DOI:	10.7795/720.20221021
resource type:	Dataset / Measurement Data	
title:	Thermal Electrical Tests for Battery Safety Standardization
summary:	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.
creators:	Frank Lienesch (Abtl. 9), Stefan Essmann (AG 3.55), Annika Stein (AG3.61), Cedric Jackmann (TU Braunschweig), Daniel Kehl (TU Braunschweig), Michael Kurrat (TU Braunschweig) 
license:	CC-BY-Lizenz	
keywords: 	lithium-ion battery; battery safety; overcharging; short circuit; standardization	
classification:		INSPEC A8245 - Electrochemistry and electrophoresis ; B8410 - Electrochemical conversion and storage ; B8410E - Secondary cells ; A8630 - Energy conversion ; A8630F - Secondary cells ; E0240C - Security aspects ; A8240P - Flames, combustion, and explosions ; A5280Q - Explosions (electrical discharges)
project short + long title:	BaSS – Batteriesicherheitsstandardisierung
funder:		BMBF
funding nr:	16EMO0318
funding acknowledgement text: -	
link to projekt homepage:	-
related objects:	-
recommended reading software:	-
description of the individual files:	

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

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