Coremax Technology is a professional manufactuer and supplier for both prismatic and cylindrical lithium iron phosphate batteries

There are different terms when people talking about lithium iron phosphate battery. Most of China supplier call it LiFePO4 battery for short or LFP battery and lithium Ferro phosphate, The are actually the same type of rechargeable lithium battery but in different writing. It is a type lithium-ion battery using LiFePO4 as the cathode material (on a battery this is the positive side), and a graphitic carbon electrode with a metallic backing as the anode. The energy density of LiFePO4 is lower than lithium cobalt oxide (LiCoO2) chemistry, and also has a lower operating voltage (LiCoO2 rated 3.6 or 3.7v, while LiFePo4 rated 3.2 volt). The main drawback of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/Because of low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO4 is widely used on Electric vehicles, Small and large energy storage battery systems, utility scale stationary applications, and UPS backup power.

History:

Arumugam Manthiram and John B. Goodenough first identified the polyanion class of cathode materials for lithium ion batteries. Lithium-ion batteries were invented in 1980 by John Goodenough; they were commercialized in 1991 by Sony. LiFePO4 was then identified as a cathode material belonging to the polyanion class for use in batteries in 1996 by Padhi et al. Reversible extraction of lithium from LiFePO4 and insertion of lithium into FePO4 was demonstrated. Because of its low cost, non-toxicity, the natural abundance of iron, its excellent thermal stability, safety characteristics, electrochemical performance, and specific capacity (170 mA·h/g, or 610 C/g) it has gained considerable market acceptance.

Commercial Production

The main problem makes it slowly for commercial production use is because of its low electrical conductivity. This problem was overcome by reducing the particle size, coating the LiFePO4 particles with conductive materials such as carbon nanotubes, or both. This approach was developed by Michel Armand and his coworkers. Another approach by Yet Ming Chiang’s group consisted of doping LFP with cations of materials such as aluminium, niobium, and zirconium. CMX is one of the earlier enterprise make produce manufacturer LiFePo4 batteries in China.

Characteristic of lithium iron phosphate battery cells

Lower voltage: Compared with other rechargeable lithium type batteries. Lithium iron phosphate battery is less active. The battery cell is also lower, which is rated 3.2 volt.

• Minimum discharge voltage = 2.5 V
• Nominal voltage = 3.0 ~ 3.2 V
• Maximum charge voltage = 3.65 V

Types of LiFePo4 battery cells

CMX offers two types of LiFePO4 battery cells – Cylindrical and Prismatic Cells. Both provide reliable and sustained power for custom battery pack applications. Standard cylindrical cell models such as 14500, 18650, 26650, 32650, 38120… Prismatic cells like 10Ah, 20Ah, 50Ah, 100Ah and 200Ah models. They are similar to Li-Polymer cells; these prismatic one can be developed to various flexible sizes. Both of the two types LiFePO4 batteries widely used on energy storage systems, electric bicycles, light electric vehicle (LEV), Power Tools.

Cylindrical Battery Cells

From factory manufacturer end, If we took prismatic cells compared, cylindrical cells can be produced much faster so more KWh per cell can be produced every day equaling lower price cost per KWh. That’s why you can find very cheap lifepo4 battery 18650 cells in market place. The electrodes in a cylindrical cell are wound tightly and encased in a metal casing, This minimizes electrode material from breaking up from the mechanical vibrations, thermal cycling from charging and discharging and mechanical expansion of the current conductors inside from thermal cycling. Many cells are combined in series and in parallel to increase voltage and capacity of the battery pack. If one cell goes bad, the impact on the entire pack is low. In the end, cylindrical cells radiate heat and control temperature more easily than prismatic cells.

Prismatic LFP Battery Cells

The Prismatic cells are made up of many positive and negative electrodes sandwiched together leaving more possibility for short circuit and inconsistency. The higher capacity makes it easier for large battery pack production. The larger cell size also make the battery price cost down by each kwh, So Prismatic cells can be used for large energy storage systems. Like solar park. And also it can be used for house residential battery system. Of cause it can be used for any other devices, just make sure the size and dimensions are not the problem. Another thing need to emphasize, Prismatic cells is big, its need much more professional production ability to make packs. For example, you may require a laser welding machine to make sure the connection more reliable.

LFP Battery For currently EV market

With the advantage of energy density, the NCM lithium powered EV has reached 500-600km NEDC, and the range of LiFeP04 lithium powered EV is still around 300-400km, which is about a year behind that of the NCM lithium Battery. However, the service life and safety of the lithium iron phosphate battery have more advantages, which makes it difficult to choose. It’s really impossible to have both the fish and the bear’s paw!

LFP for Energy storage system

Deep cycle lithium LFP batteries have been a revelation for solar energy storage. No matter for small house residention energy storage or commercial and industry. It has been wide apply with LiFeP04 technology. They’re maintenance-free and able to cycle to 100% of their rated capacity, making them great for both full-time and intermittent use in demanding solar storage applications.

There are huge demand on marine/RV sector for ‘drop-in’ replacement Life4po batteries. Lithium battery replacements are hugely expensive if you buy from local based suppliers, some people who wish to go down this route have begun to purchase via third-party resellers directly from China in an effort to save some money. There is an opportunity for the market to buy from a supplier who can import the product, provide technical support and good after-sales service with a high quality product at a good price. That is our business model.

LiFePo4 Replace Lead acid

A Majority of LiFePo4 Battery cell manufactueres production is based on China. They are located in different province and city. Like Guangdong province, Shenzhen (where CMX based) city also Dongguang city. You will find many suppliers there. There are trading companies, battery pack manufactuers, BMS PCB design and manufactuer, also Cell manufactuers. Here I would like to list some major player invoved in lithium iron phosphate manufacture. You can find these brand in market anywhere.

You probebly can find same model, some with price little expensive or some are very cheap. Just make sure you get the right battery cells.

• 1. BYD LiFePo4 Cell

BYD Company Ltd has developed PV+Storage, a new business model focused on renewable energy production, storage and applications, designed to change the world by leveraging new energy solutions. It’s not easy to purchase cells directly from BYD. However, you will spend less to buy most popular on in market.

• 2 EVE

EVE Energy Co., Ltd said expecting to manufacture the best lithium battery in the world and to be an industrial leader, EVE aims to provide high energy density green lithium batteries with high reliability to the world in a market-oriented direction by adopting global advanced technology and leading intelligent production mode. They produce Lithium ion batteries include cylindrical and prismatic polymer batteries, cylindrincal NCM, prismatic LFP batteries. Widely used in consumer electrionics, electric vehicles and energy storage industries.

• 3. CATL

Contemporary Amperex Technology Co., Limited (CATL) is a global leader in the development and manufacturing of lithium-ion batteries, with businesses covering R&D, manufacturing and sales in battery systems for new energy vehicles and energy storage systems. The company is committed to providing cutting-edge solutions for global new energy applications. CATL LiFePo4 battery cells normally are big size and capacity.The most popular model like 100Ah, 200Ah. or even more.

• 4. Gotion.

Gotion Large off the shelf storage for peak shaving, reserve or load leveling. Als provide Designs tailored to meet space and energy density constraints battery packs. Gotion is one of the ealier company started with LiFePo4 technology. The cells from Gotion safe, reliable and well developed electronics meet international standards and requirements.

• 5. CALB.

Over and Under Voltage

Lithium iron phosphate cells operate safely over a range of voltages, typically from 2.0V to 3.65V. Some lithium chemistries result in cells that are highly sensitive to overvoltage, but LiFePO4 cells is more tolerant. Still, significant overvoltage for a prolonged period during charging can cause plating of metallic lithium on the battery’s anode which permanently degrades performance. Also, the cathode material may oxidize, become less stable, and produce carbon dioxide which may lead to a buildup of pressure in the cell. All Coremax battery management systems limit each cell and the battery itself to a maximum voltage.

Under-voltage during battery discharge is also a concern since discharging a LiFePO4 cell below approximately 2.0V may result in a breakdown of the electrode materials. Lithium batteries have a recommended minimum operational voltage.

4S BMS 12.8v 10A or 20A discharge

Over current and Short Circuit Protection

Every battery has a maximum specified current for safe operation. If a load is applied to the battery which draws a higher current, it can result in overheating the battery. While it’s important to use the battery in a way to keep the current draw below the maximum specification, the BMS again acts as a backstop against over-current conditions and disconnects the battery from operation.

For example CMX12100, the maximum continuous discharge current is specified at 100A, the peak discharge current is 200A, and the BMS disconnects the battery from the circuit if the load draws about 280A.

A short circuit of the battery is the most serious form of over-current condition. It most commonly happens when the electrodes are accidentally connected with a piece of metal. The BMS must quickly detect a short circuit condition before the sudden and massive current draw overheats the battery and causes catastrophic damage.

Over-Temperature

Unlike lead-acid or lithium cobalt oxide batteries, lithium iron phosphate batteries operate efficiently and safely at temperatures up to 60oC or more. But at higher operating and storage temperatures, as with all batteries, the electrode materials will begin to degrade. The BMS of a lithium battery uses embedded NTC thermistors to actively monitor the temperature during operation and it will disconnect the battery from the circuit at a specified temperature.

8S 25.6v LiFeP04 BMS

Cell Imbalance

Lithium-ion batteries have a major difference from lead-acid batteries when it comes to balancing the voltage in each individual cell during charging. Because of small differences in manufacturing or operating conditions, each cell in a battery charges at a slightly different rate. In a lead-acid battery, if one cell charges faster and reaches its full voltage, the typical low end of charge current, along with the excess charge-return, will ensure the other cells get fully charged. In a sense, the cells in a lead-acid battery are self-equalizing during charge.

This is not the case with lithium-ion batteries. When a lithium-ion cell is fully charged, its voltage begins to rise further which may lead to electrode damage. If the charge of the entire battery is stopped when only one cell is fully charged, the remaining cells do not reach full charge and the battery will operate below peak capacity. A well-designed BMS will ensure each cell safely and fully charges before the entire charging process is complete.

A really off-the-shelf product battery should has a BMS or Battery Management System, as almost all LFP batteries that are sold as a 12/24/48 Volt pack do. The BMS takes care of protecting the battery; it disconnects the battery when it is discharged, or threatens to be over-charged. The BMS also takes care of limiting the charge and discharge currents, monitors cell temperature (and curtails charge/discharge if needed), and most will balance the cells each time a full charge is done (think of balancing as bringing all the cells inside the battery pack to the same state-of-charge, similar to equalizing for a lead-acid battery). Unless you like living on the edge, you will not want a battery without BMS!

At Coremax, all our lithium iron phosphate batteries include an internal or external BMS. Let’s have a look at how a CMX BMS protects and optimizes the operation of a lithium iron phosphate battery.

Safety and stability

LiFePO4 batteries are best known for their strong safety profile, the result of extremely stable chemistry. When subjected to hazardous events, such as impact or short-circuits, they won’t explode or catch fire.

Longest cycle life

LiFePO4 batteries perform well in several areas, especially life span. Nominal capacity should be remaining 80% after 2000 cycles.

Constant output voltage

Unlike other lithium ion batteries, LiFePO4 batteries have a very constant discharge voltage. Voltage stays close to 3.2 V during discharge until the cell is exhausted. This allows the cell to deliver virtually full power until it is discharged.

Environmentally friendly

LiFePO4 batteries are non-toxic, non-contaminating and contain no rare earth metals, making them an environmentally conscious choice.

Make cylindrical packs.

Make prismatic battery packs.

Cautions to make pack production.

Reliability and Safety
Most important makes Lithium-Iron-Phosphate (LiFePO4) popular is because it has three advantages that make it the obvious a great choice.
LFP battery can work in high temperature environment without fire risk. The batteries can be used safely in ambient temperatures up to 55°C (131°F). Most of NCM batteries will be breakdown under this. also lead acid batteries at this temperature reduces their cycle life by a whopping 80% more!

OSM’s lithium-ion LFP provides 8000 long cycle lifetimes, with competing chemistries being either too expensive (lithium Titanate), or too unstable (Lithium Nickel Cobalt Aluminum Oxide).

LFP provides more power and more energy density than lead acid and many other lithium chemistries, so it’s perfect for demanding jobs, and efficient energy storage solutions.

• Lithium iron phosphate lithium battery charging test

Before the discharge test. Here is what you should do: The lithium iron phosphate battery discharges to 2.0V voltage, standby for 1h, then charges at a constant current of 1C or whatever the battery specifications mentioned.  then charges at constant voltage by 3.65V to the battery voltage, and stops charging until the charging current drops to 0.1.

• lithium iron phosphate battery discharge capacity

At the time of inspection, its capacity shall not be less than 110% of the rating specified in the technical conditions provided by the enterprise, and the capacity shall not be higher than 110% of the rating specified in the technical conditions provided by the high sub-enterprise

• lithium iron phosphate battery -20 degrees C discharge capacity

Calculate the capacity (in A.h) with c) current value and discharge time data, and express as a percentage of the discharge capacity of 20 degrees C.At the time of the test, its capacity should not be less than 70% of the rating

• -40 degrees C discharge capacity

At the time of the test, its capacity should not be less than 50% of the rating. Note: 1-3h rate discharge current, the value of which is equal to C3/3.  C3-3h rate rated capacity (Ah).

• high temperature charge hold and capacity recovery capacity:

At the time of the test, its normal temperature and high temperature charge hold rate should not be less than 92% of the rating, and the capacity recovery capacity should not be less than 94% of the rating.

• cycle life

The cycle life should be not less than 300 times.

• high temperature full power storage

During the test, the battery cap CID (Current Interrupt Device) cannot break or the cap explosion-proof valve cannot be opened.

• AC internal resistance test

During the test, the AC ≤ 10m.

Regulations. MSDS, UN38.3. UL…… Shipping by sea. By air by express like DHL, UPS. Tracking.