Lithium-ion batteries are now widely used, and their importance is self-evident. The purpose of this article is to objectively and comprehensively give you a deep understanding of the two sides of lithium-ion batteries. We will discuss its core advantages in detail, and also analyze its disadvantages that cannot be ignored.
Lithium-ion batteries dominate the market due to a series of significant advantages.
High energy density
One of the most core and well-known advantages of lithium-ion batteries is their excellent high energy density. In other words, within the same volume, the energy density of lithium-ion batteries far exceeds that of traditional lead-acid batteries.
The energy density of lithium iron phosphate batteries is generally around 150-200 Wh/kg, and the highest energy density of a single battery is about 180 Wh/k. Some top-level power batteries can exceed 300 Wh/kg. The energy density of existing mainstream lithium-ion batteries is theoretically close to the limit, about 300-350 Wh/kg.
Lightweight
In addition to its high energy density, another significant advantage of lithium-ion batteries is their weight.
The specific energy of lithium-ion batteries can reach about 150 Wh/kg, which is twice that of nickel-metal hydride batteries and four times that of lead-acid batteries. Therefore, lithium-ion batteries weigh only 1/3 to 1/4 of lead-acid batteries while providing the same energy.
Taking electric bicycles as an example, the weight of lithium-ion batteries is generally 2.2 to 4 kilograms, while the weight of lead-acid batteries of the same capacity is 12 to 20 kilograms. Lithium batteries are about 10 kilograms lighter than lead-acid batteries, with a weight reduction of about 70%. The total weight of the vehicle is reduced by at least 20%, making the vehicle lighter and especially suitable for women and the elderly.
Long cycle life
Cycle life refers to the number of complete charge and discharge cycles that the battery can complete before its capacity decays to 80% of its original capacity.
The cycle life of lead-acid batteries is only 200 to 500 times, the theoretical cycle life of ternary lithium batteries (nickel-cobalt-manganese materials) is about 800 times, and commercial products are generally between 800 and 1500 times. The cycle life of lithium iron phosphate batteries is longer, about 2000 times.
Low self-discharge rate
One of the important advantages of lithium-ion batteries is their low self-discharge rate. Generally, the self-discharge rate of lithium-ion batteries is about 0.5% to 3% per month, which is significantly lower than that of nickel-metal hydride batteries (about 30%/month) and lead-acid batteries (about 5%/month).
When your lithium battery equipment is not used for a few months, you can still work normally after taking it out, without worrying about the equipment not being able to start up. The low self-discharge rate not only extends the storage life of the battery, but also improves customer satisfaction and equipment reliability.
No memory effect
Previous nickel-cadmium batteries had memory. If you frequently charged and discharged at a certain interval, it seemed as if it remembered this point, resulting in a much smaller discharge amount. Fortunately, lithium-ion batteries do not have this problem at all. You can charge as much as you want and discharge as much as you want, that is, charge and discharge at any time.
Fast charging capability
Lithium-ion batteries have the ability to charge quickly. We often see batteries marked with 5C fast charge, 10C fast charge, etc., which will greatly shorten the waiting time for battery charging and greatly improve the user experience and convenience.
High voltage
The nominal voltage of lithium battery is 3.7V, and the nominal voltage of lithium iron phosphate battery is 3.2V. This is much higher than the 1.2V nominal voltage of NiCd and NiMH batteries. The most direct advantage is reflected in the design and composition of the battery pack, which reduces the number of cells connected in series, thereby reducing the overall weight of the battery.
The cons of lithium-ion batteries
However, lithium-ion batteries are not perfect, and they also have some shortcomings and challenges that cannot be ignored. The following are the specific shortcomings:
Safety risks
Lithium batteries are dangerous goods. In extreme cases, they may short-circuit, smoke, or even catch fire. Therefore, all lithium batteries require additional protective devices.
High costs
The cost of lithium batteries is generally higher than that of lead-acid batteries, mainly due to raw material prices and the complexity of the manufacturing process.
With the same voltage and capacity, the market price of ternary lithium-ion batteries is about 1.7 times that of lead-acid batteries.
Although the initial purchase cost of lithium batteries is high, their cycle life is long (up to 500-800 times or more), while lead-acid batteries have a shorter cycle life (about 300 times). Calculated on a unit cycle cost basis, lithium batteries are more economical, with a lower single cycle cost than lead-acid batteries.
Temperature sensitive
Simply put, their performance will be compromised and their lifespan will be affected outside the ideal temperature range (-20°C ~ 60°C for discharge and 0°C ~ 45°C for charging).
High temperature accelerates the aging of internal battery materials, causing the battery capacity to decay faster, significantly shortening the actual service life of the battery.
In a low temperature environment, the electrolyte becomes viscous and the resistance to the movement of lithium ions increases. The actual capacity that the battery can release will be significantly reduced, and the discharge power of the battery will decrease.
Protection circuit required
Lithium batteries have risks such as overcharge, over discharge, short circuit, and over temperature, which requires additional protection boards (PCM or BMS). This will increase costs and R&D cycles. The general protection board of lithium polymer batteries is simple, consisting of 1 chip and 1 Mosfet, which can provide overcharge protection, over discharge protection, and short circuit protection.
Shipping restrictions
Lithium-ion batteries are subject to many restrictions in transportation. Transportation management agencies around the world, especially organizations responsible for aviation transportation safety (such as IATA), have established very strict regulations and restrictions on the transportation of lithium-ion batteries.
It requires the shipper to provide corresponding certification and reports, such as UN38.3, MSDS and air and sea transport identification reports. At the same time, they also have corresponding requirements for packaging.
Weighing the pros and cons and applying
LFP batteries are usually safe, have a longer cycle life, and are relatively cheaper, but have low energy density. Therefore, they are very suitable for use in scenarios that have high requirements for safety and cost, but not so extreme requirements for volume, such as energy storage power stations, electric buses, or some entry-level electric vehicles.
NMC/NCA batteries have a higher energy density, which can make devices lighter or have a longer battery life. Therefore, they are widely used in consumer electronics (mobile phones, laptops, emergency lights, blood pressure monitors) and electric vehicles that pursue long-range and high-performance, but their cost may be higher.
Conclusion
Lithium battery is an important direction of new energy now, although it has some defects. But everyone is reducing the probability of its risk, making it safer and cheaper. If you have any lithium battery needs, please send me an email for consultation.
