Now, with the energy crisis and environmental pollution, as the most ideal energy, lithium-ion battery are getting a lot of attention. However, there are some failure phenomena occur in the process of production, transportation, and use of lithium-ion battery. The failure is caused by a series of complex chemical and physical interactions within the battery. Correct analysis and understanding of failure phenomena plays an important role in improving the performance and technology of lithium-ion batteries. It mainly analyzes from internal and external cause.
Internal Causes
Reduced Capacity
The reduced capacity of ion battery is mainly divided into two categories: reversible reduced capacity and irreversible reduced capacity. Reversible reduced capacity can recover the lost capacity by adjusting the battery charging and discharging system and improving the battery using condition. However, irreversible reduced capacity means that irreversible changes occur inside the battery, resulting in irreversible capacity loss. The failure of battery reduced capacity is the failure of materials, and it is closely related to the battery manufacturing process and the battery environment. From the material, main reasons for the failure are the structural failure of the anode material, the SEI transition growth on the cathode surface, the decomposition and deterioration of the electrolyte, the corrosion of the collecting fluid, and the trace impurities of the system and so on.
Increased Internal Resistance
The internal resistance of lithium-ion battery is related to the process of electron transport in the battery system, which is mainly divided into ohmic resistance and polarization internal resistance. Among them, the polarization internal resistance is mainly caused by electrochemical polarization, which consists of electrochemical polarization and concentration polarization. Key materials of batteries and the environment used increase internal resistance of lithium-ion batteries. Que Yongchun from the university of Science and Technology of China used synchrotron radiation technology to propose that the jumping mechanism of transition elements was the reason of potential lag and voltage attenuation, and explained that in the battery system, the abnormal key materials were the fundamental factors affecting the increase of internal resistance and the polarization of the batteries.
Internal Short Circuit
Short circuit performance can be divided into: copper / aluminum collector between the short circuit. Diaphragm failure loss of electronic insulation or gap change to the positive and negative micro contact, local heating serious, and then further charge and discharge process, may spread to the four sides, forming thermal control. The transition metal impurity in the positive electrode paste is not removed, which pierces the membrane or promotes the formation of lithium dendrite in the negative electrode, resulting in internal short circuit. Lithium dendrites lead to the occurrence of internal short circuit. In addition, in the process of battery design and manufacturing or battery pack assembly, unreasonable design and excessive local pressure will also lead to internal short circuit. For example, the South Korean media SBS reported that the cause of the fire and explosion of Samsung Note 7 pointed out that the positive and negative contact caused by the internal extrusion led to the internal short circuit, which then caused the thermal runaway of the battery. Under the induction of overcharge and over discharge of the battery, there will also be internal short circuit, mainly due to the corrosion of the collecting fluid and deposition on the surface of the electrode. In serious cases, the positive and negative electrodes will be connected through the membrane.
External Causes
- Strike
- Prod
- Corrosion
- High temperature burning
- Man-made destruction
How to Extend the Life of Lithium Batteries?
1. Avoid exposing to high or low temperature, especially while charging.
If the battery gets hot while charging, remove it. Also, avoid charging in very cold condition which can accelerate battery aging. As a guide, do not charge when the temperature is over 35C or below 10C.
2. Avoid charging too much or too little.
Ideally, the battery pack should not be charged over 80 percent or discharged below to 20 percent while storing. Excessive charging and discharging will take pressure to the battery and degrade it. Before using, the battery pack can be charged fully, but use it at once.
3. Avoid fast charging and discharging
High currents charging faster than low currents, but it will degrade batteries more easily. So discharge rate is. Power-intensive application can shorten battery life.
4. Finally, avoid using or storing in humid condition, and avoid mechanical damage, such as puncture.