Note: Descriptions are shown in the official language in which they were submitted.
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
THERMAL RUNAWAY DETECTION SYSTEMS
FOR BATTERIES WITHIN ENCLOSURES AND METHODS OF USE THEREOF
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. Application No.
17/021,711, filed on
September 15, 2020, and claims the benefit of U.S. Provisional Application No.
63/202,962,
filed on July 1, 2021, the entire contents of each of which are hereby
incorporated by reference.
FIELD OF THE DISCLOSURE
[0002] The disclosure relates generally to a detection system for detecting
battery failure and
more particularly to a detection system for detecting thermal runaway of
batteries within
enclosures, for example, batteries used with electric vehicles, FIG. 2(a), or
stationary battery
energy storage systems, FIG. 2(b). The disclosure also relates to methods of
detecting thermal
runaway in a battery using such systems.
BACKGROUND OF THE DISCLOSURE
[0003] As Li-ion battery technology improves, battery energy density has
continued to increase
and this in turn increases the risk of battery failures. Li-ion battery
thermal runaway is a critical
safety issue for electric vehicles. For example, the proposed global
technology regulation No. 20
by the United Nations on Electric Vehicle Safety (EVS) requires an advanced
warning 5 minutes
prior to the evolution of hazardous conditions caused by thermal runaway.
[0004] Referring to FIGS. 1(a), 1(b), thermal runaway in lithium ion based
batteries is a process
under which an exothermic reaction occurs within a failed cell that increases
the internal
temperature, which in turn releases energy that sustains the internal
degradation reactions and
increases the temperature until ultimate failure of the cell, often
accompanied by sudden release
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
of the electrolyte and gas products of decomposition, which may result in
fire. In modern lithium
batteries, the risk of explosion can be reduced by design to incorporate a
controlled venting
location in the cell (see FIG. 4), but risk of fire and explosion due to
thermal runaway has not
been eliminated in most liquid electrolyte lithium-based batteries.
.. [0005] Turning back to FIGS. 1(a), 1(b), certain triggers and abuse
conditions can lead batteries,
e.g., lithium-ion cells, to breakdown or failure, which in turn can result in
a thermal runaway.
Thermal runaway can be caused, for example, by external short circuit,
internal short circuit
(particle, dendrites, separate failure, impact/puncture), overcharge, over-
discharge, external
heating, or over-heating (self-heating). With elevated temperatures is the
generation of gas. If
heat dissipation occurs faster than heat generation, there can be a safe
outcome.
[0006] However, if left unhindered, or if the heat cannot be dissipated faster
than it is being
generated, this can result in a rapid increase in temperature, release of
flammable and hazardous
gases during venting, flames, and possibly explosion. This can especially be
problematic for
vehicles having large format battery systems, as shown in FIG. 3, and in
particular battery
electric vehicles and stationary storage, where the thermal runaway of a
single cell (FIG. 4) can
lead to a cascade of thermal runaway events that can engulf the entire pack,
resulting in
catastrophic fire and release of hazardous gases. Although battery packs can
be constructed to
passively contain several failed cells and satisfy the EVS regulation, thermal
runaway
propagation can still happen. Therefore, detecting a cell undergoing thermal
runaway inside a
pack is important.
[0007] Sensors have been developed to detect thermal runaway. However, simple
gas sensors,
such as a hydrocarbon sensor, can only detect electrolyte gas concentration,
and also suffer from
2
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
cross sensitivity to other gases as well as substantial drift and so make poor
long-life thermal
runaway detection sensors.
[0008] There is therefore a need for a robust early detection system for
detecting thermal
runaway in mobile and stationary applications that is fast and reliable.
[0009] No admission is made that any reference cited herein constitutes prior
art. Applicant
expressly reserves the right to challenge the accuracy and pertinence of any
cited documents and
information.
SUMMARY OF THE DISCLOSURE
[0010] A detection system is disclosed that addresses the challenges of fast,
robust thermal
runaway detection within a battery enclosure that is generally agnostic to
electrochemistry, cell
packaging (cylindrical, prismatic, or pouch), cell size, as well as battery
configuration
(series/parallel) by identifying attributes of initial cell venting that are
shared between numerous
design types and responding to venting gases of a failing cell.
[0011] During thermal runaway decomposition reactions, the cell converts
substantial cathode
and electrolyte material into gas and vents the pressurized gas mixture in
time spans of seconds
when the faulted cell is at a high State of Charge, FIG. 1(b). Of the typical
cell chemistries such
as lithium-manganese-cobalt-oxide (NMC) batteries, Lithium Cobalt Oxide (LCO),
and Lithium
Iron Phosphate (LFP) batteries, thermal runaway testing has shown the release
of several gases,
including large quantities of carbon dioxide and hydrogen, see FIG. 5. Carbon
dioxide is
generally evolved during the oxidation reaction of carbonate solvents and
hydrogen is generally
released as a product of the reduction of water deriving from combustion
reactions by carbon
3
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
monoxide and/or free lithium, with methane and ethane compounds also present
from reduction
reactions of the electrolyte and ethylene carbonate at the lithiated anode.
[0012] Also disclosed in the use of such systems for the detection (e.g.,
early detection) of
thermal runaway, thereby, for example, helping to prevent cell-to-cell
propagation of thermal
runaway originating from a single cell. In one embodiment, a cell venting is
detected. In one
embodiment, thermal runaway is detected. In one embodiment, thermal runaway
decomposition
products are detected.
[0013] In other examples of the disclosure, at least one additional sensor is
provided for
detecting a secondary condition of the battery and providing information on a
rate of progression
of the cell venting and thermal runaway in real time including pressure or
temperature, wherein
said microcontroller provides a rate of progression of the thermal runaway
based on the provided
information from said secondary sensor. The at least one additional sensor can
detect a pressure
or temperature in the battery compartment housing to determine rate of
progression of the
venting/thermal runaway. A sensor housing can be provided to enclose the at
least one sensor
and the at least one secondary sensor. Output from the primary gas sensor and
the secondary gas
sensor allows for differentiation between electrolyte leakage and
venting/thermal runaway. The
system software can be embedded within the sensor microcontroller to determine
if threshold
levels for thermal runaway have been exceeded and to send an alarm to the
battery management
microcontroller or charging system controller.
[0014] In yet other example embodiments, the threshold levels for thermal
runaway are selected
from: (i) a carbon dioxide level of greater than about 10,000 ppm; (ii) a
hydrogen level of greater
than about 40,000 ppm; (iii) a carbon dioxide level above its lower explosive
limit; (iv) a
hydrogen level above its lower explosive limit; and (v) any combination of
thereof. A multichip
4
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
printed circuit board can be provided to be mounted on battery management
controller printed
circuit board. A power management system can be provided that allows for fast
data acquisition
mode during active battery system charging/discharging, and reduced
acquisition rate/lower
power mode when the battery system is neither charging nor discharging. The
detection system
can send a wake-up command to the main battery system controller upon
detection of
venting/thermal runaway. The sensor system can include multiple gas sensors
selected from
more than one hydrogen sensor, more than one carbon monoxide sensor, more than
one carbon
dioxide sensor, and any combination of any of the foregoing, for redundancy in
safety critical
applications. The detection system can also include a humidity sensor, a
pressure sensor, a
temperature sensor, or any combination thereof.
[0015] In another example embodiment, a method is provided for detecting a
thermal runaway
condition of a battery within a battery enclosure. The method includes
providing a detection
system as described above, measuring and/or analyzing one or more gases
venting from the
battery, and determining if the analyzed gas levels are at or above a
predetermined threshold
level that indicates thermal runaway of the battery. The gases analyzed can
include hydrogen,
carbon monoxide, carbon dioxide, or any combination thereof.
[0016] This summary is not intended to identify essential features of the
claimed subject matter,
nor is it intended for use in determining the scope of the claimed subject
matter. It is to be
understood that both the foregoing general description and the following
detailed description are
exemplary and are intended to provide an overview or framework to understand
the nature and
character of the disclosure.
5
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
BRIEF DESCRIPTION OF THE FIGURES
[0017] The accompanying drawings are incorporated in and constitute a part of
this
specification. It is to be understood that the drawings illustrate only some
examples of the
disclosure and other examples or combinations of various examples that are not
specifically
illustrated in the figures may still fall within the scope of this disclosure.
Examples will now be
described with additional detail through the use of the drawings, in which:
[0018] FIG. 1(a) is a flow diagram showing the progression of thermal runaway;
[0019] FIG. 1(b) is a chart of thermal runaway and temperature;
[0020] FIG. 2(a) is a typical battery pack in an electric vehicle;
[0021] FIG. 2(b) is a drawing of a typical battery pack in an energy
stationary storage enclosure;
[0022] FIG. 3 shows a battery thermal runaway detector;
[0023] FIG. 4 shows a typical battery cell before and after thermal runaway;
[0024] FIG. 5 is a diagram of gas released from thermal runaway events in
cells with different
electro-chemistries: LCO/NMC, NMC, and LFP;
[0025] FIG. 6 is a plot of cascading thermal runaway propagating through pack
enclosure
wherein initial cell triggered thermal runaway in several adjacent cells;
[0026] FIG. 7 is a plot of hydrogen concentration rise immediately after
initial vent followed by
slight pressure rise within the enclosure over one minute later as gas
expansion exceeds pack
level venting capability;
[0027] FIG. 8 is a plot of thermal runaway initiation showing rapid carbon
dioxide concentration
rise within the enclosure; and
6
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0028] FIG. 9 is a schematic of thermal runaway management system.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0029] In describing the illustrative, non-limiting embodiments illustrated in
the drawings,
specific terminology will be resorted to for the sake of clarity. However, the
disclosure is not
intended to be limited to the specific terms so selected, and it is to be
understood that each
specific term includes all technical equivalents that operate in similar
manner to accomplish a
similar purpose. Several embodiments are described for illustrative purposes,
it being understood
that the description and claims are not limited to the illustrated embodiments
and other
embodiments not specifically shown in the drawings may also be within the
scope of this
disclosure.
[0030] The Battery Thermal Runaway Detector is predisposed within the void
airspace of a
typical battery enclosure, for example as shown in FIG. 3. The enclosure
completely surrounds
.. one or more battery modules, each battery module having one or more battery
cells aligned in
parallel or series with one another. The battery cells of each module are in
electrical
communication with the adjacent cells, and the battery modules are in
electrical communication
with each adjacent module. A battery controller is in communication with each
battery module
and/or battery cell. The battery controller can operate each battery cell
either directly or via the
module, such as to turn the cell on/off or control the voltage output of each
cell.
[0031] The enclosure protects the battery cells and modules from water,
debris, and to protect
users and occupants from the electrical hazards within the enclosure.
Enclosure void space
volumes (the volume of air space within the enclosure) can vary from as little
as a few liters to as
much as 200 or more liters, typically containing air. The battery enclosure is
generally provided
7
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
with air venting features inclusive of a single or multiple small openings
that allow for pressure
equilibrium inside and outside the enclosure to prevent strain and damage to
the pack. These
openings are generally protected with hydrophobic membranes that allow for air
exchange but
prevent the direct flow of liquid water into the enclosure. The enclosure may
also include valves
or similar devices to allow over pressure from a thermal runaway to safely
vent from the
enclosure, reducing risk of explosion and harmful shrapnel.
[0032] Turning to FIG. 9, a thermal runaway detector or detection system 100
is shown in
accordance with one non-limiting exemplary embodiment of the present
disclosure. The
detection system 100 resides within the battery enclosure void space as in
FIG. 3 and includes a
primary detector, here a gas detector 110. The detection system 100 also
includes a pressure
sensor 112, relative humidity (RH) sensor 114, and/or temperature sensor 116.
[0033] In one embodiment of any of the detection systems described herein, the
primary gas
detector 100 comprises one or more sensors for the detection of decomposition
products formed
during thermal runaway.
[0034] For example, in one embodiment of any of the detection systems
described herein, the
primary gas detector 110 comprises one or more sensors, and in one embodiment
comprises one
or more of: a CO2 sensor, a carbon monoxide (CO) sensor, a HF sensor, a H2 gas
sensor and/or a
water vapor sensor.
[0035] In one embodiment of any of the detection systems described herein, the
primary gas
detector 110 comprises a CO2 sensor, a CO sensor, a HF sensor, a H2 gas sensor
and a water
vapor sensor.
[0036] In one embodiment of any of the detection systems described herein, the
primary gas
detector 110 comprises a CO2 sensor, a CO sensor, a HF sensor, and a H2 gas
sensor.
8
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0037] In another embodiment of any of the detection systems described herein,
the primary gas
detector 110 comprises a CO2 sensor, a CO sensor, a H2 gas sensor and a water
vapor sensor.
[0038] In another embodiment of any of the detection systems described herein,
the primary gas
detector 110 comprises a CO2 sensor, a CO sensor, and a H2 gas sensor.
[0039] In another embodiment of any of the detection systems described herein,
the primary gas
sensor 110 examines the unique physical properties of the sensed gas without
chemically
interacting with it, thereby providing for a reliable and robust primary
sensor.
[0040] In another embodiment of any of the detection systems described herein,
the primary gas
detector 110 further comprises one or more secondary gas sensors for the
detection of one or
more gases that are vented from a cell prior to thermal runaway (e.g., during
initial cell venting
of gas products of SET decomposition and electrolyte).
[0041] For example, in one embodiment of any of the detection systems
described herein, the
primary gas detector 110 further comprises one or more secondary gas sensors
for the detection
of one or more of: methane, ethane, oxygen, nitrogen oxides, volatile organic
compounds, esters,
hydrogen sulfide, sulfur oxides, ammonia, chlorine, propane, ozone, ethanol,
hydrocarbons,
hydrogen cyanide, combustible gases, flammable gases, toxic gases, corrosive
gases, oxidizing
gases, and/or reducing gases.
[0042] In another embodiment of any of the detection systems described herein,
the primary gas
detector 110 further comprises one or more secondary gas sensors for the
detection of one or
more of: CH4, C2H2, C2H4, C2H6, diethyl carbonate (DEC), dimethyl carbonate
(DMC), ethylene
carbonate (EC), ethyl methyl carbonate (EMC), C4H1o, C3H6, C3H8 and/or POF3.
[0043] In one embodiment of any of the detection systems described herein, the
gas detector 100
comprises one or more primary sensors for the detection of decomposition
products formed
9
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
during thermal runaway and one or more secondary gas sensors for the detection
of one or more
gases than are vented from a cell prior to thermal runaway (e.g., during
initial cell venting of gas
products of decomposition and electrolyte).
[0044] The detectors/sensors 110-116 are positioned about the enclosure, and
any suitable
combination of detectors and/or sensors 110-116 can be utilized.
[0045] The thermal runaway detection system 100 also contains a voltage
regulator 120 that
provides and regulates sufficient power to operate the sensors 110-116,
microcontroller or
microprocessor 118, and communications transceiver 122. The sensor elements
110-116 are
electrically connected to the microcontroller 118 within the detection system
100. The
microcontroller 118 interprets the sensor output from each of the sensors 110-
116 and provides
necessary signal conditioning to convert the raw sensor signals to engineering
values for each
component. The values are then transmitted to the communications transceiver
122, which
provides a data stream of sensor information to the battery management system
master controller
or other electronic monitoring system.
[0046] When a CO2 gas sensor 110 is used as one of the primary gas sensors
110, it detects
carbon dioxide levels in the enclosure (FIG. 3) and has long term reliability
and a fast response
time (under 6 seconds to record an event). Carbon dioxide background
concentration levels are
generally less than 1,000 ppm, during a battery cell venting conditions, these
concentrations can
easily exceed 60,000ppm within the enclosure, providing very robust gas signal
for detection, as
shown in FIG. 8. With ejecta speeds during venting often exceeding 200 m/s,
diffusion of carbon
dioxide within the enclosure void space happens very rapidly, reaching the gas
sensor 110 within
2 seconds or less regardless of the sensor proximity to the venting cell.
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0047] In one embodiment of any of the detection systems described herein, the
primary gas
sensor 110 for the detection of CO2 is an infrared (e.g., near-dispersive
infrared) spectroscopy
sensor.
[0048] For example, in one embodiment of any of the detection systems
described herein, the
.. gas sensor 110 provides the output to the processing device 118, which can
determine if the
sensed condition exceeds a predetermined threshold or if there is a rapid
change in the sensed
condition.
[0049] In one embodiment of any of the detection systems described herein, the
predetermined
threshold for the detection of carbon dioxide concentration signaling the
triggering of a thermal
runaway event is greater than about 1,000 ppm, such as greater than about
10,000 ppm, greater
than about 20,000 ppm, greater than about 30,000 ppm, greater than about
40,000 ppm, greater
than about 50,000 ppm, greater than about 60,000 ppm or greater than about
75,000 ppm. In one
embodiment of any of the detection systems described herein, the predetermined
threshold for
the detection of carbon dioxide concentration signaling the triggering of a
thermal runaway event
is greater than about 10,000 ppm.
[0050] Thus, in one embodiment of any of the detection systems described
herein, the system
indicates that a thermal runaway event has occurred when the concentration of
carbon dioxide
detected by the sensor is greater than about 1,000 ppm, such as greater than
about 10,000 ppm,
greater than about 20,000 ppm, greater than about 30,000 ppm, greater than
about 40,000 ppm,
greater than about 50,000 ppm, greater than about 60,000 ppm or greater than
about 75,000 ppm.
In one embodiment of any of the detection systems described herein, the system
indicates that a
thermal runaway event has occurred when the concentration of carbon dioxide
detected by the
sensor is greater than about 10,000 ppm.
11
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0051] In a similar fashion, background concentrations of hydrogen in
atmospheric air are
generally around 200 to 300 ppb. Under battery cell venting conditions,
hydrogen concentrations
inside the battery enclosure can easily exceed 140,000 ppm, also providing a
robust signal to
noise ratio for gas detection, as shown in FIG. 7
[0052] In one embodiment of any of the detection systems described herein, the
primary gas
sensor 110 for the detection of H2 is a thermal conductivity sensor.
[0053] In one embodiment of any of the detection systems described herein, the
predetermined
threshold for the detection of hydrogen concentration signaling the triggering
of a thermal
runaway event is about greater than about 200 ppb, such as greater than about
300 ppb, greater
than about 1 ppm, greater than about 100 ppm, greater than about 1,000 ppm,
greater than about
10,000 ppm, greater than about 40,000 ppm greater than about 50,000 ppm,
greater than about
100,000 ppm or greater than about 150,000 ppm. In one embodiment of any of the
detection
systems described herein, the predetermined threshold for the detection of
hydrogen
concentration signaling the triggering of a thermal runaway event is greater
than about 40,000
ppm.
[0054] Thus, in one embodiment of any of the detection systems described
herein, the system
indicates that a thermal runaway event has occurred when the concentration of
hydrogen
detected by the sensor is greater than 200 ppb, such as greater than about 300
ppb, greater than
about 1 ppm, greater than about 100 ppm, greater than about 1,000 ppm, greater
than about
10,000 ppm, greater than about 50,000 ppm, greater than about 100,000 ppm or
greater than
about 150,000 ppm. In one embodiment of any of the detection systems described
herein, the
system indicates that a thermal runaway event has occurred when the
concentration of hydrogen
detected by the sensor is greater than 40,000 ppm.
12
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0055] In one embodiment of any of the detection systems described herein, the
system indicates
that a thermal runaway event has occurred when the concentration of hydrogen
detected by the
sensor is above its lower explosive limit (4 %).
[0056] In one embodiment of any of the detection systems described herein, the
system indicates
that a thermal runaway event has occurred when the concentration of CO
detected by the sensor
is above its hazardous limit and/or its lower explosive limit (12.5 %).
[0057] The use of the principle of thermal conductivity for hydrogen and non-
dispersive
Infrared measurement of CO2 primary sensors are robust, absolute measurement
devices that
have limited cross sensitivity to other gases, making them ideal for this
application where there is
little or no opportunity to recalibrate or service the devices in the field.
This is generally due to
the selection of measurement principles based on physical behaviors unique to
these gas
molecules, while not chemically interacting with the target gases or other
gases in the
environment.
[0058] In one embodiment of any of the detection systems described herein, the
secondary gas
sensor is a MO x or Pellistor based sensor (e.g., for the detection of
hydrocarbons).
[0059] The pressure sensor 112 detects the gas pressure levels in the void
space of the battery
enclosure. Nominal air pressure within the enclosure approximates atmospheric
pressure.
During thermal runaway venting, the pressure may rise abruptly if the venting
phase is highly
energetic, as in the case of a cell that is at 100 percent state of charge as
shown in FIG. 6. But
the initial accompanying pressure rise may also be very low, especially in the
case of smaller
cells or cells whose state of charge is much lower, as shown in FIG. 8. While
there is dependence
on the enclosure venting system, an increase in gas pressure or temperature
can provide
information on the rate of thermal runaway. The pressure sensor 112 is small
and low cost, has a
13
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
fast time response with low power consumption, but has been shown to provide
poor data during
slow venting phenomenon where the battery enclosure venting system allows
release of the
trapped gas at a rate that offsets gas generation. When used to supplement the
gas sensor 110,
however, the pressure sensor 112 can provide valuable insight as to the
progression of the
.. thermal runaway as it cascades from the initiation cell to adjacent cells
within the enclosure, as
shown in FIG. 6, where the consecutive increases in hydrogen gas concentration
and
accompanying pressure spikes indicate that the thermal runaway has progressed
to additional
cells, leading to cascade failure of the pack.
[0060] The temperature sensor 116 detects the temperature within the enclosure
void space, and
like the pressure sensor 112, can be used in conjunction with the gas sensor
110 to estimate the
rate of progression of the thermal runaway (FIG. 6). Progressive increases in
temperature that
accompany each successive cell thermal runaway provide critical data in
determining if the
reaction has stopped or is progressing at such a rate as to require immediate
safety measures,
such as providing protective countermeasures including, but not limited to,
introduction of water
.. or extinguishing agents, aggressive cooling, introduction of dilution air
or nitrogen, and the
electrical isolation or discharge of suspect cells.
[0061] In one embodiment, the temperature sensor 116 detects temperatures in
the range of from
about 100 C to about 1200 C, such as from about 600 C to about 1000 C.
[0062] The relative humidity sensor 114 monitors the humidity within the void
space of the
enclosure and can also be used in conjunction with the gas sensor 110 to
observe substantial
changes in water vapor within the enclosure indicative of the formation of
water vapor due to the
decomposition reaction products.
14
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0063] The detection system 100 can be utilized for a variety of suitable
applications. In the
embodiment shown in FIGS. 2(a), 3, the detection system 100 is implemented in
a vehicle
having a battery enclosure, a power distribution unit, and a battery
controller and/or Motor
Control Unit (MCU). The battery enclosure can be made up of a plurality of
battery cells and
housed inside a battery enclosure.
[0064] The sensors 110-116 each output a sensed signal to a processing device,
such as the
microcontroller 118. The microcontroller 118 converts the analog sensor signal
to engineering
values and transmits that data, such as in the form of an alarm signal or
output signal, to the
Battery Management System via a wired or wireless transceiver 122. The
microcontroller 118
can also determine if the values from the sensors 110-116 exceed a critical
threshold value for
that sensor to indicate cell venting as well as provide algorithms to
determine if the sensors 110-
116 are operating normally and within specifications. The detection system 100
may utilize
redundant sensors 110-116 to meet Safety Index Levels.
[0065] One or more of the sensors 110-116 are located in a free space within
the battery
enclosure (FIG. 3) of the vehicle, so that the sensors 110-116 are in
communication (e.g., gas or
pressure communication) with the air space proximate to the batteries and/or
battery
compartment and receive and detect the conditions resulting from a battery
cell venting. The
sensors 110-116 provide the output to the processing device 118, which can
determine if the
sensed condition exceeds a predetermined threshold (i.e., the threshold which,
if exceeded,
signals that a thermal runaway based cell venting has initiated) or if there
is a rapid change in the
sensed condition. The entire system 100, including the sensors 110-116,
microcontroller 118,
regulator 120, and transceiver 122, can all be housed in a single sensor
housing and positioned at
one location in the battery compartment. In another embodiment, the system 100
can be separate
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
devices each with their own housing and each housing positioned at separate
locations in the
battery compartment, including surface mounted on the battery management
system electronics.
[0066] As shown and described, the detection system addresses the problem of
robust detection
of thermal runaway in lithium ion batteries, where the outgassing precursor to
thermal runaway
can occur in timespans of seconds or hours. The detection system measures
multiple physical
parameters of the outgassing event that can allow detection of rapid thermal
runaway as well as
slower events. The multiple detection technology reduces the risk of false
positive and missed
detection errors and provides sufficient redundancy to meet market safety
requirements. The
system measures, at a minimum, hydrogen and/or carbon dioxide concentration,
and may be
supplemented with air pressure and or temperature and humidity in the
enclosure.
[0067] In other variants, the detection system could also include hydrocarbon
detection of the
electrolyte, including methane, esters, and ethane gases. During the initial
cell venting that
precedes thermal runaway, vented gases include Hz, CO, CO2, and hydrocarbons
in sufficient
concentration to be detected by the individual sensors. By combining them into
a single sensor
platform with signal conditioning and analysis, it is possible to determine
with relative certainty
that the event is a single cell undergoing thermal runaway, and by monitoring
the gases
simultaneously, determine the difference between less urgent electrolyte
leakage and more
urgent thermal runaway condition. The use of the principle of thermal
conductivity for hydrogen
and non-dispersive Infrared measurement of CO2 sensor are robust, absolute
measurement
devices that have limited cross sensitivity to other gases, making them ideal
for this application
where there is little or no opportunity to recalibrate or service the devices
in the field.
[0068] Referring more specifically to FIG 6, an example runaway is shown. In
this illustrative
example, the thermal runaway cascades from one cell to adjacent cells.
Starting at T=0, the
16
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
battery system is operating under normal conditions, and the hydrogen level
150, temperature
160, and pressure 170 are all normal. At a first time period, T=1, a first
single battery cell of a
first battery module experiences thermal runaway. As a result, it releases a
gas, here Hydrogen.
The hydrogen sensor of the gas detector 110 measures the hydrogen level, and
has a sensed gas
level output. It transmits the sensed gas level output to the microcontroller
118. In addition, the
pressure sensor 112, detects the pressure, and has a sensed pressure output.
It then transmits the
sensed pressure output to the microcontroller 118. Further, the temperature
sensor 116 measures
the temperature in the enclosure, and provides a sensed temperature output. It
transmits the
sensed temperature output to the microcontroller 118.
[0069] The sensors 110-116 immediately send the sensed outputs to the
microcontroller 118 in
real time without delay or manual intervention. The sensors 110-116 can send
sensed outputs to
the microcontroller 118 continuously or at intermittent random or
predetermined periods (such as
several times a second).
[0070] In the example embodiment of FIG. 6, a cascading thermal runaway event
is shown
propagating through pack enclosures where initial cell triggers thermal
runaway in adjacent cells.
The microcontroller 118 receives a sensed gas, pressure and temperature
outputs from the gas,
pressure and temperature sensors 110, 112, 116, respectively. At T=1, the
hydrogen gas level
150 and pressure 170 both exhibit a spike. However, the temperature 160 only
increases slightly.
The venting in the battery enclosure enables the pressure 170 to quickly
dissipate back to normal
levels, though the Hydrogen vents more slowly and stays at an elevated level.
Based on these
conditions and receipt of the sensed outputs, the microcontroller 118
determines that at least a
first battery cell has experienced a thermal runaway event, and generates an
alarm signal that it
sends to the battery controller. The battery controller, in response, might
for example take a first
17
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
response, such as to indicate to the operator that service is needed, to
reduce the voltage
requirements for the battery module, or to control the battery so that it does
not get as hot.
[0071] At T=2 in the example embodiment of FIG. 6, another cell experiences a
thermal
runaway. Here, the microprocessor 118 determines, based on sensed outputs from
the gas sensor
150 and pressure sensor 160, that there is another spike in gas and pressure,
respectively, and
that the temperature has again increased slightly. The pressure again returns
to normal rather
quickly due to venting conditions, but the temperature and hydrogen level
continue a rising
pattern. Accordingly, the microprocessor 118 determines that another thermal
runaway event has
occurred, and sends another alarm signal to the battery controller. The
battery controller can
continue to take the same response or can escalate the response such as by
shortening the alert
response time, for example by indicating that immediate service is needed, or
by turning off one
or more of the battery modules. The microcontroller 118 determines that there
are further spikes
at T=3, 4. The various levels of gas, temperature and pressure may vary based
on venting
conditions and the specific thermal runaway event. For example, following T=4,
the pressure
may decrease as the enclosure hydrophobic vents fail, though spikes occur with
each successive
cell thermal runaway event as additional cells fail within the enclosure. The
microcontroller 118
or battery controller can further determine that there is a cascading pattern
to the event and take
additional responsive actions. The responsive actions can be sent from the
battery controller to
the microcontroller 118 via the transceiver 122, which then controls operation
of the cells and
modules.
[0072] Turning to FIG. 7, another example thermal runaway event is shown.
Here, the system
100 has a gas sensor 110, here a Hydrogen sensor, and a pressure sensor 112.
At T=1, the
hydrogen concentration 150 rises immediately after initial vent, followed by a
slight pressure 170
18
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
increase at T=2 (one minute after T=1) within the enclosure as gas expansion
exceeds pack level
venting capability. Thus, at T=1, the microprocessor 118 generates an alert
that thermal runaway
has initiated. The pressure rise at T2 in FIG. 7 demonstrates the delayed
response of pressure
signal in this instance, wherein there exists hydrogen gas above the Lower
Exposure Limit at Ti,
yet the pressure does not substantially increase for over one minute.
[0073] Turning to FIG. 8, yet another example embodiment is shown. Here, the
gas detector 110
is a carbon dioxide sensor. The plot shows rapid carbon dioxide concentration
150 rise within the
enclosure, while pressure 170 remains the same and the temperature 160
exhibits a slight
increase. At T=2, the microcontroller 118 determines that a thermal runaway
has occurred, and
generates an alarm that it sends to the battery controller.
[0074] Thus, the microcontroller 118 uses the sensed outputs from the gas,
pressure, RH, and/or
temperature sensors 110, 112, 114, 116, respectively, to determine if there is
a thermal runaway
event or other condition within the battery enclosure. The microcontroller 118
can base that
determination on a single sensed output, or on a combination of sensed
outputs. For example, the
microcontroller 118 can determine based on the presence of a gas spike alone,
that a thermal
runaway might be occurring and then refer to the sensed pressure output and/or
the sensed
temperature output to determine if the thermal runaway event is cascading to
additional cells
throughout the pack by utilizing a combination of gas measurement to determine
initial thermal
runaway event and monitoring for increases in pressure or temperature to
assess the magnitude
of the event. Increasing temperature or pressure within the pack coincident
with high gas
concentration levels are indicative that countermeasures have not isolated the
event to a single
cell, and generate an alert escalating a response. For example, the initial
alert could be to notify
the vehicle owner to take the vehicle in for service as soon as possible, and
the escalating alert
19
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
could be to notify the vehicle occupants to bring the vehicle to the side of
the road, exit the
vehicle and the BMS would shut the vehicle down except for the heat exchanger
system to try to
slow the process down. However, if the temperature and pressure do not
increase, the
microcontroller 118 can determine that the thermal event has ceased and has
been isolated to a
single cell or group of cells, and not generate an alert escalating the
response. Thus, in the
example given, the alert would continue to notify the vehicle owner to have
the vehicle serviced.
[0075] It is noted that a microcontroller 118 is provided to receive the
sensed outputs, determine
spikes and send an alarm to the battery controller via the transceiver 122.
However, the
microcontroller operation can instead be performed by the battery controller
itself, and sensed
outputs can be transmitted, via the transceiver, to the battery controller.
And responsive action
signals can be sent directly from the battery controller to the cells, via the
transceiver 122.
[0076] Advantages of the detection system 100 include, for example, the use of
known, validated
and field proven sensor technology, leveraging a specific combination of
sensors to allow for
layering of the detection mechanisms related to chemical and thermal physics
of phenomena
associated with the thermal runaway event. The system requires little, if any
customization to be
suited for various xEV enclosure size/cell configuration/electrochemistry. The
system also has
very fast time response (generally 3 to 5 seconds) in an environment where
positive detection of
thermal runaway requires fast response with minimal risk of missed/false
detection. The system
is compact and can be operated in multiple modes for reduced parasitic power
consumption
when the battery enclosure is neither actively charging nor discharging. These
modes can be
controlled within the sensor assembly 100 utilizing information received from
the battery
Management system on active mode (either driving or charging, where fast
detection is critical
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
and power consumption less important, or in passive mode, where power
consumption is critical
and sampling rate can be reduced to reduce device power consumption.
[0077] The system and methods of the present invention include operation by
one or more
processing devices, including the microprocessor 118. It is noted that the
processing device can
be any suitable device, such as a processor, microprocessor, controller,
application specific
integrated circuit (ASIC), or the like. The processing devices can be used in
combination with
other suitable components, such as a display device, memory or storage device,
input device
(touchscreen), wireless module (for RF, Bluetooth, infrared, WiFi, etc.). The
information may be
stored on a computer medium such as a computer hard drive, or on any other
appropriate data
storage device, which can be located at or in communication with the
processing device. The
entire process is conducted automatically by the processing device, and
without any manual
interaction. Accordingly, unless indicated otherwise the process can occur
substantially in real-
time without any delays or manual action.
[0078] In another aspect, the present disclosure relates to a method of
detecting thermal runaway
of a battery (e.g., detecting thermal runaway of one or more battery cells)
within an enclosure.
[0079] In one embodiment, the method comprises:
(i) providing a detection system according to any of the embodiments
described
herein within the battery enclosure;
(ii) measuring and/or analyzing one or more gases venting from the battery;
(iii) determining if the analyzed gas levels are at or above a
predetermined threshold
level that indicates thermal runaway of the battery.
[0080] In one embodiment, the gases analyzed comprise hydrogen, carbon
monoxide, carbon
dioxide, or any combination thereof.
21
CA 03195366 2023-03-14
WO 2022/060845
PCT/US2021/050471
[0081] In one embodiment, any of the detection systems and/or methods
described herein do not
i) receive a sensor signal, ii) evaluate the sensor signal relative to a
threshold, or iii) generate an
alert based on a result of the evaluation, or any combination of the
foregoing.
[0082] In another embodiment, any of the detection systems and/or methods
described herein do
not monitor an ambient gas in an ambient gas environment.
[0083] It will be apparent to those skilled in the art having the benefit of
the teachings presented
in the foregoing descriptions and the associated drawings that modifications,
combinations, sub-
combinations, and variations can be made without departing from the spirit or
scope of this
disclosure. Likewise, the various examples described may be used individually
or in combination
with other examples. Those skilled in the art will appreciate various
combinations of examples
not specifically described or illustrated herein that are still within the
scope of this disclosure. In
this respect, it is to be understood that the disclosure is not limited to the
specific examples set
forth and the examples of the disclosure are intended to be illustrative, not
limiting.
[0084] As used in this specification and the appended claims, the singular
forms "a", "an" and
"the" include plural referents, unless the context clearly dictates otherwise.
Similarly, the
adjective "another," when used to introduce an element, is intended to mean
one or more
elements. The terms "comprising," "including," "having" and similar terms are
intended to be
inclusive such that there may be additional elements other than the listed
elements.
[0085] Additionally, where a method described above or a method claim below
does not
explicitly require an order to be followed by its steps or an order is
otherwise not required based
on the description or claim language, it is not intended that any particular
order be inferred.
Likewise, where a method claim below does not explicitly recite a step
mentioned in the
description above, it should not be assumed that the step is required by the
claim.
22
