What is electrochemical energy storage and how it is evolving

This year, not only CATL, CALB, Sunwoda and other battery companies accelerate the expansion of energy storage battery capacity, many other companies also crossed the border into the energy storage industry. According to statistics, there are 26 expansion projects related to energy storage battery and power battery manufacturing this year, with a total investment of more than 290 billion RMB, there is still more room for the development of electrochemical energy storage.

Energy storage development trend

Even though affected by supply chain shortages, energy storage is becoming one of the projects promoted in many countries. 2021 saw the largest new global energy storage commissioning, surpassing 10GW for the first time, reaching 10.2GW, 2.2 times the new commissioning in 2020, an increase of 117% year-on-year. The US, China and Europe still lead the global energy storage market, with the three together accounting for 80% of the global market.

According to the type of technology, energy storage can be divided into electrochemical energy storage, mechanical energy storage, electromagnetic energy storage, chemical energy storage, thermal energy storage and so on. Among them, electrochemical energy storage has the advantages of high energy density, high technology maturity, long life, and long-term economy, and is the most potential energy storage technology for application.

What is electrochemical energy storage

Electrochemical energy storage is an energy storage technology and measure that uses chemical batteries to store electrical energy and release it when needed. According to the storage device, electrochemical energy storage can be divided into lithium battery, lead-acid battery, lead-carbon battery, liquid flow battery and sodium-sulfur battery energy storage. Among them, lithium batteries and lead batteries are the most widely used electrochemical energy storage technology routes for industrialization. At present, electrochemical energy storage technology is the key direction of development, while lithium-ion batteries are the focus of electrochemical energy storage technology development.

The large-scale application of electrochemical energy storage technology needs to meet three basic requirements: high safety, high cost performance, and low pollution. At present, the most mature commercial applications are lithium-ion batteries and lead-acid batteries, while sodium-ion batteries, water-based zinc-ion batteries, liquid flow batteries and other emerging electrochemical energy storage technologgy are still in the early stages of development.

Lithium-ion battery consists of five major components: cathode, anode, seperator, electrolyte and battery shell, of which the cathode material directly determines the capacity of the battery and is the most critical material. Lithium-ion batteries are mainly divided into lithium cobalt-acid batteries, lithium manganate batteries, lithium nickel-cobalt-manganese ternary batteries, lithium iron phosphate batteries according to different cathode materials.

Sodium ion batteries store energy through the embedding and de-embedding of alkali metal ions in the positive and negative electrode materials. Sodium ions have a larger ionic radius and larger relative atomic mass than lithium ions, resulting in a lower theoretical specific capacity. Since sodium does not alloy with aluminum at low potentials, the anode collector of sodium ion batteries can also be made of inexpensive and lightweight aluminum foil, thus further reducing the material cost of the battery and increasing the energy density.

Aqueous zinc ion battery is a new type of secondary battery with metallic zinc as the negative electrode, which overcomes the shortcomings of traditional organic system lithium batteries and lead-acid batteries in terms of high toxicity, flammability, low cycle life and high production cost, and can continue to provide stable power supply with high safety. With an energy density of 250 Wh/kg, zinc-ion batteries are comparable to lithium-ion batteries.

Liquid flow battery is a new large-scale electrochemical energy storage technology that realizes electrical energy storage and output through reversible state change of liquid active material. There are many types of liquid flow batteries, such as chromium-iron liquid flow batteries, zinc-bromine liquid flow batteries, and all-vanadium liquid flow batteries, among which all-vanadium liquid flow batteries are the most mature.

Metal air battery is a special fuel cell that generates electricity through redox reaction between metal and oxygen in the air. The main metal air batteries are lithium air batteries, aluminum air batteries, magnesium air batteries and so on. Aluminum air battery electrolyte is aqueous electrolyte, no risk of combustion and explosion, good safety performance. The aluminum ions generated during battery discharge combine with hydroxide ions to produce precipitation, which can be recovered and recycled. When the battery power is exhausted, only the aqueous electrolyte and aluminum block need to be replaced to continue to use, eliminating the trouble of long time charging.

Lead-carbon battery is a capacitive lead-acid battery improved from traditional lead-acid battery. By adding activated carbon with capacitive properties to the negative electrode of lead foam, lead-carbon battery has the advantages of high power and long cycle of super capacitor, but also retains the high energy density of lead-acid battery.

Electrochemical energy storage industry chain development space

China’s electrochemical energy storage industry will grow by more than 20 times in the next decade, and the overall industry will maintain high growth boom expectations. It is estimated that the cumulative market size will reach a new high of 6614.8MW in 2021, and the cumulative size will reach 32.7GW and 55.9GW in 2024 and 2025 respectively, with a compound growth rate of 84.5% from 2021 to 2025. At the same time, the global energy storage market is growing at an unprecedented rate.

The upstream of electrochemical energy storage system industry chain includes energy storage battery system, battery management system (BMS), energy management system (EMS), energy storage converter (PCS) and other equipment providers; the midstream is the energy storage system integrator and energy storage system installer; the downstream is mainly for the power grid, power stations, industrial and commercial and other end users.

In 2021, lithium-ion batteries account for 89.7% of the installed capacity of electrochemical energy storage in China, which is currently the most mature technology and the most rapidly developing energy storage method. Specifically, the industry concentration of energy storage battery systems in China is high, with CATL and BYD occupying nearly 80% of the market share. Overall, the industry pioneers in electrochemical energy storage have a first-mover advantage as batteries and PCS have large barriers to entry.