Has the Lithium-Ion Battery Reached Its Limits?

From leaf blowers and electric cars to massive grid storage systems—lithium-ion batteries are the undisputed stars of the battery world. But their environmental impact is coming under increasing scrutiny. As a result, researchers are racing to refine and even replace them.

Last year, a battery came online in California’s Mojave Desert that is nothing short of colossal. The Edwards & Sanborn project consists of 120,000 battery modules, capable of storing roughly 3.3 gigawatt-hours of electricity. At its heart: lithium-ion cells. Currently, it stands as the largest battery storage facility in the world.

Projects of this scale are driving the global energy transition forward. Wind and solar farms supply power intermittently, so storage is essential to even out the fluctuations. Batteries excel at this role because, unlike pumped hydro storage, they require no startup time and can react instantly to demand. As a result, investments in massive energy storage systems (ESS) are surging worldwide. A glance at the DOE Global Energy Storage Database reveals where these installations are springing up—and how much capacity they offer.

One thing is clear: demand for batteries will only grow in the years ahead. Germany alone will need an estimated 100 gigawatt-hours of storage capacity by 2030, according to calculations by the Fraunhofer Institute for Solar Energy Systems in Freiburg. The “Battery-Charts” website lists where such systems are located and their performance. Strikingly, most installed capacity to date is in residential storage.

This fall, Germany’s largest battery storage system is set to go online in Alfeld, Lower Saxony. Comparable in size to a factory, it will offer a storage capacity of 275 megawatt-hours—enough to rival a small coal-fired power plant. This massive battery, packed into 72 containers filled with lithium cells, will be able to power a million households for an hour.

Lithium-ion batteries are now nearly ubiquitous—not just in large-scale storage, but in smartphones, laptops, power tools, and electric vehicles. At first glance, they appear unrivaled: high energy density, minimal self-discharge, and the ability to handle many charge-discharge cycles. Above all, they are dirt cheap. Since their market debut in 1991, their price has plummeted by an astonishing 97 percent.

A Troubling Environmental Footprint

Nevertheless, scientists are working feverishly to optimize lithium-ion batteries—or replace them with new types altogether. The reasons are twofold: new applications require batteries with tailored properties, and lithium-ion batteries’ environmental and climate footprint is far from ideal. Lithium extraction consumes vast amounts of water and emits large quantities of CO2. “Environmental sustainability has become a crucial factor—one that lithium-ion batteries in their current generation struggle to meet,” says Christoph Neef, a battery researcher at the Fraunhofer Institute for Systems and Innovation Research in Karlsruhe.

Understanding how a battery works—and where there is room for improvement—requires a look inside the lithium-ion cell. Lithium initially resides at the positive electrode. During charging, positively charged lithium ions migrate through the electrolyte to the negative electrode, where they are stored. The energy is thus held in chemical form within the battery. When discharging, the ions flow back to the positive electrode, and the released energy becomes available at the terminals.

Researchers are experimenting with new material combinations for the electrodes and electrolytes to further develop these batteries:

• The positive electrode, or cathode, is the most crucial component, dictating both the voltage a cell can deliver and the amount of energy it stores. It is also the most expensive part. In terms of performance, lithium-based chemistries remain unmatched. “There is no other practical element that enables such a high cell voltage,” says Neef. Yet, there’s still wiggle room: lithium in the cathode is always paired with other elements such as cobalt or nickel—both costly and often problematic. As a result, researchers are testing cheaper alternatives, like sulfur.
• The negative electrode, or anode, is usually made from graphite. This carbon material is lightweight, affordable, and stores a lot of energy. But graphite has its downsides. “It limits both cell lifespan and fast-charging capability,” Neef explains. Researchers are therefore working with silicon-based alloys, which allow for much faster charging and higher energy densities—since silicon can interact with more lithium than graphite can.
• The electrolyte, typically a salt enhanced with up to 20 additives, permeates the entire cell and accounts for around 15 percent of its weight. It also affects efficiency. “With new electrolytes, for example, you can improve fast-charging capability or enable better operation at low temperatures,” says Neef.

The Search for the Next Big Battery

There’s still considerable room to optimize the lithium-ion battery. “There are even further gains to be made in energy density,” notes Martin Winter, director of the MEET Battery Research Center at the University of Münster. “But the leaps won’t be as dramatic as in the past.”

Which means new battery types are on the horizon. One of the most talked-about alternatives is the solid-state battery. Instead of a liquid electrolyte, it uses a solid—often ceramic. This next-gen battery is projected to achieve energy densities of 450 watt-hours per kilogram and beyond, far surpassing today’s lithium-ion technology. Solid-state batteries are also inherently safer, can be charged even more rapidly, tolerate higher temperatures, and retain capacity at subzero temperatures—a boon for electric cars in winter.

Solid-state batteries are thus widely viewed as the next evolutionary leap in battery technology. They’re expected to power the next wave of electric vehicles, making them even greener. A study by Brussels-based NGO Transport and Environment found their CO2 footprint is 24 percent lower than that of today’s standard lithium-ion batteries. But commercialization will take time, mainly because the industry must scale up manufacturing from scratch.

Yet there are limits to how much researchers can simply swap out materials in batteries. Tweaking one component often requires reworking the others. For instance, solid electrolytes are incompatible with graphite anodes—they must be replaced with lithium, which is still a rare resource. Depending on the design, even solid-state batteries require lithium.

Still, from an environmental perspective, solid-state batteries have clear advantages—not least because they do away with cobalt. Cobalt mining can release toxic substances that seep into groundwater, and the element is frequently extracted under appalling conditions. The mines of Congo, where children are reportedly forced to work, are notorious.

Another contender for the battery of the future is the sodium-ion battery, in which sodium replaces lithium. Although their energy density—about 150 watt-hours per kilogram—is not designed for peak performance, and they are currently even more expensive than their lithium counterparts, says Winter, sodium-ion batteries are already powering some electric vehicles in China. Their greatest advantage: sodium is abundant and does not require destructive extraction processes. It is found in the form of sodium chloride—common salt—in the world’s oceans.

A 200-megawatt (400 megawatt-hour) hybrid storage plant, combining lithium and sodium batteries, has just been commissioned in Yunnan province, southwest China. According to a PV Magazine report, the facility connects 30 wind and solar parks, completes two cycles daily, and is charged 98 percent with renewable energy.

Is This the End of the Lithium-Ion Era?

So, is the age of the lithium-ion battery drawing to a close? Hardly. Their performance remains unrivaled. What’s more, their environmental profile could improve dramatically through large-scale lithium recycling from retired batteries—a process only now beginning to ramp up. For Fraunhofer’s Christoph Neef, one thing is clear: “The market for recycled lithium could cover a significant portion of future demand.”

Going forward, there won’t be a one-size-fits-all battery for every application. Quite the opposite: the market will become more diverse, and requirements more specific. Is cost the priority, or performance, longevity, or scalability? Instead of chasing a single “super-battery,” technology will be tailored to the demands of individual applications.

As a result, the battery is increasingly becoming the defining component that differentiates electric vehicles from one another. The companies and countries that command the most battery know-how will dominate the market. Here, however, Germany is at risk of falling behind.

“The previous German government shamefully neglected battery research funding—despite its status as a key technology—over the past two years. We are now feeling the consequences, especially in the automotive industry. The question is whether the new government’s promises will translate into action. Only with a major catch-up effort will we be able to remain self-sufficient in battery production and technology evaluation in the future.”

Neef remains somewhat optimistic: “There’s nothing official yet, but we’re seeing positive signals from the Ministry of Research and Technology that a new battery research program is on the horizon.” Even the coalition agreement offers encouraging hints: Germany plans to promote battery cell manufacturing, including raw material extraction, recycling, and machinery.

For now, though, about 90 percent of all battery cells are made in Asia.