance at high voltage. KEYWORDS: lithium-ion battery, electrolyte additive, high voltage, alkyl 3,3,3-trifluoropropanoate, cathode electrolyte interface film

1. INTRODUCTION

Therefore, numerous modified electrolytes have been developed in recent years, including those with new solvents,18,19 new lithium salts,20,21 new additives,22−26 and even ionic liquids,27,28 resulting in high-power and high-energy density LIBs. Xue et al.18 reported that electrolytes employing mixed solvents of ethylmethyl sulfone (EMS) and dimethyl carbonate (DMC) offered excellent cycling properties and Coulombic efficiency at the LiNi0.5Mn1.5O4 cathode as well as the Li4Ti5O12 anode. Hu et al.19 reported the use of fluorinated carbonate-based solvents as a new electrolyte in high-voltage LiNi0.5Mn1.5O4/graphite cells. The study demonstrated that electrolytes containing 1.0 M LiPF 6 in methyl 2,2,2-

A number of novel high operating voltage cathode materials, including LiNi0.5Mn1.5O4,1−4 LiCoPO4,5−7 and LiMnPO4,8,9 have been developed recently to meet the demands for highenergy density lithium-ion batteries (LIBs). However, the operating potentials of these materials exceed the stability of commercial carbonate-based LIB electrolytes, which suffer decomposition at voltages greater than about 4.5 V. As such, charging conventional cathode materials, such as LiCoO2,10,11 LiNi0.5Co0.2Mn0.3O2,12−14 and LiNi1/3Co1/3Mn1/3O2,15−17 to a higher working voltage is also an effective method of meeting energy density demands. However, this method readily catalyzes the oxidation and decomposition of electrolytes on the cathode surface, resulting in deterioration of the battery cycling performance. © 2017 American Chemical Society

Received: March 1, 2017 Accepted: May 8, 2017 Published: May 8, 2017 18758

DOI: 10.1021/acsami.7b03014 ACS Appl. Mater. Interfaces 2017, 9, 18758−18765

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ACS Applied Materials & Interfaces

electrodes were 45 μm for the cathode and 40 μm for the anode. Both electrodes were dried for 12 h at 100 °C in a vacuum prior to cell assembly. A CT2001A tester (Landt Instruments, Wuhan, China) was employed to assess the charge−discharge activity of the batteries. After formation involving 0.1 C cycling three times followed by 0.2 C cycling three times, and aging for 10 h, the cells were charged to 4.6 V at a constant current of 0.2 C, and a constant potential was then maintained until the current was 0.02 C. Discharge then occurred to 3.0 V at 0.2 °C. Electrochemical impedance spectroscopy (EIS) was conducted over a frequency range of 500 kHz to 0.01 Hz and with an impedance amplitude of 10 mV using a frequency response analyzer (VSP, Bio-Logic SAS, Claix, France) after the first charge−discharge cycle and after 100 charge−discharge cycles with the cells charged to 4.6 V. All tests were conducted at room temperature unless otherwise specified. After the completing charge−discharge cycle testing, the cells were disassembled in a glovebox within an Ar atmosphere, and both of the electrodes were rinsed at least five times using DMC as a solvent to remove any residual electrolyte material. The electrodes were then dried for 12 h in vacuum at room temperature. The crystal structure was identified by X-ray diffraction (XRD, Bruker D8 Advance) using Cu Kα radiation. Fourier transform infrared-attenuated total reflectance (FTIR-ATR) analysis was conducted using a NICOLET Is10 (ThermoFisher Scientific). To better understand the surface chemistries on the cathode and anode surfaces, the chemical compositions of the surface layers at the electrode/electrolyte interfaces for cells with and without the additives were characterized by X-ray photoelectron spectroscopy (XPS, ESCALAB 250Xi, Thermo Scientific) using Al Kα radiation. The peak energy of the carbon containment (i.e., C 1s = 284.8 eV) was used to calibrate the binding energies. Scanning electron microscopy (SEM, S-4800, Hitachi) was used to investigate the morphology of the electrodes.

trifluoroethyl carbonate (F-EMC)/1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (F-EPE)/fluoroethylene carbonate (FEC) exhibited enhanced cycling stability at 55 °C relative to conventional electrolytes. Nan and co-workers23 evaluated tris(trimethylsilyl) borate (TMSB) as a new electrolyte additive. The performance of LiNi0.5Co0.2Mn0.3O2/graphite LIB cycling at 4.4 V was demonstrated to be significantly improved via the addition of 0.5% TMSB in an ethylene carbonate (EC)/DMC (1/2, v/v) electrolyte at room temperature. Zuo et al.26 employed methylene methanedisulfonate (MMDS) as an additive for a high-voltage electrolyte employed in LiCoO2/graphite LIBs. The addition of 0.5% MMDS in the electrolyte was found to dramatically improve the cycling performance of LiCoO2/graphite LIBs. To the best of our knowledge, the use of a fluorine-containing propionate ester as an electrolyte additive in high-voltage LIBs has been little reported. In the present work, we propose methyl 3,3,3-trifluoropropanoate (TFPM) and ethyl 3,3,3-trifluoropropanoate (TFPE) as new electrolyte additives and demonstrate their potential for enhancing the performance of LiNi1/3Co1/3Mn1/3O2/graphite LIBs operating at high voltage.

2. EXPERIMENTAL SECTION We obtained 1.0 M LiPF6-EC/ethyl methyl carbonate (EMC)/DMC (1:1:1, wt %) electrolytes from Dongguan Shanshan Battery Materials Co., Ltd. (Nancheng, China). TFPM and TFPE (Fujian Chuangxin Science and Technology Develops Co., Ltd., Fuzhou, China) were combined with the electrolytes in an argon-filled glovebox with a water and oxygen content that was less than 1 ppm. The purity of TFPM was 99.5% and TFPE was 99.9% (by gas chromatography (GC)). Their structures are shown in Figure 1. Considering the effect of the

3. RESULTS AND DISCUSSION 3.1. Effect of Additives on the LiNi1/3Co1/3Mn1/3O2/ Graphite Cell Performance. Figure 2 shows the cycling performances of cells with and without the additives under different conditions. When the cells were cycled in the standard voltage range (3.0−4.3 V), they showed similar discharge capacity retention behavior over 100 charge−discharge cycles (Figure 2a). However, when the charging cutoff voltage was increased to 4.6 V (Figure 2b), the cells with the alkyl 3,3,3trifluoropropanoate additives in the electrolyte exhibited significantly improved cycling performance. The capacities of the cells at the initial discharge were 191.6 mA h g−1 with TFPM, and were 186 mA h g−1 with TFPE, but were 199 mA h g−1 without an additive. After 100 charge−discharge cycles, the discharge capacity of the battery with TFPM was 144.5 mA h g−1 and that with TFPE was 141.5 mA h g−1, whereas the discharge capacity obtained for the cell without the additive was only 90.8 mA h g−1. As such, the capacity retentions were 75.4%, 76.1%, and 45.6% for cells with 0.2 wt % TFPM, 0.5 wt % TFPE, and without additive, respectively. When an additive is introduced into the electrolyte, the Coulombic efficiency of the cells was more stable during cycling when the cells were charged to 4.6 V, as shown in Figure 2d. Moreover, the additive improved the cycling performance at 55 °C (Figure S2). To understand the electrochemical behavior of cells at 4.6 V, the charge−discharge profiles of the cells and EIS results with and without the additives were obtained. The charge−discharge profiles with and without the additive exhibit little difference during the first cycle (Figure S3a). However, the respective charge−discharge profiles with and without the additive significantly deviated with increasing cell cycling (Figure S3b). The constant voltage (CV) charge profile of the cell

Figure 1. Molecular structure of TFPM and TFPE. additives on the electrochemical activity of LIBs, the optimal quantities of the additives were found to be 0.2 wt % for TFPM and 0.5 wt % for TFPE (Figure S1 of the Supporting Information). Commercial LiNi1/3Co1/3Mn1/3O2 cathode and graphite anode materials were obtained and employed to fabricate CR2025 coin cells for evaluating the effect of TFPM and TFPE addition on the electrochemical activity of the cell when operated at 4.6 V. The cathode, with an active mass loading of about 121 g m−2, was prepared by combining 94 wt % LiNi1/3Co1/3Mn1/3O2, 3.5 wt % acetylene carbon black, and 2.5 wt % polyvinylidene fluoride as a binder, and coated on Al foil. The anode, with an active mass loading of about 60 g m−2, was prepared by mixing 95.7 wt % natural graphite, 2.0 wt % acetylene carbon black, 1.5 wt % sodium carboxymethyl cellulose, and 0.8 wt % styrene butadiene rubber, and coated on a Cu foil. The thicknesses of the prepared 18759


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Figure 2. Cycle performance and Coulombic efficiency of LiNi1/3Co1/3Mn1/3O2/graphite LIBs with and without additive at (a) 3.0−4.3 V and (b) 3.0−4.6 V.

Figure 3. Electrochemical impedance spectra of LiNi1/3Co1/3Mn1/3O2/graphite cells with and without additive charged to 4.6 V after one cycle (a) and after 100 cycles (b). The equivalent circuit model is given in (c), and the fitted results are presented in (d).

Figure 4. First charge−discharge curves (a) and differential capacity (dQ/dV) versus voltage (V) (b) for LiNi1/3Co1/3Mn1/3O2/graphite cells during formation in the electrolyte with and without additive.

without additive is greater than that with additive, which indicates that the cell without the additive underwent much greater polarization. The cell containing additive exhibited smoother charge−discharge profiles and a greater discharge capacity than did the cell without the additive. Figure 3 presents the EIS results for the cells with and without additive. For the first cycle (Figure 3a), the interfacial impedance of cells with and without additive exhibit little difference. After 100 cycles (Figure 3b), the cell without additive exhibited larger interfacial impedance versus the cell with the additive. The EIS results were fitted to the equivalent

circuit model presented in Figure 3c, which was composed of a bulk resistance (Re), interfacial reaction resistance (Rf), and charge-transfer resistance (Rct). The fitting results are given in Figure 3d, which indicates that the cell without additive exhibited a greater increase in the value of Rf compared with the cells with additive. This indicates that the presence of TFPM or TFPE in the electrolyte reduces the impedance of the cell surface film, and thereby enhances the cycling performance of LIBs. 3.2. Effect of Additives on the Electrode Surfaces. 3.2.1. Differential Capacity (dQ/dV) Analysis. Figure 4 shows 18760


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Figure 5. XRD patterns of graphite anodes at (a) 3.0−4.3 V and (b) 3.0−4.6 V, and LiNi1/3Co1/3Mn1/3O2 cathodes at (c) 3.0−4.3 V and (d) 3.0−4.6 V for electrolytes with and without additive after 100 cycles.

Figure 6. FTIR spectra of graphite anodes at (a) 3.0−4.3 V, (b) 3.0−4.6 V, and LiNi1/3Co1/3Mn1/3O2 cathodes at (c) 3.0−4.3 V and (d) 3.0−4.6 V for electrolytes with and without additive after 100 cycles.

the first discharge and charge curves and differential capacity (dQ/dV) versus voltage (V) for the LiNi1/3Co1/3Mn1/3O2/ graphite cells employing electrolytes with and without additive during formation. A small plateau at ∼3.0 V can be observed in Figure 4a during the first charge for the cell with added TFPM and at ∼2.85 V for the cell with added TFPE. These obvious

peaks at ∼3.0 and ∼2.85 V are also observed in the dQ/dV versus V curves shown in Figure 4b, which may respectively correspond to the decomposition of TFPM and TFPE during charging. To further evaluate the effect of these two additives on the specific electrodes in the full cells, we also evaluated the first 18761


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Figure 7. F 1s (a), P 2p (b), C 1s (c), and O 1s (d) XPS spectra of cycled LiNi1/3Co1/3Mn1/3O2 electrodes charged to 4.6 V for electrolytes with and without additive.

Figure 8. F 1s (a), P 2p (b), C 1s (c), and O 1s (d) XPS spectra of the cycled graphite electrodes charged to 4.6 V for electrolytes with and without additive.

confirm the effect of these two additives on specific electrodes in the full cells under high voltage conditions based solely on the dQ/dV results, and other tests are therefore required. 3.2.2. XRD Analysis of the Electrodes. Figure 5 shows the XRD patterns of the pristine electrodes and electrodes with and without an alkyl 3,3,3-trifluoropropanoate additive in the

charge−discharge processes for LiNi1/3Co1/3Mn1/3O2/Li and graphite/Li half coin cells. As observed from the test results given in Figure S4, TFPM and TFPE can be subjected to reduction on the graphite electrode surface (Figure S4a) and can be subjected to oxidation on the LiNi1/3Co1/3Mn1/3O2 electrode surface (Figure S4b). However, it is difficult to 18762


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Table 1. Element Concentrations Determined by XPS on the Surface of the Cycled Graphite Electrodes with and without Additive elements (%)

C 1s

O 1s

F 1s

Li 1s

P 2p

Mn 2p

Co 2p

Ni 2p

no additive with 0.2 wt % TFPM with 0.5 wt % TFPE

31.53 42.07 33.42

30.32 28.45 30.91

10.03 5.46 9.08

25.04 21.75 23.84

1.86 1.45 1.73

0.29 0.30 0.24

0.20 0.16 0.16

0.73 0.36 0.62

electrolyte after 100 cycles. The peak at 26.5° observed in Figure 5a,b is associated with the graphite structure.29−32 The peaks shown in Figure 5c,d at approximately 18.5°, 36.8°, 38.4°, and 44.5° in the fresh LiNi1/3Co1/3Mn1/3O2 are in good agreement with previously published results.33 Figure 5a,b clearly shows that the XRD patterns of graphite remained nearly unchanged when the charging cutoff voltage was increased from 4.3 to 4.6 V. In contrast, the XRD patterns of the LiNi1/3Co1/3Mn1/3O2 cycling at 4.3 V are significantly different from the cycling at 4.6 V. The peak intensities of LiNi1/3Co1/3Mn1/3O2 are dramatically decreased or disappear after cycling for the electrolyte without additive at 4.6 V, which may be because of the structural damage sustained by LiNi1/3Co1/3Mn1/3O2 after cycling at high voltage. The XRD results of the cycled electrode suggest that alkyl 3,3,3trifluoropropanoate additives mainly affect cathode at high voltage. 3.2.3. FTIR Analysis of the Electrode Surfaces. To investigate the effects of the additives on the electrode surfaces in the LiNi1/3Co1/3Mn1/3O2/graphite full cell, the FTIR spectra of the cycled electrodes shown in Figure 6 were evaluated. A new peak around 1100 cm−1 can be observed on the cycled graphite electrode with the additive-containing electrolyte charged at 3.0−4.3 V, which corresponds to the vibration of −CF3 in 3,3,3-trifluoropropanoate additives.25 Moreover, a peak around 1100 cm−1 is also observed on the cycled LiNi1/3Co1/3Mn1/3O2 electrode with the additive-containing electrolyte charged at 3.0−4.6 V. This result confirms that the alkyl 3,3,3-trifluoropropanoate additives (TFPE and TFPM) are incorporated into the solid electrolyte interface (SEI) film on the graphite anode at standard voltage (3.0−4.3 V), and are also incorporated into the cathode−electrolyte interface (CEI) film on the LiNi1/3Co1/3Mn1/3O2 cathode at high voltage (3.0− 4.6 V). 3.2.4. XPS Analysis of the Electrode Surfaces. XPS was employed to analyze the effect of additives on the cycled electrode surface composition of the LiNi1/3Co1/3Mn1/3O2/ graphite cells cycled at 4.6 V with and without additive in the electrolyte. Figure 7 shows the F 1s, P 2p, C 1s, and O 1s spectra obtained from XPS analysis of the cycled cathode with and without additive in the electrolyte. The peak located at 684.5 eV is associated with F atoms within LiF.23 As observed from the F 1s spectra (Figure 7a), the intensity of F within LiF for the cathode without additive was greater than that for the cell with additive, indicating that a greater concentration of LiF was coated on the surface of the LiNi 1/3Co1/3 Mn1/3O2 electrode without additive in the electrolyte. As is known, the interfacial impedance of the cell increases as an increasing concentration of LiF is deposited on the cathode surface. This result is consistent with the results of EIS analysis. The intensities of F within LiF for the anodes of cells without additive in the electrolyte were also greater than those for cells with additive, as indicated in Figure 8a. Two peaks are observed in the P 2p spectra, shown in Figure 7b and Figure8b. The intensity of P atoms within compounds

of the form LixPFy, which have a characteristic energy of 136.2 eV,23 on the surface of the cathode is less in the presence of additive (particularly TFPM) relative to that of the cell without the additive. According to eqs 1−3,34 the decomposition of LiPF6 can form LiPxFy species. This result indicates that the decomposition of LiPF6 under high voltage conditions is reduced when TFPM or TFPE is added within the electrolyte. The same phenomenon is observed in the testing results for the anode surface, as shown in Figure 8b. LiPF6 + H 2O → LiF + POF3 + 2HF

(1)

POF3 + ne− + n Li+ → LiF + LixPOFy

(2)

PF6− + ne− + n Li+ → LiF + LixPFy

(3)

Peaks associated with C atoms within C−O (286.4 eV) and CO (288.8 eV) are observed for the cathode surfaces of both samples with and without additive, although the peak intensities are relatively small for the sample with TFPE (Figure 7c). This observation can be explained by the oxidation and direct polymerization of EC. The peak located at 292.5 eV is associated with C atoms in the CF3 group of the alkyl 3,3,3trifluoropropanoate. As such, this peak is detected on the surface of the cathode derived from the cell with TFPM or TFPE in the electrolyte, but it is not observed on the surface of the corresponding anode. This result suggests that the alkyl 3,3,3-trifluoropropanoate additives have no influence on the surface of the anode, which is consistent with our XRD and FTIR analyses. Increased Me−O in the cell with additive indicates a thinner CEI layer on the cathode (Figure 7d). The peak intensity associated with O atoms within Me−O for electrodes derived from the cell with TFPE is smaller than that of the cell with TFPM, which indicates that the CEI layer formed from TFPM is thinner than that formed from TFPE. The XPS data suggests that the addition of an alkyl 3,3,3-trifluoropropanoate additive in the electrolyte participates in the formation of a thinner CEI layer on the surface of the cathode at high voltage. This lowers the interfacial impedance, and enhances the cycling performance of cells operating at a high voltage. The elemental concentrations on the surface of the anodes obtained by XPS after cycle testing are also presented in Table 1. With electrochemical cycling at high operating voltages, Co, Mn, and Ni derived from the cathode, and dissolved in the electrolyte, can migrate to the anode through the separator, and be deposited onto the anode surface as inorganic salts. As such, the relatively large concentration of transition metals on the anode surface of the cell without additive in the electrolyte indicates that the addition of an alkyl 3,3,3-trifluoropropanoate additive in the electrolyte can effectively inhibit the dissolution of transition metals out of the cathode, and effectively prevents their deposition on the anode surface during electrochemical cycling. On the basis of the XPS results, we further consider that the alkyl 3,3,3-trifluoropropanoate additives (TFPM and TFPE) mainly affected the cathode surface at high voltage, and 18763


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ACS Applied Materials & Interfaces the CEI film derived from TFPM is thinner than that derived from TFPE. 3.2.5. SEM Analysis of LiNi1/3Co1/3Mn1/3O2. To further explore the effects of additives on the LiNi1/3Co1/3Mn1/3O2 cathodes at 4.6 V, SEM analysis of the cathodes was performed after conducting cyclic testing. From the SEM images shown in Figure 9, we note that the pristine LiNi1/3Co1/3Mn1/3O2 surface

Figure 10. Possible reaction pathways for the additives on the LiNi1/3Co1/3Mn1/3O2 electrode surface: (a) intermediate 1; (b) intermediate 2; (c) final product.

charge−discharge cycles, the capacity retention was significantly increased from 45.6% to 75.4% with TFPM in the electrolyte and to 76.1% with TFPE in the electrolyte. XRD, FTIR, XPS, and SEM analyses revealed that alkyl 3,3,3-trifluoropropanoate additives induced the formation of a thinner CEI film on the cathode, decreased the interfacial resistance, and reduced the rate of decomposition of the Li salt at high voltage, which effectively improved the high-voltage performance of the cells.

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Figure 9. SEM micrographs of LiNi1/3Co1/3Mn1/3O2 electrodes: (a) fresh; (b) without additive after 100 charge−discharge cycles; (c) with 0.2 wt % TFPM in the electrolyte after 100 cycles; (d) with 0.5 wt % TFPE after 100 cycles.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.7b03014. Figures of LiNi1/3Co1/3Mn1/3O2/graphite cells cycled in the different concentrations of additive; cycle performance of LiNi1/3Co1/3Mn1/3O2/graphite cells charged to 4.6 V at 55 °C; charge−discharge curves of LiNi1/3Co1/3Mn1/3O2/graphite cells at different cycles; differential capacity (dQ/dV) versus voltage (V) for the graphite/Li cells (a) and LiNi1/3Co1/3Mn1/3O2/Li cells (b) during first cycle in the electrolyte with and without additive (PDF)

is clean and smooth. When cycled at 4.6 V without additive after 100 cycles, the surface of the LiNi1/3Co1/3Mn1/3O2 electrode is covered with thick deposits, suggesting extensive electrolyte decomposition during the high-voltage cycling process. However, fewer deposits are observed on the electrodes cycled in the presence of TFPM and TFPE as shown in Figure 9c,d, respectively, suggesting the additives are able to form a protective film that inhibits electrolyte decomposition after further cycling. The concentration of deposits derived from the electrolyte with 0.2 wt % TFPM after cycling is less than that derived from the electrolyte with 0.5 wt % TFPE, which indicates that the film derived from TFPM is thinner than the film derived from TFPE. This result is consistent with the XPS analysis results (Figure 7d). On the basis of the XRD, FTIR, XPS, and SEM analysis results, we postulated the possible reaction pathways of the alkyl 3,3,3-trifluoropropanoate additives in the cells at high voltage, and present them in Figure 10. During the first step, the ion-pair intermediate 1 (a) is formed. The intermediate 2 (b) is then formed when intermediate 1 (a) reacts with radical oxyanions, which is released from LiNi1/3Co1/3Mn1/3O2 at high voltage.35 Next, final product (c) and an anion-free radical OR are produced after the structure shown in (b) gaining an electron. RR is formed due to the self-dimerization of the anion-free radical OR.

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AUTHOR INFORMATION

Corresponding Author

*Tel./Fax: +86-591-6317-3560. E-mail: [email protected]. ORCID

Maoxiang Wu: 0000-0003-2176-1151 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We acknowledge support from the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09010103), the Ministry of Science and Technology of the People’s Republic of China (Grant No. 2016YFB0100100), and the Science and Technology Planning Project of Fujian Province (Grant No. 2017H2045, 2016T3012).

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CONCLUSIONS In summary, we evaluated alkyl 3,3,3-trifluoropropanoate compounds (including TFPM and TFPE) as new electrolyte additives for LiNi1/3Co1/3Mn1/3O2/graphite LIBs operating at a high voltage of 4.6 V. The addition of 0.2 wt % TFPM or 0.5 wt % TFPE was shown to significantly enhance the cycling performance of LiNi1/3Co1/3Mn1/3O2/graphite cells. After 100

REFERENCES

(1) Yi, T. F.; Fang, Z. K.; Xie, Y.; Zhu, Y. R.; Zang, L. Y. Synthesis of LiNi0.5Mn1.5O4 Cathode with Excellent Fast Charge-Discharge Performance for Lithium-Ion Battery. Electrochim. Acta 2014, 147, 250−256. (2) Pan, J.; Deng, J. Q.; Yao, Q. R.; Zou, Y. J.; Wang, Z. M.; Zhou, H. Y.; Sun, L. X.; Rao, G. H. Novel LiNi0.5Mn1.5O4 Porous Micro18764


Research Article


(20) Yao, D.; Wang, H.; Xiao, A.; Wells, L.; Dahn, J. R. Effect of Mixtures of Lithium Hexafluorophosphate (LiPF6) and Lithium Bis(fluorosulfonyl)imide (LiFSI) as Salts in Li[Ni1/3Mn1/3Co1/3]O2/ Graphite Pouch Cells. J. Electrochem. Soc. 2015, 162, A169−A175. (21) Li, S. Y.; Zhao, W.; Cui, X. L.; Zhang, H. M.; Wang, X. X.; Zhong, W. X.; Feng, H. X.; Liu, H. N. Lithium Difluoro(sulfato)borate as a Novel Electrolyte Salt for High-Temperature Lithium-Ion Batteries. Electrochim. Acta 2014, 129, 327−333. (22) Li, S. Y.; Li, L. X.; Liu, J. L.; Jing, J.; Li, X. P.; Cui, X. L. Using a Lithium Difluoro(sulfato)borate Additive to Improve Electrochemical Performance of Electrolyte Based on Lithium Bis(oxalate)borate for LiNi0.5Mn1.5O4/Li Cells. Electrochim. Acta 2015, 155, 321−326. (23) Zuo, X. X.; Fan, C. J.; Liu, J. S.; Xiao, X.; Wu, J. H.; Nan, J. M. Effect of Tris(trimethylsilyl)borate on the High Voltage Capacity Retention of LiNi0.5Co0.2Mn0.3O2/Graphite Cells. J. Power Sources 2013, 229, 308−312. (24) Rong, H. B.; Xu, M. Q.; Xing, L. D.; Li, W. S. Enhanced Cyclability of LiNi0.5Mn1.5O4 Cathode in Carbonate Based Electrolyte with Incorporation of Tris(trimethylsilyl)phosphate (TMSP). J. Power Sources 2014, 261, 148−155. (25) Huang, W. N.; Xing, L. D.; Wang, Y. T.; Xu, M. Q.; Li, W. S.; Xie, F. C.; Xia, S. G. 4-(Trifluoromethyl)-Benzonitrile: A Novel Electrolyte Additive For Lithium Nickel Manganese Oxide Cathode of High Voltage Lithium Ion Battery. J. Power Sources 2014, 267, 560− 565. (26) Zuo, X. X.; Fan, C. J.; Xiao, X.; Liu, J. S.; Nan, J. M. HighVoltage Performance of LiCoO2/Graphite Batteries with Methylene Methanedisulfonate as Electrolyte Additive. J. Power Sources 2012, 219, 94−99. (27) Borgel, V.; Markevich, E.; Aurbach, D.; Semrau, G.; Schmidt, M. On the Application of Ionic Liquids for Rechargeable Li Batteries: High Voltage Systems. J. Power Sources 2009, 189, 331−336. (28) Markevich, E.; Baranchugov, V.; Aurbach, D. On the Possibility of Using Ionic Liquids as Electrolyte Solutions for Rechargeable 5 V Li Ion Batteries. Electrochem. Commun. 2006, 8, 1331−1334. (29) Joho, F.; Novák, P. SNIFTIRS Investigation of the Oxidative Decomposition of Organic-Carbonate-Based Electrolytes for LithiumIon Cells. Electrochim. Acta 2000, 45, 3589−3599. (30) Xu, K. Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries. Chem. Rev. 2004, 104, 4303−4417. (31) Xing, L.; Borodin, O. Oxidation Induced Decomposition of Ethylene Carbonate from DFT Calculations-Importance of Explicitly Treating Surrounding Solvent. Phys. Phys. Chem. Chem. Phys. 2012, 14, 12838−12843. (32) Lee, J. T.; Lin, Y. W.; Jan, Y. S. Allyl Ethyl Carbonate as an Additive for Lithium-Ion Battery Electrolytes. J. Power Sources 2004, 132, 244−248. (33) Li, D.-C.; Muta, T.; Zhang, L.-Q.; Yoshio, M.; Noguchi, H. Effect of Synthesis Method on the Electrochemical Performance of LiNi1/3Mn1/3Co1/3O2. J. Power Sources 2004, 132, 150−155. (34) Aurbach, D.; Zinigrad, E.; Cohen, Y.; Teller, H. A Short Review of Failure Mechanisms of Lithium Metal and Lithiated Graphite Anodes in Liquid Electrolyte Solutions. Solid State Ionics 2002, 148, 405−416. (35) Zheng, H. H.; Sun, Q. N.; Liu, G.; Song, X. Y.; Battaglia, V. S. Correlation Between Dissolution Behavior and Electrochemical Cycling Performance for LiNi1/3Co1/3Mn1/3O2-Based Cells. J. Power Sources 2012, 207, 134−140.

ellipsoids as High-Performance Cathode Materials for Lithium Ion Batteries. J. Power Sources 2015, 288, 353−358. (3) Wang, H. L.; Tan, T. A.; Yang, P.; Lai, M. O.; Lu, L. High-Rate Performances of the Ru-Doped Spinel LiNi0.5Mn1.5O4: Effects of Doping and Particle Size. J. Phys. Chem. C 2011, 115, 6102−6110. (4) Wen, W. C.; Wang, X. Y.; Chen, S. H.; Shu, H. B.; Yang, X. K. Design and Preparation of Spherical High Voltage LiNi0.5Mn1.5O4 with a Novel Concentration-Gradient Shell for Lithium Ion Batteries. J. Power Sources 2015, 281, 85−93. (5) Han, D. W.; Kang, Y. M.; Yin, R. Z.; Song, M. S.; Kwon, H.-S. Effects of Fe Doping on the Electrochemical Performance of LiCoPO4/C Composites for High Power-Density Cathode Materials. Electrochem. Commun. 2009, 11, 137−140. (6) Wang, F.; Yang, J.; Nuli, Y. N.; Wang, J. L. Novel Hedgehog-Like 5 V LiCoPO4 Positive Electrode Material for Rechargeable Lithium Battery. J. Power Sources 2011, 196, 4806−4810. (7) Liu, J.; Conry, T. E.; Song, X. Y.; Yang, L.; Doeff, M. M.; Richardson, T. J. Spherical Nanoporous LiCoPO4/C Composites as High Performance Cathode Materials for Rechargeable Lithium-Ion Batteries. J. Mater. Chem. 2011, 21, 9984−9987. (8) Gong, Z. L.; Yang, Y. Recent Advances in the Research of Polyanion-Type Cathode Materials for Li-Ion Batteries. Energy Environ. Sci. 2011, 4, 3223−3242. (9) Bakenov, Z.; Taniguchi, I. Electrochemical Performance of Nanocomposite LiMnPO4/C Cathode Materials for Lithium Batteries. Electrochem. Commun. 2010, 12, 75−78. (10) Cao, J. C.; Hu, G. R.; Peng, Z. D.; Du, K.; Cao, Y. B. Polypyrrole-Coated LiCoO2 Nanocomposite with Enhanced Electrochemical Properties at High Voltage for Lithium-Ion Batteries. J. Power Sources 2015, 281, 49−55. (11) Kim, K. C.; Jegal, J.-P.; Bak, S.-M.; Roh, K. C.; Kim, K.-B. Improved High-Voltage Performance of FePO4-Coated LiCoO2 by Microwave-Assisted Hydrothermal Method. Electrochem. Commun. 2014, 43, 113−116. (12) Liu, X. H.; Kou, L. Q.; Shi, T.; Liu, K.; Chen, L. Excellent High Rate Capability and High Voltage Cycling Stability of Y2O3-Coated LiNi0.5Co0.2Mn0.3O2. J. Power Sources 2014, 267, 874−880. (13) Wang, D.; Li, X. H.; Wang, Z. X.; Guo, H. J.; Chen, X.; Zheng, X. B.; Xu, Y.; Ru, J. J. Multifunctional Li2O-2B2O3 Coating for Enhancing High Voltage Electrochemical Performances and Thermal Stability of Layered Structured LiNi0.5Co0.2Mn0.3O2 Cathode Materials for Lithium Ion Batteries. Electrochim. Acta 2015, 174, 1225−1233. (14) Liu, K.; Yang, G. L.; Dong, Y.; Shi, T.; Chen, L. Enhanced Cycling Stability and Rate Performance of Li[Ni0.5Co0.2Mn0.3]O2 by CeO2 Coating at High Cut-Off Voltage. J. Power Sources 2015, 281, 370−377. (15) Park, J.-H.; Cho, J.-H.; Kim, S.-B.; Kim, W.-S.; Lee, S.-Y.; Lee, S.-Y. A Novel Ion-Conductive Protection Skin Based on Polyimide Gel Polymer Electrolyte: Application to Nanoscale Coating Layer of High Voltage LiNi1/3Co1/3Mn1/3O2 Cathode Materials for Lithium-Ion Batteries. J. Mater. Chem. 2012, 22, 12574−12581. (16) Yano, A.; Aoyama, S.; Shikano, M.; Sakaebe, H.; Tatsumi, K.; Ogumi, Z. Surface Structure and High-Voltage Charge/Discharge Characteristics of Al-Oxide Coated LiNi1/3Co1/3Mn1/3O2 Cathodes. J. Electrochem. Soc. 2015, 162, A3137−A3144. (17) Zheng, X. Z.; Huang, T.; Pan, Y.; Wang, W. G.; Fang, G. H.; Wu, M. X. High-Voltage Performance of LiNi1/3Co1/3Mn1/3O2/ Graphite Batteries with Di(methylsulfonyl) Methane as a New Sulfone-Based Electrolyte Additive. J. Power Sources 2015, 293, 196− 202. (18) Xue, L. G.; Ueno, K.; Lee, S.-Y.; Angell, C. A. Enhanced Performance of Sulfone-Based Electrolytes at Lithium Ion Battery Electrodes, Including the LiNi0.5Mn1.5O4 High Voltage Cathode. J. Power Sources 2014, 262, 123−128. (19) Hu, L. B.; Zhang, Z. C.; Amine, K. Fluorinated Electrolytes for Li-Ion Battery: An FEC-Based Electrolyte for High Voltage LiNi0.5Mn1.5O4/Graphite Couple. Electrochem. Commun. 2013, 35, 76−79. 18765


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