A new high speed charge and high efficiency Li-Ion battery charger interface using pulse control technique

A new Li-Ion battery charger interface (BCI) using pulse control (PC) technique is designed and analyzed in this paper. Thanks to the use of PC technique, the main standards of the Li-Ion battery charger, i.e. fast charge, small surface area and high efficiency, are achieved. The proposed charger achieves full charge in forty-one minutes passing by the constant current (CC) charging mode which also included the start-up and the constant voltage mode (CV) charging mode. It designed, simulated and layouted which occupies a small size area 0.1 mm2 by using Taiwan Semiconductor Manufacturing Company 180 nm complementary metal oxide semi-conductor technology (TSMC 180 nm CMOS) technology in Cadence Virtuoso software. The battery voltage VBAT varies between 2.9 V to 4.35 V and the maximum battery current IBAT is 2.1 A in CC charging mode, according to a maximum input voltage VIN equal 5 V. The maximum charging efficiency reaches 98%.

Modelling the Impedance Response of Graded LiFePO4 Cathodes for Li-Ion Batteries

Graded electrodes for Li-ion batteries aim to exploit controlled variations in local electrode microstructure to improve overall battery performance, including reduced degradation rates and increased capacity at high discharge rates. However, the mechanisms by which grading might deliver performance benefit, and under what conditions, are not yet fully understood. A Li-ion battery electrochemical model (a modified Doyle-Fuller-Newman type model capable of generating impedance functions) is developed in which local microstructural changes are captured in order to understand why and when graded electrodes can offer performance benefits. Model predictions are evaluated against experimental electrochemical impedance data obtained from electrodes with micro-scale, controlled variations in microstructure. A region locally enriched with carbon at the electrode/current collector interface is shown to significantly reduce the overpotential distribution across the thickness of a LiFePO$_4$-based Li-ion battery cathode, resulting in a lower charge transfer resistance and impedance. The insights gained from the LiFePO$_4$-based electrodes are generalised to wider design principles for both uniform and graded Li-ion battery electrodes.