Classification of photovoltaic energy storage batteries

Energy storage can be divided into mechanical energy storage and chemical energy storage. Electrochemical energy storage refers to the energy storage of various secondary batteries. It is the use of chemical elements as the energy storage medium, and the charging and discharging process is accompanied by the chemical reaction or change of the energy storage medium. It mainly includes lead-acid batteries, flow batteries, sodium-sulfur batteries, lithium-ion batteries, etc.

1. Lithium-ion battery

Lithium battery is a kind of battery made of lithium metal or lithium alloy as the anode material and using non-aqueous electrolyte solution, because the chemical characteristics of lithium metal are very active, so that the processing, storage and use of lithium metal have very high environmental requirements. With the development of science and technology, lithium batteries have now become the mainstream.

The main advantages of lithium-ion batteries are: long service life, high storage energy density, light weight, and strong adaptability; The disadvantages are poor safety, explosiveness, high cost, and limited use conditions.

2. Ternary lithium battery

Ternary polymer lithium battery refers to the cathode material using nickel-cobalt-manganese oxide lithium (Li(NiCoMn)O2) ternary cathode material lithium battery, ternary composite cathode material is nickel salt, cobalt salt, manganese salt as raw materials, the proportion of nickel-cobalt-manganese can be adjusted according to actual needs, ternary material as the cathode battery is relatively safe compared with lithium cobalt oxide battery, but the voltage is too low, used in mobile phones (mobile phone cut-off voltage is generally about 3.0V) will have an obvious feeling of insufficient capacity.

The main advantages of ternary lithium batteries are: high energy density and small volume of the same capacity. The disadvantages are: poor thermal stability, internal short circuit is easy to produce open flame, fast capacity attenuation, and short life.

3. Lead-acid battery

It is a battery in which the electrode is mainly made of lead and its oxide, and the electrolyte is a sulfuric acid solution. In the discharged state of lead-acid battery, the main component of the positive electrode is lead dioxide, and the main component of the negative electrode is lead; In the charging state, the main components of the positive and negative electrodes are lead sulfate.

The main advantages of lead-acid batteries are: safety sealing, degassing system, simple maintenance, long service life, stable quality and high reliability; The disadvantages are: Lead is more polluting and has a low energy density (i.e. too bulky).

4. Lithium iron phosphate battery

Lithium iron phosphate battery refers to a lithium-ion battery that uses lithium iron phosphate as the cathode material. The cathode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium iron phosphate, etc. Among them, lithium cobalt oxide is the cathode material used in most lithium-ion batteries.

The main advantages of lithium iron phosphate batteries are: excellent charging and discharging performance, no memory effect, long life, good high temperature resistance, good safety performance, and environmental protection; The disadvantages are: low energy density, large volume of the same capacity, slightly reduced low-temperature performance, and high manufacturing cost.

5. Sodium-sulfur battery

Sodium-sulfur battery is a kind of secondary battery with sodium metal as the negative electrode, sulfur as the positive electrode, and ceramic tube as the electrolyte separator. At a certain degree of operation, sodium ions pass through the reversible reaction that occurs between the electrolyte separator and sulfur, forming the release and storage of energy.

The main advantages of sodium-sulfur batteries are: specific energy up to 760Wh/kg, no self-discharge phenomenon, discharge efficiency up to almost 100%, life can reach 10~15 years; The disadvantage is that sulfur and sodium are melted at a high temperature of 350°C.

6. Flow battery

Compared with the commonly used lead-acid batteries, nickel-cadmium batteries and other secondary batteries, the flow energy storage battery is a kind of device suitable for stationary large-scale energy storage, which has the advantages of independent design of power and energy storage capacity (the energy storage medium is stored outside the battery), high efficiency, long life, deep discharge, environmental friendliness, etc., and is one of the preferred technologies for large-scale energy storage technology.

The main advantages of flow batteries are: flexible layout, long cycle life, fast response, and no harmful emissions; The disadvantage is that the energy density varies greatly.

7. Lithium manganese oxide battery

Lithium manganese oxide battery refers to the battery that uses lithium manganese oxide material for the positive electrode, the nominal voltage of lithium manganese oxide battery is 2.5~4.2V, and lithium manganese oxide battery is widely used for its low cost and good safety.

The main advantages of lithium manganese oxide batteries are: high energy density, low cost, high safety, and stable low temperature performance; The disadvantage is that the high temperature performance is poor and the life is relatively short.

8. Lithium cobalt oxide battery

Lithium cobalt oxide battery has stable structure, high capacity ratio, outstanding comprehensive performance, but its safety is poor, the cost is very high, mainly used in small and medium-sized batteries, widely used in laptops, mobile phones, MP3/4 and other small electronic equipment, nominal voltage 3.7V.

The main advantages of lithium cobalt oxide batteries are: large tap density, good stability, stable structure and good product consistency; The disadvantages are poor safety, very high cost, average cycle life, and poor material stability.