Does lithium iron phosphate battery count cobalt free battery?

Does lithium iron phosphate battery count cobalt free battery?  What is a cobalt-free battery?

Cobalt is a chemical element whose chemical symbol is Co.  The pure element is a hard, shiny silver-gray metal.

As the name implies, from the material structure, as long as the battery material does not contain cobalt elements of the battery, can be called cobalt free battery.  Although lithium iron phosphate batteries also do not contain cobalt, but strictly speaking, cobalt free batteries are mainly aimed at removing the cobalt in ternary lithium batteries.  Do you consider a cobalt-free battery (lithium iron phosphate LFP) for a material that has no cobalt in the first place?  For example: cobalt free gasoline, cobalt free glass, cobalt free rims...  See this you may be a little confused, not directly add cobalt is not good, after adding efforts to remove it.

Why is lithium cobalt oxide in batteries?

Why is cobalt in batteries?  For our commonly used lithium battery, according to the cathode material, there are several types: lithium iron phosphate, lithium manganese acid, lithium cobalt acid, three yuan nickel cobalt manganese (NCM).  Lithium cobalt acid and nickel cobalt manganese ternary batteries contain cobalt.  Adding cobalt into the cathode material can not only inhibit the phenomenon of "nickel-lithium mixed arrangement", but also reduce the impedance value of the material, improve the electronic conductivity of the material, improve the rate performance, reduce the internal resistance of the cell and so on.  In our familiar words, it can improve battery discharge current, improve charging power, prolong battery life and increase battery safety.  It can be said that cobalt comprehensively improves the performance of ternary lithium batteries.  

Ternary lithium (NCM/NCA) is layered in microstructure due to material properties, as shown on the left in the figure above. Nickel (Ni) builds a frame structure that can be embedded with lithium ions, which improves the energy density of the battery and achieves the dominant capacity of ternary lithium batteries.  The lithium iron phosphate on the right is not layered and has a birth defect in energy density.  When the battery is charged, the layered three-element lithium battery becomes unstable because the lithium ions fall off the positive electrode, and the place where the lithium ions are stored may be "grabbed" by nickel.  As a result, the lithium ions that return to the positive electrode when the battery is discharged are "homeless" and can only attach to the original nickel, a phenomenon known as "nickel-lithium mixing".  Cobalt, on the other hand, has a more stable frame that keeps the nickel in its proper place.

If "nickel-lithium mixing" occurs, the microstructure of ternary lithium-ion batteries can be completely messed up, resulting in reduced battery capacity, shortened battery life, and other hazards.  In order to suppress this phenomenon and improve the performance of lithium battery, cobalt element is added in ternary lithium battery.

Why cobalt-free batteries?  

Resources are scarce and prices are high.

If cobalt has so many benefits, why are battery makers trying so hard to get rid of it?  As we all know, rare things are precious. The average abundance of cobalt in the earth's crust is only 0.0025%. It is not only dispersed, but also associated with copper, nickel and iron ore, and its output depends on the corresponding mining of copper and nickel ore.  At the end of 2019, the world had only 7 million tons of proven cobalt deposits, according to the US Geological Survey.  A few years ago, cobalt cost less than 180 yuan per kilogram.  But since the fourth quarter of 2017, cobalt has risen to around 420 yuan per kilogram.  In 2018, the price of cobalt rose to more than 650 yuan per kilogram.  Cobalt is already very expensive, accounting for about 10% of the cost of a power battery.  And a new energy car ternary lithium battery pack, cobalt content may reach more than 10kg, if not considering recycling and reducing the amount of cobalt, by 2026, there will be "cobalt free available" state.  

Not only is it expensive, but the supply is unreliable.

I don't care if it's expensive, just pay more for it.  Congo (DRC) is both the world's largest cobalt reserves and producer, contributing about 70 percent of global cobalt production.  But its turbulent political situation in recent years has affected cobalt production and prices, sometimes at a cost.  In contrast, the domestic market, China's cobalt ore quantity is only 80,000 tons, accounting for only 1.14%, in the world is not ranked, but it is the world's largest cobalt consumer, external dependence reached more than 80%.  Cobalt is not only needed in the new energy vehicle industry, but also has important applications in many fields such as aerospace, and is a typical strategic resource.  

The need for an energy boost.

Since it is expensive and the supply is not stable, let's get rid of it, but what to replace it with?  As mentioned earlier, the ternary material also contains nickel, which forms a cage for storing lithium ions in the positive electrode of the battery. The higher the content, the better the battery's capacity, and the higher the nickel content, the lower the cobalt content.  In the trend of pursuing higher energy density, the use of higher nickel content ternary materials is a common development trend in the industry, which represents the direction of industrial upgrading.  The pursuit of increased capacity coincides with the reduction of cobalt usage.  

Where does the cobalt-free battery come from?  

Removing cobalt from power batteries is possible in theory, but difficult in practice.  After the removal of cobalt, the cathode material will become binary lithium nickel-manganate or quaternary material nickel-cobalt-mangano-aluminum (NCMA) polymer. The composition of the material will change greatly, but the frame structure will remain unchanged.  Currently, battery giants such as LG Chem and Panasonic are unable to mass produce cobalt-free batteries.  

As mentioned before, cobalt mainly plays a role in stabilizing the frame structure in battery materials. How to stabilize the structure of the battery after removing cobalt?  To this end, Honeycomb Energy proposed cationic doping and single crystal technology.

What is a positive doping technique?  In the production of cathode materials, cations with high bond energy with oxygen are doped into the crystal structure to enhance the stability of the frame structure, which is conducive to the stability of the structure of the battery after the battery is fully charged.

So what is single crystal technology?  At present, the cathode materials of ternary lithium battery produced in mass production are mostly composed of primary particle agglomeration at nanometer level, and the secondary spherical polycrystalline materials of about 10 microns.  The essence of polycrystals is the aggregation of a large number of small single crystals.  For example, white sugar and single crystal rock sugar are both sucrose. White sugar can be considered a polycrystalline material, while single crystal rock sugar can be considered a single crystal material.  Single crystal materials have higher particle strength than traditional spherical polycrystalline particles, which is beneficial to improve safety and cycling performance.  Through two key technological breakthroughs of cationic doping and single crystal technology, Honeycomb Energy mass produced cobalt-free batteries.  

Advantages of cobalt-free batteries  

The energy density is higher than lithium iron phosphate

The energy density of the cobalt-free battery is comparable to that of the ternary lithium battery and has the advantage of high energy density compared with the lithium iron phosphate battery.  The cobalt-free battery has an energy density of 240Wh /kg.  

The falling cost

Not only that, but because the cobalt-free battery removes the original price sin of cobalt, the cost of the battery is significantly lower than that of the ternary lithium battery, and only slightly higher than that of the lithium iron phosphate battery.  

They're safer than ternary lithium batteries

In terms of safety, Honeycomb says the cobalt-free battery is safer than traditional ternary lithium batteries and similar to lithium iron phosphate batteries.  For example, a cobalt-free battery can easily pass a 150 ° C hot box, while a conventional ternary lithium-ion battery typically passes a 130 ° C hot box.