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Self-discharge refers to the loss in stored charge of a battery without connection between its electrodes as a consequence of internal chemical reactions. Self-discharge processes can be tested in a loadfree state for a fixed time. Two self-discharge reactions are possible in a Li-ion cell: one is chemical and the other electrochemical. Because of their reactivity, charged cells can undergo side reactions, and factors such as purity of the active material or electrolyte, the specific surface area of the electrodes, conductors, binders or separators can have effect on the self-discharge performance. These reactions are mostly irreversible while electrochemical reactions can be reversible. For example, lithium re-intercalation can lead to self-discharge of Li-ion batteries, as has been demonstrated by many researchers who have studied the different factors that could affect self-discharge of

A novel sulfur/polyacrylonitrile/graphene nanocomposite has been synthesized via a simple combination of ballmilling with low temperature heat-treatment. The nanocomposite was examined as a cathode for high performance lithium/sulfur batteries. The SEM and TEM observations revealed that sulfur/polyacrylonitrile particles are incorporated into graphene networks homogenously. Charge/discharge tests and ac impedance spectroscopy have shown improved conductivity and electrochemical properties of the composite with the addition of graphene. The lithium cell with this ternary composite cathode delivered a discharge capacity of 612 mAh g −1 in the second cycle at 0.1 C, and retained about 77% of this value over 100 cycles. Even up to 4 C rate, the lithium cell demonstrated an excellent rate capability, delivering a highly reversible discharge capacity of 360 mAh g −1 .

Alternative energy sources have received great attention since traditional energy sources, fossil fuels, are non-renewable and causing critical environmental damage. Rechargeable lithium-ion batteries (LIBs) with high power density, long cycle life and environmental friendliness are of huge interest for application as power supply in electric vehicles and renewable energy storage [1]. However, current wide implementation of LIBs is restricted by several factors, such as a low capacity, instability and toxicity of the electrode materials. Silica (SiO2) is an eco-friendly candidate for the next generation anode materials for high energy density LIBs with a high lithium (Li) storage capacity (1961 mAh g-1 for silica) at a lower cost [2]. However, pure silica has a poor electrical conductivity and suffers from rapid capacity fading due to significant volume changes during charge/discharge. These limitations could be overcome by applying carbon and/or polymer coatings [3] and engineering various hollow nanostructures [4] to increase the conductivity and accommodate the volume changes, respectively [5]. Herein, we propose an innovative chemical free approach to prepare a novel composite anode material combining hollow SiO2nanospheres, carbon nanotube and graphene. Hollow SiO2 sphere/carbon nanotube/graphene ternary composite was synthesized using sonication (by Ultrasonic Elma S 30) of SiO2 (30 nm, 25%), multi-walled carbon nanotubes (MWNT, 3 %) and graphene (G, 1%) water suspensions in different ratios. Derived mixtures were dried at 50 ºC overnight in vacuum oven (Memmert), and further annealed in air oven (Carbolite) at 500 ºC for 2 h. Finally, SiO2/MWNT/G composites were obtained. Also, for comparison similar composite with single-walled carbon nanotubes (SiO2/SWNT/G) was prepared. The resulting composites of SiO2/MWNT/G and SiO2/SWNT/G were investigated and characterized by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis confirmed the amorphous nature of the powders and FTIR spectroscopy identified the existence of Si-O, C-C and C=C bonds in these samples. TGA allowed for determination of the carbon content in the prepared composites. SEM revealed morphology of the samples and distribution of the elements in the composites. The TEM results allowed for characterization of the interior structure of the composite materials. CR2032 coin-type cells were used to evaluate the electrochemical performance of SiO2/MWNT/graphene and SiO2/SWNT/graphene composites in a lithium half-cell structure. The cells were tested galvanostatically in a voltage range of 0.01 – and 3.0 V vs. Li+/Li at a current density of 50 mA g-1 (Neware A602-3000W-CT-A). The further results of these studies will be presented at the conference. Acknowledgements This work was supported by the project grant 5097/GF4 “Development of a novel quartz (SiO2) based anode material for Li-ion batteries” from the Ministry of Education and Science of the Republic of Kazakhstan. References [1] S. Goriparti, C. Capiglia, J. Power Sources 257 (2014) 421-443 [2] X. Cao, G. Cao, Part. Part. Syst. Charact. 33 (2016) 110-117 [3] X. Cao, G. Cao, J. Mater. Chem. A, 3 (2015) 22739–22749 [4] N. Yan, Scientific Reports (2013) 1568 [5] A. Lisowska-Oleksiak, Int. J. Electrochem. Sci. 11 (2016) 1997 - 2017

Due to its high theoretical capacity of 1672 mAh g-1 and high energy density of 2600 Wh kg-1 sulfur is an attractive candidate as a cathode material for rechargeable lithium battery [1-2]. However, both LIBs and Li/S batteries rely on conventional liquid organic carbonate based electrolytes, which intrinsically has several critical drawbacks including volatility, flammability and potential leakage, which are triggering the safety issues [3]. Therefore, investigation for safer and more reliable electrolytes is urged, and polymer electrolytes are promising candidate in this regard. Poly(ethylene oxide)-based solid polymer electrolytes are common examples of a safe electrolyte. However, since they are limited by low ion conductivity at ambient temperature, the development of novel gel electrolytes, which entraps large amount of liquid electrolyte batteries attracts big interest. One of the major problems of sulfur cathode comes from solubility and shuttling phenomenon of the long chain lithium polysulfides in a conventional organic solvent based electrolyte, which causes a rapid irreversible loss of sulfur of the cathode over repeated cycles, and deposition of products of their transformation on the anode, leading to both electrodes degradation. In this work, we develop novel composite gel polymer electrolytes (GPEs) with high conductivity, high organic solvent uptake and high mechanical and thermal stability, which advantageously use the complementary properties of temperature-responsive polymer and ceramic filler. The composite GPEs are fabricated allowing for facile transport of Li+ ions but preventing leakage of electrolyte solution contained within the polymer membrane structure. Such GPEs have three unique features: electrolyte solution immobilization during battery cycling with rapid lithium ion transport, blocking of polysulfides shuttling phenomenon and battery shut down function in case of temperature increase. Furthermore, addition of functionalized natural and synthetic clay nanoparticles as ceramic filler allows overcoming the main problem of GPE – the loss of their mechanical strength when they are plasticized. We have combined polymers and temperature responsive polymers with Li-ion containing salt solutions. Among the inorganic layered hosts, montmorillonite and halloysite offer high aspect ratio, high cation exchange capacity, large specific surface area, appropriate interlayer charge. Undesired diffusion of polysulfide through electrolyte in Li/S batteries might be hindered in case of using composite GPE. A Li/S polymer cell containing a composite GPE has exhibited a good cycling performance with improved coulombic efficiency. The systems are under investigation with evaluation of polymer matrices and their ratio in the composite electrolyte. References [1] M. Armand, J.M. Tarascon, Nature 451(2008) 652-657. [2] Y. Zhao, Z. Bakenova, Y. Zhang, Z. Bakenov, Ionics DOI: 10.1007/s11581-015-1376-4. [3] R.D. Rogers, K.R. Seddon, ACS Symposium Series 818, Washington. DC. 2002. Acknowledgements This research was supported by the Research Grants #5156/GF4 and #4649/GF4 from the Ministry of Education and Science of the Republic of Kazakhstan for 2015-2017.

Lithium/sulfur batteries have gained intense attention as one of the most promising candidates for high energy density rechargeable batteries due to their high theoretical specific capacity of 1672 mAh g-1 and theoretical energy density of 2600 Wh kg-1 based on cathode materials. In addition, sulfur has the advantages such as low cost, natural abundance, and environmental friendliness. Herein, we report on the preparation of the long-time stabilized MWNT aqueous suspension with the addition of sodium dodecylbenzene sulfonate (SDBS) surfactant, and a well-dispersed sulfur/multiwalled carbon nanotube (S/MWNT) composite synthesis via a simple stirring mixing of the resultant MWNT suspension with commercial nanosized sulfur aqueous suspension. This preparation method based on the suspension mixing possesses the advantages of simplicity and low cost. Homogeneous dispersion and integration of MWNT in the composite results in a porous, highly conductive and mechanically flexible framework with enhanced electronic conductivity and ability to absorb the polysulfides into its porous structure. The cell with this S/MWNT composite cathode demonstrates a high reversibility, resulting in a stable reversible specific discharge capacity of 708 mAh g-1 after 100 cycles at 0.1 C. Furthermore, the S/MWNT composite cathode with sulfur content of 62.5 wt% exhibits a good rate capability with discharge capacities of 946, 780 and 516 mAh g-1 at 0.5, 1 and 1.5 C, respectively.

The SnO2 material has been considered as a promising lithium-ion battery anode candidate, and recently, the importance has been increased due to its high performance in sodium-ion batteries. Tin oxide (SnO2) has been studied as a promising alternative to the commercially used graphite anode material because of its much higher theoretical specific capacity 1491 mAh/g [1, 2]. Synthesis of tin oxide (IV) thin films was carried out in Picosun R-150 ALD reactor. Synthesis temperature of the process varied from 2500C to 3500C. As a source of tin was used Russian-made tetraethyltin (TET - Sn(C2H5)4, CAS № 597-64-8), purity 99.999%. Inductively coupled remote oxygen plasma and ozone was used as oxygen sources. Thickness of thin films was measured using spectroscopic ellipsometry UVISEL 2 UV-Vis-NIR, and corresponded 75-80 nm. Surface morphology were obtained by scanning electron microscope Mira Tescan. Valence state of tin was studied by X-ray photoelectron spectroscopy (XPS). Electrochemical study of obtained thin-film electrodes was also carried out. The voltage of cycling was ranged from 0.01 V to 0.8 V. Current density was 25 µA/cm2. During cycling tests was shown that tin oxide has a stable discharge capacity about 900 mAh/g during 500 charge/discharge cycles, with efficiency about 99,5 %, fig.1. Capacity fluctuations likely to be associated with changes in ambient temperature. Financial support was made by Ministry of Education and Science of Russian Federation. Unique identifier of the project is RFMEFI57814X0096. [1] Jiajun Chen Materials 6 (2013), 156-183 [2] S.-Y. Lee et al. Nano Energy 19 (2016), 234–245 Figure 1

Introduction Lithium batteries have the highest energy density among the commercialized secondary batteries and they are leading the path for energy storage and sources for portable applications, including electric vehicle transportation. Commercial lithium batteries are based on oxide cathodes such as LiCoO2, LiFePO4 and LiMn2O4, which can deliver only up to 200 mAh g-1 of capacity, limiting their use for energy demanding applications. The elemental sulfur could be a best choice for the cathode due its theoretical capacity of 1672 mAh g-1, which is one of the highest among all known cathode materials. Combined with its abundant availability, this makes sulfur a most promising cathode for lithium batteries. However, this cathode material suffers from its low conductivity and capacity fading due to the dissolution of electrochemical reaction products [1, 2]. In this work, we report on the preparation of a novel hierarchical porous sulfur/polypyrrole/multiwalled carbon nanotube composite (S/PPy/MWNT), and on its physical and electrochemical properties as a cathode for lithium secondary batteries. Experimental The S/PPy/MWNT composite preparation is schematically presented in Fig.1. The porous S/PPy/MWNT composite was synthesized via in situpolymerization of pyrrole monomer with nano-sulfur and MWNT aqueous suspension followed by a low temperature heat-treatment. The S/PPy/MWNT composite was characterized using chemical analysis, XRD, SEM and HRTEM. The composite cathode electrode was prepared by mixing S/PPy/MWNT composite with conductive carbon and PVdF binder and coating this mixture on Al foil. The electrochemical properties of the composite cathode were investigated in a lithium half cell (coin-type CR2032) by cyclic voltammetry (CV) and galvanostatic cycling. Results and Discussion Figure 2 a present that SEM result, which reveal that a porous structure with interconnected spherical pores has been formed. While the pore sizes are about 500-1000 nm in diameter, the holes with the diameters of about 20-30 nm connect them with each other in the sample structure. This S/PPy/MWNT composite with hierarchical nano/microstructures can utilize the advantages of both nanometer-sized building blocks and micro- or submicrometer-sized assemblies. While the former could provide negligible lithium ion diffusion time and distances, and possibly a new Li storage mechanism for the favorable kinetics and high capacities, the latter could be beneficial to afford good stability of the electrode materials, which are important for enhancing the cycle performance of the electrodes. The elemental analysis (mapping) of the S/PPy/MWNT composite carried out by EDS is shown in Fig. 2 (b and c), demonstrating the existence and homogeneous distribution of sulfur and MWNT in the composite. Further development of this research will be presented at the Meeting. References 1. X. Ji, K.T. Lee, Linda F. Nazar, Nat. Mater., 2009, 8, 500. 2. X. He, W. Pu, J. Ren, L. Wang, J. Wang, C. Jiang, C. Wan, Electrochim. Acta, 2007, 52, 7372. Acknowledgements The authors are grateful of financial support by the National Natural Science Foundation of China (Grant No. 21406052) and financial support by Program for the Outstanding Young Talents of Hebei Province (Grant No. BJ2014010). Figure 1

1. Introduction Rechargeable aqueous lithium batteries (RALBs) are promising alternative to bypass safety issues of lithium-ion batteries (LIBs) with organic electrolyte. Furthermore, fast lithium diffusion in aqueous electrolyte media could allow for the operations under high electric current conditions required for high power supply [1]. J. Dahn et al [2] reported on a VO2/LiMn2O4rechargeable aqueous battery, based on the “rocking chair” concept adopted from LIBs. However, this type of batteries had serious issues with cyclability. Here, we report for the first time on a system comprising an intercalation LiFePO4(LFP) cathode and a Zn metal anode in an aqueous electrolyte, and on large-scale RALB based on this concept with enhanced cycle performance and energy density. 2. Experimental All electrochemical tests were carried out using galvanostat/potentiostat VMP3 (Biologic) and two-electrode Swagelok-type cells and a rolled cylindrical battery configuration (ca. 600 mAh per cell). The commercial LiFePO4 (Hohsen Co, Japan) powder and zinc foil (Good Fellow, England) were used as cathode and anode, respectively. Graphite (Sigma Aldrich) and stainless steel (SUS316) rods were used as current collectors for the positive and negative sides, respectively. Absorptive glass mat (AGM) acted as a separator. The electrolyte was a mixed aqueous solution of zinc and lithium salts. Galvanostatic charge/discharge cycling was performed at various current densities from 0.6 C to 60 C (1 C corresponds to a current density of 170 mA g-1) at room temperature and the voltage cutoffs 1.0-1.4 V vs. Zn2+/Zn. 3. Results and discussion The electrochemical performance of Zn|LFP is presented in Fig. 1. The battery exhibited discharge capacities of 75 mAhg-1 and 43 mAhg-1 at high current densities of 30 C and 60 C, respectively, and maintained excellent stability and coulombic efficiency with a capacity of 102 mAhg-1 after 300 cycles when cycled at 6 C (Fig. 1b). The large scale battery (stack of cylindrical cells) showed 590 mAh/cell capacity at the initial cycle and could maintain 550 mAh/cell capacity after 10 cycles as shown in Fig. 1c. The further details of these studies will be presented at the Meeting. Acknowledgments This research was supported by the “Nazarbayev University Corporate Fund of Social Development” grant. References 1. Wei Tang, Yuping Wu, Kian Ping Loh, Energy Environ. Sci., 6 (2013) 2093–2104 2. W. Li, J.R. Dahn, D.S. Wainwright, Science 264 (1994) 1115-1118.

Introduction Due to low cost, environmental friendliness and high theoretical capacity of sulfur, rechargeable Li/S batteries are very promising power sources for various applications. However, the insulating nature of sulfur and solubility of polysulfides as discharge products restrict its practical application [1]. Among the approaches to overcome these problems, carbon nanotubes are widely used to obtain a flexible conductive matrix for S cathode [2]. Nitrogen doping of carbon nanotubes (N-CNTs) significantly improves its electronic conductivity because the nitrogen atoms provide additional free electrons for the conduction band [3]. In this work, we report for the first time on a high performance S/N-CNT cathode for Li/S battery. Exclusion of heat-treatment in the composite preparation avoided the sulfur loss; the composite contained 61 wt% of sulfur. Thanks to the self-weaving behavior of N-CNT, binders and current collectors are rendered unnecessary, thereby simplifying the electrode manufacturing process and increasing the sulfur content in the total electrode weight. The N-CNT core provides a highly conductive and mechanically flexible framework, enhancing the electronic conductivity and consequently the rate capability of the material. This resulting composite cathode sustains 833 mAh g-1 reversible specific discharge capacity after 100 cycles at 0.1 C, and 676 mAh g-1at 1 C with a coulombic efficiensy about 100%. Experimental The S/N-CNT composite preparation is schematically shown in Fig. 1. Nitrogen doped carbon nanotubes were dispersed in deionized water by sonication at room temperature. The obtained N-CNT suspension was mixed ultrasonically with the aqueous suspension of nano-sulfur. The resulting system was vacuum-filtered and thoroughly washed with deionized water and ethanol. The binder-free S/N-CNT composite was obtained by further drying in a vacuum oven at 60 °C overnight to remove the solvent. Acknowledgments This research was supported by a Research Grant from the Ministry of Education and Science of Kazakhstan and by a Subproject supported under the Technology Commercialization Project by the World Bank and the Government of Kazakhstan. References 1. X. Ji, K.T. Lee, L.F. Nazar, Nat. Mater., 2009, 8, 500. 2. Y.S. Su, A. Manthiram, Chem. Commun., 2012, 48, 8817. 3. X.G.Sun, X. Wang, R.T. Mayes, S. Dai, ChemSusChem ,2012, 5, 2079.

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