The types of high-energy batteries are introduced as follows:
1. Magnesium dry high-energy batteries with magnesium as the negative electrode active material: their structure is basically the same as zinc manganese dry batteries. The standard electrode potential of magnesium is relatively low, with a small electrochemical equivalent, and it has excellent conditions as a negative electrode active material for high-energy batteries. For example, the actual specific energy of magnesium manganese dry batteries is four times that of zinc manganese dry batteries, the voltage is stable during operation, and they also have good working ability at low temperatures, and can withstand high temperature storage. Its disadvantage is the phenomenon of voltage lag (it takes some time for the voltage to rise to the termination voltage value after being connected), with a lag time of about 2-3 seconds; Due to corrosion, the current efficiency of magnesium electrodes is low; Not suitable for intermittent discharge with low current for a long time.
2. Metal air high-energy battery: A battery that uses oxygen in the air as the positive electrode active material and metal as the negative electrode active material.
3. Lithium non-aqueous electrolyte solution high-energy battery: The electrochemical equivalent of lithium is about half of magnesium, so as the negative electrode of high-energy batteries, lithium is superior to magnesium. But for lithium to react strongly with water, it is necessary to use organic solvents or non-aqueous inorganic solvents to prepare electrolyte solutions, and then add inorganic salts to make them conductive. The main positive electrode materials used include solid fluorides, chlorides, oxides, and sulfides. The theoretical specific energy of these batteries is mostly above 1000 watt hours per kilogram. Its actual specific energy is also relatively high. For example, in lithium copper fluoride (Li/CuF2) batteries, the actual specific energy can reach 250 watt hours/kg when the discharge current density is 2 milliamperes/cm2. Due to the low specific conductivity of organic electrolyte solutions and the inability to increase current density, lithium non-aqueous electrolyte solution batteries are a type of high specific energy and low power battery. And lithium sulfide batteries discharge under heavy loads, especially when there is an external short circuit, which can cause explosions.
4. Sodium sulfur high-energy battery: It is a relatively mature secondary high-energy battery developed in recent years. Its negative electrode is molten metal sodium (Na); The positive electrode active substance is molten sodium polysulfide (Na2Sx), usually filled with porous carbon as the positive electrode current collector. Conductive ceramic tubes need to be used to separate sodium from sodium polysulfide to prevent direct reaction and self discharge. In addition, ceramic tubes also serve as electrolytes in batteries. When the battery is discharged, the reaction on the negative electrode is 2Na - → 2Na++2e-Na+
Enter the positive electrode through a conductive ceramic tube and react with sulfur to form polysulfides. When the sodium in the negative electrode is depleted, the discharge terminates. To keep both sodium and sodium polysulfide in liquid state, discharge needs to be carried out at around 300 ℃. The actual specific energy of sodium sulfur batteries has reached 100 watt hours/kg, and the charging and discharging cycle life can reach 2000 deep discharge cycles, making them particularly suitable for use as power batteries in vehicles.
5. Lithium high-temperature and high-energy battery: A battery that uses lithium as the negative electrode, sulfur (including sulfides) and chlorine as the positive active substances, and molten salt as the electrolyte. Due to the use of molten salt, the battery operates between 300-600 ℃, so lithium high-temperature high-energy batteries and sodium sulfur batteries are collectively referred to as high-temperature batteries. Liquid lithium electrodes are prone to losing their wettability after multiple charge and discharge cycles; Sulfur volatilizes at high temperatures and is corrosive; Chlorine is a gas that is difficult to treat. Therefore, the development direction of lithium high-temperature batteries will be towards using lithium alloys as negative electrodes and sulfides as positive electrodes. For example, in lithium aluminum alloy iron sulfide batteries, the battery reaction is 4LiAl+FeS2- → 2Li2S+Fe+4Al