As the positive electrode material of energy storage batteries, lithium iron phosphate(LFP) has great advantages in safety performance and cycle life, which are also one of the most important technical indicators of power batteries. LFP has good safety performance, long cycle life, high energy density, and is environmentally friendly. Compared with lead-acid batteries, which have low initial costs and high maintenance costs, lithium iron phosphate batteries have high initial costs, but low maintenance costs. Generally, household energy storage systems can maintain a good operating level with little manual maintenance.
But low maintenance cost is relative, no matter what type of battery, it is very sensitive. Especially in the process of using the battery, it is inevitable that there will be a loss. Due to the difference in the external environment and the way of use, the degree of this loss is also different. Through professional maintenance, the battery loss can be minimized, thereby prolonging the service life of the battery.
When using an LFP battery energy storage system, what are the specific points that need to be paid attention to? Below we list some points that need attention for the maintenance and maintenance of the energy storage system to help you extend the service life of the energy storage system as much as possible.
The operating temperature range of lithium iron phosphate battery is extensive (-20°C-75°C), but this does not mean that the working state of the battery at different temperatures within the interval is the same. Generally speaking, the ambient temperature of the energy storage system is kept at 15°C-35°C. At this temperature level, the battery can fully release the capacity while avoiding damage to the battery capacity.
The low-temperature performance of lithium iron phosphate batteries is poor. If lithium iron phosphate batteries work and charge and discharge in a low-temperature environment for a long time, metal lithium will be precipitated on the surface of the battery anode. This process is irreversible and will cause permanent damage to the battery capacity.
The discharge capacity of the lithium iron phosphate battery at a temperature of 0 to -20°C is equivalent to 88.05%, 65.52%, and 38.88% out of the discharge capacity at a temperature of 25°C, respectively. That is to say, as the temperature decreases, the average discharge voltage and discharge capacity of lithium-ion batteries decrease, and the lower the temperature, the more obvious the decrease.
Although the high-temperature performance of the lithium iron phosphate battery is very good, too high a temperature can easily cause corrosion inside the battery, which will also affect the working performance of the battery. Therefore, to keep the battery at a suitable working temperature, the installation location of the energy storage system is very important.
When a lithium battery is left unused, self-discharge, passivation of positive and negative electrode materials, and decomposition of electrolytes will occur due to the nature of the battery itself. However, the unstable SEI performance of the negative electrode will lead to the rapid decline of the negative electrode active material, and the precipitation of lithium metal is easy to occur, and this process is also irreversible.
For lithium iron phosphate batteries, over-discharging and over-charging will damage the battery's capacity. The way to use the lithium battery correctly is to charge it when the power is not enough, avoid recharging when the power is exhausted and avoid overcharging. Under normal circumstances, we recommend that you charge the device when the power is used below 20%.
Usually, the battery packs of our energy storage products are realized by connecting single cells in series and parallel. Due to its characteristics, the lithium battery pack has high requirements for the consistency of the monomers. As long as one of the batteries in a group is different from the other batteries, the overall effect will be greatly reduced. Similar to the principle of wooden barrels, inconsistent single batteries are used in series, and the life of the battery pack is always shorter than that of the shortest single battery.
Therefore, we do not recommend that you mix new and old batteries or different types of batteries. However, with the use of the battery, there will inevitably be inconsistencies between the individual batteries. At this time, it is necessary to balance the states of different batteries through equalization.
Some families place heavy objects on the energy storage battery for convenience. However, if the weight of the item is too high, mechanical deformations due to material penetration, crushing, and bending may occur in the long run. Mechanical deformation is also often one of the causes of thermal runaways, which can lead to fires. In addition, excessive external temperature, excessive charging and discharging, and internal circuit short circuits also usually easy to cause thermal runaway. So we have to eliminate the triggers at the outset.
In general, the service life of lithium batteries is mainly affected by two aspects, one is the external use conditions, and the other is the factors of the internal batteries.
From the perspective of external use conditions, the factors that affect the service life of lithium batteries mainly include charge and discharge methods, charge and discharge cut-off voltage, charge and discharge rate, use temperature, and storage conditions.
From the perspective of internal battery factors, the use of lithium batteries on ESS is often in the form of battery packs. Battery packs generally connect hundreds of battery cells in series and parallel. The consistency of the cells is another important factor affecting service life. The main performance is the inconsistency of parameters such as voltage, capacity, and internal resistance.
Therefore, after understanding the factors affecting the service life of lithium batteries, solving these problems can greatly improve the cycle life of lithium batteries, and the service life of lithium iron phosphate batteries with better maintenance can reach more than 10 years.