The Future of Battery Technology: Chemistries, Comparisons, and the Close Prospects

Recent technological advances have ensured that lithium-ion batteries will play an increasingly important role in our lives and society. With the accelerating shift towards electric vehicles, and the growing integration of inherently intermittent renewables into our energy system, an increasingly larger portion of the world is battery-powered.

The stationary battery market is seeing a transition from lead to lithium, and with the commercialization of new materials like solid-state batteries, lithium is poised to dominate further. Nonetheless, sodium-ion batteries have emerged as the complement of choice to lithium-ion batteries, being cost-effective, safe and sustainable.

The Chemistry of Choice – Lithium-ion
The considerable success of lithium-ion batteries is in large part due to the technological improvements made in recent years. In the past decade alone, the energy density of lithium-ion batteries has more than doubled. The first lithium-ion battery was commercialized in 1991, combining high energy density, long cycle life, and low self-discharge in a single package. Because of these properties, and the significant price drop since its introduction, lithium has become the chemistry of choice for most applications requiring rechargeable battery solutions and a key driver for its growth in use worldwide.

However, the lithium-ion battery is not a single chemistry. Rather, it comes from a family of chemistries that all shuttle lithium-ions in between host electrodes using a process called intercalation. There are two dominant chemistries on the market today for this: nickel-based, such as NMC (nickel manganese cobalt oxide) or NCA (nickel cobalt aluminum oxide) and iron-based, mainly LFP (lithium iron phosphate). These are examples of positive electrodes (often referred to as cathodes).

Lithium is Replacing Lead
The lead-acid battery was invented in 1859 and has been the dominating rechargeable battery chemistry at least since the beginning of the 20th century. However, its low gravimetric energy density of about 30 Wh/kg makes it impractical for mobile applications. State-of-the-art lithium-ion battery cells now offer ten times that energy density. With commonly available lithium cells, this means that a lithium-ion battery module with the same performance (rated voltage and capacity) as a corresponding lead-acid battery, has a weight of approximately a fifth of the lead battery and approximately a third of the volume.

In hindsight, it may be argued that the very commercial success of the lead-acid batteries hindered its technological development, rather than trying to push its low energy density towards its theoretical maximum of about 180 Wh/kg.

The decrease in the cost of lithium-ion batteries has resulted in many industries making the switch from lead to lithium for stationary applications. This enables industries to provide a lower total cost of ownership combined with a significantly reduced space and weight requirement. Cycle life is also increased, and self-discharge is reduced.

The Potential of Solid-state
Small incremental improvements in lithium-ion battery energy density can be expected in the years ahead. However, the next major leap will likely come with the introduction of lithium metal negative electrodes. This will lead to an energy density increase of about 30-50 percent compared to today.

The introduction of lithium metal electrodes is often discussed together with another technological advance: solid-state batteries. In short, solid-state batteries replace the liquid electrolyte of traditional lithium-ion batteries with a solid-state material (e.g., a ceramic). Solid-state materials will make lithium-ion batteries safer because they effectively remove the fuel for the fire. Lithium metal electrodes and solid-state batteries are expected to be commercialized at scale within the next five to ten years.

Sodium-ion: The Perfect Complement to Lithium-ion
Another promising quantum leap in battery technology is sodium-ion technology, having emerged as the premier complement to lithium-ion technology. Sodium-ion batteries (NIBs) are analogues to lithium-ion batteries where the lithium ion (Li+) is replaced by sodium ions (Na+), having the same basic cell construction, and working principle.

Using sodium-ion battery cells brings distinct advantages. Sodium-ion batteries cost less to make compared to lithium-ion batteries, thanks to sodium’s abundance. They perform well, enduring many cycles, operate across a range of temperatures, and are safe. Importantly, these batteries are sustainable. The materials used are widely available across Europe, and they recycle easily.

Yet, today, their energy density falls short of lithium-ion, but still making them fit for stationary storage. The field advances quickly, fueled by significant resources being allocated to enhance sodium-ion batteries’ performance. In late 2023, Polarium initiated a partnership with the Swedish sodium-ion battery developer Altris, to develop and demonstrate an energy storage solution based on sodium-ion.

By: Ulf Krohn, VP Research & Development at Polarium