Which lithium ion battery is best?

Ternary lithium ion battery

Ternary polymer lithium battery is a lithium ion battery that uses lithium nickel, cobalt and manganese ternary cathode material. There are many kinds of cathode materials of lithium ion battery, mainly lithium cobalt acid, lithium manganese, lithium nickel acid, ternary material, lithium iron phosphate and so on.

Ternary material combine the advantages of lithium cobalt, lithium nickel and lithium manganese with high capacity, low cost, good safety and other excellent characteristics, and gradually occupy a certain market share of lithium ion battery. And it has a good development prospect in the field of power lithium batteries.

Cobalt is essential for lithium ion battery. However, cobalt is expensive and toxic. Leading Japanese and Korean companies as well as Chinese battery manufacturers have been working to reduce cobalt in batteries in recent years. Under this trend, nickel-cobalt-lithium manganate ternary materials prepared from nickel salt, cobalt salt and manganese salt are gradually being promoted. From the perspective of chemical properties, ternary materials belong to excessive metal oxides, and the energy density of the battery is high.

Although the role of cobalt in ternary materials is still indispensable, the mass fraction is usually controlled at about 20%, and the cost is significantly reduced. It also has the advantages of lithium cobalt and lithium nickel. In recent years, with the increasing production, the trend of lithium ion battery with ternary material as the cathode material to replace the commercial lithium cobalt oxide has been very obvious.

From electric cars to smart phones, wearable devices or power banks, this new technology works perfectly.Tesla is the first to apply ternary lithium ion battery in electric vehicles. The driving range of Model S can reach 486 kilometers, and the battery capacity can reach 85kWh. 8142 Panasonic 18650 batteries of 3.4AH are used.

From a global perspective, the development and production of ternary materials are constantly advancing. In this process, material performance has been greatly improved, and the application field has been expanded again and again. Japanese and Korean enterprises are the leaders in the research and development of ternary lithium ion battery. Chinese ternary material production started from about 2005, so far there have been more than ten large-scale enterprises.

Lithium iron phosphate battery

Lithium iron phosphate has only emerged as a material for lithium power batteries in recent years, and the large-capacity lithium iron phosphate battery was developed in China in 2005. Its safety performance and cycle life are comparable to other materials, and these are also the most important technical indicators of power battery.

The cycle life of lithium iron phosphate battery with 1C charge and discharge can up to 2000 times.  If you overcharge the single 30V lithium iron phosphate battery, it does not burn, and it does not explode when punctured. Large capacity lithium ion battery made of lithium iron phosphate cathode material is easier to use in series to meet the needs of frequent charging and discharging of electric vehicles.

Lithium iron phosphate is an ideal cathode material for a new generation of lithium ion battery because of its advantages of non-toxic, pollution-free, good safety performance, wide source of raw materials, low price and long life. But lithium iron phosphate battery also has its disadvantages. For example, the vibration density of lithium iron phosphate cathode material is small, and the volume of lithium iron phosphate battery with equal capacity is larger than lithium cobalt acid and other lithium ion battery, so it does not have advantages in micro battery.

Due to the inherent characteristics of lithium iron phosphate, its low temperature performance is inferior to that of other positive materials such as lithium manganese acid. Under normal circumstances, for a single cell (note: we are talking about a single battery pack, not the battery pack. 

The measured low temperature performance may be slightly higher, which is related to the heat dissipation conditions), The capacity retention rate of it is about 60~70% when the temperature is 0℃, and 40~55% for-10℃, 20~40% for-20℃. Such low temperature performance obviously can not meet the requirements of power supply. At present, some manufacturers improve the low temperature performance of lithium iron phosphate by many methods such as improving the electrolytic liquid system, improving the cathode formula, improving the material performance and improving the cell structure design.

The battery has a consistency problem. The life of a single lithium iron phosphate battery is currently over 2,000 cycles, but that of battery pack will be significantly reduced, maybe 500 cycles. Because a battery pack consists of a large number of individual cells strung together, it works like a group of people running together on a rope.

Even if everyone is a good sprinter, if their movements are not consistent, the team will not run fast, and the overall speed will be even slower than that of the slowest individual runner. Similarly, battery life can approach that of a single battery only when the performance of the battery is highly consistent.

Manganese acid lithium ion battery

Manganese acid lithium is a promising one of lithium ion battery anode materials. Compared with the traditional anode materials such as cobalt acid lithium manganese acid lithium, it’s has some advantages such as rich resources, low cost, no pollution, high safety and good performance ratio and so on. It is the ideal power battery cathode material, but its poor circulation and electrochemical stability performance greatly limit its industrialization. Lithium manganate mainly includes spinel type lithium manganate and laminar structure lithium manganate in which spinel type lithium manganate structure is stable and easy to achieve industrial production. 

Now the market products are all use this kind of structure. Spinel type lithium manganate belongs to the cubic crystal system, Fd3m space group, theoretical specific capacity is 148mAh/g. Due to the three-dimensional tunnel structure, lithium ions can be reversively removed from the lattice of spinel,  and will not cause the collapse of the structure. So it has excellent rate performance and stability.

Nowadays, the traditional disadvantages of low energy density and poor cycling performance of lithium manganese have been greatly improved. Surface modification and doping can effectively modify its electrochemical properties, and surface modification can effectively inhibit the dissolution of manganese and the decomposition of electrolyte.

Doping can effectively inhibit Jahn-teller effect in the electrical processes of charge and discharge.The combination of surface modification and doping can undoubtedly further improve the electrochemical properties of the materials, and it is believed that it will become one of the research directions for the modification of spinel lithium manganate in the future.