Effect of Connector Temperature Rise on Lithium Battery Performance


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At present, in the field of energy storage, the application and development of lithium batteries are very rapid. The energy storage of lithium batteries has the advantages of high energy density, long service life and green environment protection. However, there are also some disadvantages, such as high production cost, poor safety performance and the risk of explosion. Therefore, the safety design of thermal management system should be applied to lithium batteries. It is very important to use connectors as indispensable components in series and parallel connection between batteries. Its temperature rise effect has a great impact on the whole lithium battery energy storage system. Therefore, low temperature rise design has become an inevitable trend in the development of connectors.
In the energy storage system of lithium batteries, the temperature sensitivity of lithium batteries is mainly due to the temperature sensitivity of their physical and chemical properties. Temperature will directly affect the activity and conductivity of electrode materials, the insertion and de-insertion of lithium ions on the electrode, and the permeability of lithium ions in the diaphragm, thus affecting the electrochemical reactions inside the battery, and its external performance is the temperature sensitivity of the power battery. Because the power battery has a suitable working temperature range, the higher the activity of the active substance in the battery, the higher the charge-discharge voltage and capacity of the battery, the smaller the internal resistance of the battery, and the higher the charge-discharge efficiency of the power battery. However, when the temperature exceeds a certain range, excessive temperature will accelerate the internal side reactions of the battery, which consume lithium ions, solvents and electrolytes, leading to the degradation of battery performance. The results show that the cycle life of the battery decreases significantly when the battery continues to work above 45 C, especially when the battery is charged and discharged at a high rate. Therefore, if working in high temperature environment for a long time, the life of power battery will be significantly shortened, its performance will be greatly reduced, and even lead to safety accidents. Similarly, when the temperature is too low, the activity of active substances in the battery decreases significantly, and the charging and discharging power and capacity decrease significantly with the increase of the internal group and polarization voltage, which even causes the irreversible decay of the battery capacity and buries potential safety hazards. Especially in the charging process, under the action of the electric field applied to the charging equipment, lithium ions are removed from the cathode material, enter the electrolyte and move to the negative electrode, then enter the negative material composed of graphite, and form LiC compound. If the temperature decreases and the charging speed is too fast, the lithium ion will not enter the negative pole to form LiC compound, then the lithium ion near the negative pole will capture electrons and form lithium dendrite, and the growth of lithium dendrite may puncture the diaphragm and form a short circuit.
In addition, the long-term non-uniform distribution of the temperature field inside the battery box will also cause the imbalance of the performance of each battery module and monomer, especially in the high temperature area, the aging rate of the battery will be significantly faster than that of the low temperature part, and the physical property difference between different batteries will be more obvious with the accumulation of time, thus making the difference between batteries more obvious. The poor consistency, even early failure, shortens the life of the whole power battery system.
Connector is a necessary component in series and parallel connection between battery packs. When battery packs are charged and discharged, the passage of large current will cause thermal effect of connector. When the temperature of connector rises above the temperature of battery pack, the temperature will be transmitted to the inside of battery, which will affect the stability of battery, so the connector will reach a low level. The characteristic of temperature rise becomes a necessary condition. The special connector for connecting energy storage adopts the terminal technology of independent intellectual property rights of the company, which keeps the contact surface between the terminal and the pin in the optimum area, effectively reduces the contact resistance, reduces the overcurrent density and reduces the current temperature rise. At the same time, the new appearance design will have more than one. The surface is designed as a corrugated fan, which improves the heat dissipation function. In addition, the metal material uses imported high-purity copper with high conductivity, stable overcurrent temperature rise, plastic material uses unique alloy material, which combines a variety of plastic characteristics, high strength and high toughness, meets the fire protection requirements, and has a high degree of resistance. In the connection technology of internal terminal and wire nose, FIRST patented technology is adopted to ensure the reliability of the connection, increase the contact area, and effectively reduce the temperature rise of overcurrent. At the same time, stable and solid multi-point pressing technology effectively reduces the temperature rise of the connection between wire nose and wire. The consistency of temperature rise is guaranteed. At present, the temperature rise test results of connectors with different current levels can be controlled below 35 degrees Celsius (ambient temperature 20 degrees Celsius).
Energy storage of lithium batteries is an inevitable trend in the development of the times. Safe and reliable operation of lithium batteries is the primary condition for the operation of energy storage system. As an indispensable part of energy storage of lithium batteries, high current connectors are always adhered to the product design concept of safety, reliability and environmental protection in Jiangsu Lianyou Electric Power Co., Ltd. Batteries provide dedicated electrical connector products.

2019-07-05 597People Browsing
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