Capacity Retention (capacity + retention)

Distribution by Scientific Domains
Polymers and Materials Science85%

Selected Abstracts

Capacity Fading Mechanism in All Solid-State Lithium Polymer Secondary Batteries Using PEG-Borate/Aluminate Ester as Plasticizer for Polymer Electrolytes

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Fuminari Kaneko
Abstract Solid-state lithium polymer secondary batteries (LPB) are fabricated with a two-electrode-type cell construction of Li|solid-state polymer electrolyte (SPE)|LiFePO4. Plasticizers of poly(ethylene glycol) (PEG)-borate ester (B-PEG) or PEG-aluminate ester (Al-PEG) are added into lithium-conducting SPEs in order to enhance their ionic conductivity, and lithium bis-trifluoromethansulfonimide (LiTFSI) is used as the lithium salt. An improvement of the electrochemical properties is observed upon addition of the plasticizers at an operation temperature of 60,°C. However, a decrease of discharge capacities abruptly follows after tens of stable cycles. To understand the origin of the capacity fading, electrochemical impedance techniques, ex-situ NMR and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) techniques are adopted. Alternating current (AC) impedance measurements indicate that the decrease of capacity retention in the LPB is related to a severe increase of the interfacial resistance between the SPE and cathode. In addition, the bulk resistance of the SPE film is observed to accompany the capacity decay. Ex situ NMR studies combined with AC impedance measurements reveal a decrease of Li salt concentration in the SPE film after cycling. Ex situ SEM/EDS observations show an increase of concentration of anions on the electrode surface after cycling. Accordingly, the anions may decompose on the cathode surface, which leads to a reduction of the cycle life of the LPB. The present study suggests that a choice of Li salt and an increase of transference number is crucial for the realization of lithium polymer batteries. [source]

Aqueous Lithium-ion Battery LiTi2(PO4)3/LiMn2O4 with High Power and Energy Densities as well as Superior Cycling Stability**,

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2007
J.-Y. Luo
Abstract Porous, highly crystalline Nasicon-type phase LiTi2(PO4)3 has been prepared by a novel poly(vinyl alcohol)-assisted sol,gel route and coated by a uniform and continuous nanometers-thick carbon thin film using chemical vapor deposition technology. The as-prepared LiTi2(PO4)3 exhibits excellent electrochemical performance both in organic and aqueous electrolytes, and especially shows good cycling stability in aqueous electrolytes. An aqueous lithium-ion battery consisting of a combination of LiMn2O4 cathode, LiTi2(PO4)3 anode, and a 1 M Li2SO4 electrolyte has been constructed. The cell delivers a capacity of 40 mA,h,g,1 and a specific energy of 60 W,h,kg,1 with an output voltage of 1.5 V based on the total weight of the active electrode materials. It also exhibits an excellent cycling stability with a capacity retention of 82,% over 200 charge/discharge cycles, which is much better than any aqueous lithium-ion battery reported. [source]

Ultrathin Direct Atomic Layer Deposition on Composite Electrodes for Highly Durable and Safe Li-Ion Batteries

ADVANCED MATERIALS, Issue 19 2010
Yoon Seok Jung
Direct atomic layer deposition (ALD) on composite electrodes leads to ultrathin conformal protective coatings without disrupting inter-particle electronic pathways. Al2O3 -coated natural graphite (NG) electrodes obtained by direct ALD on the as-formed electrode show exceptionally durable capacity retention even at an elevated temperature of 50,°C. In sharp contrast, ALD on powder results in poorer cycle retention than bare NG. [source]

High Lithium Electroactivity of Nanometer-Sized Rutile TiO2,

ADVANCED MATERIALS, Issue 11 2006
Y.-S. Hu
Nanometer-sized rutile shows much higher electroactivity towards Li insertion than micrometer-sized rutile. Up to 0.8,mol of Li per mole of TiO2 can be inserted into nanometer-sized rutile at room temperature (see figure), which is able to reversibly accommodate Li up to Li0.5TiO2 with excellent capacity retention and high rate capability on cycling, rendering it a promising anode material for high-power lithium-ion batteries. [source]

Preparation of tin nanocomposite as anode material by molten salts method and its application in lithium ion batteries

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2009
Mohd Faiz Hassan
Abstract A nanocomposite material (SnO2Co3O4) has been synthesized as an anode material for lithium-ion batteries by the molten salt method. Characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the composite has a small particle size. The electrochemical performance was examined, including the charge,discharge and cycling properties. The experimental results showed that the sample containing the highest amount of Co3O4 compound exhibited a specific capacity of 355,mAh g,1 after 40 cycles, with cycling at 70,mA g,1 (35.2% higher than for the sample containing a lower amount of Co3O4). It seems that increasing the amount of Co3O4 can give good capacity retention and high specific capacity. [source]

Silicon Inverse-Opal-Based Macroporous Materials as Negative Electrodes for Lithium Ion Batteries

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2009
Alexei Esmanski
Abstract Several types of silicon-based inverse-opal films are synthesized, characterized by a range of experimental techniques, and studied in terms of electrochemical performance. Amorphous silicon inverse opals are fabricated via chemical vapor deposition. Galvanostatic cycling demonstrates that these materials possess high capacities and reasonable capacity retentions. Amorphous silicon inverse opals perform unsatisfactorily at high rates due to the low conductivity of silicon. The conductivity of silicon inverse opals can be improved by their crystallization. Nanocrystalline silicon inverse opals demonstrate much better rate capabilities but the capacities fade to zero after several cycles. Silicon,carbon composite inverse-opal materials are synthesized by depositing a thin layer of carbon via pyrolysis of a sucrose-based precursor onto the silicon inverse opals. The amount of carbon deposited proves to be insufficient to stabilize the structures and silicon,carbon composites demonstrate unsatisfactory electrochemical behavior. Carbon inverse opals are coated with amorphous silicon producing another type of macroporous composite. These electrodes demonstrate significant improvement both in capacity retentions and in rate capabilities. The inner carbon matrix not only increases the material conductivity but also results in lower silicon pulverization during cycling. [source]