Shenzhen Dazheng Weiye Electronic Technology Co., Ltd.
Contact: Zhan Zhenyu
QQ: 1605140880, 416126808
Contact: Chen Yaye
Address: 4th Floor, Building 19, Area C, Nanlian Fangxing Technology Park, Longgang District, Shenzhen
The service environment of forklift lithium battery is also very important to its cycle life. Among them, ambient temperature is a very important factor. Low or high ambient temperature will affect the cycle life of lithium battery.
Chen studied such as C/LiCoO2 is lithium battery forklift in - 20 ℃ under the condition of charge and discharge performance. The results show that the discharge performance of the battery becomes worse at low temperature. The 0.2c discharge capacity is only 77% of the room temperature capacity, and the 1c discharge capacity is only 4% of the 0.2c discharge capacity. At low temperature, the charging time of constant voltage increases and the charging performance deteriorates obviously.
The main reasons for the reduced capacity of the forklift lithium battery at low temperature include: poor electrolyte conductivity, poor wetting and/or permeability of the membrane, slower migration of lithium ions, and slower charge transfer rate at the electrode/electrolyte interface, etc. . In addition, the impedance of the SEI film increases at low temperatures, slowing the flow of lithium ions through the electrode/electrolyte interface. The reason for the increase in impedance of SEI film is that it is easier for lithium ions to escape from the negative electrode at low temperature and more difficult to embed. When charging, the lithium metal will appear and react with the electrolyte to form a new SEI film covering the original SEI film, which increases the impedance of the battery and thus leads to the decrease of the battery capacity.
Lian-xing etc.  the same batch of lithium battery in 60 ℃ and room temperature to 300 times charging and discharging cycle experiment. The initial stage, 60 ℃ under the condition of battery showed higher discharge capacity. However, with the progress of the cycle, the battery capacity attenuation is accelerated and the cycle stability is reduced. The charging and discharging cycle of the forklift lithium battery is unstable under high temperature. The high temperature leads to the intensification of the electrochemical polarization of the battery electrode and the generation of gas, resulting in swelling phenomenon. At the same time, the charge transmission resistance increases, and the dynamic performance of ion transmission decreases.
At present, most of the forklift lithium batteries use LiPF6 as the electrolyte. Due to the impure electrolyte or the catalytic decomposition of conductive salt by trace water, the electrolyte contains HF, a certain acid substance. HF will react with the main components of SEI film, such as ROLi and ROCO2Li, to generate LiF deposition on the negative electrode surface. SEI membranes containing LiF block the migration of lithium ions. At the same time, the resulting high impedance material insulates the graphite particles from each other. With the progress of high temperature charge and discharge, the negative electrode performance will gradually deteriorate and eventually lead to battery failure.
Equipment using forklift lithium batteries may be subjected to vibration, shock, impact and other conditions during transportation or normal operation. Some lithium batteries charge and discharge when communicating with the system and receive data information according to a certain frequency. The frequency of equipment vibration may interfere with the battery frequency, which may lead to errors in chip data or lead to protection circuit action. Under strong vibration or impact, the pole ears, external wires, terminals and solder joints of the forklift lithium battery may break or fall off, and the active substances on the battery pole may also peel off, which will affect the battery life and even produce dangerous situations.