Offline State-of-Health Estimation for High-Power Lithium-Ion Batteries Using Three-Point Impedance Extraction Method

Abstract

This paper presents an offline state-of-health (SoH) estimation based on charge transfer resistance for high power lithium-ion batteries, such as lithium iron phosphate or LFP batteries. As shown in the experimental results, the charge transfer resistance has a great aging change with battery degradation and good abilities against the state-of-charge (SoC) drift and external resistance variation in the impedance parameter set of a single-time-constant equivalent circuit model (ECM) including ohmic resistance, charge transfer resistance, doublelayer capacitance, and time constant, for SoH estimation. A fast and efficient three-point (TP) impedance extraction method is also proposed in this paper for accurately extracting the charge transfer resistance in offline SoH estimation. The results of longterm cycling test demonstrate that the TP impedance extraction method can successfully indicate the SoH of LFP batteries with low estimation error of 6.1%.Index Terms-Lithium battery, state-of-health (SoH), impedance estimation, offline battery measurement, battery second-use.

Characterization of a Practical-Based Ohmic Series Resistance Model under Life-Cycle Changes for a Lithium-Ion Battery

“…The EECM has different structures, depending on the application point of view, the scope of the study, the accuracy of the model, and various types of battery chemistry [12][13][14][15]. The EECM generally comprises of three main parts, as follows: (1) an equivalent voltage source called open circuit voltage (OCV), which has a nonlinear potential characteristic, depending on the property of electrode materials and the SOC of the battery; (2) a bulk equivalent resistance called an ohmic series resistance (OSR), representing the resistance of the electrodes, an electrolyte, separator, and connecting wires inside the battery, which mainly affects the changes of the resistance values in the battery; and (3) a pair of equivalent RC-transient elements, which reflects the resistances during the process of charge transfer and charge diffusion (R 1 and R 2 , respectively), and the capacitances of the double-layer structure and diffusion process of the battery (C 1 and C 2 , respectively).…”

Open-circuit-voltage characterization system design for studies of phase-transition mechanism and deterioration in Mn-type Li-ion batteries

“…The cell deterioration can be explained in term of the phase transformation during lithium intercalation/de-intercalation. In the intercalation process, Li-ion occupies a tetrahedral coordination and Mn-ion occupies an octahedral coordination in the form of MnO 6 . During the intercalation and deintercalation, the transformations between cubic and orthorhombic crystal systems are occurring.…”

“…The state of health (SOH) of the LIB is one of the important elements in the BMS to observe the trends of deterioration before reaching the damage and end of life (EOL) of the batteries [1,2]. Numerous researchers have reported interesting studies about the SOH and capacity deterioration of LIBs [3,4,5,6]. However, they focused on the utilization in model applications, which is based on the impedance changes and capacity and power fades of the cells to estimate the battery lifetime and healthiness without considering the electrochemical processes inside the battery.…”

A Low-Cost Programmable High-Frequency AC Electronic Load with Energy Recycling for Battery Module Diagnostics

“…Based on these advantages, countries and major automakers all over the world are investing in the development and promotion of hybrid electric vehicles or electric vehicles. The battery module is the power source of electric vehicles and is one of the most essential components of electric vehicles because its capacity will determine the endurance of electric vehicles and its characteristics will determine their performance [6][7][8][9][10]. However, the price of battery modules is still high, accounting for a relatively high proportion of the overall cost, directly affecting the penetration rate of electric vehicles within the market.…”

“…One of the reasons for the high price of battery modules is that their electrochemical properties are difficult to grasp. Nowadays, battery-related research, in addition to materials and electrochemical fields, generally includes monitoring of battery characteristics [1][2][3][4][5][6][7][8][9][10], design of battery management systems [11][12][13][14], estimation of state of charge [15][16][17][18][19][20], estimation of state of health [21][22][23][24][25][26], and so on.…”