Although SES Power is a manufacturer of customized lithium-ion batteries, we have more than ten years of experience in the field of battery energy storage systems, although we often use lithium batteries, especially those that can perfectly replace lead-acid batteries. LiFePO4 electromagnetic, but we are still concerned with the development of other types of secondary rechargeable batteries, of which metal-air batteries are one of our concerns.

　　Metal-air batteries work by providing electrical energy through the oxidation of metals during discharge.

　　The metal acts as the negative electrode and is paired with the air positive electrode. The positive electrode itself does not store any charge, but takes oxygen from the air through an electrochemical reduction process during discharge and generates hydroxyl ions in the electrolyte. Electrons flow from the metal negative electrode to the positive electrode through an external circuit and provide electricity.

　　In rechargeable metal-air batteries, this metal oxidation reaction can store electrical energy by applying voltage and current. While almost any metal that can spontaneously oxidize can serve as a metal-air base material, only relatively few have the properties required for rechargeable batteries.

　　Historically, metal-air batteries have been used primarily as batteries in disposable low-power small consumer devices, the most common example being zinc-air batteries used in hearing aids. Research on rechargeable metal-air batteries has been going on for decades, but the real commercialization is in the form of rechargeable zinc-air batteries.

　　(Development history and working principle diagram of metal-air battery)

　　To date, two major categories of metal-air batteries have received the most attention. They differ by the type of electrolyte used, either aqueous (usually alkaline) or non-aqueous (usually based on ether or alkyl carbonate organic solvents).

　　The choice of electrolyte reflects its stability to side reactions at the battery operating voltage: zinc-air batteries, iron-air batteries, aluminum-air batteries can use alkaline aqueous solutions, while lithium-air and sodium-air batteries require non- Aqueous electrolytes are attractive for higher energy and power densities because of their higher battery voltages.

　　Both types of metal-air batteries have theoretically high specific energy. The specific energy of Li-air battery and Zn-air battery is about 50 times and 5 times that of Li-ion battery, respectively. However, in practice zinc-air batteries only reach about 35% of their theoretical energy density.

　　Aqueous metal-air batteries are safer than lithium-ion batteries, mainly because aqueous electrolytes are not flammable, and they are one of the cheapest rechargeable batteries to store energy.

　　Metal-air batteries have lower open circuit voltages than lithium-ion batteries—2.9V for lithium-air, 1.65V for zinc-air, and 1.28V for zinc-air. And the low voltage means that more batteries need to be connected in series to reach the higher system voltage. Systems using metal-air batteries would be more complex and expensive than lithium-ion batteries.

　　Currently, metal-air batteries using alkaline water electrolytes are more attractive for stationary electric energy storage system applications, mainly due to their safety and cost advantages. The cost of non-aqueous metal-air batteries tends to be higher than that of aqueous metal-air batteries, mainly because of the higher cost of metals and electrolytes. Lithium, zinc, iron, the three metal-air chemistries have energy storage costs of about $40/kWh, $6/kWh, and $0.6/kWh, respectively. Water-based alkali metal-air batteries have the potential to enable energy storage applications with system costs below $10/kWh.

　　Zinc-air battery technology is the most mature and has been developed into primary and secondary batteries. In the 1970s, there was a brief interest in iron-air batteries for developing electric vehicle applications. And this battery technology is now trying to find its way into grid-scale energy storage. Aluminum-air batteries are also chemically less expensive, but have poor charging performance; for this reason, they have been mostly used as primary batteries to date.

　　Two other variants of metal-air batteries may have the potential to deploy grid-scale energy storage systems. One is a "mechanically rechargeable" battery, where the oxidized metal negative electrode or the entire battery is replaced after the battery is discharged. The used anode material can then be recycled back to its metallic form and reprocessed as part of the system's cost structure. Aluminum-air batteries are one of the candidates for this approach because of their high energy density and low cost, but poor electrical reversibility.

　　The second type of battery is the air-breathing water-sulfur flow battery. Changes in the concentration of sodium ions in the electrolytes used in air or sulfur electrodes result in the uptake or release of oxygen with a concomitant change in the sulfur charge state. The cost of this variant electrolyte can be as low as $1/kWh, and in a flow battery configuration, it provides independently adjustable power and energy for long-term energy storage. A major disadvantage of air-breathing aqueous sulfur flow batteries is the challenging requirement for ion-selective membranes that can separate low- and high-pH cathode and anode electrolytes, respectively.

　　Extremely low material cost, high energy density, relatively simple design, and inherent safety make aqueous metal-air batteries one of the more promising electrochemical cells.

　　Compared with lithium-ion batteries, current metal-air batteries have lower round-trip energy efficiency, higher electricity cost, and lower cycle life. This characteristic makes metal-air batteries ideal for deployment in energy storage applications lasting more than 12 hours.

　　Metal-air batteries are expected to have relatively high electricity costs ($590/kW to $950/kW), compared to $30/kW to $50/kW for lithium-ion batteries and $290/kW for flow batteries ~$530/kW, but the expected cost of energy storage capacity is extremely low ($0.1-$4.0/kWh), suggesting a potentially important role for this technology in long-duration energy storage applications.

　　Of course, under the existing circumstances, lithium-ion batteries are still the first choice for energy storage systems, which is a view that SES Power agrees with. , 24V100Ah, 36V100Ah, 48V100Ah, household energy storage 3KW, 5KW systems, rack-mounted energy storage systems and other products, lithium iron phosphate batteries that can work at -40 degrees Celsius, are widely used in the field of energy storage.