The aqueous processing of lithium-ion battery (LIB) electrodes has the potential to notably decrease the battery processing costs and paves the way for a sustainable and environmentally benign production (and recycling) of electrochemical energy storage devices. Although this concept has already been adopted for the industrial production of LIB graphite anodes, the performance decay of cathode electrodes based on transition metal oxides processed in aqueous environments is still an open issue. In this study, we show that the addition of small quantities of phosphoric acid into the cathodic slurry yields Li[Ni0.33 Mn0.33 Co0.33 ]O2 electrodes that have an outstanding electrochemical performance in lithium-ion cells.

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In this paper we report on the investigation of ionic liquid-based electrolytes with enhanced characteristics. In particular, we have studied ternary mixtures based on the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and two ionic liquids sharing the same cation (N-methyl-N-propyl pyrrolidinium, PYR 13 ), but different anions, bis(trifluoromethanesulfonyl)imide (TFSI) and bis(fluorosulfonyl)imide (FSI). The LiTFSI-PYR 13 TFSI-PYR 13 FSI mixtures, found to be ionically dissociated, exhibit better ion transport properties (about 10 −3 S cm −1 at −20 • C) with respect to similar ionic liquid electrolytes till reported in literature. An electrochemical stability window of 5 V is observed in carbon working electrodes. Preliminary battery tests confirm the good performance of these ternary electrolytes with high-voltage NMC cathodes and graphite anodes. Ionic liquids (ILs) are being investigated as substitutes of volatile and flammable organic electrolyte solvents in rechargeable lithiumion battery systems 1,2 to enhance safety of the electrochemical device. ILs are considered, in fact, strong flame retardants, displaying negligible vapor pressure in combination with relatively fast ion transport properties and wide chemical/electrochemical/thermal stability.3,4 So far, single ILs did not generally fully satisfy the requirements and/or operative conditions of practical devices, although their properties can be finely tuned by properly modifying their architecture.3,4 A promising approach, however, is represented by suitably combining different ionic liquids, leading to beneficial synergic effects on the physicochemical properties of the resulting mixtures. [5][6][7] In previous work, 8,9 we have demonstrated the possibility of favorably combining two ionic liquids, sharing the N-methyl-Npropyl pyrrolidinium cation (PYR 13 + ) and bis (trifluoromethanesulfonyl)imide (TFSI − ) and bis(fluorosulfonyl)imide (FSI − ) anions. The TFSI ion was proved to be stable toward oxidation and thermally robust 2 while FSI-based ILs exhibit good ion conduction even at low temperature and protective film-forming capability onto electrodes. 2,10,11 In particular, proper PYR 13 TFSI-PYR 13 FSI formulations 8,9 were found to display ionic conductivities largely overcoming 10 −4 S cm −1 at −20 • C whereas the pure IL materials, still in solid state, exhibit conduction values about four orders of magnitude lower. This behavior is likely due to the different hindrance of the anions, resulting in worse ion packing and, therefore, inhibiting the crystallization process of the IL blend. [5][6][7] In addition, average, even if moderate, variation of the linear density vs mole composition behavior of the PYR 13 TFSI-PYR 13 FSI mixtures was observed at intermediate FSI mole fraction. 9 This issue suggests rearrangement of the ion structural organization within the IL blend, which may positively reflect on the transport properties. On the basis of the obtained results, the TFSI:FSI mole ratio of 2:3 was selected. 9 * Electrochemical Soci...

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In this manuscript the investigation of the heat-curable polyurethane (PU)/carboxymethyl cellulose (CMC) mixture as binder for Li-ion battery electrodes is reported. The experimental results demonstrate the outstanding thermal and electrochemical stability of PU, as well as the good electrochemical performance of cathode (NMC) and anode (graphite) electrodes in which PU is used as binder. The most important finding is the ability of PU to prevent current collector corrosion usually occurring when an aqueous dispersion (slurry) of NMC is coated on aluminum foils. SEM investigation shows that PU encapsulates the positive active material particles preventing a pH raise in the slurry. Finally, the cycling performance of PU/CMC based anodes and cathodes are tested in half as well as full lithium-ion cell setups. The awareness of the finite nature of our earth´s natural resources as well as growing concerns for increased greenhouse gas emissions are leading to a strong demand for a more environmentally-friendly generation of energy. Considering the importance of sustainable energy solutions, strong efforts are made to develop improved systems for large and small scale energy storage.1,2 Currently, Li-ion batteries seem to be suitable energy storage devices to fulfil the requirements of small energy storage due to their high energy density and long lifetime.3 Additionally, their lightweight fulfils very well the rising demand for use in smartphones, computers and other portable devices, as well as for electromobility solutions, facilitating the development toward a modern mobile society.Lithium-ion batteries are composed of several materials including metals and metal oxides, graphite and other carbonaceous materials, organic solvents, lithium salts and polymers. These latter are present in the porous separator, laying in between the electrodes (usually a polyolefin), and as binding components in the composite electrodes. Binders are counted among the so-called inactive components since they do not directly contribute to the capacity of the cells. However, their key role in the electrode processing and their dramatic influence on the electrochemical performance of electrodes has been extensively outlined. [4][5][6] Relevant physical and chemical properties for binder materials are (i) thermal stability, chemical and electrochemical stabilities, (ii) tensile strength (strong adhesion and cohesion), (iii) flexibility, and (iv) viscosity (of the slurries). 4,[7][8][9] The main purpose of using a binder is to form stable networks of the solid electrode components, i.e., the active materials and conducting agents (cohesion). Moreover, the binder has to ensure a close contact of the composite electrode toward the current collector (adhesion).In state-of-the-art commercial Li-ion batteries polyvinylidene-difluoride (PVdF) is the binder material of choice due to its superior adhesion properties and electrochemical stability.10 Important points of criticism for this polymer, however, are the requirement of volatile and toxic so...

Herein we report the investigation on the use of guar gum and two of its derivatives as LIB positive electrodes binders. These polymers are electrochemically stable within the operating voltage of LIBs (0.01-5 V vs Li/Li +) and do not show evidence of thermal decomposition up to 200 °C. The electrochemical performance of lithium nickel manganese cobalt oxide (NMC) electrodes made using guar gum is excellent as indicated, for instance, by the delivered capacity of 100 mAh g-1 upon 5C rate cycling. X-ray Photoelectron Spectroscopy (XPS) measurements of pristine electrodes reveal as the binder layer surrounding the active material particles is thin, resulting in the above-mentioned electrochemical performance. Full lithium-ion cells, utilizing guar gum on both positive and negative electrodes, display a stable 2 discharge capacity of ~110 mAh g-1 (based on cathode active material) with high coulombic efficiencies. Post-mortem investigation by XPS of cycled graphite electrodes from full lithiumion cells revealed the formation of a thin solid electrolyte interface (SEI).

This work elucidates the manufacturing of lithium titanate (Li 4 Ti 5 O 12 , LTO) electrodes via the aqueous process using sodium carboxymethylcellulose (CMC), guar gum (GG) or pectin as binders. To avoid aluminum current collector dissolution due to the rising slurries' pH, phosphoric acid (PA) is used as a pH-modifier. The electrodes are characterized in terms of morphology, adhesion strength and electrochemical performance. In the absence of phosphoric acid, hydrogen evolution occurs upon coating the slurry onto the aluminum substrate, resulting in the formation of cavities in the coated electrode, as well as poor cohesion on the current collector itself. Consequently, the electrochemical performance of the coated electrodes is also improved by the addition of PA in the slurries. At a 5C rate, CMC/PA-based electrodes delivered 144 mAh¨g´1, while PA-free electrodes reached only 124 mAh¨g´1. When GG and pectin are used as binders, the adhesion of the coated layers to the current collector is reduced; however, the electrodes show comparable, if not slightly better, electrochemical performance than those based on CMC. Full lithium-ion cells, utilizing CMC/PA-made Li[Ni 0.33 Mn 0.33 Co 0.33 ]O 2 (NMC) cathodes and LTO anodes offer a stable discharge capacity of~120 mAh¨g´1 (NMC) with high coulombic efficiencies.