Lithium battery internal micro-short-circuit hazard control must be from the single battery design, material selection, environmental process control and many other aspects to prevent internal micro-short circuit. Furthermore, in order to minimize the influence of the internal short-circuit of the single-cell battery, the chain reaction does not occur, and the following problems must be noted in the design of the battery pack.
1. Single battery overheat isolation device
Single battery overheat isolation device can occur in the single-cell internal short-circuit or external shocks play a role in isolation, to stop the failure of the battery pack on the battery charge / forced overdischarge effect and to prevent failure of single cell high temperature, flame, explosive caused by the adjacent unit cell interlocking, which play a blocking role.
2. Single cell connection measures
Electrical connections (eg, wires, nickel straps, setscrews) in the battery pack can cause local resistance to be too high, resulting in high temperatures in the area of the drop-off point and causing internal shorts in adjacent cell cells.
3. Minimize the energy of the single cell
Generally, the greater the energy of single cells, the number of groups of parallel and serial number of batteries less, the higher the reliability, which is from the parallel and parallel group reliability analysis is correct. However, if the single battery energy is too large, once out of control after the battery pack on the destructive power of the greater, in principle, the more likely to produce a chain reaction of the entire battery, resulting in uncontrollable situation. Therefore, it is important to select the proper cell energy design.
4. Single cell battery series and parallel methods
Single battery series and parallel and the number of single-cell have a great impact on short-circuit and chain reaction. For example, Series cells easily lead to a mandatory discharge, the parallel likely to cause a single cell forced charging, may cause the single cell internal pressure, current is too large, thus forming an internal short circuit.
This requires more research and improvement on the consistency of the single cell and the symmetry design of the battery pack.
5. Temperature control system
Need to use the temperature control system to control the single cell, battery pack temperature in a safe range to ensure safety. Temperature monitoring system, forced air cooling, water cooling, oil cooling have been examples of applications, and to gradually appear in the corresponding standards.