As early as 1870, the French prophet writer Verne put forward the idea of sodium battery for the first time in "20,000 miles under the Sea": the Nautilus made a sodium battery as a source of energy by obtaining the electrolyte sodium in the sea water.

150 years later, the stun guns, diving suits and undersea tunnels predicted in the book have all been realized, but sodium battery submarines have not made much progress. Until July this year, Ningde Times released a sodium ion battery, which gave Captain Nemo's "new energy submarine" an idea, and let more people see this "ill-fated" technology.

A battery that is 40 years late

Sodium and lithium, located in the same main group on the periodic table, are chemically similar. Both sodium-ion batteries and lithium-ion batteries originated in the 1970s and 1980s, but their fates are very different.

Lithium-ion battery has become an indispensable device for large and small appliances such as mobile phones, cameras, cars and so on because of its excellent electrochemical performance, while sodium-ion battery has no interest because of its low capacity and short cycle life. It was not until 2010 that researchers began to pick up the old technology of sodium batteries.

Like lithium batteries, sodium-ion batteries have a number of technical routes.

High temperature sodium ion batteries require high working temperature and poor safety. Researchers pay more attention to room temperature sodium ion batteries and develop cathode and anode materials suitable for their properties, such as alloys, metal oxides and carbon materials, while cathode materials include polyanions, Prussian blue derivatives, layered oxides and so on.

Among themThe sodium battery with layered oxide and Prussian blue derivative as cathode is not only cheap, but also has an energy density close to that of lithium iron phosphate battery, and even exceeds that of lithium iron phosphate battery.[1]. Hard carbon is used as anode material, which can improve the reversible specific capacity and cycle life of sodium battery.

In the Ningde Times press conference, mentioned these three electrode materials, according to the press release, Ningde Times confirmed that its sodium battery uses "Prussian white" as the cathode material, which is the reduction product of Prussian blue.

The key problems of capacity and life have been solved, and the application of sodium ion battery has become more and more. The sodium battery was heated up in the Ningde era, butIt is not the first Chinese company to produce sodium batteries.Before it, many companies, such as Chaowei, Xingtian and Zhongke Hainna, have been involved in the research and development and production of sodium batteries.

In addition, China Great Wall, Penghui Energy, Shengyang Co., Ltd. and other companies have developed sodium ion battery samples. Xinwanda and Baichuan are also storing technology and patents for sodium ion batteries.

From being abandoned by researchers to the scramble for research and development by big companies, why are sodium-ion batteries suddenly popular?

The future of new energy lies in "sodium"

New energy is booming and carbon neutralization has become a world issue. Many countries have launched policies to put "stop-production fuel vehicles" on the agenda and replace them with electric vehicles. But this leads to another problem:Lithium resources are not enough.。

The world's proven lithium reserves can only meet 1.48 billion electric vehicles, while according to the forward-looking Industrial Research Institute, the number of cars in the world will exceed 1.49 billion in 2020.[2]。

Not to mention, China is highly dependent on imports because of its shortage of lithium resources.

In 2019, the basic lithium salt processed by our own lithium resources is only 65000 tons, and the rest of the lithium concentrate depends on imports, a total of 1.72 million tons of spodumene concentrate are imported, and the imported ores are mainly from Australia.[3]. Given the strained Sino-Australian relations in recent years, it is of great significance to find alternatives to lithium batteries.

The industry has high hopes for sodium ion batteries.

On the one hand,The content of sodium is rich enough.. The content of lithium in the earth's crust is only 0.0065%, while the content of sodium is 2.75%, which is more than 400 times that of the former.

On the other handSodium ion battery has the advantages of low cost and high safety.. According to CNKHNA's calculation, the material cost of sodium-ion battery is 30% and 40% lower than that of lithium-ion battery.[4]. And because the chemical performance of sodium battery is stable, it is not easy to form hard dendrite like lithium dendrite, so it has an advantage in safety compared with the same type of lithium ion battery system.[5]。

But where should sodium batteries be used?

Who is calling the sodium ion battery?

It is generally believed that sodium ion batteries are very useful in energy storage systems.

Under the requirements of carbon peak in 2030 and carbon neutralization in 2060, the central government clearly proposed to establish a new power system with new energy as the main body, and named wind power and photovoltaic power generation. But wind photovoltaic power generation is unstable, so if you want to connect these clean energy to the grid, you have toBuild energy storage stations to create a "buffer zone" for electric power[6]。

The energy storage modes of energy storage stations include mechanical energy storage, electromagnetic energy storage, electrochemical (battery) energy storage, thermal energy storage and so on. At present, pumped energy storage occupies an absolute dominant position. According to the Polaris Power Network, by 2020, the total installed scale of pumped storage power stations in China is 31.79 million kilowatts, and the total installed capacity under construction is 52.43 million kilowatts. In March this year, with the carbon neutralization target put forward, energy storage demand has promoted the construction of a new batch of energy storage facilities. As of July 2021, 39 pumped storage power stations with a total installed capacity of 47.7 million kilowatts have been signed, approved, started and other important progress.

However, pumped storage also has disadvantages, which leads to its slow development in recent years. Shengang Securities believes that pumped storage has geographical limitations, long construction period and high cost, so it is suitable to be used as a complete set of large-scale power generation equipment. Battery energy storage is the most suitable energy storage form for large-scale development in terms of use efficiency, layout flexibility, cycle life, investment cost and so on.[7]。

Lithium battery, lead-acid battery and all-vanadium flow battery are the main means of battery energy storage. Among them, lithium battery has higher energy density, energy conversion efficiency is more than 90%, and the industrial chain is more mature.[8]. By the end of 2019, lithium-ion batteries accounted for more than 75% of the electrochemical energy storage equipment, which played a leading role.[9]。

Since 2019, sodium ion battery has come to the fore in the energy storage industry, and three sodium ion battery energy storage systems have been built in China.

Everbright Securities estimates that the potential demand for energy storage of domestic sodium ion batteries will reach 48GWh by 2025, which is measured by the price of lithium iron phosphate batteries.Corresponding to the market space of nearly 21 billion yuan[10]。

In addition to the energy storage industry, the electric vehicle industry is also calling for sodium ion batteries with higher safety factors. It remains to be seen how much sodium ion batteries can improve the performance of electric vehicles, butIt is a good thing if we can solve the problems of low temperature "lying on the nest" and collision spontaneous combustion.

"Sodium" is still a "child".

Commercially, the sodium battery is still a "child". Patsnap Smart Bud global patent database shows that sodium battery-related patent applicants are concentrated in universities and research institutes. Shaanxi University of Science and Technology, which applied for the most patents, had 169 patents, while Ningde Times and Zhongke Hainna had only 35 combined.

For example, the life of sodium ion batteries is still not satisfactory.

According to CITIC's statisticsThe cycle life of mainstream sodium ion batteries is only 1000 to 1500 times.Only Ningde era and Zhongke Hainna have a product life of 3000 times. This is barely equal to the ternary battery, but it is also far less than the lithium iron phosphate battery.

The manufacturing cost of sodium ion battery is also on the high side for the time being.

On the one hand, the sodium battery industry chain is immature, driving up the manufacturing cost.

In February this year, on the tender of China Tower Corporation and China Telecom CorporationThe price of lithium iron phosphate battery pack is less than 0.5 yuan / Wh, but the actual production cost of sodium ion battery is more than 1 yuan / Wh at present.

Only when the production capacity of sodium ion battery reaches GWh level, can we rely on the depreciation expense of dilution equipment, which reflects the advantage of low material cost of sodium ion battery.[10]However, by 2020, the cumulative installed scale of domestic battery energy storage projects is only 3.3GW.[11]。

On the other hand, the material production method of sodium battery also needs to be optimized.

Universities and enterprises have been looking for cheaper ways to prepare electrode materials for sodium batteries. However, most of these patents and researches are in the theoretical stage, and there is still a long way to go before large-scale production.

There is no need to say much about the advantages of sodium batteries, but it is unclear when the balance of fate will tilt.