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Principle of lead-acid battery for photovoltaic energy storage system
- Jul 30, 2018 -

Energy storage batteries and devices are indispensable components of solar energy photovoltaic power generation systems. Their main function is to store the power of photovoltaic power generation systems, and to supply power to the load in the absence of sunshine, nighttime and emergency conditions. Commonly used energy storage batteries are lead-acid batteries, alkaline batteries, lithium batteries, and super capacitors, which are used in different occasions or products. At present, the most widely used lead-acid battery has been developed since the 1950s. It has been more than 160 years old and has been derived from many types, such as rich liquid lead-acid batteries, valve-regulated sealed lead-acid batteries, colloidal batteries, lead carbon. Battery, etc.

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1. Basic structure

Lead-acid battery is a chemical energy storage device with lead and two lead oxide as negative electrode and positive active substance, and diluted sulfuric acid as electrolyte. It has the characteristics of high energy conversion efficiency, long cycle life, high end voltage, high security, high cost performance, simple installation and maintenance, etc., and is currently a kind of energy storage, emergency power supply and start-up installation. Select the preferred chemical power supply. The main components of the lead-acid battery include:

1) Pole plate: the positive and negative plates are all obtained by applying the active material on the special alloy grid. The plate can store and release energy when charging and discharging, so that the capacity and performance of the battery are reliable.

2) Partition: it is an isolating medium placed in the middle of the positive and negative pole of the battery to prevent the direct contact between the positive and negative electrode of the battery. The material of different types of lead-acid battery separators is different. The main type of valve controlled battery is AGM, PE and PVC.

3) Electrolyte: the electrolyte of the lead-acid battery is a dilute sulfuric acid prepared from the distilled water. The electrolyte plays the role of ion in the positive and negative poles when charging and discharging, thus the electrolyte must be free of impurities.

4) Container (battery shell cover): the battery coated container, electrolyte and plate are all in the container. It mainly plays a supporting role and prevents the internal material from spillover, and the external material enters the internal structure to pollute the battery.

2. Working principle

The working principle of lead-acid batteries is to convert between electric energy and chemical energy through electrochemical reaction. The electrodes are mainly made of lead and its oxide. The electrolyte is a kind of storage battery of sulfuric acid solution.

In the discharge state, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead.

In the state of charge, the main components of the positive and negative electrodes are lead sulfate.