The Future of Battery Storage, with Dr. Shirley Meng

Why Sodium? The global transition to renewable energy has accelerated the global development of lithium-ion batteries, but the mining and processing of its materials can be harmful to workers, local communities, and the environment. Sodium has a recently emerged as a potentially cheaper and more environmentally friendly alternative that could revolutionize battery storage systems. Dr. Shirley Meng is one of the scientists leading the way in this field, spearheading the creation of the world's first anode-free sodium solid-state battery.  Diving Deeper  Dr. Meng’s batteries have three key qualities: they are anode-free, sodium based, and solid-state. Though other researchers have developed batteries with similar characteristics, this is the first time all three have been combined.  Most batteries consist of three main parts: a cathode, anode, and electrolyte. The cathode is the positive pole, the anode is the negative pole, and the electrolyte is the material between the poles. As explained by the MIT School of Engineering, when a battery is connected to an external circuit, electrons move through the circuit, while simultaneously ions move through the electrolyte. The anode in a standard battery stores ions, while an anode-free battery starts out with no active anode material—the ions come entirely from the cathode. According to laser tech company Laserax, there is one key difference between Lithium-ion Batteries (LIBs) and Solid State Batteries (SSBs): the electrolyte material. In an LIB, this is a liquid, typically liquid salt dissolved in an organic solvent, which is highly flammable. In an SSB, this liquid is replaced by a solid electrolyte. Dr. Meng calls the electrolyte in her team’s batteries the “magic salt” because it’s primarily made out of sodium chloride - the same chemical as table salt. By supplementing the magic salt with other chemicals like oxygen, yttrium, and zirconia, an ion-conducting electrolyte can be formed.  The Pros and Cons  Dr. Meng’s batteries use sodium in place of the lithium in LIBs. Lithium and other LIB components can only be mined in particular regions, and production - besides being deleterious to the environment - is tightly controlled by a handful of powerful countries. Sodium, on the other hand, is predicted to be about 1200 times more plentiful than lithium in the earth’s crust, and can be accessed from other sources like sea water.  Anode-free batteries are often lighter, cheaper, and more energy-dense than similarly capable standard batteries. However, they can be harder to manufacture and can have shorter lifetimes. As advances are made by other researchers working on alternate battery structures, these challenges will likely be overcome, as have similar difficulties with LIBs. Dr. Meng’s batteries operate best in the lab at low external temperatures, which fills a gap in the battery market in extremely cold climates; however, scalability and widespread use demands that batteries function in a wide temperature range.  Solid-state batteries also come with a range of benefits and challenges. Besides being less flammable, they can have faster charging, higher energy capacity, and longer lifetimes compared to LIBs. However, they are susceptible to the formation of dendrites - or, tree-like metallic structures on the anode - which form during charging and can cause short circuits. Solid electrolytes are prone to cracking under mechanical stress, both in manufacturing and use. Like anode-free batteries and other cutting edge battery tech, SSBs have a long way to go in terms of scalability, but show promise in the future of battery development.  Dr. Meng’s Take Dr. Meng emphasizes that Sodium-ion battery technology is not new - research began back in the 1960s, but was outpaced by lithium-ion research, which at the time showed better results. Additionally, sodium batteries aren’t necessarily a replacement for lithium batteries, but rather a complementary technology that many companies will be able to produce without much capital investment. With the combination of these battery technologies, there