How to improve the safety in lithium battery storage system？
Lithium batteries have become the industry standard for rechargeable storage devices. Lithium battery fires and accidents are on the rise and present risks that can be mitigated if the technology is well understood. Lithium batteries have higher energy densities than legacy batteries (up to 100 times higher). They are grouped into two general categories: primary and secondary batteries. Primary (non-rechargeable) lithium batteries are comprised of single-use cells containing metallic lithium anodes.
Non-rechargeable batteries are referred to throughout the industry as“Lithium”batteries.Secondary (rechargeable) lithium batteries are comprised of rechargeable cells containing an intercalated lithium compound for the anode and cathode. Rechargeable lithium-ion batteries, also known as LiFePO4 batteries, are widely used in energy storage systems. Single lithium-ion batteries (also referred to as cells) have an operating voltage (V) that ranges from 2.88–3.65V. LiFePO4 move from the anode to the cathode during discharge. The ions reverse direction during charging. LiFePO4 batteries have electrolytes that are typically a mixture of organic carbonates such as ethylene carbonate or diethy carbonate. The flammability characteristics (flashpoint) of common carbonates used in lithium-ion batteries vary from 18 to 145 degrees C.
How can the safety of lithium-ion batteries be improved?
Improving the safety of lithium-ion batteries is essential, given the fire hazards associated with their high energy densities and flammable organic electrolytes. This creates new challenges for use, storage, and handling. Physical damage, electrical abuse, and exposure to elevated temperatures can all cause thermal runaway, a severe and difficult to extinguish event.
The construction of the battery can also play a role in the severity of a fire incident. Lithium iron phosphate (LiFePO4) batteries, for example, are generally considered to be safer than lithium nickel cobalt manganese oxide (NMC) batteries because they are less likely to undergo thermal runaway.
The severity of a lithium-ion battery fire is also affected by a number of other factors, including the size of the battery, its chemistry, and its state of charge (SOC). The products of a lithium-ion battery fire are typically flammable gases, such as carbon dioxide, carbon monoxide, hydrogen, and hydrocarbons. These gases pose a fire and explosion risk. In Europe, two necessary tests for lithium-ion batteries are IEC 62619 and IEC 62610.
Best practices for storing and using LiFePO4 battery pack or unit
There are two ways for the Best practices for storing and using LiFePO4 battery pack or unit
LiFePO4 battery Storage
Store LifePO4 batteries away from combustible materials.
Remove batteries from the device for long-term storage.
Store the batteries at temperatures between 5°C and 20°C (41°F and 68°F).
Separate fresh and depleted cells (or keep a log).
If practical, store batteries in a metal storage cabinets.
Avoid bulk-storage in non- dangerous warehouse areas such as offices 、home.
Visually inspect lifepo4 battery storage areas at least weekly.
Charge lifepo4 batteries in storage to approximately 50% of capacity at least once every six months.
LiFePO4 battery Procurement
Purchase LifePO4 battery from a reputable manufacturer or supplier.
Avoid batteries shipped without protective LifePO4 battery packaging (hard plastic or equal).
Inspect batteries upon receipt and safely dispose of damaged batteries.
What are the safety considerations for storing and using LiFePO4 battery cells?
There are some safety considerations for storing or using lifepo4 batteries for you.
Never charge a primary battery; store one-time use batteries separately.
Charge or discharge the lifepo4 battery to approximately 50% of capacity before long-term storage.
Use chargers or charging methods designed to charge in a safe manner cells or battery packs at the specified parameters.
Disconnect batteries immediately if, during operation or charging, they emit an unusual smell, develop heat, change shape/geometry, or behave abnormally. Dispose of the batteries.
Remove cells and pack from chargers promptly after charging is complete. Do not use the charger as a storage location.
Charge and store batteries in a fire-retardant container like a high quality LiPo Sack when practical. Do not parallel charge batteries of varying age and charge status; chargers cannot monitor the current of individual cells and initial voltage balancing can lead to high amperage, battery damage, and heat generation. Check voltage before parallel charging; all batteries should be within 0.5 Volts of each other.
Do not overcharge (over-charge greater than 4.2V for most batteries) or over-discharge (over discharge below 3V) batteries.
Improving the safety of lithium-ion batteries in applications
Here are some applications of improving the safety of lifepo4 batteries. To help keep yourself and others safe, follow these tips when handling and using lithium-ion batteries in research and experimental applications:
Be careful not to damage the battery casing or connections.
Keep batteries away from conductive materials, water, seawater, strong oxidizers, and strong acids.
Do not place batteries in direct sunlight, on hot surfaces, or in hot locations.
Inspect batteries for signs of damage before use. If a battery is damaged or puffy, do not use it. Dispose of it properly.
Keep all flammable materials away from the operating area.
Allow batteries to cool before charging or using them.
Consider using batteries with soft casings and vents. You may also want to consider using protective shielding to prevent accidental contact with the battery.
Be aware of the specific hazards associated with the type of research or experiments that you are conducting. For example, if you are working with high-power batteries or batteries that are being used in extreme conditions, you may need to take additional safety precautions.
Have a plan in place in case of an accident. This plan should include procedures for extinguishing fires, evacuating the area, and seeking medical attention.
What are the unique safety challenges associated with using lithium-ion batteries in research and experimental settings?
Lithium-ion batteries system design is a highly interdisciplinary topic that requires qualified designers.
Best practices outlined in Europe standard such as ICE , IEEE , TUV , VDE should be followed.
Lithium battery system designs should include a hazard assessment that identifies health, physical and environmental hazards, with all hazards appropriately mitigated through engineering and administrative controls. Examples of baseline criteria for system design include:
Failure scenarios, including thermal runaway should be considered during design and testing so that a failure is not catastrophic.
Maintain cells at manufacturers recommended operating temperatures during charging or discharging.
Size/specify battery packs and chargers to limit the charge rate and discharge current of the battery during use to 50% of the rated value (or less).
Practice electrical safety procedures for high capacity battery packs (50V or greater) that present electrical shock and arc hazards. Use personal protective equipment (PPE) and insulate or protect exposed conductors and terminals.
How does a BMS protect a lithium battery from overheating or catching fire?
The lithium battery is protected by BMS， the logic is when BMS detect over voltage, over current , or high temperature etc. It will cut off the circuit. The is the main method to avoid bad happens.
For the safety concern, we have added one small module inside battery please see picture , it can detect high temperature or fire happens, it release the gas and this gas will become glue to attach the high temperature point(fire point) to insulate the oxygen to stop flame.
The lithium battery is protected by a BMS (battery management system). The BMS detects overvoltage, overcurrent, and high temperature, and cuts off the circuit to prevent the battery from overheating or catching fire.
To further improve safety, we have added a small module inside the battery. This module detects high temperature or fire, and releases a gas that forms a glue-like substance. This substance can then be used to attach the fire point and insulate the oxygen, which can help to stop the flame from spreading.
The BMS and thermal runaway stopper are important safety features that can help to prevent fires and other accidents involving lithium battery storage systems.
