Q-Batteries蓄电池铅酸蓄电池简介

一、铅酸蓄电池简介

铅酸蓄电池在各类蓄电池中应用时间最久，也是制造技术最成熟、成本最低廉的蓄电池。铅酸蓄电池已被大批量生产，早期电动车辆多以铅酸蓄电池为能量源。但铅酸蓄电池比能量低，单次充电行驶里程较短，自放电率较高，循环寿命较低，不适合现代电动汽车的发展需求。目前，铅酸蓄电池主要用于内燃机汽车的启动动力源。

二、铅酸电池的分类

（1）免维护铅酸电池

免维护铅酸蓄电池由于结构优势，电解液的消耗量小，在使用寿命内基本不需要补充蒸馏水。免维护铅酸蓄电池具有耐震、耐高温、体积小、自放电小的特点，使用寿命一般为普通铅酸蓄电池的两倍。免维护铅酸蓄电池又可被分为两类：购买时添加电解液的电池和出厂时已完成注液的电池。

（2）阀控密封式铅酸电池

阀控密封式铅酸蓄电池在使用期间不需补充硫酸或水，电池结构密封性良好，不漏酸且不排酸雾。电池盖上设计有溢气阀 (安全阀) ，当电池内部气体超量时溢气阀将自动打开排气，排气后溢气阀将关闭。阀控密封式铅酸电池又可被分为两类：玻璃纤维电池和胶体电池(氧化硅凝固剂)。

三、铅酸蓄电池结构

一般，铅酸蓄电池结构包括：正负极板、隔板、电解液、溢气阀、外壳等。

图片来源：学堂在线《新能源汽车》

（1）正负极板

为了增加电池容量，铅酸蓄电池内部结构含有多组正负极板，各组正负极板采用横板焊接的方式组成一个并联的正负极板组，组成正负极板组的正负极板相互嵌合（正极板负极板交替排列）。正极板表面的活性物质为二氧化铅(PbO2)，呈深褐色（因此，铅酸蓄电池外壳正极标志为深褐色的“+”号），负极板表面的活性物质是海绵状纯铅(Pb)，呈青灰色（铅酸蓄电池外壳负极的标志一般为“-”号）。正负极板间插入隔板。

每个单体电池中，负极板的数量比正极板数量多一片(以使两侧放电均匀)。极板表面活性物质的有效数量越多，在一定放电电流的情况下，放电时间越长，即容量越大。

国产负极板厚度为1.8mm，正极板为2.2mm。国外生产的铅酸蓄电池多采用薄型极板，厚度为1.1mm~1.5mm，薄型极板可提高蓄电池的比容量，并改善起动性能（个人理解：起动性能指内燃机的启动性能）。

图片来源：学堂在线《新能源汽车》

（2）隔板

为了减小蓄电池的内阻和尺寸，蓄电池的正负极板应尽可能靠近。为了防止相邻正、负极板彼此接触而短路，正、负极板之间需使用隔板隔开。隔板也是电解液的载体，能够吸收大量的电解液，且隔板具有许多微孔，可以使电解液顺畅流动。

（3）电解液

在蓄电池充放电过程中，电解液不但起导电作用，而且参与化学反应。铅酸蓄电池的电解液由纯硫酸和蒸馏水按一定的比例配制而成。铅酸蓄电池电解液密度一般处于1.24~1.31g/cm3之间，不同地区、不同气候条件对电解液密度的选择略有不同。

（4）溢气阀

溢气阀位于电池顶部，起到安全、密封、防爆等作用。

1、 Introduction to lead-acid battery



Lead-acid battery has been used for the longest time in all kinds of batteries, and is also the most mature and cheapest battery in manufacturing technology. Lead-acid batteries have been produced in large quantities, and most of the early electric vehicles used lead-acid batteries as energy sources. However, lead-acid battery has low specific energy, short driving distance of single charge, high self-discharge rate and low cycle life, which is not suitable for the development of modern electric vehicles. At present, lead-acid batteries are mainly used as starting power source for internal combustion engine vehicles.



2、 Classification of lead-acid batteries



(1) Maintenance-free lead-acid battery



Due to its structural advantages and low consumption of electrolyte, maintenance-free lead-acid batteries do not need to supplement distilled water during their service life. Maintenance-free lead-acid batteries have the characteristics of shock resistance, high temperature resistance, small size and small self-discharge, and their service life is generally twice that of ordinary lead-acid batteries. Maintenance-free lead-acid batteries can also be divided into two categories: batteries with electrolyte added at the time of purchase and batteries with liquid injection completed at the time of delivery.



(2) Valve-regulated sealed lead-acid battery



The valve-regulated sealed lead-acid battery does not need to be supplemented with sulfuric acid or water during its use. The battery structure has good sealing performance, no acid leakage and no acid mist discharge. The battery cover is equipped with an overflow valve (safety valve). When the gas inside the battery exceeds the limit, the overflow valve will automatically open for exhaust, and the overflow valve will close after exhaust. The valve-regulated sealed lead-acid battery can be divided into two types: glass fiber battery and colloidal battery (silicon oxide coagulant).



3、 Lead acid battery structure



Generally, the structure of lead-acid battery includes: positive and negative plate, separator, electrolyte, overflow valve, shell, etc.





Image source: New Energy Vehicles, Xuetang Online



(1) Positive and negative plates



In order to increase the battery capacity, the internal structure of lead-acid batteries contains multiple groups of positive and negative plates. Each group of positive and negative plates forms a parallel positive and negative plate group by transverse plate welding, and the positive and negative plates forming the positive and negative plate group are embedded with each other (the positive and negative plates are arranged alternately). The active substance on the surface of the positive plate is lead dioxide (PbO2), which is dark brown (therefore, the positive sign of the lead acid battery shell is dark brown "+"), and the active substance on the surface of the negative plate is spongy pure lead (Pb), which is cyan gray (the negative sign of the lead acid battery shell is generally "-"). Insert a partition between the positive and negative plates.



In each single cell, the number of negative plates is one more than the number of positive plates (to ensure uniform discharge on both sides). The more effective quantity of the surface active substance on the electrode plate, the longer the discharge time, i.e. the larger the capacity, under the condition of a certain discharge current.



The thickness of domestic negative plate is 1.8mm, and that of positive plate is 2.2mm. Most lead-acid batteries produced abroad use thin plates with a thickness of 1.1 mm~1.5 mm. Thin plates can improve the specific capacity of the battery and improve the starting performance (personal understanding: starting performance refers to the starting performance of the internal combustion engine).





Image source: New Energy Vehicles, Xuetang Online



(2) Clapboard



In order to reduce the internal resistance and size of the battery, the positive and negative plates of the battery should be as close as possible. In order to prevent the adjacent positive and negative plates from contacting each other and causing short circuit, the positive and negative plates need to be separated by baffles. The separator is also the carrier of electrolyte, which can absorb a large amount of electrolyte, and the separator has many micropores, which can make the electrolyte flow smoothly.



(3) Electrolyte



In the process of battery charging and discharging, the electrolyte not only conducts electricity, but also participates in chemical reactions. The electrolyte of lead-acid battery is made of pure sulfuric acid and distilled water in a certain proportion. The electrolyte density of lead-acid battery is generally 1.24~1.31g/cm3, and the selection of electrolyte density is slightly different in different regions and different climatic conditions.



(4) Overflow valve



The overflow valve is located on the top of the battery and plays the role of safety, sealing and explosion-proof.