Energy storage refers to converting energy that is difficult to store, such as solar energy, wind energy, tidal energy, geothermal energy, and electrical energy, into easily stored forms such as chemical energy and thermal energy for later use when needed.
Traditional energy storage technologies mainly include mechanical energy storage such as pumped storage and hydropower, and electrochemical energy storage such as lead-acid batteries and lithium iron phosphate batteries.
New energy storage technologies mainly include lithium-ion batteries, sodium-ion batteries, flow batteries, molten salt energy storage, compressed air energy storage, and hydrogen energy storage.
Currently, among the new energy storage technologies, lithium-ion batteries, vanadium redox flow batteries, sodium-ion batteries, and hydrogen fuel cells are the mainstream approaches.
Lithium-ion batteries VS Sodium-ion batteries
In terms of working principle, both lithium-ion and sodium-ion batteries are rechargeable batteries. The storage of electrical energy mainly relies on the insertion and extraction of lithium ions (sodium ions) between the positive and negative electrodes.
Currently, lithium-ion batteries, especially lithium iron phosphate batteries which have the highest safety profile, dominate the energy storage market.
Sodium-ion batteries are currently in the research and development stage. Considering safety, sodium-ion batteries may eventually surpass lithium-ion batteries in the energy storage market and gradually seize market share.
Regarding battery costs, the price of raw materials for lithium-ion batteries is high. On October 24, 2022, the price of 99.2% industrial grade zero lithium carbonate, the main raw material, was 516,000 yuan/ton.
Sodium-ion battery materials have lower costs, with prices remaining relatively stable in the range of 1,000 to 4,000 yuan per ton for the past decade. According to calculations by FARADION, a leading sodium battery company, the cost of sodium-ion batteries after industrialization is about 70% of that of lithium-ion batteries.
Furthermore, all other things being equal, the choice of material for the negative electrode current collector has a significant impact on cost. Sodium-ion batteries can use aluminum foil as the negative electrode current collector, while lithium-ion batteries must use copper foil, resulting in a price difference of up to 10%.
Taking specific raw material costs as an example, currently, the cost of copper-based sodium-ion batteries is 0.29 yuan/Wh, and the cost of lithium iron phosphate batteries is 0.43 yuan/Wh.
In terms of resource abundance, lithium accounts for only 0.006% of the Earth's crust, and in my country, it is mainly concentrated in harsh environments such as the Qinghai-Tibet Plateau, making extraction difficult.
Sodium, on the other hand, accounts for 2.74% of the Earth's crust, is widely distributed in my country, and is easy to mine.
Regarding companies involved in the industry: my country's lithium battery industry chain has taken shape, with major players including Ronbay Technology, Guoxuan High-Tech, CALB, CATL, BYD, and SAIC Motor.
The sodium battery industry layout is largely inherited from that of lithium batteries. Currently, my country's sodium battery market is in the initial layout stage, with CATL driving the formation of the industry chain. Major Chinese companies involved in the sodium battery sector include CATL, Zhongke Haina, Sodium Innovation Energy, Penghui Energy, and Sunwoda.
Vanadium redox flow battery VS hydrogen fuel cell
Regarding battery composition, the vanadium redox flow battery is a redox battery, mainly composed of a positive electrode sulfuric acid electrolyte storing vanadium ions in different valence states, a negative electrode sulfuric acid electrolyte, an external pump, a battery stack (including bipolar plates and electrodes), a storage tank, and a proton exchange membrane.
Regarding the working principle: The battery pack separator is a proton exchange membrane. An external pump pumps sulfuric acid electrolyte from the storage tank into the battery stack. Under the action of mechanical power, the electrolyte circulates in the closed loop formed by the storage tank and the half-cell. When the electrolyte flows over the electrode surface, a chemical reaction occurs, converting chemical energy into electrical energy. The bipolar plates in the battery stack are responsible for collecting and conducting current.
The structure of a hydrogen fuel cell differs slightly from that of a vanadium redox flow battery. The hydrogen fuel cell's liquid storage tank is replaced with a high-pressure hydrogen storage tank, the sulfuric acid electrolyte is replaced with hydrogen gas, and a catalyst and a gas diffusion layer are added; however, the working principle is similar.
In terms of cost, vanadium redox flow batteries are relatively expensive, currently costing approximately 3-3.2 yuan/Wh. Stack materials and electrolytes account for the largest share of the cost, approaching 70%. The core of a hydrogen fuel cell is the stack, and my country relies on imports for key materials and faces technological shortcomings in this area, resulting in higher costs.
In terms of resource abundance, my country is rich in vanadium resources. According to USGS data, China currently has proven vanadium reserves of 9.5 million tons, accounting for 43% of the global total. At the same time, China produces about 60% of the world's vanadium metal.
Hydrogen is abundant in nature. In addition to hydrogen gas in the air, it also exists in water in compound form. It is estimated that the total energy content of hydrogen in the world's seawater is more than 9,000 times that of global fossil energy. According to statistics from the Petroleum and Chemical Industry Planning Institute, my country's current hydrogen production capacity is 40 million tons and its output is 33 million tons.
In terms of market positioning, vanadium redox flow batteries have technological advantages, but their cost is too high. For the same capacity, the cost of vanadium redox flow batteries is about 2.5 times that of lithium batteries, which seriously restricts their commercialization progress.
Companies in my country that have deployed vanadium redox flow batteries include State Grid Yingda, Panzhihua Iron & Steel Vanadium Titanium, Xizi Clean Energy, Haide Energy, and Zhonghe Energy Storage.
In the field of hydrogen fuel cells, my country's overall research is still relatively underdeveloped, making it difficult to compete with developed countries. Companies in my country involved in hydrogen fuel cell development include State Power Investment Corporation Hydrogen Energy Co., Ltd., Snowman Co., Ltd., Shanghai Shenli, Zhongke Hydrogen Energy, Longpan Technology, YiHydrogen Technology, and General Hydrogen Energy.
