Difference between lead-acid batteries and lithium batteries
Speaking of lead-acid batteries, the first application we can think of is electric bicycles. In fact, according to its structure and use, the industry will lead-acid batteries are divided into four categories: 1, start-up 2, power 3, fixed valve-controlled sealed 4, small valve-controlled sealed. This method mainly classifies from the structural aspect, but also wants to give consideration to the use, for non-battery practitioners still has certain difficulty in understanding, if from the perspective of pure market application classification is better understood, according to this standard, lead-acid batteries are divided into two categories:
1, main power supply, including: communication equipment, industrial instrument and equipment, power control machine tool, portable equipment;
2. Standby power supply includes emergency equipment, communication base station, electronic switch system and solar energy system. This classification of applications intersects many of the applications of lithium-ion batteries. In terms of market capacity, this intersection is mainly concentrated on power batteries, such as electric bicycles and mini-passenger cars. In the field of power batteries, there is also a major controversy between the two technologies, so it is representative to compare the difference between lead-acid batteries and lithium batteries in this field. Otherwise, the reference is uncertain, and the comparison is endless.
The source of all the differences between the two is based on the performance of materials. The positive and negative materials of lead-acid batteries are lead oxide, metallic lead and concentrated sulfuric acid. The lithium-ion batteries have four components: the positive electrode (lithium cobalt/manganese/lithium iron phosphate/ternary), the negative graphite, the diaphragm and the electrolyte.
1, nominal voltage is different: single lead acid battery 2.0V, monomer lithium battery 3.6V;
2, energy density is different: lead-acid battery 30WH/KG, lithium battery 110WH/KG;
3. The cycle life is different. The average lead-acid battery is 300-500 times and the lithium battery is more than 1000 times. According to the two main technical routes of lithium bicycle, the ternary lithium battery and the lithium iron phosphate battery are quite different. The discharge life of ternary lithium battery is 1000 times, and the life of lithium iron phosphate battery can reach 2000 times.
4. Charging mode: Lithium batteries adopt voltage-limiting and current-limiting method, that is to say, the current and voltage are given a limited threshold, and lead-acid batteries are more charging methods, the choice is: constant current charging method, constant voltage charging method, stage constant current charging method and floating charging, can not be described in detail.
The above is based on the working principle of the two show different electrical performance characteristics, in addition, there are two other factors affecting the promotion of the two: safety and cost, can be called market factors. Unlike lithium batteries, which are characteristic of electrical performance, lead-acid batteries are dominant in market conditions.
1. Safety: High current discharge of lead-acid batteries is not easy to accidental, because it has a higher sealing, even if there is an accident (such as leakage), its positive and negative electrolyte and lead-acid electrolyte is not inflammable. The electrolyte of lithium ion battery is ester solution, which is flammable and volatile. The working principle of lithium batteries is that lithium ions are embedded or embedded between the positive and negative electrodes through a diaphragm, and dendrites are formed when high current passes through them. These two factors are the source of combustion and explosion of lithium batteries.
2. Cost: Lead-acid batteries used materials and work requirements are much lower, in terms of electric bicycles, lithium-ion trolley is battery alone may be the value of the whole electric vehicle assembled with lead-acid batteries.
Lead-acid batteries and lithium-ion batteries are both used in the electric bicycle and small domestic vehicle markets because of their comparative advantages, lithium-ion batteries have the advantages of electricity performance and convenience, while lead-acid batteries have the advantages of safety and cost. The performance of these two types of batteries is similar to that of other applications.