Energy Storage System (ESS): Introducing the pros and cons of lithium-ion batteries and/or next-generation batteriesby Fermaud ADOUMADJI MBAIORNOM | 30-11-2022 07:22 |
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 Lithium-Ion batteries are recent products compared to lead batteries. They have been on the market since the 1980s. Lithium-ion technology has proven itself to power electronic products such as telephones and laptops or even cordless hand tools. However, several incidents have taken place in recent years, attributed to Lithium-Ion batteries. The incriminated technology was Lithium Cobalt Oxide (LCO), composed of an unstable chemistry in the event of overload or overcapacity and generating self-ignition (thermal runaway). This is the reason why Lithium has rarely been used to create power batteries. But in 1996, a new technology appeared: Lithium Iron Phosphate (Known as LifePo4 or LFP) and its derivatives. These batteries have a slightly lower energy density but are inherently non-combustible, and therefore extremely safe.
Unlike lead batteries, lithium batteries can be discharged almost completely (from 90% to 100%) without degrading. Considering a 100Ah battery, if a Lead battery has a useful capacity of between 30 to 50Ah, the Lithium battery can provide up to 100Ah. Manufacturers and laboratories indicate that several tens of thousands of cycles can be expected from a superior quality LiFePo4 battery. However, these are theoretical values that could not really be verified but simply anticipated. From a practical point of view, and in real use, standard quality LiFePo4 batteries can deliver at least 2000 charge/discharge cycles at 1C and 80% of DoD, and the remaining capacity remains above 80%. These values are dependent on the rate of charge, the depth of discharge but above all on the quality of the cells used. For batteries, such as those produced by PowerTech Systems, using top quality, sorted and matched cells, 4000 to 5000 cycles can be delivered at 1C and 80% DoD. This number of cycles can still increase drastically by decreasing the depth of discharge (DoD). Unlike lead or nickel batteries, Lithium Iron Phosphate batteries do not degrade if they are not regularly charged to 100% and the charging process is faster than for lead. For solar applications, a long rainy period preventing full charge will not affect battery life. The voltage curve of a Lithium battery is flat throughout the discharge. This means that a 20% charged battery will provide almost the same voltage as an 80% charged battery. This avoids the voltage drop problems specific to lead batteries and allows constant energy to be delivered to the application it powers 2.Energetic efficiency Lead acid batteries are less efficient at storing energy than Lithim-Ion. The charge of Lithium batteries has a yield close to 100% while lead is around 80%. This is particularly important for solar applications where the aim is to capture and store the maximum energy from the solar panels. 20% of captured energy is lost when stored in a lead acid battery. One of the great advantages of Lithium-ion is that Peukert losses are almost non-existent. This means that a LiFePo4 battery can deliver its full capacity even at high discharge currents, unlike lead acid batteries which can lose up to 40% capacity in power applications. 3. Climatic resistance Lead and Lithium batteries lose capacity in cold environments. However, we notice on the diagram below that Lithium-ion batteries are much more efficient at low temperatures. Furthermore, the rate of discharge influences the performance of lead batteries. We therefore see that at -20¡ÆC, a Lithium battery delivering a current of 1C (one time its real capacity) can deliver more than 80% of its energy, when the AGM battery can only deliver 30% of its capacity. For harsh environments (hot and cold), Lithium-Ion is the technological choice. |
