Coulombic Efficiency In First Cycle Research Articles

Precise Perforation and Scalable Production of Si Particles from Low-Grade Sources for High-Performance Lithium Ion Battery Anodes.

Alloy anodes, particularly silicon, have been intensively pursued as one of the most promising anode materials for the next generation lithium-ion battery primarily because of high specific capacity (>4000 mAh/g) and elemental abundance. In the past decade, various nanostructures with porosity or void space designs have been demonstrated to be effective to accommodate large volume expansion (∼300%) and to provide stable solid electrolyte interphase (SEI) during electrochemical cycling. However, how to produce these building blocks with precise morphology control at large scale and low cost remains a challenge. In addition, most of nanostructured silicon suffers from poor Coulombic efficiency due to a large surface area and Li ion trapping at the surface coating. Here we demonstrate a unique nanoperforation process, combining modified ball milling, annealing, and acid treating, to produce porous Si with precise and continuous porosity control (from 17% to 70%), directly from low cost metallurgical silicon source (99% purity, ∼ $1/kg). The produced porous Si coated with graphene by simple ball milling can deliver a reversible specific capacity of 1250 mAh/g over 1000 cycles at the rate of 1C, with Coulombic efficiency of first cycle over 89.5%. The porous networks also provide efficient ion and electron pathways and therefore enable excellent rate performance of 880 mAh/g at the rate of 5C. Being able to produce particles with precise porosity control through scalable processes from low-grade materials, it is expected that this nanoperforation may play a role in the next generation lithium ion battery anodes, as well as many other potential applications such as optoelectronics and thermoelectrics.

The lamella SnSbCux/MCMB/carbon composite as high stability and durable anodes for lithium ion battery

Lamella SnSbCux/MCMB/carbon composite were prepared by a multi-step synthesis method for high stability and long life lithium ion battery electrodes. The lamella composite were synthesized via co-precipitation method combining with high-speed ball milling and subsequent pyrolysis. The resultant composite are consisted of nano SnSbCux particles, lamella mesophase carbon microbeads (MCMB, after ball milling) and amorphous carbon coating pyrolyzed from phenolic resin. The lamella MCMB was treated as the inner terrace, which offered efficient electron conducting pathway for connection of nano SnSbCux particle and pyrolysis carbon. With the increasing of the content of inactive element Cu, the SnSbCux/MCMB/carbon composite are propitious to improve the cycling performance. When cycled at a constant current of 100mAg−1 between 0.01 and 2.0V, the coulombic efficiency of first cycle exceeds 88.45% and the reversible capacity of 100th cycle attains to 485mAhg−1 (91.4% capacity retention) in SnSbCu0.5/MCMB/carbon alloy anodes.

Oxidized FeCoNi alloys as novel anode in Li-ion batteries

Oxidised FeCoNi alloys are prepared by an electrodeposition-annealing method. The performances of this type of nanostructured electrode are studied by the combination of structural techniques (transmission electron microscopy and X-ray diffraction) and electrochemical tests in lithium cells. The oxidised FeCoNi alloy achieves an excellent Coulombic efficiency in first cycle (85–90%) as well as a minimal discharge polarization on subsequent cycles because the voltage plateau ascribable to metal reduction is kept invariable at around 0.8 V. These results disclose new pathways to fabricate low-cost and high-performance conversion electrodes as anode material for Li-ion secondary batteries.