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The dilemma of employing high-capacity battery materials and maintaining the electronic and mechanical integrity of electrodes demands novel designs of binder systems. Here, we developed a binder polymer with multifunctionality to maintain high electronic conductivity, mechanical adhesion, ductility, and electrolyte uptake. These critical properties are achieved by designing polymers with proper functional groups. Through synthesis, spectroscopy, and simulation, electronic conductivity is optimized by tailoring the key electronic state, which is not disturbed by further modifications of side chains. This fundamental allows separated optimization of the mechanical and swelling properties without detrimental effect on electronic property. Remaining electronically conductive, the enhanced polarity of the polymer greatly improves the adhesion, ductility, and more importantly, the electrolyte uptake to the levels of those available only in nonconductive binders before. We also demonstrate directly the performance of the developed conductive binder by achieving full-capacity cycling of silicon particles without using any conductive additive.

A conductive polymer and silicon nanoparticles were used to form elastic and porous micron-sized composite secondary particles using spray precipitation method. These composite secondary particles are used to fabricate a lithium-ion anode electrode. Although the Si volume changes during charge and discharge process, the composite secondary particles retain their size during these processes, to maintain a stable electrode microstructure. This dimension stability leads to improved electrode cycling stability and enhanced rate performance. © 2013 The Electrochemical Society. All rights reserved.

Pure tin (Sn) nanoparticles can be cycled in stable and high gravimetric capacity (>500 mAh/g) with a polyfluorene-type conductive polymer binder in composite electrodes. Crystalline Sn nanoparticles (

A conductive polymer is developed for solving the long-standing volume change issue in lithium battery electrodes. A combination of synthesis, spectroscopy and simulation techniques tailors the electronic structure of the polymer to enable in situ lithium doping. Composite anodes based on this polymer and commercial Si particles exhibit 2100 mAh g -1 in Si after 650 cycles without any conductive additive. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

LiNi0.5Mn1.5O4 is regarded as a promising cathode material to increase the energy density of lithium-ion batteries due to the high discharge voltage (ca. 4.7 V). However, the interface between the LiNi0.5Mn1.5O4 cathode and the electrolyte is a great concern because of the decomposition of the electrolyte on the cathode surface at high operational potentials. To build a stable and functional protecting layer of Li3PO4 on LiNi0.5Mn1.5O4 to avoid direct contact between the active materials and the electrolyte is the emphasis of this study. Li3PO4-coated LiNi0.5Mn1.5O4 is prepared by a solid-state reaction and noncoated LiNi0.5Mn1.5O4 is prepared by the same method as a control. The materials are fully characterized by XRD, FT-IR, and high-resolution TEM. TEM shows that the Li3PO4 layer (<6 nm) is successfully coated on the LiNi0.5Mn1.5O4 primary particles. XRD and FT-IR reveal that the synthesized Li3PO4-coated LiNi0.5Mn1.5O4 has a cubic spinel structure with a space group of Fd $\bar 3$ m, whereas noncoated LiNi0.5Mn1.5O4 shows a cubic spinel structure with a space group of P4332. The electrochemical performance of the prepared materials is characterized in half and full cells. Li3PO4-coated LiNi0.5Mn1.5O4 shows dramatically enhanced cycling performance compared with noncoated LiNi0.5Mn1.5O4. [ABSTRACT FROM AUTHOR]

Abstract: Li4P2O7-stabilized LiNi0.5Mn1.5O4 was prepared by solid-state synthesis. The material was characterized by X-ray diffraction and high-resolution transition electron microscopy, which showed a coating layer (<10nm) of Li4P2O7 crystallite co-existing with a little Li3PO4 on the LiNi0.5Mn1.5O4/Li4P2O7 primary particles. LiNi0.5Mn1.5O4/Li4P2O7 synthesized at 760°C for 200h had a cubic spinel structure with a space group of Fd m; its estimated crystallite size was 527nm. LiNi0.5Mn1.5O4/Li4P2O7 possessed better rate capability and cycling capability. The introduced Li4P2O7 coating layer acted as a solid electrolyte or artificial SEI layer: by separating the active material from the electrolyte, the coating layer prevented the Ni2+/Ni3+ or Ni3+/Ni4+ redox couple from decomposing the electrolyte. Stress/strain from the Ni2+⇌Ni3⇌Ni4+ spinel phase change caused fractures and pulverization of the cycled stoichiometric LiNi0.5Mn1.5O4 crystal surface, especially noticeable for this well-developed micro-sized crystal. The ordered stoichiometric LiNi0.5Mn1.5O4 had more side reactions, led to a quick fading of the material''s capacity. Both the Li4P2O7 coating layer and the disordered Fd m space group LiNi0.5Mn1.5O4 structure bring benefit to the LiNi0.5Mn1.5O4/Li4P2O7 performance. Thus, the introduced Li4P2O7 coating layer can build an effective solid electrolyte or artificial SEI layer to protect the interface between LiNi0.5Mn1.5O4 and electrolyte. [Copyright &y& Elsevier]

Abstract: Anodes containing spherical natural graphite (SNG12) and cathodes containing LiFePO4, both from HydroQuebec, were prepared with aqueous-based polyacrylic acid (PAAH), its neutralized derivatives polyacrylic acid (PAAX) (X=Li, Na, and K), and with conventional poly(vinylidene difluoride) (PVDF) binders. A comparison of electrode performance was made between these three binder systems. The electrodes were optimized by adding elastic styrene butadiene rubber (SBR) and conductive vapor grown carbon fiber (VGCF) in the place of some of the PAAX. Initially, SNG12 and LiFePO4 electrodes were characterized in half cells with Li as the counter electrode. The electrochemistry results show that the use of PAAX binders can significantly improve the initial coulombic efficiency, reversible capacity, and cyclability of SNG12 anodes and LiFePO4 cathodes as compared to that of electrodes based on a PVDF binder. By using an optimized composition for the anode and cathode, SNG12/LiFePO4 full cells with PAALi binder cycled 847 times with 70% capacity retention, which was a significant improvement over the electrodes with PVDF (223 cycles). This study demonstrates the possibility of manufacturing Li-ion batteries that cycle longer and use water in the processing, instead of hazardous organic solvents like NMP, thereby improving performance, reducing cost, and protecting the environment. [Copyright &y& Elsevier]

We synthesized Fe3O4nanoparticle/reduced graphene oxide (RGO-Fe3O4) nanocomposites and evaluated their performance as anodes in both half and full coin cells. The nanocomposites were synthesized through a chemical co-precipitation of Fe2橷 Fe3 the presence of graphene oxides within an alkaline solution and a subsequent high-temperature reduction reaction in argon (Ar) environment. The morphology and microstructures of the fabricated RGO-Fe3O4nanocomposites were characterized using various techniques. The results indicated that the Fe3O4nanoparticles had relatively homogeneous dispersions on the RGO sheet surfaces. These as-synthesized RGO-Fe3O4nanocomposites were used as anodes for both half and full lithium-ion cells. Electrochemical measurement results exhibit a high reversible capacity which is about two and a half times higher than that of graphite-based anodes at a 0.05C rate, and an enhanced reversible capacity of about 200 mAh g−1even at a high charge/discharge rate of 10C (9260 mA g−1) in half cells. Most important of all, these fabricated novel nanostructures also show exceptional capacity retention with the assembled RGO-Fe3O4/LiNi1/3Mn1/3Co1/3O2full cell at different C rates. This outstanding electrochemical behavior can be attributed to the unique microstructure, morphology, texture, surface properties of the nanocomposites, and combinative effects from the different chemical composition in the nanocomposites. [ABSTRACT FROM AUTHOR]

LiNi0.5Mn1.5O4 is regarded as a promising cathode material to increase the energy density of lithium-ion batteries due to the high discharge voltage (ca. 4.7 V). However, the interface between the LiNi0.5Mn1.5O4 cathode and the electrolyte is a great concern because of the decomposition of the electrolyte on the cathode surface at high operational potentials. To build a stable and functional protecting layer of Li3PO4 on LiNi0.5Mn1.5O4 to avoid direct contact between the active materials and the electrolyte is the emphasis of this study. Li3PO4-coated LiNi0.5Mn1.5O4 is prepared by a solid-state reaction and noncoated LiNi0.5Mn1.5O4 is prepared by the same method as a control. The materials are fully characterized by XRD, FT-IR, and high-resolution TEM. TEM shows that the Li3PO4 layer (<6 nm) is successfully coated on the LiNi0.5Mn1.5O4 primary particles. XRD and FT-IR reveal that the synthesized Li3PO4-coated LiNi0.5Mn1.5O4 has a cubic spinel structure with a space group of Fd3m, whereas noncoated LiNi0.5Mn1.5O4 shows a cubic spinel structure with a space group of P4(3)32. The electrochemical performance of the prepared materials is characterized in half and full cells. Li3PO4-coated LiNi0.5Mn1.5O4 shows dramatically enhanced cycling performance compared with noncoated LiNi0.5Mn1.5O4., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)