In modern life, we can't live without electricity at all times. Basically all the electricity we use comes from the power plant. Since the large household appliances in the house do not move often, they are plugged into sockets. Those who use electronic products that need to be handled frequently need batteries to provide us with electricity.
Discovery of Volt Stacks
In 1799, Volt immersed a zinc plate and a silver plate in salt water, and found that a current passed through the wire connecting the two metals. Therefore, he put a lot of zinc flakes or paper on the silver fleece or paper When you stack them and touch both ends with your hands, you will feel a strong current stimulation. Volt successfully used this method to make the world's first battery, the "Volt Stack." The battery was invented in this way. After hundreds of years of development, the battery has changed from the previous "volt stack" to the current dry battery and secondary battery. The efficiency of the battery is getting higher and higher, and the energy is getting higher and higher, so the time required to fully charge the electricity is getting longer.
How the battery works
The generation of current is the directional flow of current. If the lost electron flows to another electrode through a wire, it will not be able to generate current. A battery is called a chemical power source. It is an energy conversion device. When discharged, the battery converts chemical energy into electrical energy; when charged, it converts electrical energy into chemical energy and stores it. When the positive and negative electrodes of the battery are connected with an electronic conductor and a load is applied, a current will pass through the load. As long as the positive and negative electrodes participating in the reaction continue to react, the battery will continue to output current until the reaction of the reacting substances is complete.
When the battery is being charged, the whole process is reversed. The principle of a lithium battery is similar to this, except that it is lithium metal that loses electrons. So why do we use lithium batteries, but not aluminum or iron batteries? In fact, lithium batteries have many unique advantages over batteries made of other metals.
Advantages of lithium-ion batteries
1. High specific energy. The energy-to-mass ratio of lithium-ion batteries can reach 120 ~ 200Wh / kg, which is the highest among current storage batteries. Since metallic lithium is very light, it has the most charge under the same mass.
2. The discharge voltage is high, and the discharge voltage is generally above 3.2V ~ 4.2V.
3. Low self-discharge. Under normal storage conditions, the monthly self-discharge rate of lithium-ion batteries is only about 5%.
4. Long cycle life, no memory effect, ordinary lithium secondary battery can be charged and discharged more than 500 times at 100% discharge depth. Such as lithium iron phosphate battery and lithium titanate battery as the negative battery cycle life of more than 2000 times and 5000 times.
5. High charging efficiency, the energy conversion efficiency can reach more than 90% during the cycle charging and discharging of the battery.
Lithium-ion batteries seem to have had little development in recent years. In fact, the factors restricting the high-performance of lithium-ion batteries are mainly the development and application of lithium storage materials and electrolyte materials. The graphene battery that has been studied particularly now uses the layered structure of graphite to embed lithium ions into the graphite layer, which can greatly increase the capacity of the battery, and because of the super-conductivity of graphene, the charge and discharge efficiency of the battery is improved.