The difference between lead acid battery and lithium battery

October 29, 2019

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The difference between lead acid battery and lithium battery


When we talk about lead-acid batteries, the first application we can think of is electric bicycles. In fact, according to its structure and use, the industry's lead-acid batteries are divided into four categories: 1, start-up 2, power use 3, fixed valve-controlled seal type 4, small valve-controlled seal type. This method is mainly classified from the structural aspect, but also wants to take into account the use. It is difficult for non-battery practitioners to understand. If it is classified from the perspective of pure market application, it is better to understand. According to this standard, lead-acid battery Divided into two categories:

1. Main power supply, including: communication equipment, industrial equipment, power control machine tools, portable equipment;

2. Backup power supply, including: emergency equipment, communication base station, electronic switch system, solar energy system. This type of application has many intersections with the application of lithium-ion batteries. In terms of market capacity, this intersection is mainly concentrated on power batteries, such as electric bicycles and small passenger cars. In the field of power batteries, the main reason is the dispute between these two technologies. Therefore, we compare the difference between lead-acid batteries and lithium batteries in this field. Otherwise, the reference materials are uncertain, and the comparison is boundless.

The difference between the two is based on the performance of the material. The positive and negative materials of lead-acid batteries are lead oxide, metal lead and concentrated sulfuric acid. The lithium-ion battery has four components: positive electrode (lithium cobaltate/manganese) Lithium acid / lithium iron phosphate / ternary), negative graphite, separator and electrolyte, the main differences are:

1, the nominal voltage is different: single lead acid battery 2.0V, single lithium battery 3.6V;

2, the energy density is different: lead-acid battery 30WH / KG, lithium battery 110WH / KG;

3, cycle life is not the same, lead-acid battery average 300-500 times, lithium battery up to more than a thousand times, from the two mainstream technical routes of lithium battery bicycle, the difference between ternary lithium battery and lithium iron phosphate battery is also relatively large, The discharge life of the ternary lithium battery is 1000 times, and the life of the lithium iron phosphate battery can reach 2000 times;

4. Charging mode: The lithium battery adopts the voltage limiting current limiting method, that is, the threshold value is given for both current and voltage, and the charging method of the lead acid battery is more. The main ones are: constant current charging method, constant The charge charging method, the stage equal-current charging method, and the floating charge cannot be described one by one.

The above are the differences in the electrical performance characteristics of the two based on the different working principles. In addition, there are two other factors that affect the promotion of the two: safety and cost, which can be called market factors. Unlike lithium-ion batteries, which are characterized by electrical characteristics, lead-acid batteries are dominant in market factors.

1. Safety: High-current discharge of lead-acid batteries is not prone to accidents because it has a high seal. Even if there are accidents (such as leakage), the positive and negative electrodes and the lead-acid electrolyte are not flammable. The electrolyte of a lithium ion battery is an ester solution, which is flammable and volatile. The working principle of the lithium battery is that lithium ions are intercalated/embedded through the separator between the positive electrode and the negative electrode, and a large current passes through to form lithium dendrites, which are the root causes of the burning and explosion of the lithium battery.

2. Cost: The materials and work requirements of lead-acid batteries are much lower. As far as electric bicycles are concerned, lithium batteries are the value of the entire electric vehicle assembled with lead-acid batteries.

In the electric bicycle and small family car market, lead-acid batteries and lithium batteries are in use. Because of their comparative advantages, lithium batteries have electrical and convenience advantages, while lead-acid batteries have safety and cost advantages. These two types of batteries also perform so well in other applications.