Analysis Of New Energy Race-Research On Sodium Salt Batteries

Sodium salt battery technology source introduction

From 1967 to 1982, the British Railway research sodium nickel battery, and in 1982, the Beta Institute was established in the United Kingdom, to carry out the mass production of this battery research;

1987 to 1997, carried out in the electric passenger car research, did five years of one hundred thousand kilometers of life test, then there was no big problem;

In 1999, MES-DEA acquired the technology of Beta Research Institute and started mass production.

In 2001, GE in the United States carried out energy storage technology evaluation. After a long time of exploration, it found that sodium nickel battery was an excellent energy storage battery. In 2007, GE acquired Beta Research Institute in the United Kingdom, and in 2012, GE completed the construction of the plant.

In 2017, Chilwee established Zhejiang AMPower Co., Ltd. in April 2019, which started the first mass production enterprise in China.

At the beginning of the New Year in 2023, AMPower continued to make a big order which sold more than 290 groups of batteries , leading in a good start!

Process route of sodium salt battery

This type of battery is also called all-solid sodium battery. In the battery system, the negative electrode is sodium metal and the positive electrode is nickel chloride. The first electrolyte is beta-alumina, and the other is an inorganic salt, sodium tetrachloroaluminate. The operating temperature is about 250 to 350 degrees. Sodium ions migrate back and forth through the solid electrolyte diaphragm to realize the gain and loss of the battery, and finally realize the charge and discharge. This is the mechanism of the battery. The runtime reaction is as follows:

When a battery is charged, electrons flow from the positive to the negative. The sodium ions in the salt (sodium chloride) migrate through the solid ceramic electrode towards the negative tank terminal. The remaining chloride ions adhere to the nickel and form nickel chloride in the cathode medium. The sodium forms a molten anode layer on the outside of the ceramic tube, which comes into contact with the steel tank and the battery is fully charged. During the discharge, the electrons return and the molten sodium is oxidized into Na+ ions, which are returned through solid ceramic tubes to form sodium chloride. Nickel chloride is reduced to nickel metal. The electrochemical reaction of the battery is as follows:

The technical route can be roughly classified as follows:

The cathode material of the sodium-nickel battery is solid sodium chloride and nickel particles, the diaphragm is ceramic tube, and the electrolyte is sodium tetrachloroaluminate, all of which are very common, so the cost is very low.

Second, in the absence of chemical reactions, monomer sodium is not produced; There are no acids or other organic solvents inside the battery, so the sodium-nickel battery is non-toxic and does not pose any harm to the environment.

Generally, the relatively safe battery energy density will be relatively low, sodium nickel battery volume energy density can reach 400Wh/L, close to ternary lithium; The weight energy density can reach 160Wh/kg, and the weight energy density after group can reach 110-120Wh/kg, which is similar to the level of lithium iron phosphate material. The sodium-nickel battery is a good alternative to the lithium iron phosphate battery currently used in large-scale energy storage.

In terms of cycle life, sodium-nickel batteries are also built for energy storage. Its individual specific energy reaches 135 watt-hours per kilogram, service life is 2 to 5 times that of lithium battery, 80%DOD cycle life is up to 7500 times, after the composition of the system, the volume is more than 50% smaller than lithium battery system, the whole life cycle cost is 50% lower than lithium battery.

Advantage of sodium salt battery

(1) Cost, not using any expensive metals, such as copper, lithium and cobalt. Instead, it uses solid ceramic electrolytes and common sodium salt. It's abundant, it's easy to get, there are no supply chain issues and it's cheap.

(2) High safety, do not need cell level safety protection and fire extinguishing device, because the internal battery is composed of inorganic salt, inorganic metal, sodium, nickel, solid electrolyte is β-alumina, unlike lithium inside the electrolyte, the existence of organic matter, we are inorganic matter exists, there is no burning matter. The battery will not burn or explode in any way. This is the battery's biggest feature.

(3) Good environmental tolerance, the battery has a very good tolerance to wide temperature, capacity and energy test at minus 40℃, can release 100.9% of the room temperature; Capacity and energy test at +60℃ can release 101.6% of room temperature; So sodium batteries can be used in the desert in very, very hot climates as well as very, very cold climates.

(4) Long cycle life. The battery's most important technology is a solid electrolyte, beta-alumina, which acts as an electrolyte and a diaphragm. On the other hand, a good technique is to combine the positive electrode and the negative electrode and make particles into the ceramic tube. In terms of battery life, the folks in the UK did 80% of the DOD's tests, and after 3,500 weeks there was probably more than 90% power left. The normal cycle life of a battery module is greater than 4500 times. According to the existing test situation, the life of the battery is predicted. If it is 2 hours, the life of the battery is estimated to be 6,000 times, 3 hours is 10,000 times, 8 hours is 25,000 times.

The second aspect of overcharge and release performance is better, over charge and release process, the generated material is the battery itself, either active material, or the raw material of the battery, raw material will occur in the case of high temperature compound reaction, and become active substance.

The third aspect of short circuit resistance is good, lithium ion will cause thermal control of battery module due to short circuit; When the ceramic tube in the sodium salt battery is broken and short-circuited, the metal sodium and electrolyte sodium tetrachlorochlorate react to form aluminum. The gap between the cracks in the ceramic tube is filled with aluminum to prevent the reaction from going further, and the positive and negative electrodes are conductive. In this way, the short-circuited battery is equivalent to a conductor, and the voltage of the whole battery module is equivalent to a drop in the voltage of a cell of 2.58 volts. In addition, 5% to 10% of battery modules are allowed to fail, and the module can be used normally within the failure range of the cell.