While lithium ion vehicles batteries are the leading BESS form factor/chemistry, are they the best tech for static deployments?
In addition to covering fusion energy, The Fusion Report also frequently covers adjacent technologies and topics. One of those adjacent technologies is battery energy storage systems (BESS), which plays a growing role in the overall US electricity picture. While lithium-ion batteries, long the battery technology of choice for electric vehicles (EVs) and in other mobile battery use cases, is currently the dominant technology, there are a number of other technologies (in development, deployment trials, or in production) that have significant advantages for BESS when weight is not an issue. In this article we will look at the various technologies, the players making them, and the status and advantage/disadvantages of these various technologies.
The BESS Picture Today: Lithium-Ion Batteries Dominate
Today, the dominant storage for BESS is undoubtedly lithium-ion batteries. And the reason for this is simple: EVs use lithium ion batteries. At the end of 2023, over 90% of lithium-ion battery production was used for EVs, significantly driving down battery prices. Between 2010 and 2023, lithium-ion battery prices have declined by 90%, going from $1,400 (US) per kilowatt-hour (kWh) to $140 per kWh. While the technology’s declining costs are largely the result of the 45 million EVs on the road today, lithium-ion battery prices are driven by the proliferation of personal electronic devices such as smartphones, cameras and laptop computers.
Moreover today, the most important innovations in BESS come from batteries destined for EVs. An example are last month’s announcements at the Contemporary Amperex Technology Company Ltd. (CATL) Super Tech Day 2026. The Chinese battery company, which is the world’s largest EV battery manufacturer, holds a 39.2% global EV market share. At Super Tech Day 202 6, CATL announced their third generation Shenxing battery, which can charge from 10% to 98% in under six minutes and thirty seconds, as well as their Qilin Condensed Battery, which reaches 350 Wh/kg and 760 Wh/L, enabling up to 1,500 km of range in executive-class sedans. This is one of the reasons that CATL has been world’s largest battery manufacturer for eight years straight, and in a larger sense why Li-ion batteries have dominated the BESS ecosystem for so long.
This is also one of the reasons for the growth in BESS for grid storage, with installations rising over 75% in 2022, and surpassing 85 gigawatts (GW) in capacity. As a result, the IEA expects EV battery use to reach 3.45 TWh (of the total battery use of ~3.85 TWh) by 2030 in the stated policy scenario (STEPS) model, or up to 5.4 TWh (of the total battery use of 6 TWh) by 2030 in the net zero emissions (NZE) model.
For grid storage uses, lithium ion batteries are highly scalable, making them a popular choice for rapid and flexible deployment by utilities. While pumped storage hydropower is still the most widely used grid storage technology today (and has the advantage of being a long-term storage medium), it is lossy and is limited by geographical and size constraints. This is one of the drivers why utility scale batteries will overtake pumped hydro as a storage medium for grid storage, as well as for behind the meter batteries.
Despite the size of the EV market, lithium ion battery technology has already started to diverge for static batteries versus mobile batteries. The leading mobile lithium ion technology, the nickel magnesium cobalt version of lithium-ion batteries, is losing market share to the lithium ion phosphate version for stationary storage uses due to its superior safety and longer life cycle. However, lithium ion batteries have generated significant concern when used for static BESS deployments because of its issues with fires, which have unfortunately happened a number of times. Beyond flavors of lithium-ion batteries, there are several other challenger technologies for use in stationary BESS applications.
Sodium Ion Batteries: The Challenger Technology
Sodium-ion batteries are considered the most promising alternative to lithium-ion batteries, primarily because of the abundance of sodium around the Earth. While sodium ion batteries have a somewhat lower energy density than lithium ion batteries, this is less of an issue in stationary BESSs than the fire and safety concerns, where sodium ion batteries are considerably superior. Additionally, sodium ion batteries have a superior cycle life (they lose less charge per cycle) than lithium ion batteries. Today, sodium ion batteries are in early commercial scale stationary BESS deployments, And they are available globally from a number of companies. Global sodium ion battery shipments reached 9 gigawatt hours in 2025, up 150% the year previous and are expected to exceed 1,000 gigawatt hours by 2030. An example is CATL’s Naxtra sodium-ion battery, which is set to enter mass production in 2026.
Redox Flow Batteries: Purpose-Built for Large-Scale BESSs
In many ways, lithium-ion and sodium-ion batteries are very similar, from a chemistry standpoint (except the for the use of sodium instead of lithium), a use case standpoint, and their appearance. The same cannot be set for vanadium redox flow (VRF) batteries, the most popular form of redox flow batteries. In VRF batteries, the power (kW, modulated by stack size) and energy density (kWh, modulated by tank size) are independent of each other, allowing systems to be customized to the need. In addition, they have a long life cycle, high safety from using an aqueous electrolyte, and can be completely discharged without damaging the battery. From a negative standpoint, VRF batteries have very low energy density and require considerable amount of space. Additionally, they have high system complexity because they need pumps and sensors, which considerably raises the initial capital cost of VRF batteries compared to lithium ion or sodium ion batteries (though they are competitive on lifecycle costs). However, VRF batteries are highly mature and are widely available.
The Emerging Technology: Iron-Air Batteries
Even more of a contrast with lithium ion batteries are iron air batteries, an emerging technology that still needs optimization of its long-term reliability and optimization in manufacturing costs to make it viable. While having even lower energy density than sodium ion or VFR batteries (think a LOT lower), iron is extremely abundant and inexpensive, with iron-air batteries having a cost of less than $20/kWh. Additionally, they are non-flammable and non-toxic, and capable of 100+ hours of energy storage. On the negative side, they have slower response time (i.e., they cannot deliver quick bursts of power), and lower round-trip efficiency, losing energy during the charge/discharge cycle. In essence, iron-air batteries do not play in the same use case as lithium-ion or sodium-ion batteries, being more suited to multi-day (long-term) storage like pumped hydropower energy storage.
Conclusion: Batteries Are An Important Part of Our Energy Picture
In 2018, there was roughly 500 MW of grid-scale battery energy storage system (BESS) capacity in California. In 2025 that number reached 16.9 GW, almost 34x the number in 2018. This growth has been at least partly driven by the rapid drop in cost of grid-scale BESS, which has fallen 93% since 2010. Highlighting the importance of batteries to California’s utility grid was its performance in late March 2026, where on a hot Sunday evening the BESS capacity switched on and provided 12.3 gigawatts of power to the grid as the state approached sunset. That is the equivalent of 12 nuclear power plants, or six Hoover dams, switching on all at once.
Whether the Trump administration likes it or not, solar energy is one of the most abundant resources on our planet. However it is also highly variable, depending on both the time of day and on weather conditions which affect its output. The same is also true of wind power, which is even more variable from time to time and day to day. To make these power sources dispatchable (i.e., arbitrarily variable during the day, regardless of weather conditions) so they can be used for baseload power, we need effective grid-scale BESS infrastructure, which are being deployed by states like California and Texas (together having nearly 2/3 of the US BESS capacity of 45 GW), as well as countries like Germany (27 GW of BESS capacity), Spain, Italy, and China (the world leader in BESS grid usage with 144.7 GW, 3X that of the US). For similar reasons, BESS resources are also critical to balance power availability during power spikes, which strain the power grid and can result in brownouts or blackouts. Even with abundant baseband power resources, BESS resources are still a necessary part of a resilient power grid. The development of new technologies for BESS provide an expanding array of tools for us to utilize to achieve that.
