Optimized Operating Range for Large-Format LiFePO₄/Graphite Batteries

Abstract

Long-term cycling performances of LiFePO 4 /graphite batteries have been investigated in different state-of-charge (SOC) ranges. It is found that batteries cycled in the medium SOC range exhibit superior cycling stability over those cycled at both ends of the SOC ranges. A variety of characterization techniques, including galvanostatic intermittent titration technique (GITT) analysis, model-based parameter identification, electrochemical impedance spectroscopy analysis, and entropy change test, were used to investigate the performance difference of the batteries cycled in different SOC ranges. The results reveal that batteries at the end of SOC exhibit much higher polarization impedance than those within the medium-SOC range. This result can be attributed to the significant structural change of the cathode and anode materials as revealed by the large entropy change within these SOC regions. Identification of the best operating conditions for LiFePO 4 /graphite batteries will significantly extend their cycle life. The general control principle obtained in this work, such as modulating the charge/discharge current to minimize the impedance extremes can also be used in the operation control of other battery systems.

Synthesis of Copper Oxide/Graphite Composite for High‐Performance Rechargeable Battery Anode

“…After 30 charge/discharge cycles at 0.2 C, the capacityo ft he graphite cell had decreased from 66 to 28 mAh g À1 .T he GCuO cell maintained an averagec apacity of 70 mAh g À1 after 30 cycles. The graphite/LFPf ull-cell has already been commercialized, and is knownt ob estable in the range 2.5-3.5 V. [38] The stabilityo ft he proposed cells was tested over aw ide voltage range (0.3-3.5 V) for the reactiono f Cu oxide nanoparticles. The active mass was 75 %o ft he total loaded cathodee lectrode mass.…”

“…The active mass was 75 %o ft he total loaded cathodee lectrode mass. The graphite/LFPf ull-cell has already been commercialized, and is knownt ob estable in the range 2.5-3.5 V. [38] The stabilityo ft he proposed cells was tested over aw ide voltage range (0.3-3.5 V) for the reactiono f Cu oxide nanoparticles. However,i ncreasing the operating voltage range adversely affects the stabilityo fg raphite, because excessive Li ion intercalation increasest he stress on the graphite interlayers.…”

Research on an Electric Vehicle Owner-Friendly Charging Strategy Using Photovoltaic Generation at Office Sites in Major Chinese Cities

“…The battery capacity of the E150 EV is 25.6 kWh, therefore, 30% of the SOC is required for the 40 km of travel. In addition, in order to extend the life of EV batteries, the SOC should not be less than 20% [35]. Given the traffic congestion, a 10% SOC margin is necessary, so the SOC D is set to 60%.…”

Lithium Metal Battery Pouch Cell Assembly and Prototype Demonstration Using Tailored Polypropylene Separator

“…However, the anode possesses intrinsic limitations such as solid–electrolyte interface (SEI) formation and its stability at a high rate for use in high‐power applications, viz., EVs, hybrid electric vehicles (HEVs), and grid energy storage . Indeed, there is a concern in LIBs with an electrode mass balance between the anode and cathode in terms of specific capacities and their formation cycle process carried out at a low current density . During formation cycles, Li + loss occurs due to the formation of SEI as a passivation film on an anode surface, consumed from the cathode source and simultaneous electrolytic decomposition reactions, leading to an overall reduced full cell capacity .…”