Tris(2,2,2-trifluoroethyl) phosphite as an electrolyte additive for high-voltage lithium-ion batteries using lithium-rich layered oxide cathode

et al. 2016

J. Electrochem. Soc.

Performance of LiNi 0.5 Mn 1.5 O 4 /graphite cells cycled to 4.8 V at 55 • C with the 1.2 M LiPF 6 in EC/EMC (3/7, STD electrolyte) with and without added lithium catechol dimethyl borate (LiCDMB) has been investigated. The incorporation of 0.5 wt% LiCDMB to the STD electrolyte results in an improved capacity retention and coulombic efficiency upon cycling at 55 • C. Ex-situ analysis of the electrode surfaces via a combination of SEM, TEM, and XPS reveals that oxidation of LiCDMB at high potential results in the deposition of a passivation layer on the electrode surface, preventing transition metal ion dissolution from the cathode and subsequent deposition on the anode. NMR investigations of the bulk electrolyte stored at 85 Lithium-ion batteries are widely used for portable electronics and are currently being incorporated into electric vehicles due to their high energy density.1,2 However, there is significant interest in further increasing the energy density of lithium-ion batteries.3 One method to achieve higher energy density is increasing the operating potential of the cathode material. Most commercial lithium-ion batteries contain a lithiated transition metal oxide cathode that typically operates at ∼4.0 V vs. Li/Li + . 3,4 Several novel cathode materials with operating potentials over 4.0 V are currently under investigation, including LiNiPO 4 , 5 LiCoPO 4 , 5,6 and LiNi 0.5 Mn 1.5 O 4 . While the high operating potential of the LiNi 0.5 Mn 1.5 O 4 spinel cathode (4.8 V vs. Li/Li + ) offers high energy density, commercialization has been hampered by severe capacity fade and poor efficiency. 7 The capacity fade is particularly pronounced at moderately elevated temperatures (>45• C) and in full cells employing a graphite anode. 7 The failure mechanisms of LiNi 0.5 Mn 1.5 O 4 cells at high voltage and elevated temperature have been recently investigated. [8][9][10][11][12][13][14] Electrolyte decomposition, electrode/electrolyte interface degradation, and transition metal dissolution are the leading factors reported for performance fade. One effective method for improving the performance of high voltage cathodes involves the incorporation of SEI (solid electrolyte interface) and CEI (cathode electrolyte interface) forming electrolyte additives that are sacrificially oxidized on the surface of electrodes to generate a passivation film which inhibits transition metal dissolution and further electrolyte oxidation.There have been several reports where electrolyte additives have improved the performance of cathodes cycled to high potential. [15][16][17][18]23 Lithium bis(oxalato borate) (LiBOB) has been reported to be one of the better additives for LiNi 0.5 Mn 1.5 O 4 cathodes. 16,17,[20][21][22][23][24][25] The related additive, lithium difluorooxalato borate (LiDFOB) 27-31 has also been reported to improve the properties of Li 1.2 Ni 0.15 Mn 0.55 Co 0.1 O 2 cathodes cycled to high potential 19 In addition to the lithium oxalato borates, 26,32 we have recently reported on the beneficial effect of the incorpor...

Section: 37mentioning

confidence: 99%

Section: 37mentioning

confidence: 99%

Improving the Performance at Elevated Temperature of High Voltage Graphite/LiNi_0.5Mn_1.5O₄Cells with Added Lithium Catechol Dimethyl Borate

Dong

Demeaux

et al. 2016

J. Electrochem. Soc.

“…288 eV), and -CO 3 (289.9 eV) consistent with the deposition of electrolyte decomposition products. 38,[41][42][43] The presence of PVdF peaks at 290.7 eV and 286.5 eV confirm that the active material is not fully covered by the cathode surface film. 43 The C1s spectrum of the cathode cycled with the 0.1% DMF-SO 3 electrolyte contains peaks at 284.3 eV (C-C), 285.6 eV (C-H), 286.5 eV (C-O), 288 eV (C=O), and 289.9 eV (CO 3 ).…”

Section: Electrochemical Impedance Spectroscopy-eis Nyquist Plots Ofmentioning

confidence: 94%

“…38,[41][42][43] The presence of PVdF peaks at 290.7 eV and 286.5 eV confirm that the active material is not fully covered by the cathode surface film. 43 The C1s spectrum of the cathode cycled with the 0.1% DMF-SO 3 electrolyte contains peaks at 284.3 eV (C-C), 285.6 eV (C-H), 286.5 eV (C-O), 288 eV (C=O), and 289.9 eV (CO 3 ). The absence of peaks characteristic of PVdF in the C 1s spectrum suggests the surface film is thicker than the depth of penetration of XPS (∼ 5 nm) which is consistent with the O 1s XPS data.…”

Section: Electrochemical Impedance Spectroscopy-eis Nyquist Plots Ofmentioning

confidence: 94%

“…The fresh cathode contains C 1s peaks characteristic of hydrocarbons (C-C (284.3 eV), C-H (285.6 eV)) along with peaks of the PVdF binder at 286.5 eV (CH 2 ) and 290.7 eV (CF 2 ). 38,[41][42][43] The C 1s spectrum of the cathode cycled with the STD electrolyte contains peaks characteristic of CH 2 (285.6 eV), C-O (286.5 eV), C=O (ca. 288 eV), and -CO 3 (289.9 eV) consistent with the deposition of electrolyte decomposition products.…”

Section: Electrochemical Impedance Spectroscopy-eis Nyquist Plots Ofmentioning

confidence: 99%

See 1 more Smart Citation

Improving the Performance of Graphite/LiNi_0.5Mn_1.5O₄Cells with Added N,N-dimethylformamide Sulfur Trioxide Complex

Dong

Demeaux

et al. 2017

J. Electrochem. Soc.

N,N-dimethylformamide sulfur trioxide complex (DMF-SO 3 ) has been investigated as an electrolyte additive for LiNi 0.5 Mn 1.5 O 4 /graphite cells cycled to 4.8 V. Addition of 0.1% DMF-SO 3 to 1.2 M LiPF 6 in EC/EMC (3/7, v/v) standard electrolyte (STD) results in a significant improvement in the capacity retention and coulombic efficiency of LiNi 0.5 Mn 1.5 O 4 /graphite cells after 50 cycles at 45 • C. Ex-situ surface analysis of the electrodes after cycling has been conducted via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy with attenuated total reflectance (IR-ATR). The surface analysis suggests that a uniform interfacial film is formed on the LiNi 0.5 Mn 1.5 O 4 surface composed of the decomposition products of DMF-SO 3 . The novel cathode surface films passivates the surface at high potential leading to the improved electrochemical performance.

Armoring LiNi_1/3Co_1/3Mn_1/3O₂ Cathode with Reliable Fluorinated Organic–Inorganic Hybrid Interphase Layer toward Durable High Rate Battery

Chen

Zhao

et al. 2020

Adv Funct Materials

Ternary layered oxide materials have attracted extensive attention as a pro mising cathode candidate for high-energy-density lithium-ion batteries. However, the undesirable electrochemical degradation at the electrode-electrolyte interface definitively shortens the battery service life. An effective and viable approach is proposed for improving the cycling stability of the LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode using lithium difluorophosphate (LiPO 2 F 2 ) paired with fuoroethylene carbonate (FEC) as co-additives into conventional electrolytes. It is found that the co-additives can greatly reduce the interface charge transfer impedance and significantly extend the life span of LiNi 1/3 Co 1/3 Mn 1/3 O 2 //Li (NMC//Li) batteries. The developed cathode demonstrates exceptional capacity retention of 88.7% and remains structural integrity at a high current of 5C after 500 cycles. Fundamental mechanism study indicates a dense, stable fluorinated organic-inorganic hybrid cathode-electrolyte interphase (CEI) film derived from LiPO 2 F 2 in conjunction with FEC additives on the surface of NMC cathode material, which significantly suppresses the decomposition of electrolyte and mitigates the dissolution of transition metal ions. The interfacial engineering of the electrode materials stabilized by the additives manipulation provides valuable guidance for the development of advanced cathode materials.