DOI: 10.7795/720.20221021
title: Research data for the publication "Thermal electrical tests for battery safety standardization"

description: Battery safety tests are defined by several international standards in different ways and with heterogenous termination and failure criteria. In this work, lithium-ion cells were examined regarding their behavior in the event of overcharging and also in the event of an external short circuit with varied parameters specified by standards. The voltage, current, and temperature curves were evaluated. In addition, the changes in the cells were analyzed using electrochemical impedance spectroscopy (EIS). It is shown that the cells exhibit reproducible behavior in a clamped state. Further, it could be determined that the position of the cell opening during an overcharge has an influence on the further behavior of the cell. EIS data showed that the cells have a significantly higher internal resistance after an overcharge. The short-circuit tests at different ambient temperatures indicated that the internal resistance of the cell decreases with increasing temperature. However, no reproducible effects in impedance spectra were present after the short-circuit test. This work illustrates that the choice of test parameters and termination criteria undoubtedly influence the test results and thus may change the classification of cells as either safe or unsafe. Thus, cells may be classified as safe regarding a certain standard but unsafe regarding another.
description: The files "overchg_[Iov]_[Tamb]_[mount]_[nr].csv" contain the results of the overcharge tests performed on four clamped battery cells ("269", "271", "272", "274") plus an unclamped one ("270"). Parameters: Iov = normalised overcharge current = "1C" (= full discharge in one hour) Tamb = ambient temperature = (20±2) °C mount = mounting = "clamped" or "not clamped" nr = cell number = "269", "270", "271", "272", "274" Variables: time = time from the measurement beginning, in seconds Tcell1,2,3 = cell temperature, in degrees Celsius (three independent measurements) Tamb = ambient temperature, in degrees Celsius (measured for control) Ucell = cell voltage, in volt Iov = overcharge current, in ampere Qcell = cell charge, in ampere-hours SoC = cell state of charge relative to the maximum nominal charge, in % The files "EIS_[timept]_[nr].csv" contain the results of the electrochemical impedance measurements performed on one of the test cells ("272") before and after the overcharge test. Parameters: timept = time point of the EIS measurement = before or after the overcharge test nr = cell number = "272" Variables: Freq = frequency of the probe voltage, in hertz Ucell = cell voltage, in volt ReZ = cell electrochemical impedance, resistive component, in milliohm ImZ = cell electrochemical impedance, inductive component, in milliohm The files "shortcircuit_[Tamb]_[mount]_[nr].csv" contain the results of the short circuit tests performed on three test cells at (20±2) °C ambient temperature ("256", "263", "266") and on another cell at (55±2) °C ambient temperature ("260"). Parameters: Tamb = ambient temperature = (20±2) °C or or (55±2) °C mount = mounting = "clamped" nr = cell number = "256", "260", "263", "266" Variables: t = time from the measurement beginning, in seconds / in minutes Dt = time during the short circuit, in minutes Tcell1,2,3 = cell temperature, in degrees Celsius (two or three independent measurements) Tamb = ambient temperature, in degrees Celsius (measured for control) Ucell = cell voltage, in volt Ushunt = shunt voltage, in volt Isc=Ishunt = short circuit current = shunt current, in ampere