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==Sodium Ion Technology Overview and CATL Announcement==
Lithium ion battery development and manufacturing leader Contemporary Amperex Technology Co., Limited (CATL) announced that it will start marketing sodium ion batteries in early July 2021 (Source). CATL’s move to offer sodium ion battery solutions is, in part, a response to the dependence on foreign resources and a pressured materials value chain required for lithium ion battery manufacturing. Sodium ion batteries have the same operating principle as lithium ion batteries; however, instead of lithium ions shuttling between cathode and anode, it utilizes sodium ions. 

There are currently two sodium ion battery developers that have deployed commercial systems: Natron Energy and HiNa Battery Technology. Natron Energy, based out of Santa Clara, California, began shipping 6kW sodium ion modules for datacenter applications in 2019. In 2020, Natron Energy became the first sodium ion developer to receive UL 1973 certification (Source). HiNa Technology, a Chinese sodium ion battery vendor, commissioned a 30 kW, 100 kWh system in 2019 (Source). Faradion, a UK based developer, demonstrated a sodium ion battery used in an e-bike (Source). Additionally, Aquion Energy deployed 250 sodium ion systems but went bankrupt in 2017. The bankruptcy is suspected to be a result of a production plan that didn’t anticipate the rapid decrease of lithium ion battery costs (Source). Aquion Energy was acquired at auction by Juline-Titans LLC, an affiliate of China Titans Energy Technology Group. 

The list below highlights a few of the potential advantages and technical challenges for sodium ion batteries.

Potential Advantages:
*Materials availability: Uses abundant and cheap materials. Does not use cobalt like lithium ion NMC, NCA, and LCO battery types, which have a supply chain subject to price uncertainty and ethical concerns.
*Safety: Uses stable materials that result in reduced flammability properties compared to lithium ion. 

Technical Challenges:
*Energy density / footprint: Lower energy density than lithium ion. Current sodium ion batteries have an energy density range from 75-150 Wh/kg, whereas lithium ion batteries have an energy density range of 126-285 Wh/kg (Source).

Commercial readiness: Must address production scale-up and product validation. Electrode design and other cell components such as additives, binders, and separator still need to be optimized.

''EPRI Perspective''
As a result of sodium ion’s significantly lower energy density than lithium ion, stationary energy storage applications are likely to be the technology’s main market. CATL’s experience with scaling-up its lithium ion batteries in the electric vehicle market, acquiring 32.5% of the 2021 market share according to a Bloomberg report, may be beneficial when navigating the production challenges that may await this emerging technology. Although, theoretically, sodium ion batteries could have a lower cost than lithium ion, a thorough cost analysis for the technology is dependent upon further commercialization. Over the past two decades, lithium ion battery costs have decreased by 97% according to MIT researchers. Since sodium ion batteries may not be adopted by electronic devices and electric vehicles, which contributed significantly to the rapid decline of lithium ion costs, the sodium ion cost trend may not decrease as rapidly. Sodium ion’s low material cost, versus lithium ion, could enable a lower price point in the future if vendors manage to come down the cost curve in the absence of initial markets. EPRI is also conducting a cost study that compares engineering, procurement, and construction (EPC) costs to understand how this will vary based on technology characteristics (e.g. energy density, safety design requirements). This cost study will be published in December 2021.   

Related Research: EPRI will be updating the Energy Storage Technology Database entry on sodium ion batteries in July.