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Li Y.,Jiangsu University of Science and Technology | Wang L.,Tsinghua University | He X.,Tsinghua University | Tang B.,Jiangsu Huadong Institute of Li ion Battery | And 2 more authors.
Journal of Energy Chemistry | Year: 2016

Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li-O2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 mAh/g at a current density of 0.1 mA/cm2, and the capacity is about 2.3 times as that of the pristine KB. When the batteries are cycled with different restricted capacity, the boron-doped Ketjenblack based cathodes exhibits higher discharge platform and longer cycle life than Ketjenblack based cathodes. Additionally, the boron-doped Ketjenblack also shows a superior electrocatalytic activity for oxygen reduction in 0.1 mol/L KOH aqueous solution. The improvement in catalytic activity results from the defects and activation sites introduced by boron doping. © 2015 Science Press and Dalian Institute of Chemical Physics. All rights reserved.


Gao J.,Tsinghua University | Gao J.,Jiangsu Huadong Institute of Li Ion Battery | Huang Z.,Tsinghua University | Li J.,Tsinghua University | And 4 more authors.
Ionics | Year: 2014

Lithium-rich cathode materials Li1.2Ni0.13Co0.13Mn0.54O2 with (sample SF) and without (sample SP) formamide was synthesized by a spray-dry method. The crystalline structure and particle morphology of as-prepared materials were characterized by X-ray diffraction and scanning electron microscope. The specific surface area (SSA) of the Li1.2Ni0.13Co0.13Mn0.54O2 prepared from different routes was determined by a five-point Brunauer-Emmett-Teller (BET) method using N2 as absorbate gas. Being compared with the material synthesized without spray-drying process (sample CP), sample SP has much higher SSA. The additive formamide is helpful to form regular and solid precursor particles in spray-drying process, which results in a slightly aggregation of grains and reduction of SSA for sample SF. The electrochemical activities of the materials are closely related to their morphology and SSA. In the voltage range of 2-4.8 V at 25 °C, sample SP present a discharge capacity of 257 mAh g-1 at 0.1 C rate and 170 mAh g-1 at 1 C rate. The sample CP delivered only 136 mAh g-1 when discharged at 1 C rate. The elevated specific capacity and rate capability are attributed to smaller primary particle and higher SSA. Both cycle performance and rate capability of Li1.2Ni0.13Co0.13Mn0.54O2 were improved when formamide was used in spray-dry process. Discharge capacity of SF is 140.5 mAh g-1 at 2 C rate, and that of SP is 132.3 mAh g-1. Overlarge SSA of SP may provoke serious side reaction, so that its electrochemical performance was deteriorated. © 2013 Springer-Verlag Berlin Heidelberg.


Li J.,Tsinghua University | Wang L.,Tsinghua University | Wang L.,Jiangsu Huadong Institute of Li ion Battery | Ren Y.,Jiangsu Huadong Institute of Li ion Battery | And 5 more authors.
Ionics | Year: 2015

A distinctive structure of carbon materials for Li-ion batteries is proposed for the preparation of red phosphorus-carbon composites. The slit-shaped porous carbon is observed with aggregation of plate-like particles, whose isotherm belongs to the H3 of type IV. The density functional theory (DFT) method reveals the presence of micro-mesopores in the 0.5–5 nm size range. The unique size distribution plays an important role in adsorbing phosphorus and electrochemical performance. The phosphorus-slit-shaped porous carbon composite shows initial capacity of 2588 mAh g−1, reversible capacity of 1359 mAh g−1 at a current density of 100 mA g−1. It shows an excellent coulombic efficiency of ∼99 % after 50 cycles. © 2015 Springer-Verlag Berlin Heidelberg


Zhang S.,Tsinghua University | Zhang S.,Yanshan University | Cao J.,Tsinghua University | Cao J.,Jiangsu Huadong Institute of Li ion Battery | And 10 more authors.
Journal of Materials Chemistry A | Year: 2015

With the aim to overcome the high thermal shrinkage of conventional polyolefin separators and improve the electrochemical properties of lithium ion batteries, a nano-composite polymer electrolyte membrane (NCPE) is attempted by introducing highly dispersed nano-TiO2 hybrid doped poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) into a glass fiber nonwoven, which is easily available at low costs. The physical and electrochemical properties of the obtained NCPE are characterized using SEM, thermal shrinkage tests, AC impedance measurements, and charge-discharge and cycling tests. The results show that the NCPE possesses higher porosity and higher thermal dimensional stability temperature than a conventional PP separator. In addition, the electrochemical properties, such as liquid uptake, ionic conductivity and interface compatibility, of the polymer electrolyte membrane and the metallic Li electrode was improved significantly. In particular, the LiCoO2/Li coin cell with NCPE exhibits good C-rate performances of up to 85% at 10C-rate of the capacity at 1C-rate, and capacity retention ratios up to 80% after 1500 cycles at 1C/2C charge-discharge cycling. This study shows that the glass fiber nonwoven, which is easily available at low cost, can be a high performance separator for Li-ion battery applications. © The Royal Society of Chemistry 2015.

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