Lithium-ion batteries are a type of battery that uses lithium metal or lithium alloys as the positive/negative electrode material and a non-aqueous electrolyte solution. Lithium-ion batteries can be broadly classified into two categories: lithium metal batteries and lithium-ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. The fifth generation of rechargeable batteries, the lithium metal battery, was developed in 1996, and its safety, specific capacity, self-discharge rate, and performance-price ratio are all superior to lithium-ion batteries.
A lead-acid battery is a type of rechargeable battery whose electrodes are primarily made of lead and its oxides, and whose electrolyte is a sulfuric acid solution. In the discharged state, the positive electrode is mainly composed of lead dioxide, and the negative electrode is mainly composed of lead; in the charged state, both the positive and negative electrodes are mainly composed of lead sulfate. A single lead-acid battery cell has a nominal voltage of 2.0V, can discharge to 1.5V, and can charge to 2.4V. In practice, six single lead-acid batteries are often connected in series to form a nominal 12V lead-acid battery; 24V, 36V, and 48V batteries also exist.
Lithium-ion batteries and lead-acid batteries both play a crucial role in the energy storage field, and neither can completely replace the other. However, their focuses are clearly different. Lead-acid batteries are more commonly used in electric bicycles and motorcycles, while lithium-ion batteries are more prevalent in automobiles. So, which is better, lithium-ion batteries or lead-acid batteries? Let's compare the advantages and disadvantages of lithium-ion batteries and lead-acid batteries from the following aspects.
1. Gravimetric energy density
Currently, the energy density of lithium batteries is generally between 200 and 260 Wh/g, while that of lead-acid batteries is generally between 50 and 70 Wh/g. Therefore, the gravimetric energy density of lithium batteries is 3 to 5 times that of lead-acid batteries. This means that for the same capacity, lead-acid batteries are 3 to 5 times more powerful than lithium batteries. Thus, lithium batteries have an absolute advantage in terms of lightweight energy storage devices.
2. Volumetric energy density
The volumetric capacity density of lithium batteries is typically about 1.5 times that of lead-acid batteries, so for the same capacity, lithium batteries are about 30% smaller in volume than lead-acid batteries.
3. Usage cycle
Currently, the most popular material systems are ternary lithium and lithium iron phosphate. Ternary lithium batteries typically have more than 1,000 cycles, lithium iron phosphate batteries have more than 2,000 cycles, and lead-acid batteries typically have only about 300 to 350 cycles. Therefore, the lifespan of lithium batteries is about 3 to 6 times that of lead-acid batteries.
4. Price
Currently, lithium batteries are about three times more expensive than lead-acid batteries. However, considering the lifespan, lithium batteries still have a longer lifespan for the same investment.
5. Applicability
Because lithium batteries are slightly less safe than lead-acid batteries, various safety precautions need to be taken during use, such as preventing external forces or accidents from damaging the lithium batteries, as this may cause fire or explosion. Currently, lithium batteries also have good temperature adaptability, so in other aspects of adaptability, lithium batteries are no less than lead-acid batteries.
6. National policies
Lead-acid batteries cause significant environmental damage during production and when discarded. As a result, national policies are restricting further investment in lead-acid batteries and limiting their use in certain sectors. The trend of lithium batteries replacing lead-acid batteries will become increasingly apparent and the pace of this replacement will gradually accelerate.
Therefore, whether comparing lead-acid batteries with lithium batteries, or lithium batteries made of different materials, they each have their own advantages and disadvantages, and we cannot simply define them as "good" or "bad." When purchasing an electric bicycle, if you don't need to remove the battery for charging, don't prioritize a lightweight design, and the charging environment is relatively complex (e.g., very hot in summer or very cold in winter), then you can choose lead-acid batteries, which offer higher safety and better cost-effectiveness. If you want a lightweight vehicle with a long range, or if you sometimes need to remove the battery for charging (in a safe environment), then you can choose lithium batteries, which have higher energy density and can be removed.
