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In this work, we propose that 1,1,3,3-tetramethyldisiloxane (TMDS) is beneficial for electrochemical property enhancement of LiNi0.5Mn1.5O4/Li cells at high temperatures. The LiNi0.5Mn1.5O4/Li cells with 1 vol % TMDS revealed capacity retention of 81.2% after a cycling test at 55 °C, while the cells without additive showed capacity retention of only 32.3%. The cells with 1 vol % TMDS also presented a better rate performance, reaching 100 mAh g-1 under 3C. Physical characterization and theoretical calculations revealed that TMDS formed a thinner and better conductive layer on the LiNi0.5Mn1.5O4 surface and effectively scavenged HF/F- from the electrolyte, contributing to high stabilization of LiNi0.5Mn1.5O4.

In the work reported in this article, di(methylsulfonyl) ethane (DMSE) was examined as a neoteric S-related electrolyte additive to elevate LiCoO2/electrolyte interfacial stability at 3.0-4.5 V (compared to Li/Li+). DMSE, when added to the electrolyte, can significantly enhance the high-voltage performance of LiCoO2/graphite cells. Meanwhile, capacity retention increased from 20.8 to 66.5% after 100 cycles owing to the adjunction of 0.5 wt % DMSE to the electrolyte (carbonate solvents and lithium salt). The density functional theory calculation results indicate that DMSE has a greater highest occupied molecular orbital energy in contrast to ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Differential capacity versus voltage analysis and linear sweep voltammetry result indicate that DMSE is decomposed in preference to the electrolyte solvents. DMSE's effects are distinguished by electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, X-ray-diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The outcomes indicate that the enhanced cycling performance is attributed to the involvement of DMSE in the generation of a thinner film on LiCoO2, which results in lower interfacial impedance and it protects the electrolyte from decomposition at high voltage.

Tributyl borate (TBB) is studied as a protective additive that enhances the interfacial stability of a LiNi0.5Mn1.5O4 cathode/electrolyte at 5 V and 55 °C. Upon addition of 0.5 vol % TBB to the ele...

Methanesulfonic acid 2,2,3,3-tetrafluoropropyl (TFPMS) is newly explored as a protection additive to improve the interfacial stability of LiMn2O4 cathode/electrolyte at an elevated temperature. At 1C rate, the addition of 0.5 vol% TFPMS improves the capacity retention of an LiMn2O4/Li cell from 56.9% to 72.9% after 200 cycles at 55 °C. Electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM) results suggest that the electrolyte with 0.5 vol% TFPMS forms a thinner and less resistive interface. X-ray photoelectron spectroscopy (XPS) analysis reveals that the addition of TFPMS restrains the formation of LiF and Li2CO3. Moreover, X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis confirms the effectiveness of TFPMS-enhanced structural stability of LiMn2O4.

We synthesized and investigated (2-chloro-4-methoxy)-phenoxy pentafluorocyclotriphosphazene (2-Cl-4-MPPFPP) as a safety additive for lithium-ion batteries. Experimental results demonstrate that the addition of 2-Cl-4-MPPFPP into the base electrolyte reduces electrolyte flammability. Moreover, 2-Cl-4-MPPFPP, which is electro-polymerized at 4.5 V (vs. Li/Li + ), is demonstrated to protect LiMn 2 O 4 /Li cells from voltage runaway at overcharge. A 5 vol% concentration of 2-Cl-4-MPPFPP in the electrolyte was shown to have a negligible effect on the cycling and lower discharge rate performances of LiMn 2 O 4 /Li cells.

The present study demonstrates that the use of alkyl 3,3,3-trifluoropropanoate, including methyl 3,3,3-trifluoropropanoate (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 TFP...

We evaluate (4-methoxy)-phenoxy pentafluorocyclotriphosphazene (4-MPPFPP) as a novel flame retardant and overcharge protection additive for lithium-ion batteries. The flammability of electrolytes containing 4-MPPFPP was studied by measuring the self-extinguishing time of the electrolytes. We found that 4-MPPFPP suppresses the flammability of the electrolyte. Moreover, 4-MPPFPP can be electrochemically polymerized on the surface of an electrode. This will protect batteries from voltage runaway. The influence of proper 4-MPPFPP addition on the cycling performance and capacity is negligible. The results may be helpful for the further design of advanced lithium ion battery electrolytes. We discuss the effect of the additive on the electrode/electrolyte interface and propose possible reaction paths.

This study demonstrates a sulfur-based compound, di(2,2,2-trifluoroethyl) sulfite (DTFES), as a new solid electrolyte interphase (SEI) forming additive on mesocarbon microbeads (MCMB). When placed in the electrolyte, it can dramatically enhance the performance of lithium-ion batteries (LIBs). The capacity loss was significantly decreased from 17.4% to 6.3% after 100 charge-discharge cycles due to the addition of DTFES. Differential capacity (dQ/dV) versus voltage (V) analysis showed that DTFES was decomposed in advance versus to electrolyte solvents. The effects of DTFES were characterized by charge-discharge testing, electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). These results indicate that the SEI film formed on MCMB by DTFES plays an important role in LIBs performance. Their subsequent reaction pathways are proposed in the paper.

Our study shows that 3, 3′-sulfonyldipropionitrile (SDPN), as an electrolyte additive, can dramatically enhance the performance of LiNi 1/3 Co 1/3 Mn 1/3 O 2 /graphite lithium-ion batteries (LIBs) at high voltages (3.0–4.6 V vs. Li/Li + ). After adding 0.2 wt% SDPN to the electrolytes; i.-e., 1.0 M LiPF 6 -EC/DMC/EMC, the capacity for the LiNi 1/3 Co 1/3 Mn 1/3 O 2 /graphite cell to retain power was significantly increased from 59.5% to 77.3% after only 100 cycles, which shows the promising application of SDPN at higher voltages. Density functional theory calculation results indicate that SDPN had reduced oxidative constancy compared to ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC). The effects of SDPN on cell performance are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The testing results indicate that the improvement in cycling activity could be ascribed to the thinner cathode electrolyte interface film originated from SDPN on the LIB using LiNi 1/3 Co 1/3 Mn 1/3 O 2 , which reduced the interfacial resistance at a high voltage, but also protected the decomposition of electrolytes and suppressed transition metal dissolution.

Ethyl 3,3,3-trifluoropropanoate (TFPE) is an additive that extends the life of the LiMn 2 O 4 /Li cell. After 200 charge and discharge cycles at 55 °C, a LiMn 2 O 4 /Li cell increases the capacity retention by 13.2% (48.2% without additive versus 61.4% with additive) when 0.5 vol% TFPE is added to the electrolyte. Versus TFPE-free cells, the additive inhibits the formation of HF induced erosion of the LiMn 2 O 4 electrode and reduces the interfacial impedance by 61.2% (drops to 139 from 227 Ohm).

In order to overcome the capacity fading of LiNi1/3Co1/3Mn1/3O2/graphite lithium-ion batteries (LIBs) cycled in the voltage range of 3.0–4.6 V (vs. Li/Li+), di(methylsulfonyl) methane (DMSM) is evaluated as a new electrolyte additive. This study demonstrated that DMSM additive in the electrolyte can dramatically improve the cycling performance of LiNi1/3Co1/3Mn1/3O2/graphite cell at a higher voltage operation. In addition, the effects of this additive are characterized by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), as well as transmission electron microscopy (TEM). With the addition of 0.1 wt. % DMSM into the electrolyte, the capacity loss of the LiNi1/3Co1/3Mn1/3O2/graphite cell cycled at the voltage range of 3.0–4.6 V significantly decreased from 39.0 % to 19.9 % after 100 cycles, which shows the promising application of DMSM at higher voltage. The enhanced cycling performance is attributed to the thinner cathode electrolyte interface film originated from DMSM on the LiNi1/3Co1/3Mn1/3O2, which not only resulted in lower interfacial impedance, but also protected the decomposition of electrolyte and prevented the cathode transition metal dissolution at the high voltage.

Fluoroethylene carbonate (FEC) and lithium difluorophosphate (LiPO2F2) are evaluated as hybrid functional additives to improve the electrochemical performance of SiC-based lithium-ion batteries. When added to the electrolyte, FEC + LiPO2F2 significantly enhance the performance of SiC/Li cells. The capacity retention increases from 28.5% to 76.2% after 200 cycles. The effects of FEC + LiPO2F2 are characterized by charge–discharge testing, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Combining the results of these analyses reveals that hybrid functional additives are beneficial for forming a uniform and thinner solid–electrolyte interface film on the SiC surface. The solid–electrolyte interface film derived from FEC + LiPO2F2 greatly inhibits particle pulverization and electrolyte decomposition, which play an important role in the performance of SiC-based cells.