This year’s Nobel Prize in chemistry was awarded to John B Goodenough, M·Stanley Whittingham and Akira Yoshino for their contribution to the development of lithium batteries.
John Goodenough, who is 97, also becomes the oldest ever Nobel laureate. His lifelong exploration of lithium batteries is truly admirable. As one of his important discoveries, lithium iron phosphate (LiFePO4) is currently the safest cathode material for lithium batteries.
Thanks to Goodenough’s remarkable identification of LiFePO4, LiFePO4 batteries, or LFP batteries have been created and widely used in various places. Among them data centers and communications base stations are two of the most common application scenarios. Lightweight and powerful lithium battery is also used in fields like electric vehicles.
Compared with lead-acid batteries, lithium batteries are smaller, lighter, and have higher energy density, higher availability, longer service life, and more cycle times.
According to a global survey conducted by Uptime, 10% of data centers use lithium batteries as backup power. For data center operators, the optimal space utilization and minimum operating costs (especially power costs of UPS cooling and battery maintenance and replacement costs) are what they are most concerned about. Lithium batteries can help them meet all these requirements.
Telecom base station
During the process of 5G evolution, the total power consumption of a site rockets. Traditional lead-acid batteries cannot support smooth capacity expansion to adapt to 5G evolution because of their large size and weight, short service life, and inferior performance. Small, lightweight lithium batteries feature longer service life and better performance. They can enable sites to evolve smoothly to 5G and improve site values. Therefore, lithium batteries have become the first choice for 5G sites. Currently, more than 200 telecom operators use lithium batteries as energy store.
In data centers and telecom base stations, LFP and lithium nickel manganese cobalt oxide (NMC) cells are most commonly used. LFP is at present the safest cathode material of a lithium battery for it contains no heavy metal that is harmful to human. Compared with NMC batteries, LFP batteries are more reliable, which better meets high reliability requirements of data centers and telecom base stations.
Why Are LFP Batteries Needed?
- Stable Structure
- LFP batteries feature high thermal stability as well as a low rate and amount of heat yield.
- LFP batteries do not release oxygen in case of overcharge and overdischarge
Test conclusion: LFP batteries are more reliable than NCM batteries.
Common test method:
- Puncture the cell with a needle to check its stability in the case of an internal short circuit.
- Secure the fully charged battery
- Use an 8 mm diameter high-temperature-resistant steel needle to puncture through the geometrical center of the cell in the direction vertical to the cell polarity plate at a speed of 25 mm/s, keep the needle in the cell, and observe for 1 hour.
- After an LFP battery is punctured with a needle (internal short circuit), the heat of reaction inside the cell is minimal. The highest surface temperature of the cell is only 80° C, the cell does not catch ﬁre or leak electrolytes, and its shell is intact.
- After an NCM battery is punctured with a needle (internal short circuit), the cell reacts violently internally and generates a large amount of heat and oxygen in a short time. The battery burns within one second, thermal runaway occurs within four seconds, the highest surface temperature reaches 458° C, and the shell melts.
LiFePO4 vs NCM in Nail Test
Though its technology has been improved a lot, the lithium battery still has many problems in practical application.
- When multiple battery cabinets are connected in parallel, current imbalance occurs due to inconsistent cell resistance and capacity and power distribution differences, especially for short-time discharge of large current. As a result, overcurrent protection is triggered in each battery cabinet
- Partial failure is unavoidable in a lithium battery system. New and old battery cabinets may be connected in parallel. If resistance and capacity are inconsistent in this case, serious bias current can be caused, and a battery cabinet can even be disconnected in case of overcurrent
- Inconsistency of cell resistance and capacity in a battery can cause cell charge overvoltage, so that the entire battery system cannot be fully charged.
- If a battery module in a battery string is faulty, the entire battery string cannot work properly
- If fire occurs in a lithium battery cabinet after lithium batteries are deployed in a modular data center, it is hard to control the fire inside the cabinet and prevent it from spreading to ICT equipment nearby
- Lithium batteries at base stations are prone to be stolen
In view of this, Huawei launched the new-generation data center lithium battery solution SmartLi. Characterized with high reliability, efficiency, and flexible expansion, SmartLi is aimed to help customers reduce investment, simplify O&M, and build a stable and efficient data center power supply system.