"There are three main words with relatively obvious distinguishing
characteristics for battery thermal runaway. This can be used for reference in
the safety of lithium-ion batteries in electric vehicles, namely leakage, fire,
and explosion. Leakage is not thermal runaway but a state that causes thermal
runaway, because It is dangerous."
——Li Mingming, chief technical engineer of Yantai Chuangwei New Energy
Technology Co., Ltd.
Focusing on "double innovation in technology application, a new starting
point for large-scale energy storage", it will accurately connect the global
energy storage market and the global energy storage market in multiple
dimensions by organizing keynote speeches, exhibitions, innovation competitions,
special seminars, project inspections, new product releases, technical exchanges
and other activities. The application helps Chinese energy storage companies
integrate with international standards and builds a communication and
interaction platform for energy storage companies with policy makers, planners,
grid managers, power companies, and energy service providers. From May 18 to 20,
2019, the Zhongguancun Energy Storage Industry Technology Alliance and the
Institute of Engineering Thermophysics of the Chinese Academy of Sciences held
the "ESIE 2019 Energy Storage International Summit and Exhibition", and the
entire event was broadcast live on the Polaris Energy Storage Network and the
Electric Power Toutiao APP.
Li Mingming, chief technical engineer of Yantai Chuangwei New Energy
Technology Co., Ltd.
Good afternoon, fellow experts! I am from Yantai, Shandong. The topic I
brought today is "Research on Application Technology of Thermal Runaway Early
Warning Based on Gas Phase Analysis." Mr. Tan has already introduced the safety
design in energy storage applications. I will be more specific, because fire
protection includes fire protection and prevention. I mainly analyze from the
perspective of prevention, how to analyze early thermal runaway warnings and
detect them as early as possible.
Our company is mainly engaged in new energy vehicles and energy storage
power stations. As long as battery-related safety facilities are involved, we
are committed to research. The company was rated as a high-tech enterprise last
year, achieving an annual growth rate of 100% every year, and currently uses
more than 300,000 sets of technology applications in electric vehicles. We are
engaged in the participation and formulation of standards for electric vehicles
and energy storage.
Let’s talk about it mainly from three levels:
Current status of first energy storage safety regulations,
Research on the second thermal runaway early warning,
The third energy storage system application plan.
1. The current status of energy storage safety regulations. I will only
make a brief introduction. There will be a forum this afternoon mainly talking
about regulations and the current status of standard formulation. Regulations
and current situation are mainly due to the current social influence caused by
fire accidents in power stations or fire accidents in electric vehicles. Based
on these, everyone pays more attention to operation and maintenance safety
during the operation and maintenance of energy storage power stations. What
method is more reliable and effective in operation and maintenance? For us, what
we are studying is the integrated fire protection operation strategy of
large-scale energy storage based on multi-factor analysis.
Fire accidents have been reported online, especially in 2018 when pure
electric vehicles caught fire. Recently, around May Day, more than ten electric
vehicle fire accidents have occurred continuously during this period, which has
also attracted widespread attention from the society. Once a fire accident
occurs, it will cause relatively serious consequences. This time is particularly
important for early warning and protection of thermal runaway of lithium-ion
batteries. The standards for automobiles are relatively sound, and many
standards have been issued. Regarding energy storage standards, various
localities are now drafting corresponding standards. For example, power grid
companies are also drafting their own safety implementation standards. These can
all be collected online.
There are three main words for battery thermal runaway that are more
clearly distinguishable. This can be used for reference in the safety of
lithium-ion batteries in electric vehicles. They are leakage, fire, and
explosion. Leakage is not thermal runaway but a state that causes thermal
runaway, because It is dangerous. This happens to many batteries during
operation. How is thermal runaway measured? An explanation is given in the
standard. Based on electric shock signals, these have corresponding standards.
For non-electric shock signals, we use the gas phase.
Research on thermal runaway early warning, what kind of technology is
currently used at home and abroad to achieve early warning of abnormal
conditions. There is a red and blue bar on it. If the ministries are handed over
between red and blue, when we are on the blue bar, this is what the BMS is
doing. It mainly measures electrical signals, voltage, current, and discharge
rate. Through it, we can more accurately measure the electrical signal, voltage,
current, and discharge rate. In the early stage of obtaining the normal
operating status, the red ministries may have experienced thermal runaway.
Thermal runaway has occurred or is in a thermal spread state. The resulting
action is burning or smoking, and continuous smoking. We can take a look at the
characteristics of this kind of battery combustion accident. First of all,
thermal runaway has a negative reaction that cannot be eradicated. Through a
variety of technologies, the electrolyte or improved separator, adding some
protective additives, or flame retardant resistance fluid can implement
comprehensive technological improvements.
Regarding the induction or spread of thermal runaway, from one monomer to
another monomer, it is a bit like a firecracker-like heat spread. How to prevent
thermal spread is a key topic we should study. Currently, many industries are
studying thermal insulation materials. Another characteristic of lithium-ion
batteries is that they have re-ignition properties. The re-ignition properties
are quite prominent. In an experiment done last week, the battery re-ignited
after 3 minutes. A large amount of water was used to extinguish the fire
later.
Based on these characteristics, if we can identify it through the change of
internal resistance in the blue bar area, lead-acid batteries use this method.
Currently, Professor Ouyang Minge of Tsinghua University has been committed to
research.
Many laboratories are studying gases. These foreign papers are relatively
early. Recently, there are several experimental centers in China, including
Zhongqiyan, which are also studying related thermal runaway gases. After
extracting the gas, the components are analyzed. At the same time, let’s take a
look at what kind of sensor applications can be configured for earlier
detection. These materials lead to the conclusion that they mainly contain
harmful gases such as carbon dioxide, carbon monoxide, and hydrogen. The
following is based on the experiments done by other colleagues at home and
abroad. We have built some platforms ourselves, mainly doing the following three
tasks: one is the selection rules of gas detectors and what kind of gas sensors
to choose; It is necessary to analyze the data in the development process and
make a data judgment, which is equivalent to a model. The third step is to build
an experimental platform.
Our work is qualitative. If thermal runaway occurs, what gases will be
released? We first need to know that this is a measurement of 5 gases including
oxygen and carbon monoxide. The conclusion is that carbon monoxide is
representative and ethylene is also representative. This is qualitative.
Quantitatively measure from 60 degrees Celsius to 100 degrees Celsius.
When we detect gas in a battery, we must encounter interfering gases, which
are nothing more than rubber and electrolyte. We need to remove these. Another
one is that hydrogen is added to the energy storage power station. At the same
time, the rising curves of carbon monoxide and hydrogen are very consistent. At
the highest level, hydrogen reaches 17,000PPM, so there is a problem of
cross-infection, but it is still necessary to use it in space. Because its mass
is higher than that of hydrogen, it floats easily. This is a comparison of total
VOC gas data.
The conclusions drawn after completing these experiments should be suitable
for early detection of composite sensors. In this case, it is necessary to
perform appropriate data fitting on this data, make effective judgments, and
smooth the data.
What we do: sensor calibration, intelligent algorithms, high durability,
etc. The whole protection, early thermal runaway and early warning, and finally
there is an external interface. This is an example of the system we made. This
is each battery pack. The battery pack uses a detector. For the energy storage
power station, the method we use is to recommend each battery cluster and
battery cabinet as well as the space and outside of the container. Fire
protection interface provides final protection. Finally, reserve rain-type fire
sprinklers. This is a schematic picture of what we did. This is a state that is
linked to water fire protection. Because you need water, you need to link it.
However, water fire protection should be used with caution. It is best to start
it manually instead of letting it start by itself. This is a project we have
done ourselves, and we have done more of it in recent years. This is the
situation of some of the projects we have done. These are all on the grid side,
and we were distributing seven pentane propane. This is from Hunan Power Grid.
The main control room is here. On the left are 24 containers. This is the
operating status. This is a small wind power or solar power generation device we
made. It uses heptafluoropropane or is suspended. The picture at the back is
more interesting. The picture on the right shows that the cabinet type has been
changed to a pipe network type. It is currently If the wind circulates, there is
wind speed. In this case, if it is discharged in the overall space, it may not
be effectively transported to the battery. Through this kind of pipe, we can
send it to the channel to effectively treat the battery core. protection.
We are currently used in many vehicles and in the energy storage industry.
We are currently doing transitional research on lithium iron phosphate batteries
and ternary batteries. In the future, ternary batteries will be used in more
passenger cars. We have done model analysis to get the protection requirements.
Strategy.
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