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26 articles found

E0324 – On the synthesis conditions for tailoring lithium composition in ramsdellite phases: Application for Li-ion batteries

TiO2 with the ramsdelitte-type (R) structure has a potential use as negative electrode for Li-ion battery due to its high theoretical capacity (335 mAh g?1), a weak irreversible loss during the first cycle and a low polarization. However due to its metastability, TiO2 (R) has been rarely reported. In the present work we report on the carbothermal synthesis of some LixTiO2 delithiated R phases (0 < x < 0.57), from TiO2 to Li2Ti3O7, with ramsdellite-type structure. The variation of the synthesis parameters such as wt% of carbonaceous additive and reductive gas flow has conducted to the formation of poor lithiated LixTiO2 phases and Li2TiO3 as additional phase. Their ratio was found to be strongly dependent on the amount of carbonaceous precursor. These new LixTiO2(R)/Li2TiO3 composites (with (0 ? x ? 0.57)) were characterized by chemical analysis, X-ray diffraction and thermogravimetric analysis and finally by electrochemical tests. High capacities as well as good cycleability have been reached.
A. Soares, B. Fraisse, F. Morato, C.M. Ionica-Bousquet, L. Monconduit, Journal of Power Sources 208 (2012) 440–446

B3316 – Heat generation behavior during charging and discharging of lithium-ion batteries after long-time storage

Thermal design and management are important for lithium-ion batteries (LIBs) to prevent thermal runaway under normal and abnormal conditions such as overcharge and short circuit. A sound understanding of the heat generation behaviors of LIBs is needed for their thermal design and management. Since battery characteristics such as capacity and power capability degrade with time and the number of cycles, one can infer that the amount of heat generated by LIBs may also be changed by this degradation. Calorimetry is an effective method of studying the heat generation mechanisms of LIBs. In this study, we apply calorimetry to characterize the heat generation behavior of LIBs during charging and discharging after degradation due to long-time storage. At low rates of charging and discharging, such as 0.1C, significant differences dependent on the degree of degradation are not observed. On the contrary, more degraded batteries exhibit greater heat generation related to overvoltage increase at high rates of charging and discharging, such as 1 C. The solution resistance increase is particularly striking in an LIB stored at 50 °C. The chief cause of this increase may be leakage of electrolyte solution, resulting in greater heat generation at high rates of charging and discharging.
Yoshiyasu Saito, Masahiro Shikano, Hironori Kobayashi, Journal of Power Sources 244 (2013) 294-299

B3006 – Comparisons of graphite and spinel Li1.33Ti1.67O4 as anode materials for rechargeable lithium-ion batteries

The aim of this work was to compare the electrochemical behaviors and safety performance of graphite and the lithium titanate spinel Li1.33Ti1.67O4 with half-cells versus Li metal. Their electrochemical properties in 1MLiPF6/EC + DEC (1:1 w/w) or 1MLiPF6/PC + DEC (1:1w/w) at room and elevated temperatures (30 and 60 ?C) have been studied using galvanostatic cycling. At 30 ?C graphite has higher reversible capacity than Li1.33Ti1.67O4 when using the LiPF6/EC + DECas electrolyte. At 60 ?Cgraphite declines in cell capacity yet Li1.33Ti1.67O4 remains almost unchanged. In a propylene carbonate (PC) containing electrolyte, graphite electrode exfoliates and loses its mechanical integrity while Li1.33Ti1.67O4 electrode is very stable. An accelerating rate calorimeter (ARC) and microcalorimeter have been used to compare the thermal stability of lithiated lithium titanate spinel and graphite. Results show that Li1.33Ti1.67O4 may be used as an alternative anode material offering good battery performance and higher safety.
X.L. Yao, S. Xie, C.H. Chen, Q.S. Wang, J.H. Sun, Y.L. Li, S.X. Lu, Electrochimica Acta 50 (2005) 4076–4081

B2917 – The influence of Li sources on physical and electrochemical properties of LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

LiNi0.5Mn1.5O4 cathode materials were successfully prepared by sol–gel method with two different Li sources. The effect of both lithium acetate and lithium hydroxide on physical and electrochemical performances of LiNi0.5Mn1.5O4 was investigated by scanning electron microscopy, Fourier transform infrared, X-ray diffraction, and electrochemical method. The structure of both samples is confirmed as typical cubic spinel with Fd3m space group, whichever lithium salt is adopted. The grain size of LiNi0.5Mn1.5O4 powder and its electrochemical behaviors are strongly affected by Li sources. For the samples prepared with lithium acetate, more spinel nucleation should form during the precalcination process, which was stimulated by the heat released from the combustion of extra organic acetate group. Therefore, the particle size of the obtained powder presents smaller average and wider distribution, which facilitates the initial discharge capacity and deteriorates the cycling performance. More seriously, there exists cation replacement of Li sites by transition metal elements, which causes channel block for Li ion transference and deteriorates the rate capability. The compound obtained with lithium hydroxide exhibits better electrochemical responses in terms of both cycling and rate properties due to higher crystallinity, moderate particle size, narrow size distribution and lower transition cation substitute content.
Tongyong Yang, Kening Sun, Zhengyu Lei, Naiqing Zhang, Ye Lang, J Solid State Electrochem (2011) 15, 391–397

B2909 – Short-Chain Di-Ureasil Ormolytes Doped with Potassium Triflate: Phase Diagram and Conductivity Behavior

Di-urea cross-linked poly(oxyethylene)/siloxane hybrids, synthesized by the sol-gel process and containing a wide concentration range of potassium triflate, KCF3SO3, have been analyzed by x-ray diffraction and differential scanning calorimetry. The pseudo-phase diagram proposed has been taken into account in the interpretation of the complex impedance measurements. The xerogels prepared are obtained as transparent, thin monoliths. At room temperature the highest conductivity found was 2 × 10?6 ??1cm?1.
V. De Zea Bermudez, S.M. Gomes Correia, M.M. Silva, S. Barros, M.J. Smith, R.A. Sa Ferreira, L.D. Carlos ,C. Molina, S.J.L. Ribeiro, Journal of Sol-Gel Science and Technology 26, 375–381, 2003

B2891 – C80 Calorimeter Studies of the Thermal Behavior of LiPF 6 Solutions

The thermal behavior of several LiPF6 solutions was studied using a C80 calorimeter. It was found that oxygen might react with the solvents and decrease their thermal stability. The dissolution of LiPF6 influences the thermal behavior remarkably with more heat generation and a lower onset temperature. Furthermore, the exothermic peak of LiPF6 based on an electrolyte containing diethyl carbonate (DEC) was found around 185 ?C, which is 9.5–13.6 ?C lower than that containing dimethyl carbonate (DMC), which may be due to the relative activity of C2H5— and CH3— in DEC and DMC, respectively
Qingsong Wang, Jinhua Sun, Xiaolin Yao, Chunhua Chen, Journal of Solution Chemistry, February 2006, Volume 35, Issue 2, pp 179-189

B2762 – Structural, electrochemical and thermal stability investigations on LiNi(0.5-x)Al2xMn(1.5-x)O4 (0 < 2x < 1.0) as 5 V cathode materials

A series of Al-substituted spinel powders LiNi0.5!xAl2xMn1.5!xO4 (0 < 2x < 1.0) have been prepared and the effects of Al concentration on the structural, electrochemical and thermal properties are investigated. The XRD patterns show that impurity arises when 2x > 0.6. The FTIR and Raman spectra indicate that the introduction of Al in the LiNi0.5Mn1.5O4 increases the disordering degree of Ni/Mn ions, changing the spinel structure from P4332 to Fd3m. Cyclic voltammetry tests show that the voltage step between Ni2+/Ni3+ and Ni3+/Ni4+ have a sudden leap at 2x = 0.075, responding to the structural difference of the spinels. The Al concentration is optimized in the range of 0.05 < 2x < 0.1, in which the cyclic stability and rate capability of the LiNi(0.5-x)Al2xMn(1.5-x)O4 spinels are significantly improved. At room temperature the LiNi0.45Al0.10Mn1.45O4 presents the best cycle performance with the capacity retention of 95.4% after 500 cycles at 1C rate, and the best rate capability with the discharge capacity of 119 mAh g-1 at 10C rate, which is about 93.7% of its capacity at 0.5C. The thermal properties of the spinels have been tested by C80 calorimeter and the results show that introduction of Al in LiNi0.5Mn1.5O4 can effectively suppress the exothermic reaction below 225°C, thus improve the safety of the high voltage cathode material.
G.B. Zhong, Y.Y. Wang, X.J. Zhao, Q.S. Wang, Y. Yu, C.H. Chen, Journal of Power Sources 216 (2012) 368-375

B2576 – Thermal stability of LiPF6based electrolyte and effect of contact with various delithiated cathodes of Li-ion batteries

Thermal stability of LiPF6based electrolyte (1M LiPF6/EC +DMC) was studied by insitu FTIR spectroscopy and C80 calorimetry, which indicated that the electrolyte underwent furious polymerization and decomposition reactions and sharp heat flow was generated below 225 ?C. The thermal stability of the electrolyte in contact with various delithiated cathodes (LixCoO2, LixNi0.8Co0.15Al0.05O2, LixNi1/3Co1/3Mn1/3O2, LixMn2O4, LixNi0.5Mn0.5O2, LixNi0.5Mn1.5O4 and LixFePO4) was also investigated by C80 calorimetry. The results showthat the cathodematerials except for LixFePO4 usually have an enhancement effect on the decomposition of the electrolyte, but LixFePO4 exhibits a suppression effect on the reactions of the electrolyte. LixFePO4 is found to bewith excellent thermal stability. Among the other cathodes, LixCoO2, LixNi0.8Co0.15Al0.05O2, LixNi0.5Mn0.5O2 and LixNi0.5Mn1.5O4 promote the decomposition of electrolyte by releasing oxygen and thus considered not favorable for safety, but LixNi1/3Co1/3Mn1/3O2 with a lesser reaction heat and LixMn2O4 with even less heat flowin the lowtemperature range (50–225 ?C) are believed as promising cathodes for better safety. By comparing Xray diffraction (XRD) patterns of these cathode materials at room temperature and those heated to 300 ?C in the presence of the electrolyte, we have found that LixFePO4 only has experienced tiny structure change, which is greatly different from the other cathode materials.
H.F. Xiang, H.Wang, C.H. Chen, X.W. Ge, S. Guo, J.H. Sun, W.Q. Hu, Journal of Power Sources 191 (2009) 575–581

B2575 – Cresyl diphenyl phosphate effect on the thermal stabilities and electrochemical performances of electrodes in lithium ion battery

To improve the safety of lithium ion battery, cresyl diphenyl phosphate (CDP) is used as a flame-retardant additive in a LiPF6 based electrolyte. The electrochemical performances of LiCoO2/CDP-electrolyte/Li and Li/CDP-electrolyte/C half cells are evaluated. The thermal behaviors of Li0.5CoO2 and Li0.5CoO2–CDP-electrolyte, and LixC6 and LixC6–CDP-electrolyte are examined using a C80 micro-calorimeter. For the LiCoO2/CDP-electrolyte/Li cells, the onset temperature of single Li0.5CoO2 is put off and the heat generation is decreased greatly except the one corresponding to 5% CDP-containing electrolyte. When Li0.5CoO2 coexists with CDP-electrolyte, the thermal stability is enhanced. CDP improves the thermal stability of lithiated graphite anode effectively and the addition of 5% CDP inhibits the decomposition of solid electrolyte interphase (SEI) films significantly. The electrochemical tests on LiCoO2/CDP-electrolyte/Li and Li/CDP-electrolyte/C cells show that when less than 15% CDP is added to the electrolyte, the electrochemical performances are not worsen too much. Therefore, the addition of 5–15% CDP to the electrolyte almost does not worsen the electrochemical performance of LiCoO2 cathode and graphite anode, and improves theirs thermal stability significantly; thus, it is a possible choice for electrolyte additive.
Qingsong Wang, Ping Ping, Jinhua Sun, Chunhua Chen, Journal of Power Sources, 196 (2011) 5960–5965

B2574 – Improved thermal stability of lithium ion battery by using cresyl diphenyl phosphate as an electrolyte additive

To enhance the safety of lithium ion battery, cresyl diphenyl phosphate (CDP) is explored as an additive in 1.0 M LiPF6/ethylene carbonate (EC) + diethyl carbonate (DEC) (1:1 wt.). The electrochemical performances of LiCoO2/CDP-electrolyte/C cells are tested. At the thermal aspect, the thermal stability of the electrolyte with CDP is detected firstly by using a C80 micro-calorimeter, and then the charged LiCoO2/CDP-electrolyte/C cells are disassembled and wrapped to detect the thermal behaviors. The results indicate that CDP-containing electrolyte enhances the thermal stabilities of electrolyte and lithium ion battery, and the electrochemical performances of LiCoO2/CDP-electrolyte/C cell become slightly worse by using CDP in the electrolyte. Furthermore, the cell with 10% (wt.) CDP-containing electrolyte shows better cycle efficiency than that of other CDP-containing electrolyte, such as containing 5% (wt.) CDP and 15% (wt.) CDP. This maybe because that the mass ratio between CDP and electrolyte is close to the reaction stoichiometric ratio in the 10% (wt.) CDP-containing electrolyte, where stable solid electrolyte interphase (SEI) is formed. Therefore, 10% CDP-containing electrolyte improves the safety of lithium ion battery and keeps its electrochemical performance
Qingsong Wang, Ping Ping, Jinhua Sun, Chunhua Chen, Journal of Power Sources, 195 (2010) 7457–7461

B2573 – The effect of mass ratio of electrolyte and electrodes on the thermal stabilities of electrodes used in lithium ion battery

The mass ratio between electrode and electrolyte in lithium-ion battery plays a key role for the battery thermal stability. Its effect on the thermal stability of their coexisting system was studied using C80 micro-calorimeter. For the Li0.5CoO2–LiPF6/ethylene carbonate (EC) + diethyl carbonate (DEC) coexisting system, when the mass ratios of Li0.5CoO2–LiPF6/EC + DEC are 2:1, 1:1, 1:2 and 1:3, one, two, three and four main exothermic peaks are detected with total heat generation of ?1043.8 J g?1, ?1052.6 J g?1, ?1178.5 J g?1 and ?1684.5 J g?1, respectively. For the LixC6–LiPF6/EC + DEC coexisting system, the thermal behavior trend is similar, and the heat generation increases with the electrolyte content increasing, however, and the onset temperature are very close to each others. The heating rate also influence the heat generation rate for the two coexisting system, too far or too low heating rate could results in varies heat generation.
Qingsong Wang, Ping Ping, Jinhua Sun, Chunhua Chen, Thermochimica Acta, 517 (2011) 16–23

B2572 – Enhancing the safety of lithium ion batteries by 4-isopropyl phenyl diphenyl phosphate

To enhance the safety of lithium ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was explored as an additive in 1.0 M LiPF6/ethylene carbonate (EC)+diethyl carbonate (DEC) (1:1 wt.%). The electrochemical performances of LiCoO2/IPPP electrolyte/C cells were tested. And then the LiCoO2/IPPP electrolyte/C cells were disassembled and wrapped to detect the thermal behaviors using a C80 microcalorimeter. The results indicated that 5% and 10% IPPP content in the electrolyte can enhance the safety of lithium ion batteries. Furthermore, the electrochemical performances of LiCoO2/IPPP electrolyte/C cells become slightly worse by using 5% and 10% IPPP content electrolyte. Therefore, 5–10% IPPP content in electrolyte can enhance the safety of lithium ion batteries with minimum sacrifice in electrochemical performance.
Qingsong Wang, Jinhua Sun, Materials Letters 61 (2007) 3338–3340

B2353 – Thermal behavior of small lithium-ion battery during rapid charge and discharge cycles

The secondary batteries for electric vehicles (EV) generate much heat during rapid charge and discharge cycles at current levels exceeding the batteries’ rating, such as when the EV quickly starts consuming battery power or when recovering inertia energy during sudden stops. During these rapid charge and discharge cycles, the cell temperature may increase above allowable limits. We calculated the temperature rise of a small lithium-ion secondary battery during rapid charge and discharge cycles. The heat-source factors were measured again by the methods described in our previous study, because the performance of the battery reported here has been improved, showing lower overpotential resistance. Battery heat capacity was measured by a twin-type heat conduction calorimeter, and determined to be a linear function of temperature. Further, the heat transfer coefficient, measured again precisely by the method described in our previous study, was arranged as a function of cell and ambient temperatures. The temperature calculated by our battery thermal behavior model using these measured data agrees well with the cell temperature measured by thermocouple during rapid charge and discharge cycles. Also, battery radial temperature distributions were calculated to be small, and confirmed experimentally.
Kazuo Onda, Takamasa Ohshima, Masato Nakayama, Kenichi Fukuda, Takuto Araki, Journal of Power Sources 158 (2006) 535–542

B2352 – Heat accumulations and fire accidents of waste piles

In order to prevent fires from waste storages and piles, heat generation and accumulation mechanism of waste piles were investigated by calorimetric and chemiluminescence (CL) studies. As measurement samples, we used refuse-derived fuel (RDF), car shredder dust (SD), and model materials such as papers and plastics. A primary heat generation and a heat accumulation were evaluated by using some calorimeters such as DSC (Mettler Toledo, Schweiz), ARC (Columbia Scientific Ind., USA) and C80 (Setaram, France). Self-ignition temperature was also evaluated by using HP-TG/DTA (Rigaku, Japan). However, these values of wastes vary with respect to each sample due to the heterogeneity of the wastes. For instance, the self-ignition temperature of SD was 154–186 C and that of RDF was 174–224 C. In this study, we chose the lowest value from the safety point of view. The results of ARC measurement indicated that the heat accumulation by self-heating started from 83 C for RDF, and from 96 C for SD, and the heat accumulation under adiabatic condition gave self-ignition eventually. We also studied the oxidation of them in the low temperature region (between room temperature and 130 C) using CL analyzer (Tohoku Electronic Ind., Japan). The experimental data showed that RDF containing oxidized polymer and some organic peroxides initiated autoxidation reaction in the low temperature region.
Yoshitada Shimizu, Masahide Wakakura, Mitsuru Arai, Journal of Loss Prevention in the Process Industries 22 (2009) 86–90

B2054 – Thermal behavior of small lithium-ion battery during rapid charge and discharge cycles

The secondary batteries for electric vehicles (EV) generate much heat during rapid charge and discharge cycles at current levels exceeding the batteries' rating, such as when the EV quickly starts consuming battery power or when recovering inertia energy during sudden stops. During these rapid charge and discharge cycles, the cell temperature may increase above allowable limits. We calculated the temperature rise of a small lithium-ion secondary battery during rapid charge and discharge cycles. The heat-source factors were measured again by the methods described in our previous study, because the performance of the battery reported here has been improved, showing lower overpotential resistance. Battery heat capacity was measured by a twin-type heat conduction calorimeter, and determined to be a linear function of temperature. Further, the heat transfer coefficient, measured again precisely by the method described in our previous study, was arranged as a function of cell and ambient temperatures. The temperature calculated by our battery thermal behavior model using these measured data agrees well with the cell temperature measured by thermocouple during rapid charge and discharge cycles. Also, battery radial temperature distributions were calculated to be small, and confirmed experimentally.
K. Onda, T. Ohshima, M. Nakayama, K. Fukuda, T. Araki, Journal of Power Sources 158 (2006) 535-542

B1757 – Thermal behaviors of lithium-ion batteries during high-rate pulse cycling

Heat generation due to electrochemical side-reaction during high-rate pulse cycling has been studied. In order to measure the value, calorimetry was carried out. The excess heat was observed comparing with the electric energy loss for each cycle, which was thought to be caused by side-reactions. Some side-reactions affect the surface characteristics of the electrodes and enlarge the impedance of the battery resulting in more heat generation.
Y. Saito, Journal of Power Sources 146 (2005) 770-774

B1134 – A calorimetric study on a cylindrical type lithium secondary battery by using a twin-type heat conduction calorimeter

Thermochemical properties of a lithium secondary battery are calorimetrically studied. A twin-type heat conduction calorimeter was used and its accuracy was determined by the specific heat capacity measurement of a standard material, synthetic sapphire. The inaccuracy was smaller than 1.1% in the range of 303-343 K. The thermal transitions corresponding to crystal phase transitions of the positive electrode material, Li1-xCoO2, between hexagonal and monoclinic symmetry were observed. An attempt was made to measure the apparent specific heat capacity of the battery and to study its dependence on the state of charge. The influences of the diffusion of lithium ions in the electrode materials and the self-discharge to the apparent specific heat capacity are discussed.
Y. Saito, K. Kanari, K. Takano and T. Masuda, Thermochimica Acta 296 (1997) 75-85

B1014 – Thermal measurements of rechargeable lithium batteries (4) Specific heat capacity of a lithium ion cell

Y. Saito, K. Kanari, K. Takano, T. Masuda, JSCTA (1995) 26-27

B0961 – Thermal properties of rechargeable lithium batteries (1) – Heat capacity measurement by using a large sample holder

Y. Saito, K. Kanari, K. Takano, T. Masuda, JSCTA (1994) 132-133

A2308 – Mechanochemical synthesis and electrochemical behavior of Na3FeF6 in sodium and lithium batteries

We report Na3FeF6 as a novel cathode material for sodium and lithium batteries. The material is synthesized through a mechanochemical process by reacting precursors (NaF and FeF3) in a ball mill under argon flow. These syntheses are environmentally friendly and safe because the entire processes do not require any hazardous gasses or high temperatures. XRD spectra confirm that the synthesized material has a well-defined crystal structure and can be indexed to a monoclinic crystal structure under the P21/C space group. Thermal analyses up to 500 °C confirm the stability of the crystal structure and safety of this material. Electrochemical results indicate that Na3FeF6 is electrochemically active in both Na and Li cells while undergoing conversion reactions and exhibiting decent reversible capacities of larger than 100 and 200 mAh g? 1 at room temperature, respectively.
R. A. Shakoor, Soo Yeon Lim, Hyungsub Kim, Kwan-Woo Nam, Jeung Ku Kang, Kisuk Kang, Jang Wook Choi, Solid State Ionics 218 (2012) 35–40

A1989 – Three-dimensional sponge-like architectured cupric oxides as high-power and long-life anode material for lithium rechargeable batteries

Cupric oxide (CuO) nanoparticles (NPs) with three-dimensional (3D) sponge structure are obtained through the sintering of Cu NPs at 360 ?C. Their morphology is analyzed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and their crystal structure is checked by X-ray diffraction. CuO NPs have a 3D porous structure. The NPs are assembled to form larger secondary particles with many empty spaces among them, and they have a CuO phase after the heat treatment. CuO NPs with this novel architecture exhibit good electrochemical performance as anode material. The anode material with a sponge-like structure is prepared at 360 ?C, as the Li-ion battery exhibits a high electrochemical capacity of 674 mAh g?1. When the sample is sintered at 360 ?C, the charge/discharge capacities increase gradually and cycle up to 50 cycles at a C/10 rate, exhibiting excellent rate capability compared with earlier reported CuO/CuO-composite anodes. Electrochemical impedance spectroscopy (EIS) measurements suggest that the superior electrical conductivity of the sample sintered at 360 ?C is the main factor responsible for the improved power capability.
Chung Seok Choi, Young-Uk Park, Hyungsub Kim, Na Rae Kim, Kisuk Kang, Hyuck Mo Lee, Electrochimica Acta 70 (2012) 98– 104

A1919 – SnO2–graphene–carbon nanotube mixture for anode material with improved rate capacities

SnO2–graphene–carbon nanotube (SnO2–G–CNT) mixture is synthesized using graphene oxide as precursor for application as anode material in rechargeable Li ion batteries. It is shown that the SnO2 nanoparticles of 3–6 nm in diameter are not only attached onto the surface of graphene sheets by anchoring with surface functional groups, but they also are encapsulated in pore channels formed by entangled graphene sheets. The incorporation of carbon nanotubes reduces the charge transfer resistance of the anode made from the mixture through the formation of 3D electronic conductive networks. The SnO2–G–CNT anodes deliver remarkable capacities of 345 and 635 mAh g 1 at 1.5 and 0.25 A g 1, respectively. Flexible electrodes consisting of highly-aligned SnO2–G–CNT papers are also prepared using a simple vacuum filtration technique. They present a stable capacity of 387 mAh g 1 at 0.1 A g 1 after 50 cycles through the synergy of the high specific capacity of SnO2 nanoparticles and the excellent cycleability of G–CNT paper.
Biao Zhang, Qing Bin Zheng, Zhen Dong Huang, Sei Woon Oh, Jang Kyo Kim, Carbon 49 (2011) 4524-4534

A1916 – Sulfur-graphene composite for rechargeable lithium batteries

Sulfur-graphene (S-GNS) composites have been synthesized by heating a mixture of graphene nanosheets and elemental sulfur. According to field emission electron microscopy, scanning electron microscopy with energy dispersive X-ray mapping, Raman spectroscopy, and thermogravimetric analysis, sulfur particles were uniformly coated onto the surface of the graphene nanosheets. The electrochemical results show that the sulfur-graphene nanosheet composite significantly improved the electrical conductivity, the capacity, and the cycle stability in a lithium cell compared with the bare sulfur electrode.
Jia-Zhao Wang, Lin Lu, Mohammad Choucair, John A. Stride, Xun Xu, Hua-Kun Liu, Journal of Power Sources 196 (2011) 7030–7034

A1914 – Sucrose assisted hydrothermal synthesis of SnO2/graphene nanocomposites with improved lithium storage properties

SnO2/graphene nanocomposites are synthesized by a new hydrothermal treatment strategy under the assistance of sucrose. From the images of the scanning electron microscope (SEM) and transmission electron microscope (TEM), it can be observed that SnO2 nanoparticles with the size of 4~5 nm uniformly distribute on the graphene nanosheets. The result demonstrates that sucrose can effectively prevent graphene nanosheets from restacking during hydrothermal treatment and subsequently treatment. The charging/discharging test result indicates that the SnO2/graphene nanocomposites exhibit high specific capacity and excellent cycleability. The first reversible specific capacity is 729 mAh.g?1 at the current density of 50 mA.g?1, and remains 646 mAh.g?1 after 30 cycles at the current density of 100 mA.g?1, 30 cycles at the current density of 200 mA.g?1, 30 cycles at the current density of 400mA.g?1, 30 cycles at the current density of 800 mA.g?1, and 30 cycles at the current density of 50 mA.g?1.
Xiao-Yong Fan, Xiao-Yuan Shi, Jing Wang, Yong-Xin Shi, Jing-Jing Wang, Lei Xu, Lei Gou, Dong-Lin Li, J Solid State Electrochem (2013) 17:201–208

A1756 – Reversible lithium intercalation in disordered carbon prepared from 3,4,9,10-perylenetetracarboxylic dianhydride

The electrochemical properties of the 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)-based carbon, synthesized by directly pyrolyzing PTCDA under an argon gas flow, have been firstly explored as an anode material for lithium-ion batteries. PTCDA is decomposed in a single-step reaction, which was completed around 650 °C. X-ray diffraction studies indicated a disordered carbon structure, and scanning electron microscopy (SEM) results revealed that this PTCDA-based carbon had a pillar-like morphology with a diameter of approximately 1–4 ?m and length of 5–20 ?m. Electrochemical measurements showed that it delivered lithium insertion and deinsertion capacities of 496 and 311 mAh g?1, respectively, during the first cycle. The charge capacity retention from the 1st to the 50th is 93.2% with an average capacity fade of 0.14% per cycle. The coulombic efficiency of the Li insertion/deinsertion processes reached 99% after five cycles.
Zonghui Yi, Xiaoyan Han, Changchun Ai, Yongguang Liang, Jutang Sun, J Solid State Electrochem (2008) 12, 1061–1066

A1717 – Electrochemical evaluation of CuFe2O4 samples obtained by sol–gel methods used as anodes in lithium batteries

CuFe2O4 with a tetragonally distorted spinel structure has been prepared by the thermal decomposition of a citrate precursor. The copper–iron mixed organic salt was precipitated by either water evaporation or ethanol dehydration. The level of impurities of the final products depended on the precursor precipitation route and annealing temperature. EDH(800) material performed capacity values of 520 mAh/g after 50 cycles. Electron microscopy evidenced that the extrusion of copper yielded both transition metals separately at the end of discharge.
M. Bomio, P. Lavela, J. L. Tirado, J Solid State Electrochem (2008) 12, 729–737