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Cathode Materials

Xia Wu, Shi-Xi Zhao, Lü-Qiang Yu, Jin-Lin Yang, Ce-Wen Nan
Based on the existing calculation reports, sulfur doping is an effective approach to alleviate the structure collapse of Li2MnSiO4 during cycling. Herein, we investigate the feasibility and limitations of S doping in Li2MnSiO4 by experiment. In our work, the solid solubility of S is confirmed and exceeding the threshold results in MnS impurity. The existence state and site of the S element in a Li2MnSiO4 crystal structure is also confirmed. It is found that S doping significantly improves the structural reversibility and cycling stability...
August 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Seungjun Myeong, Woongrae Cho, Wooyoung Jin, Jaeseong Hwang, Moonsu Yoon, Youngshin Yoo, Gyutae Nam, Haeseong Jang, Jung-Gu Han, Nam-Soon Choi, Min Gyu Kim, Jaephil Cho
Lithium-excess 3d-transition-metal layered oxides (Li1+x Niy Coz Mn1-x-y-z O2 , >250 mAh g-1 ) suffer from severe voltage decay upon cycling, which decreases energy density and hinders further research and development. Nevertheless, the lack of understanding on chemical and structural uniqueness of the material prevents the interpretation of internal degradation chemistry. Here, we discover a fundamental reason of the voltage decay phenomenon by comparing ordered and cation-disordered materials with a combination of X-ray absorption spectroscopy and transmission electron microscopy studies...
August 16, 2018: Nature Communications
Byung Hyuk Kim, Ki Yoon Bae, Sung Ho Cho, Woo Young Yoon
A new coating method called vapor-phase polymerization (VPP) is used to coat a conductive polymer on LiV3 O8 (LVO) surfaces for the first time in lithium-metal secondary batteries to protect the interface layer and enhance the electrochemical properties of the cathode. The VPP method can be used to coat an appropriate amount of the polymer and homogeneously coat the LVO active material surfaces because of the use of vapor-phase monomers. The presence of the coating layer was confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy...
August 16, 2018: ACS Applied Materials & Interfaces
Almudena Benítez, Marcos González-Tejero, Álvaro Caballero, Julián Morales
A microporous carbon derived from biomass (almond shells) and activated with phosphoric acid was analysed as a cathodic matrix in Li⁻S batteries. By studying the parameters of the carbonization process of this biomass residue, certain conditions were determined to obtain a high surface area of carbon (967 m² g-1 ) and high porosity (0.49 cm³ g-1 ). This carbon was capable of accommodating up to 60% by weight of sulfur, infiltrated by the disulphide method. The C⁻S composite released an initial specific capacity of 915 mAh g-1 in the Li⁻S cell at a current density of 100 mA g-1 with a high retention capacity of 760 mAh g-1 after 100 cycles and a coulombic efficiency close to 100%...
August 14, 2018: Materials
Yuting Luo, Luis R De Jesus, Justin L Andrews, Abhishek Parija, Nathan Fleer, Daniel Juarez Robles, Partha P Mukherjee, Sarbajit Banerjee
Increasing intercalation of Li-ions brings about distortive structural transformations in several canonical intercalation hosts. Such phase transformations require the energy dissipative creation and motion of dislocations at the interface between the parent lattice and the nucleated Li-rich phase. Phase inhomogeneities within particles and across electrodes give rise to pronounced stress gradients, which can result in capacity fading. How such transformations alter Li-ion diffusivities remains much less explored...
August 14, 2018: ACS Applied Materials & Interfaces
Hong Li, Yanhui Li, Meng Wang, Zhen Niu, Xiutong Wang, Baorong Hou
For improving the photocathodic protection performance of TiO2 photoanode, ZnIn2S4/reduced graphene oxide (RGO)/TiO2 nanotubes (NTs) composite was synthesized by electrochemical anodizing combined with hydrothermal method. The photoelectrochemical and photocathodic protection properties of the ZnIn2S4/RGO/TiO2 composite were investigated in detail. Compared with pure TiO2 NTs, the ZnIn2S4/RGO/TiO2 composite showed a significant improvement in photocathodic protection performances. The photogenerated open circuit potential (OCP) drop of ZnIn2S4/RGO/TiO2 coupled with Q235 carbon steel (CS) in 3...
August 14, 2018: Nanotechnology
Simeng Dai, Yan Yuan, Jiangsheng Yu, Jian Tang, Jie Zhou, Weihua Tang
Metal-organic frameworks (MOFs) provide great opportunities for synthesizing advanced electrode materials with hierarchical hollow architectures for energy storage. Herein, we report the facile fabrication of core-sheath nanoarrays (NAs) on carbon cloth (CC@CoO@S-Co3O4) for binder-free electrode materials with MOFs as versatile scaffolds. The hollow S-doped Co3O4 sheath has been facilely prepared using a two-step synthetic protocol, which includes the surface etching of CoO nanowires for synchronous in situ growth of well-aligned ZIF-67 and its following hydrothermal process...
August 14, 2018: Nanoscale
Yonguk Kwon, Yongho Lee, Sang-Ok Kim, Hyung-Seok Kim, Ki Jae Kim, Dongjin Byun, Wonchang Choi
The surface of 5V class LiNi0.5Mn1.5O4 particle is modified with poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer by utilizing the hydrophobic characteristics of the 3,4-ethylenedioxythiophene (EDOT) monomer and the tail group of cetyl trimethyl ammonium bromide (CTAB) surfactants, in addition to the electrostatic attraction between cationic CTAB surfactant and cathode materials with a negative zeta potential in aqueous solution. With this novel concept, we design and prepare a uniform EDOT monomer layer on the cathode materials, and chemical polymerization of the EDOT coating layer is then carried out to achieve PEDOT-coated cathode materials via a simple one-pot preparation process...
August 13, 2018: ACS Applied Materials & Interfaces
Kelu Liu, Ping Lei, Xin Wan, Wenting Zheng, Xingde Xiang
Sodium vanadium fluorophosphate (Na3 (VO)2 (PO4 )2 F, denoted as NVPF) has attracted particular interests as cathode for high-energy sodium-ion batteries (SIBs) owing to the high working potential, high specific capacity, and robust structural framework. However, it is challenged by the low electron conductivity and lack of available facile synthesis method. Herein, an environmentally benign, cost-effective synthesis route is reported to produce NVPF nanoparticles encapsulated in conductive graphene network (NVPF/C), involving low-temperature synthesis of NVPF nanoparticles in absolute aqueous solvents and subsequent construction of conductive network through thermally induced transformation of graphene-oxide nanosheets...
July 27, 2018: Journal of Colloid and Interface Science
Kyungho Kim, Geoffrey Daniel, Vadim G Kessler, Gulaim A Seisenbaeva, Vilas G Pol
Nano α-MnO₂ is usually synthesized under hydrothermal conditions in acidic medium, which results in materials easily undergoing thermal reduction and offers single crystals often over 100 nm in size. In this study, α-MnO₂ built up of inter-grown ultra-small nanoflakes with 10 nm thickness was produced in a rapid two-step procedure starting via partial reduction in solution in basic medium subsequently followed by co-proportionation in thermal treatment. This approach offers phase-pure α-MnO₂ doped with potassium (cryptomelane type K0...
August 9, 2018: Nanomaterials
Ortal Breuer, Arup Chakraborty, Jing Liu, Tatyana Kravchuk, Larisa Burstein, Judith Grinblat, Yaron Kauffmann, Alexandr Gladkih, Prasant Kumar Nayak, Merav Tsubery, Anatoly Frenkel, Michael Talianker, Dan Thomas Major, Boris Markovsky, Doron Aurbach
Doping Ni-rich LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material by small amount of Mo6+ ions, around 1 mol.%, affects pronouncedly its structure, surface properties, electronic and electrochemical behavior. Cathodes comprising Mo6+ doped NCM523 exhibited in Li cells higher specific capacities, higher rate capabilities, lower capacity fading and lower charge-transfer resistance that relates to a more stable electrode/solution interface due to doping. This, in turn, is ascribed to the fact that the Mo6+ ions tend to concentrate more at the surface, as a result of a synthesis that always includes a necessary calcination - high temperature stage...
August 10, 2018: ACS Applied Materials & Interfaces
Jiangquan Lv, Yan-Xi Tan, Jiafang Xie, Rui Yang, Muxin Yu, Shanshan Sun, Ming-De Li, Daqiang Yuan, Yaobing Wang
Directly converting and storing solar to electrochemical energy are of potential higher efficiency to sustainable energy society, which is bottlenecked by lacking bifunctional materials of harvesting light and reversible electrochemical energy storage simultaneously. Herein, we synthesize a covalent organic framework integrated naphthalenediimide (NDI) and triphenylamine (TPA) units (NT-COF) firstly. The NT-COF exhibits packing two-dimensional porous nanosheets with a high specific surface area of 1276 m2/g...
August 9, 2018: Angewandte Chemie
Luis Ignacio Perea-Ramírez, Alfredo Guevara-García, Marcelo Galván
In this paper, the use of chemical local softness s(r) is proposed as an alternative way of analyzing the initial redox processes that occur in cathode materials used for lithium-ion batteries. It is shown that the chemical local softness is a quantity able to capture the same effects as the standard analysis based on the projected density of states. Because of its own nature, the local softness reveals the atomic sites involved in charge-transfer events and allows a quantitative comparative analysis between different materials...
August 9, 2018: Journal of Molecular Modeling
Tie Liu, Xiuhui Zhang, Tao Huang, Aishui Yu
The rational design and synthetic route to fabricate hybrid materials with desirable electrocatalytic functionalities remain critical but still challenging for sustainable energy devices. Here, we constructed a tungsten trioxide nano-lamellae chemically anchored with pyridinic-N-dominated doped CNT/graphene frameworks (W-NCG) via a general solution-based synthesis method. The detailed results indicated that this hybrid structure is composed of vacancy-defect abundant WO3 porous nanoflakes anchoring through or onto a 3D N-doped carbon matrix...
August 10, 2018: Nanoscale
Dantong Qiu, Liangjie Fu, Chun Zhan, Jun Lu, Di Wu
Development of portable devices and electric vehicles calls for Li-ion batteries (LIBs) with higher energy density and better stability. Integration of FeF3 phases and carbon structures leads to promising cathode materials for LIBs with high voltage, capacity and power. In this study, FeF3·0.33H2O nanoparticles (NPs) were synthesized on reduced graphite oxide (rGO) nanosheets using an in situ approach. By chemically tuning the interfacial bonding between FeF3·0.33H2O and rGO, we successfully achieved high particle loading and enhanced cycling stability...
August 9, 2018: ACS Applied Materials & Interfaces
Xiaoyue Shi, Jian Du, Timothy G J Jones, Xilong Wang, Han-Pu Liang
Capacity decay has been a well-known phenomenon in battery technology. V6O13 has been proved to be one of promising cathode materials for the lithium-metal polymer battery owing to high electrochemical capacity and electronic conductivity. However, these V6O13-based cathodes suffer from characteristic capacity decline under operating conditions and it is also difficult to achieve the theoretical capacities of V6O13. Herein, we report, for the first time, the thermal instability between the components in the cathode composites using various analytical methods, such as in situ thermal gravimetric analysis - infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques...
August 9, 2018: ACS Applied Materials & Interfaces
Panpan Dong, Kee Sung Han, Jung-In Lee, Xiahui Zhang, Younghwan Cha, Min-Kyu Song
High-energy lithium/sulfur (Li/S) batteries still suffer from unsatisfactory cycle life and poor rate-capability caused by the polysulfides shuttle and insulating nature of S cathodes. Here we report our findings in the controlled synthesis of selenium (Se)-containing S-rich copolymers of various compositions as novel cathode materials through a facile inverse vulcanization of S with selenium disulfide (SeS2) and 1,3-diisopropenylbenzene (DIB) as comonomers. Nuclear magnetic resonance and X-ray photoelectron spectroscopy results show that divinyl functional groups of DIB were chemically cross-linked with S/SeS2 chain radicals through a ring-opening polymerization...
August 9, 2018: ACS Applied Materials & Interfaces
Weiwei Wang, Li Zhang, Guancheng Xu, Huijun Song, Lifan Yang, Chi Zhang, Jinling Xu, Dianzeng Jia
Metal-organic framework-based supercapacitors have been widely recognized as the best energy storage devices for future portable electronic equipment. Herein, CoP- T ( T = 300, 350, and 400 °C) microcubes with a solid and hollow microstructure were successfully synthesized by low-temperature phosphorization of [CH3 NH3 ][Co(HCOO)3 ] precursor at desired temperatures. The morphology, structure, and composition of the prepared CoP-350 °C samples were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy...
August 8, 2018: Inorganic Chemistry
K Kuchler, B Prifling, D Schmidt, H Markötter, I Manke, T Bernthaler, V Knoblauch, V Schmidt
It is well known that the microstructure of electrodes in lithium-ion batteries has an immense impact on their overall performance. The compaction load during the calendering process mainly determines the resulting morphology of the electrode. Therefore, NCM-based cathode films from uncompacted (0 MPa) to most highly compacted (1000 MPa) were manufactured, which corresponds to global porosities ranging from about 50% to 18%. All samples have been imaged using synchrotron tomography. These image data allow an extensive analysis of the 3D cathode microstructure with respect to increasing compaction...
August 8, 2018: Journal of Microscopy
Guang Liu, Qingguo Chi, Yongquan Zhang, Qingguo Chen, Changhai Zhang, Kai Zhu, Dianxue Cao
Incorporation of reduced graphene oxide (rGO) optimizes the interfacial properties of MgMn2O4 and improves the Mg2+ diffusion in the electrode. This results in enhanced specific capacity and rate capability. MgMn2O4/rGO nanocomposites show a large discharge specific capacity of 140.1 mA h g-1 at a current density of 1000 mA g-1.
August 8, 2018: Chemical Communications: Chem Comm
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