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 divides lead-acid batteries into four categories: 1, start-up 2, power 3, fixed valve-controlled seal 4, small valve-controlled seal. This method is mainly classified in terms of structure and purpose. It is difficult for non-battery practitioners to understand this method. If it is classified from the perspective of pure market application, it is better to understand. According to this standard, lead-acid batteries can be divided into two categories: lead-acid batteries, lead-acid batteries, lead-acid batteries and lead-acid batteries.
1. Main power supply, including: communication equipment, industrial instrument equipment, power control machine tools, portable equipment;
2. Standby power supply, including emergency equipment, communication base station, electronic switch system, solar energy system. This application classification has many intersections with the application of lithium ion batteries. In terms of market capacity, this intersection mainly focuses on power batteries, such as electric bicycles and small passenger cars. In the field of power batteries, the main issue is the dispute between the two technologies. Therefore, it is representative for us to compare the differences 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. Lead oxide, metal lead and concentrated sulfuric acid are the positive and negative materials of lead-acid batteries, while lithium ion batteries have four components: positive electrode (lithium cobalt/lithium manganate/lithium iron phosphate/ternary), negative graphite, diaphragm and electrolyte.
1. The nominal voltage is different: 2.0V for single lead-acid battery and 3.6V for single lithium battery.
2. Different energy density: lead-acid battery 30WH/KG, lithium battery 110WH/KG;
3. Cycle life is different. Lead-acid batteries have an average of 300-500 cycles and lithium batteries have more than 1000 cycles. Judging from the two main technical routes of lithium-electric bicycles, lithium ternary batteries and lithium iron phosphate batteries are quite different. The discharge life of lithium ternary batteries is 1000 cycles and that of lithium iron phosphate batteries is 2000 cycles.
4. Charging mode: Limited voltage and current method is adopted for lithium batteries, that is to say, a threshold value is set for both current and voltage, while there are many charging methods for lead-acid batteries. The main ones are constant current charging method, constant voltage charging method, stage equal current charging method and floating charging method, which can not be described in detail.
In addition, there are two other factors affecting their promotion: safety and cost, which can be called market factors. Unlike lithium batteries, lead-acid batteries dominate the market.
1. Safety: High current discharge of lead-acid batteries is not easy to cause accidents, because it has a high sealing, even if there are accidents (such as leakage), its positive and negative electrodes and lead-acid electrolyte are not flammable. The electrolyte of lithium ion battery is ester solution, flammable and volatile. The working principle of lithium batteries is that lithium ions are embedded/embedded in the diaphragm between the positive and negative electrodes, and lithium dendrites are formed when large current passes through them. These two factors are the source of combustion and explosion of lithium batteries.
2. Cost: Lead-acid batteries are much lower in materials and working requirements. From the point of view of electric bicycles, lithium trams alone may be the value of the whole electric vehicle assembled with lead-acid batteries.
Lead-acid batteries and lithium batteries are both used in the market of electric bicycles and small household cars because of their comparative advantages. Lithium batteries have the advantages of electrical performance and convenience, while lead-acid batteries have the advantages of safety and cost. The performance of these two types of batteries in other applications is almost the same.