Additives For Lithium-ion Batteries Research Articles

A comparative study on electrochemical performances of the electrodes with different nanocarbon conductive additives for lithium ion batteries

Three nanocarbon materials (0 D acetylene black (AB), 1 D carbon nanotubes (CNTs) and 2 D reduced graphene oxide (RGO)) were used as conductive additives (CAs) in the mesocarbon microbead anodes for lithium ion batteries. The electrochemical performances of the electrodes were investigated. The results show that the CAs have a significant impact on the electrode performance because they can influence the electron conduction and lithium ion transportation within the electrode. The electrode with RGO achieves a maximum capacity of 387 mAh g−1 after 50 cycles at a current density of 50 mA g−1, much higher than those of the electrodes with AB (334 mAh g−1) and CNTs (319 mAh g−1). The improvement should be mainly ascribed to the “plane-to-point” conducting network formed in the electrode with 2 D RGO which can favor the electron conduction and enhance the lithium ion transportation.

Application of Anisole, 2-Bromoanisole and 3-Bromoanisole as Overcharge Protection Additives in Lithium-Ion Batteries

Application of Anisole, 2-Bromoanisole and 3-Bromoanisole as Overcharge Protection Additives in Lithium-Ion Batteries

Trimethyl borate and triphenyl borate as electrolyte additives for LiFePO4 cathode with enhanced high temperature performance

Alkyl- and phenyl-substituted borate anion receptors, triphenyl borate (TPB) and trimethyl borate (TMB), are investigated as electrolyte additives in lithium ion batteries (LiFePO4 cathode, 1 M LiPF6 EC-DMC 1:1 electrolyte) at 25 and 60 °C. TPB shows formation of a thick surface/electrolyte interface (SEI) which hampers ion flow and does not protect the electrode from degradation. Although useful at 25 °C, TPB at 60 °C results in only 7% capacity after 100 cycles, whereas 0.1 M TMB results in 53% capacity. TMB performance improves with increasing concentration. TMB also suppresses thermal decomposition of the electrolyte and formation of the SEI film.

1,1-Difluoro-1-alkenes as new electrolyte additives for lithium ion batteries

Five 1,1-difluoro-1-alkenes bearing aryl groups are investigated as electrolyte additives for high-charge-voltage lithium ion batteries with an aim to induce favorable solid electrolyte interphase (SEI) formation. Among them, 1,1-difluoro-4-phenylbut-1-ene (DF-1) forms appropriate SEIs on the cathode and anode by its reactions under oxidative and reductive conditions, respectively, which was suggested by linear sweep and cyclic voltammetry. The SEIs formed with the DF-1 containing electrolyte on the cathode and anode were analyzed by X-ray photoelectron spectroscopy and time of flight-secondary ion mass spectrometry, indicating the following: (i) the cathode surface has a LiF-rich layer with unsaturated hydrocarbons, and (ii) the anode surface also has a LiF-rich layer, which probably includes fluoromethylene (CHF) compounds. The formation of the SEIs on both electrodes with DF-1 results in low impedance being maintained, and thus, particularly good cycle performance even at high-charge-voltage.

Performance Enhancing Electrolyte Additives for Lithium Ion Batteries with Silicon Anodes

The cycling performance of silicon thin film electrodes was investigated in the presence of anode solid electrolyte interphase (SEI) forming additives. Incorporation of vinylene carbonate (VC), flouroethylene carbonate (FEC), and lithium difluorooxalatoborate (LiFOB) improve the cycling efficiency and capacity retention of cells. Ex-situ surface analysis of the silicon anodes after cycling indicates that incorporation of the additives changes the structure of the SEI. Additives decrease the concentration of LiF on the anode surface consistent with inhibition of LiPF6 decomposition. The changes in surface structure correlate with improved cycling performance.

Application of 1,2-Dimethoxy-4-nitro-benzene and 1,4-Dimethoxy- 2-nitro-benzene as Overcharge Protection Additives in Lithium-Ion Batteries

在锂离子电池电解液1mol·L-1 LiPFd（碳酸乙烯酯（EC）＋碳酸二乙酯（DEC）＋碳酸甲乙酯（EMC）（1：1：1，体积比））中分别添加1，2-二甲氧基-4-硝基苯（DMNBl）和1，4．二甲氧基-2-硝基苯（DMNB2）作为防过充添加剂．采用循环伏安（CV）、恒流充放电、过充测试、电化学阻抗谱（EIS）、扫描电子显微镜（SEM）等手段研究了DMNB1和DMNB2的防过充效果，以及添加剂与LiNi1/3Co1/3Mn1/3O2材料的相容性．结果表明：DMNBl和DMNB2的氧化电位都在4．3V（VSLi／Li＋）以上，且均能显著提高电池的过充保护性能．100％过充和5V截止电压过充测试表明，DMNBl的防过充性能优于DMNB2．采用基础电解液、添加0．1mol·L-1 DMNB1和添加0．1mol·L-1 DMNB2电解液的LiNi，mComMnmOdLi电池。0．2C倍率下循环100次。容量保持率分别为98．4％、95．9％和68．1％．证明硝基在添加剂苯环上的取代位置和其电化学性能之间有着密切联系．

Methyl phenyl bis-methoxydiethoxysilane as bi-functional additive to propylene carbonate-based electrolyte for lithium ion batteries

Methyl phenyl bis-methoxydiethoxysilane (MPBMDS) was prepared and its effects were investigated as an additive in 1.0 mol dm −3 LiPF 6-propylene carbonate (PC)/dimethyl carbonate (DMC) (1:1, v/v) electrolyte for lithium ion batteries. The electrochemical properties of the electrolyte with MPBMDS were characterized by discharge/charge tests, cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The addition of MPBMDS can effectively prevent the decomposition and the co-intercalation of PC. In addition, burning tests showed that the addition of 4–13 wt.% MPBMDS to the bare PC-based electrolyte effectively reduces the flammability. This eco-friendly compound provides a new promising direction for the development of bi- or multi-functional additives for lithium ion batteries.

Effect of Single-Walled Carbon Nanotubes as Conductive Additives on the Performance of LiCoO2-Based Electrodes

Single-walled carbon nanotubes (SWNTs) and carbon black (CB) were used as conductive additives in lithium-ion batteries. Composites containing nanostructured and carbon additives were applied as positive electrodes in coin-type electrochemical cells with Li metal as a counter electrode. The conductive SWNTs with their wirelike shape and high aspect ratio are proved to have significant impact on the electrochemical performance of the electrode. The electrode composite containing of SWNTs has an internal resistance comparable to that of the of carbon black. Whereas the discharge capacity of the electrode containing of CB drops to 0 when increasing the rate to 5C, the capacity of the electrode containing the same weight fraction of SWNTs retains 67% of its initial capacity even at 18C. Cycling performance measured up to demonstrates that the SWNTs at a low concentration are as efficient in the capacity retention as the of carbon black. We interpret the SWNT-induced electrode performance by formation of a flexible, electrically wired network of conducting SWNTs in close contact with nano-particles, which accelerates the exchange of the Li ions and allows a rapid transfer of electrons throughout the electrode.

Perfluoro Aryl Boronic Esters as Redox Shuttle Additives in Lithium-Ion Batteries

A new family of redox shuttle additives is being developed at Argonne National Laboratories and tested at EnerDel for eventual application in large format batteries that will be used in military, vehicular, and grid storage applications. Perfluoro aryl boronic esters are redox active in the 4.4 to 4.6 V range, making them ideal for use in lithium ion batteries employing high voltage cathodes. Electrochemical testing has been performed on the initial candidate from this family, namely 2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole (BDB), to determine the E0 value of 4.43 V vs. Li/Li+ and the diffusion coefficient of 1.38 x 10-5 cm2/sec in standard electrolyte. Initial battery testing has been performed using a lithium nickel cobalt manganese oxide cathode and a carbonaceous anode. The shuttle molecule has little or no detrimental effect on the cell performance; however, the overcharge protection is not robust and this may be due to contaminants.

The study of carbon nanotubes as conductive additives of cathode in lithium ion batteries

Carbon nanotubes (CNTs), including multi-walled CNTs (MWCNTs) and single-walled CNTs (SWCNTs), are employed as conductive additives in lithium ion batteries. The effects of MWCNTs’ carbon precursors, diameter, and weight fraction on the electrochemical behavior of MWCNTs/LiCoO2 composite cathode are investigated. Meanwhile, a comparison is made between SWCNTs /LiCoO2 and MWCNTs/LiCoO2. Among the three kinds of carbon precursors: CH4, natural gas, and C2H2, MWCNTs prepared from CH4 are very fit for acting as conductive additives due to their better crystallinity and lower electrical resistance. MWCNTs with smaller diameter favor improving the electrochemical behavior of MWCNTs/LiCoO2 composite cathode at higher charge/discharge rate owing to their advantage in primary particle number in unit mass. To make full use of LiCoO2 at higher rate, it is necessary to add at least 5 wt.% of MWCNTs with a diameter 10~30 nm. However, SWCNTs are not expected to be added into LiCoO2 composite cathode since they tend to form bundles.

Carbon Nanomaterials Used as Conductive Additives in Lithium Ion Batteries

As the vital part of lithium ion batteries, conductive additives play important roles in the electrochemical performance of lithium ion batteries. They construct a conductive percolation network to increase and keep the electronic conductivity of electrode, enabling it charge and discharge faster. In addition, conductive additives absorb and retain electrolyte, allowing an intimate contact between the lithium ions and active materials. Carbon nanomaterials are carbon black, Super P, acetylene black, carbon nanofibers, and carbon nanotubes, which all have superior properties such as low weight, high chemical inertia and high specific surface area. They are the ideal conductive additives for lithium ion batteries. This review will discuss some registered patents and relevant papers about the carbon nanomaterials that are used as conductive additives in cathode or anode to improve the electrochemical performance of lithium ion batteries.

Perfluoro Aryl Boronic Esters as Redox Shuttle Additives in Lithium-Ion Batteries

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Effect of mesoporous carbon containing binary conductive additives in lithium ion batteries on the electrochemical performance of the LiCoO 2 composite cathodes

Binary conductive additives (BCA), formed by sonication of mesoporous carbon (MC) and acetylene black (AB), were used as conductive additives to improve the electrochemical performance of a LiCoO 2 composite cathode. The electrochemical performance of the LiCoO 2 composite cathode dispersed with BCA was investigated. The results showed that the electrochemical performance (including the discharge capacity, the discharge voltage and the total internal resistance) of a BCA loaded LiCoO 2 composite cathode was better than that of a cathode loaded with AB. The possible mechanism is that the MC in BCA can adsorb and retain electrolyte solution, which allows an intimate contact between the lithium ions and the cathode active material LiCoO 2 due to its large mesopore specific surface area. A simplified model was also proposed.

The effect of different kinds of nano-carbon conductive additives in lithium ion batteries on the resistance and electrochemical behavior of the LiCoO 2 composite cathodes

Acetylene black, chemical vapor deposit carbon fibers and carbon nanotubes (CNTs) are employed as conductive additives in lithium ion batteries. Among them, carbon nanotubes are proved to be the most effective for decreasing the resistance and improving electrochemical behavior of the composite cathode. Their wire-like shape, crystallinity and nano-size are all considered to be important factors. Their wire-like shape favors developing continuous conductive network and then assures an efficient electronic transport throughout the cathode. Their higher crystalline and nano-size make them show better ability to rapidly transfer electrons and lower percolation threshold in comparison with vapor carbon fiber. Moreover, their higher surface energy guarantees their close contact with the active materials LiCoO 2. The results suggest that much conductive additives could be saved by employing CNTs as conducting agents, and the cathode with only a small amount of CNTs conductive additives shows excellent rate capacity. A simplifying model to explain the phenomena is also presented.

리튬이온전지용 난연성 첨가제(TCP, TFPP)의 전기화학적 특성

Flame retardant(FR) properties were investigated with tricredyl phosphate(TCP) and tris(pentafluorophenyl)phosphine(TFPP) as additives for lithium-ion batteries. Thermal stability was improved with additives in <TEX>$Li/LiNi\frac{1}{3}Mn\frac{1}{3}Co\frac{1}{3}O_2$</TEX> cells comparing to non-additive electrolytes. Oxygen evolution reaction of the cathode material was delayed to up <TEX>$55^{\circ}C$</TEX>, from <TEX>$275^{\circ}C\;to\;330^{\circ}C$</TEX>. Electrolytes with the 1 wt.% additives provided good FR properties while the resonable battery performance is maintained.

4-Bromobenzyl isocyanate versus benzyl isocyanate—New film-forming electrolyte additives and overcharge protection additives for lithium ion batteries

Electrochemical properties and working mechanisms of benzyl isocyanate compounds as polymerizable electrolyte additives for overcharge protection of lithium ion batteries have been studied by cyclic voltammetry, charge–discharge cycling, overcharge tests, accelerating rate calorimetry (ARC) and in situ Fourier transform infrared spectroscopy (FTIRS). The overcharge and FTIRS data clearly reveal that 4-bromobenzyl isocyanate (Br-BIC) can electrochemically polymerize at 5.5 V (versus Li/Li +) to form an overcharge-inhibiting (probably insulating) film on the cathode surface. In addition, is found the Br-BIC does slightly improve the charge/discharge performance of a lithium ion battery. Furthermore, Br-BIC and benzyl isocyanate show beneficial solid electrolyte interphase (SEI) formation behaviour on graphite in propylene carbonate based electrolyte solutions.

Effects of Aromatic Esters as Propylene Carbonate-Based Electrolyte Additives in Lithium-Ion Batteries

The role of aromatic esters as additives in propylene carbonate (PC) based electrolytes used in lithium-ion batteries has been investigated. The addition of aromatic esters into the 1.0 M -PC:DEC (3:2 in volume) suppresses the co-intercalation of PC and solvated ions and inhibits the further decomposition of electrolytes during the first lithium intercalation process. A graphitic anode (MCMB-2528, mesocarbon microbeads) in a PC-based electrolyte with the aromatic esters exhibits a high reversible capacity. Scanning electron microscopy and the first discharge curve results show that the aromatic esters decompose and form a proper solid electrolyte interphase (SEI) film on the MCMB surface to not only prevent exfoliation of the graphite electrode but also stabilize the electrolyte. Both cyclic voltammogram and the lowest unoccupied molecular orbital energy level show that the aromatic esters have higher reduction potentials than that of the electrolyte solvents. An increase in reverse capacity may be achieved by increasing the addition. However, when the addition exceeds a certain critical value, the SEI film inhibits the intercalation of lithium ions and lowers the capacity. Furthermore, the percentage of the aromatic esters in electrolytes directly influences the low-temperature performance and the rate capability of the cells. An optimal result may be obtained when the addition is approximately 2-4%.

Improved Thermal Stability of LiCoO2 by Cyclotriphosphazene Additives in Lithium-ion Batteries

Abstract Fluorinated cyclotriphosphazene is selected as a novel flame-retarding additive in the electrolyte for lithium-ion batteries. The effect of the phosphazenes on the thermal stability of LiCoO2 cathode has been investigated by the thermal analyses on charged LiCoO2 electrodes in the presence of the electrolyte with or without the additives. Possible mechanism for the influence of the additive on the thermal stability of LiCoO2 has been proposed.

Comparative study of trimethyl phosphite and trimethyl phosphate as electrolyte additives in lithium ion batteries

Safety concerns of lithium ion batteries have been the key problems in their practical applications. Trimethyl phosphite (TMP(i)) and trimethyl phosphate (TMP(a)) were used as the electrolyte additives to improve the safety and electrochemical performance of lithium cells. Gallvanostatic cell cycling, flammability test and thermal stability measurements by means of accelerated rate calorimeter (ARC) and micro calorimeter were performed. It is found that both TMP(i) and TMP(a) reduce the flammability of the electrolyte. The TMP(i) additive not only enhances the thermal stability of the electrolyte, but also improves its electrochemical performance. The TMP(a) additive can improve the thermal stability of the electrolyte at the expense of some degree of degradation of its electrochemical performance. Therefore, TMP(i) is a better flame retardant additive in the electrolyte compared with TMP(a).

Cyclic and acyclic sulfites: new solvents and electrolyte additives for lithium ion batteries with graphitic anodes?

The low viscosities of the linear sulfites dimethyl sulfite and diethyl sulfite are suggesting an investigation of their suitability as low viscosity co-solvents for ethylene carbonate based electrolytes. In this study, electrochemical performances at graphitic anodes and conductivities in the temperature range −60 to +60°C are presented. Comparisons with the linear carbonates dimethyl carbonate and diethyl carbonate, which have been currently used as low viscosity solvents in lithium ion batteries, are made.