Search

The use of laser direct imaging in PCB production has led to important breakthroughs in the production of today's complex designs with the quality, cost and turn-around time demanded by [...]

LiMn1.5Ni0.5O4 (LMN) has attracted considerable attention as 5-volt cathode materials for Li-ion batteries. Here, the coating of nano LiFePO4 (LFP) onto the surface of the spinel particles is reported for the first time. Two processes were used to prepare LFP-coated LMN: a traditional sol-gel method in Ar and a mechano-fusion dry process, which provides a simple way to obtain surface coating for battery materials. Surface elemental analyses indicate that nano-LFP is intimately covered on the LMN surface. LiMn1.5Ni0.5O4 showed better rate property especially at high rate (>10C) after LiFePO4 coating. Good performance such as 82 mAh g-1 of capacity was still obtained for the LiFePO4-coated LiMn1.5Ni0.5O4 with 75% of capacity retention after 140 cycles under 1C.

LiFePO4 nano-particles have been prepared by grinding ingot synthesized in the molten state. Formatting 25-nanometer particles was obtained by subsequent jet and wet milling. These primary particles tend to segregate to form secondary particles of size [?]100 nm, for which surface effects become increasingly important. Study of the electrochemical properties of Li//LiFePO4 cells showed that the cell performance appeared to be strongly dependant of the synthetic route used. The best electrode material formed by wet milling followed by 2 wt.% carbon coating delivered discharge capacity of 157 mAh g-1 at C/10 rate without capacity fading after 60 cycles.

LiFePO4 (LFP) nano-particles have been obtained by grinding ingot synthesized in the molten state. This process, followed by jet milling, and then wet milling, provides a simple way to obtain powders with monitored size of the particles in the whole range from macroscopic to 25 nm, although at this stage, we find that these particles tend to segregate to form secondary particles of size ~100 nm. The electrochemical performance of LFP particles has been evaluated in Li/1M LiPF6 in EC:DEC (1:1)/C-LiFePO4 cells. After carbon coating, LFP particles can be obtained free from any impurity, with a high rate capability. Even with an amount of carbon limited to 2 wt.% appropriate to commercial batteries, the capacity is 157 mAh/g at 0.1C; 58 mAh/g at 10C without capacity fading after 60 cycles.

Graphites MCMB-2810 and OMAC-15 (made by Osaka Gas Inc.), and SNG12 (Hydro Quebec, Inc.) were evaluated in lithium half-cells as anode materials for lithium-ion cells intended for use in hybrid electric vehicles. Though the reversible capacity obtained for SNG was slightly higher than that of OMAC or MCMB, its 1st cycle efficiency was considerably lower. Voltage vs capacity plots of cycling data show that the discharge and charge limits shift to higher capacity values due to continuation of anode side reactions. Varying the cycle charge and discharge limits was found to have an insignificant effect on fractional capacity shift per cycle.

A new water soluble elastomer was evaluated as a binder with LiFePO4 -VGCF cathode material in Li-ion batteries and different carbon origin anodes. The electrochemical characteristics of this cathode and anodes were compared to that with PvdF-based cathode binder. The elastomer-based cathode and anodes show high flexibility with good adhesion. The electrochemical performance was also evaluated and compared to PvdF-based cathodes at 25a and 60{degree sign}C. A lower irreversible capacity loss was obtained with the elastomer- based cathode and graphite-based anode , The Li-ion gel electrolyte developed by Hydro-Quebec shows high stable cycle life but lower power density at rates less than 5C compared to liquid electrolytes

Hybrid supercapacitor that contain high-surface-area carbon and metal oxide electrodes are attracting interest for use in electrochemical devices. Metal oxide electrodes containing Li4Ti5O12 in liquid electrolytes (ionic liquid or nonaqueous liquid) were investigated. A new procedure developed at Hydro Quebec produced Li4Ti5O12 powders with diameters in the range of 100 nm. At high-rate (1 minute) charge-discharge, the hybrid supercapacitor had an average voltage of about 2.21 V, with 85% nominal capacity. These hybrid supercapacitors also exhibited a very long cycle life of >20,000 cycles at high- rate charge-discharge. The results of this study demonstrate that the Li4Ti5O12-based electrochemical system has attractive characteristics for high-power application such as in portable devices and HEVs

LiFePO4 nano-particles have been prepared by grinding ingot synthesized in the molten state. Formatting 25-nanometer particles was obtained by subsequent jet and wet milling. These primary particles tend to segregate to form secondary particles of size ∼100 nm, for which surface effects become increasingly important. Study of the electrochemical properties of Li//LiFePO4 cells showed that the cell performance appeared to be strongly dependant of the synthetic route used. The best electrode material formed by wet milling followed by 2 wt.% carbon coating delivered discharge capacity of 157 mAh g-1 at C/10 rate without capacity fading after 60 cycles.

LiFePO4 (LFP) nano-particles have been obtained by grinding ingot synthesized in the molten state. This process, followed by jet milling, and then wet milling, provides a simple way to obtain powders with monitored size of the particles in the whole range from macroscopic to 25 nm, although at this stage, we find that these particles tend to segregate to form secondary particles of size ~100 nm. The electrochemical performance of LFP particles has been evaluated in Li/1M LiPF6 in EC:DEC (1:1)/C-LiFePO4 cells. After carbon coating, LFP particles can be obtained free from any impurity, with a high rate capability. Even with an amount of carbon limited to 2 wt.% appropriate to commercial batteries, the capacity is 157 mAh/g at 0.1C; 58 mAh/g at 10C without capacity fading after 60 cycles.