3
rate increased with increasing temperature and was caused
by solid-electrolyte interphase growth on the anode and
degradation of the cathode.
Lithium dendrite growth is a significant concern with
LIBs. Dendrite formation can cause internal short circuits
leading to TR [18]. During charging, these metallic micro-
structures develop when extra lithium ions accumulate on
the anode surface. Dendrites can pierce the battery sepa-
rator and cause an internal short circuit. Dendrite growth
during charging is a function of temperature. Love et al.
[19] investigated lithium dendrite growth at -10°C, 5°C,
and 20°C. At -10°C, dendrite growth was the fastest as
more than twice the number of dendrites formed compared
to 5°C and 20°C. However, internal shorting occurred the
fastest at 5°C due to the needle-like shape of the dendrites
produced at this temperature. Needle-like dendrites are
more likely to pierce a LIB’s separator. If the separator is
pierced by dendrites, an internal short circuit could occur
possibly leading to TR.
The separator is a critical component of LIBs [20].
As a safety feature, separators exhibit a large increase in
impedance that occurs just below the separator’s melting
temperature. The purpose of this feature—referred to as
shutdown—is to prevent TR. In BEV applications, the
separator is roughly 40-mm thick. Due to the thinness of
the separator, high puncture strength is required, especially
in wound cells such as the cylindrical 18650. If electrode
material penetrates the separator, possibly from mechani-
cal abuse, an internal electrical short could be created that
might lead to TR.
Mechanical shock and vibration are important envi-
ronmental concerns for LIBs as vehicles in mining drive
over rough terrain and underground vehicles may regularly
bump into the rib or other vehicles. The state of charge
(SOC) of LIBs affects their vibration response. Pham et al.
[21] studied the vibration response of LIB pouch cells as
a function of SOC from 0% to 80% SOC in 10% incre-
ments. The researchers found that the frequency response
of the cells shifted to higher frequencies as SOC increased,
indicating a stiffening effect.
Brand et al. [22] studied mechanical shock and vibra-
tion effects on pouch-type and cylindrical 18650 lithium-
ion cells. The researchers subjected the cells to 300∙shocks
with a peak amplitude of 150 g and a duration of 6 ms,
following the UN 38.3 T4 standard. In addition, sinusoidal
vibration was applied to the cells according to the UN 38.3
T3 standard with 10 logarithmic sweeps from 7 Hz to 200
Hz over a period of 3 hours with a peak acceleration of 1 g
from 7 Hz to 18 Hz, a peak displacement of 0.8 mm from
18 Hz to 50 Hz, and a peak acceleration of 8 g from 50 Hz
to 200 Hz. In addition, a six-month-long sine sweep vibra-
tion test was conducted on the cells at a root-mean-square
(RMS) acceleration of 1.9 g and frequencies from 4 Hz to
20 Hz. The tests did not harm the pouch cells, but they
damaged the 18650 cells. The mechanical shocks caused
the 18650 cells to have loose mandrels—center pins—
and movement of the current interrupt device (CID).
According to the authors, “The CID as well as the connec-
tion to the jelly roll are already turned upward. Thus, the
CID is likely to be deactivated and therefore might not be
able to prevent any dangerous incident anymore.” In addi-
tion, the jelly roll–so named because of the appearance of
the cross section of the battery–had scorch marks where the
mandrel contacted the separator. Scanning electron micro-
scope (SEM) inspection confirmed that the separator had
melted at the scorch marks. Upon disassembly, the 18650
cells subjected to the UN 38.3 sine sweep test exhibited
loose mandrels. After the six-month-long vibration tests,
the mandrels of the 18650 cells moved enough to strike
against the terminals. The mandrel damaged the separator
causing internal short circuits that were confirmed with
SEM analysis.
Hooper and Marco [23, 24, 25] investigated the vibra-
tion levels and frequencies experienced by passenger car
BEVs, hybrid vehicles (HVs), and internal combustion
engine (ICE) vehicles. The vehicles were driven across
various surfaces at various speeds to compare the result-
ing vibration across a variety of road input conditions.
The researchers found that significant vibration occurs at
frequencies below 7 Hz because the vehicle suspension
vibration modes are in this frequency range. For automo-
biles, LIB pack mounting could be an integral part of a
vehicle’s frame stiffness which affects its vibration response
in the 20 Hz to 40 Hz region where torsional vibration
modes are important. The researchers compared the results
of their vehicle vibration data to recommended vibration
test profiles from SAE J2380, USABC Procedure 10, ECE
Regulation 100, and BS EN 62660-2:2011. The authors
concluded that electric vehicles (EVs) may be exposed to
vibration levels outside the range of existing standards.
Further, they used the measured vibration data to develop
a durability profile for EV testing using HBK nCode soft-
ware. The nCode-developed profile allows 100,000 mi of
vehicle life—a full lifetime of vibration—to be simulated in
a short time, for example, fewer than 100 hours.
Hooper et al. [26] also tested the vibration durabil-
ity of nickel manganese cobalt oxide (NMC) lithium-ion
18650 cells. The researchers subjected groups of NMC cells
rate increased with increasing temperature and was caused
by solid-electrolyte interphase growth on the anode and
degradation of the cathode.
Lithium dendrite growth is a significant concern with
LIBs. Dendrite formation can cause internal short circuits
leading to TR [18]. During charging, these metallic micro-
structures develop when extra lithium ions accumulate on
the anode surface. Dendrites can pierce the battery sepa-
rator and cause an internal short circuit. Dendrite growth
during charging is a function of temperature. Love et al.
[19] investigated lithium dendrite growth at -10°C, 5°C,
and 20°C. At -10°C, dendrite growth was the fastest as
more than twice the number of dendrites formed compared
to 5°C and 20°C. However, internal shorting occurred the
fastest at 5°C due to the needle-like shape of the dendrites
produced at this temperature. Needle-like dendrites are
more likely to pierce a LIB’s separator. If the separator is
pierced by dendrites, an internal short circuit could occur
possibly leading to TR.
The separator is a critical component of LIBs [20].
As a safety feature, separators exhibit a large increase in
impedance that occurs just below the separator’s melting
temperature. The purpose of this feature—referred to as
shutdown—is to prevent TR. In BEV applications, the
separator is roughly 40-mm thick. Due to the thinness of
the separator, high puncture strength is required, especially
in wound cells such as the cylindrical 18650. If electrode
material penetrates the separator, possibly from mechani-
cal abuse, an internal electrical short could be created that
might lead to TR.
Mechanical shock and vibration are important envi-
ronmental concerns for LIBs as vehicles in mining drive
over rough terrain and underground vehicles may regularly
bump into the rib or other vehicles. The state of charge
(SOC) of LIBs affects their vibration response. Pham et al.
[21] studied the vibration response of LIB pouch cells as
a function of SOC from 0% to 80% SOC in 10% incre-
ments. The researchers found that the frequency response
of the cells shifted to higher frequencies as SOC increased,
indicating a stiffening effect.
Brand et al. [22] studied mechanical shock and vibra-
tion effects on pouch-type and cylindrical 18650 lithium-
ion cells. The researchers subjected the cells to 300∙shocks
with a peak amplitude of 150 g and a duration of 6 ms,
following the UN 38.3 T4 standard. In addition, sinusoidal
vibration was applied to the cells according to the UN 38.3
T3 standard with 10 logarithmic sweeps from 7 Hz to 200
Hz over a period of 3 hours with a peak acceleration of 1 g
from 7 Hz to 18 Hz, a peak displacement of 0.8 mm from
18 Hz to 50 Hz, and a peak acceleration of 8 g from 50 Hz
to 200 Hz. In addition, a six-month-long sine sweep vibra-
tion test was conducted on the cells at a root-mean-square
(RMS) acceleration of 1.9 g and frequencies from 4 Hz to
20 Hz. The tests did not harm the pouch cells, but they
damaged the 18650 cells. The mechanical shocks caused
the 18650 cells to have loose mandrels—center pins—
and movement of the current interrupt device (CID).
According to the authors, “The CID as well as the connec-
tion to the jelly roll are already turned upward. Thus, the
CID is likely to be deactivated and therefore might not be
able to prevent any dangerous incident anymore.” In addi-
tion, the jelly roll–so named because of the appearance of
the cross section of the battery–had scorch marks where the
mandrel contacted the separator. Scanning electron micro-
scope (SEM) inspection confirmed that the separator had
melted at the scorch marks. Upon disassembly, the 18650
cells subjected to the UN 38.3 sine sweep test exhibited
loose mandrels. After the six-month-long vibration tests,
the mandrels of the 18650 cells moved enough to strike
against the terminals. The mandrel damaged the separator
causing internal short circuits that were confirmed with
SEM analysis.
Hooper and Marco [23, 24, 25] investigated the vibra-
tion levels and frequencies experienced by passenger car
BEVs, hybrid vehicles (HVs), and internal combustion
engine (ICE) vehicles. The vehicles were driven across
various surfaces at various speeds to compare the result-
ing vibration across a variety of road input conditions.
The researchers found that significant vibration occurs at
frequencies below 7 Hz because the vehicle suspension
vibration modes are in this frequency range. For automo-
biles, LIB pack mounting could be an integral part of a
vehicle’s frame stiffness which affects its vibration response
in the 20 Hz to 40 Hz region where torsional vibration
modes are important. The researchers compared the results
of their vehicle vibration data to recommended vibration
test profiles from SAE J2380, USABC Procedure 10, ECE
Regulation 100, and BS EN 62660-2:2011. The authors
concluded that electric vehicles (EVs) may be exposed to
vibration levels outside the range of existing standards.
Further, they used the measured vibration data to develop
a durability profile for EV testing using HBK nCode soft-
ware. The nCode-developed profile allows 100,000 mi of
vehicle life—a full lifetime of vibration—to be simulated in
a short time, for example, fewer than 100 hours.
Hooper et al. [26] also tested the vibration durabil-
ity of nickel manganese cobalt oxide (NMC) lithium-ion
18650 cells. The researchers subjected groups of NMC cells