Our daily life and industrial applications are inseparable from the use of batteries. With the continuous development of technology, there are more and more types of batteries. This article compares the advantages and disadvantages of lithium batteries, lead-acid batteries, and gel batteries.
lithium battery
The working principle of a lithium battery is shown in the figure below. During the discharge process, the anode loses electrons, and lithium ions migrate from the electrolyte to the negative electrode. On the contrary, during the charging process, lithium ions migrate to the anode.
Charging and discharging is a process of removing lithium and inserting lithium. The reaction process is as follows:
Lithium batteries have a higher energy-to-weight ratio and energy-to-volume ratio; they have a longer lifespan. Under normal working conditions, the number of battery charge/discharge cycles is far greater than 500; lithium batteries are usually charged with a current of 0.5 to 1 times the capacity. The charging time can be shortened in time; the battery composition does not contain heavy metal elements, which does not pollute the environment; it can be used in parallel at will, and the capacity is easy to deploy. However, the battery cost is relatively high, mainly due to the high price of the cathode material LiCoO2 (the resource of Co is less), the electrolyte system is difficult to purify, and the high current discharge is not possible. Due to the organic electrolyte system and other reasons, the internal resistance of the battery is larger than other types of batteries. .
Lead-acid batteries
The principle of the lead-acid battery is as follows. When the battery is connected to the load during the discharge process, the dilute sulfuric acid will chemically react with the active materials on the anode and anode to generate a new compound lead sulfate. The sulfuric acid component is released from the electrolyte through the discharge, and the longer the discharge, the thinner the concentration; so as long as the concentration of sulfuric acid in the electrolyte is measured, the remaining power can be measured. As it is charged on the anode plate, the lead sulfate produced on the cathode plate will be decomposed and reduced into sulfuric acid, lead and lead oxide. Therefore, the concentration of sulfuric acid gradually increases. When the lead sulfate at the two poles is reduced to the original substance, it is equal to the end of charging and waiting for the next discharge process.
Lead-acid batteries have been industrialized for the longest time, so they have the most mature technology, stability and applicability. The battery uses dilute sulfuric acid as the electrolyte, which is non-flammable and has high safety; the use temperature and current range are wide, and the storage performance is good. However, its energy density is relatively low, its cycle life is relatively short, and there is a problem of lead pollution.
Gel battery
Gel batteries are sealed using the principle of cathode absorption. When the battery is charged, the positive electrode will release oxygen and the negative electrode will release hydrogen. Oxygen evolution on the positive electrode starts when the positive electrode charge reaches 70%. The precipitated oxygen reaches the negative electrode and reacts with the negative electrode to achieve the purpose of cathode absorption.
2Pb ten O2=2PbO
2PbO ten 2H2SO4: 2PbS04+2H20
The hydrogen evolution of the negative electrode starts when it is charged to 90%, coupled with the reduction of oxygen on the negative electrode and the increase of the hydrogen overpotential of the negative electrode itself, so as to avoid a large number of hydrogen evolution reactions.
For AGM sealed lead batteries, although most of the electrolyte of the battery is kept in the AGM diaphragm, it is necessary to prevent the electrolyte from entering 10% of the pores of the diaphragm. The oxygen generated by the positive electrode reaches the negative electrode through this part of the pores and is absorbed by the negative electrode.
The colloidal electrolyte in the colloidal battery can form a solid protective layer around the electrode plate, which will not cause a decrease in capacity and a longer life; it is safe to use, environmentally friendly, and belongs to the true sense of green power; self-discharge is small, deep discharge performance is good, and charging Strong acceptance, small upper and lower potential difference, and large capacitance. However, its production technology is difficult and costly.
Through the introduction of the above three kinds of batteries, we should have a certain understanding of these three kinds of batteries. The process of lead-acid battery is more mature, the cost is lower, but the life is shorter. As a new force in recent years, lithium batteries have greatly improved their lifespan compared to lead-acid batteries, and are smaller in size but relatively expensive. The gel battery also has the characteristics of longer life, but its technical difficulty is relatively large, so there is no advantage in price.
