The main components of an electrochemical cell (the basic components of a battery) are the anode, cathode, and electrolyte. The main focus of a battery is the electrolyte and cathode. Organic carbonates are commonly used as electrolytes and are susceptible to decomposition reactions. These reactions involve the breakdown of molecules, producing two or more compounds.
These reactions are often exothermic and release energy in the process, further promoting the decomposition of compounds, creating a chain reaction known as thermal runaway. In the case of electrolyte decomposition, the result of the reaction is usually gases, some of which may be flammable. Decomposition reactions in batteries are often evidenced by damage to the structural integrity of the battery itself.The cathode, on the other hand, usually consists of a metal oxide such as LiCoO2. These metal oxides decompose when exposed to high temperatures, such as those caused by thermal runaway.
The results of this decomposition will be metals and oxygen.This is the main problem with lithium-ion batteries. The combination of flammable gases and oxygen and the additional heat provided can cause fires and battery explosions.The separator is another component of the battery that is susceptible to thermal hazards. The separator is designed to act as a physical barrier between the anode and cathode in the event of a battery failure, preventing a short circuit event.
However, most separators today are made of polymers, which in some cases melt or shrink at high temperatures. If this happens, thermal runaway may occur.solutionAdiabatic calorimeters are designed to prevent heat exchange between the battery and its surrounding environment. Batteries experience changing conditions during their service life, including heating and cooling. It is critical to understand how battery components perform under different temperatures and environments and whether they are susceptible to thermal runaway. An adiabatic calorimeter simulates the worst-case scenario where the battery is unable to dissipate heat while operating. The BTC-130 is a benchtop adiabatic calorimeter designed for component and cell testing including thermal, electrical and mechanical stress. Using the BTC- 130, you can evaluate battery pack safety performance, safe operating limits, and the consequences of thermal runaway.Superior battery
How to develop batteries with superior performance?
Calorimetry is an important tool in helping build better batteries, including thermally stable cells, higher energy density, shorter charge times and longer run times. In the previous section, we described how different components of a battery are susceptible to failure due to thermal hazards. However, a battery is more than just its basic components or sub-components, and interactions between them can exacerbate problems such as thermal runaway, but also help mitigate their consequences.The electrolyte and cathode in lithium-ion batteries are the components most susceptible to damage from thermal hazards. We can use calorimetry to predict the temperature at which thermal runaway is likely to occur, which can be demonstrated by a sudden increase in temperature. Processes such as charging/discharging will increase battery temperature and trigger decomposition reactions.
The accumulation of energy from the decomposition of the electrolyte increases the temperature, triggering the decomposition temperature of the cathode. The result of this decomposition is oxygen, which reacts with the flammable gases that accumulate in the battery, potentially causing fires and explosions.Additionally, when developing batteries, additional elements such as separators can be placed to prevent thermal runaway. Separators are usually composed of polymers with holes in their structure, allowing ion transport. Separators are designed to close these pores at high temperatures, preventing chemical reactions.
However, the separator can also fail and may shrink at high temperatures, allowing ions to move and cause a short circuit. Calorimetry can help understand how much energy can be released by a decomposition reaction, the temperatures required to trigger secondary runaway reactions, and the consequences of the process. The results of this analysis will determine the safe value at which the battery can operate.Designing thermal management systemsCalorimetric data can guide the design of battery thermal management systems.
Components such as heat sinks, cooling fans, and other cooling strategies are critical to maintaining optimal operating temperatures, improving performance, extending service life, and preventing hazardous situations.Solid Electrolyte Interface (SEI)SEI plays a critical role in the safety, performance and operation of lithium-ion batteries. SEI is a thin layer that forms on the metal surfacee anode during the initial charge cycle of the battery. It is the result of the interaction between the electrolyte and the anode and consists of lithium salts dissolved in organic solvents.The SEI acts as a physical barrier between the anode and electrolyte, insulating yet ionically conducting. Because it prevents further physical contact between the electrolyte and anode, it prevents allowing further degradation of the latter, lithium to move.
However, over long periods of time and through continuous charge/discharge cycles, its capacity may weaken, causing the battery to lose its ability to hold a charge. In addition, it increases internal resistance, resulting in reduced charging and discharging efficiency and increased temperature.Accelerated aging testBattery performance degrades over time due to many processes, such as SEI formation and growth, progressive degradation of the electrolyte, partial dissolution of the electrode in the electrolyte, and increased internal resistance. Understanding these processes is critical to predicting battery life and the consequences of using older batteries. When using accelerated aging testing, the battery is exposed to harsh conditions, simulating long-term use over a shorter time frame. The thermal response of a battery can provide insight into how its performance and safety properties change.
Battery failure testThe formation of a low-resistance current path between the electrodes can cause a short circuit, which can lead to rapid battery discharge, overheating, and potential fire. At the battery level, this process can occur under a variety of circumstances, such as separator rupture or lithium dendrite formation. This happens when the battery is charged too quickly or is exposed to cold temperatures. Lithium ions can be deposited to form a spiked structure that can grow by separation, creating a conductive path between the anode and cathode. Destructive testing allows for irreversible physical damage to the battery, such as punctures, to simulate these
processes.solutionSuperior attributes can refer to a battery performing better under safer conditions, or it can refer to a battery’s ability to withstand harsher conditions.There are some key points when developing new batteries: greater energy storage, long-term charging stability and discharge process HEL’s iso-BTC is an isothermal calorimeter designed to characterize batteries under normal and long-term efficient use conditions unit. iso-BTC supports the integration of charge/discharge cells, allowing the battery cells to automatically repeat cycles while recording electrical performance and heat generated.The BTC-130 and BTC-500 are powerful tools for testing battery behavior beyond safe limits.
Both BTC systems are fully integrated with the charge and discharge unit and support electrical stress testing, including external short circuits. Using adiabatic calorimetry, the BTC-130 and BTC-500 can help evaluate the thermal stability of batteries and characterize thermal events. Additionally, the BTC-500 can be equipped with a range of piercing tools and cameras to characterize physical damage events.
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