Lithium batteries have helped power society’s shift to renewable energy, serving as the industry standard for everything from electric vehicles to grid-scale energy storage. Scientists are continually looking for sustainable non-lithium battery alternatives because lithium-ion batteries come with safety risks and environmental consequences in their production.
Lithium batteries are the most widely used rechargeable batteries in today’s technology. They power devices ranging from smartphones to electric cars. These batteries are composed of individual lithium-ion cells and a protective circuit board. The history of lithium-ion battery technology dates back to the 1970s when researchers began exploring the potential of lithium as a battery material due to its low electrochemical potential. In the 1980s, Sony introduced the first commercial lithium-ion batteries using lithium cobalt oxide as the cathode material. Over the years, scientists have developed different cathode materials like lithium iron phosphate (LFP / LiFePO4) and lithium nickel manganese cobalt oxide (NMC) to improve the safety, stability, and energy density of Li-ion batteries. Researchers continue to explore new materials and technologies to enhance the performance of battery technology, aiming to increase energy storage capacity and reduce costs.
Here is a look at the challenges of lithium-ion, or Li-ion, and how emerging battery technologies strive to be safer and lower-cost alternatives to lithium batteries while still balancing performance, cost, and environmental impact.
What Are Non Lithium Battery Alternatives?
As demand for sustainable and efficient energy storage solutions rises, researchers and engineers are exploring lithium alternatives. New promising emerging battery technologies include solid-state lithium batteries, sodium-ion batteries, lithium-sulfur batteries, and flow batteries. These innovative approaches aim to enhance energy density, improve safety, reduce environmental impact, and lower costs, ultimately shaping the future of battery energy storage systems and electric vehicles.
Solid-State Lithium Batteries
Instead of a flammable liquid electrolyte, solid-state batteries use a solid electrolyte to reduce the risk of fires caused by thermal runaway. Solid-state batteries can potentially pack more energy into a smaller space, making them useful for applications like EVs where more energy translates to more miles per charge.
Solid-state batteries may also exhibit better cycling stability, which is the ability of a battery to maintain its performance and capacity over repeated discharge cycles without significant degradation. They can also operate over a wider temperature range, making them more suitable for extreme environments.
Despite recent advancements in solid-state technology, scientists are still trying to find an electrolyte that simultaneously offers high conductivity, stability, and low manufacturing costs. The most promising solid-state battery chemistries have been difficult to scale up for mass production at an affordable price point, and developers need a cost-effective means of manufacturing the batteries before they can be used commercially.
While solid-state batteries may be safer when it comes to thermal runaway imposed by normal operation, researchers at Sandia National Labs have concluded that they could pose similar risks as traditional lithium-ion batteries when punctured or crushed.
Sodium-Ion Batteries
Sodium-ion cells work like lithium-ion, shuttling sodium ions (Na+) instead of lithium ions (Li+), and can be built on existing lithium-ion lines with minor modification. Sodium is the sixth most abundant element in the crust and is not a critical mineral. Sodium-ion cells also use aluminum current collectors on both electrodes, rather than the copper lithium-ion uses. That matters twice over: aluminum trades at roughly a quarter of copper’s price, so one of the costlier line items comes out of the bill of materials entirely, and it allows the cells to be discharged to 0% state of charge for transport and storage.
The category splits into three cathode families: layered metal oxide, Prussian blue analogues, and polyanionic. Layered metal oxides have the highest energy density but cycle life in the 3,000 to 4,000 range. Prussian blue analogues have high power density — their open framework moves sodium quickly — but can release hydrogen cyanide at elevated temperatures. Polyanionic chemistries, including sodium iron pyrophosphate (NFPP), trade some energy density for a rigid structure and long life.
Thermal performance, including flammability, is a function of the cathode and what it does under stress — not of sodium-ion as a category. Layered oxides release oxygen from the cathode lattice as they decompose, which sustains a runaway reaction much as NMC lithium-ion does. Polyanionic cathodes bind their oxygen in rigid phosphate groups and don’t release it, so there’s no internal oxidizer to feed. That same rigid structure holds its shape through cycling — volume change stays under 4% — which is what gives polyanionic cells their long cycle life.
Polyanionic is the chemistry Alsym selected for its Na-Series NFPP+ cells — NFPP with proprietary electrode dopants and electrolyte additives — non-flammable at the chemistry level rather than by system design, so no fire suppression and no thermal management for safety. They deliver 97% cell-level round-trip efficiency, 15,000 cycles over 20+ years, 100% usable capacity, and −40°C to 60°C on passive cooling — a combination well suited to stationary storage deployed across widely different climates.
Lithium-Sulfur Batteries
Some companies are looking into lithium-sulfur (Li-S) batteries as a sustainable alternative to Li-ion. Rather than relying on scarce materials like cobalt, Li-S batteries would benefit from the wider availability of sulfur, making them less dependent on limited resources and cheaper to produce. Li-S batteries also have a theoretical energy density several times higher than that of lithium-ion batteries, storing an equal amount of energy in a more lightweight form.
However, Li-S batteries tend to degrade more rapidly due to poor cycling stability. Sulfur does not have high electrical conductivity to begin with. It also undergoes significant volume expansion and contraction during charge and discharge, resulting in the dissolution of active material and a loss of charge capacity. Additionally, the chemical reaction between sulfur and lithium results in the formation of compounds that reduce Li-S batteries’ efficiency over time.
Further, lithium metal supplants the graphite anode in Li-S batteries. Li metal anodes have a host of other issues associated with dendritic plating, excessive Li consumption in the formation of SEI, and an increased risk of thermal runaway from shorting.
Flow Batteries
Flow batteries, also known as redox flow batteries, are a type of rechargeable battery where energy is stored in liquid electrolyte solutions that are kept in external tanks, as opposed to conventional batteries where the energy is stored by electrodes within the battery cell itself.
Flow batteries consist of two separate tanks of liquid electrolyte solutions. The electrolytes are pumped from these tanks into a cell where they are separated by a membrane. One electrolyte acts as the cathode and the other as the anode. The electrochemical reactions take place in the cell. During the discharge phase (i.e., when energy is being supplied for an external device), electrons are transferred from the anode to the cathode, creating an electric current that oxidizes and reduces the electroactive species in the electrolyte on the respective sides of the cell. During charge, the electroactive species in the anolyte (anode side of the membrane) decreases oxidation state while that of the catholyte (cathode side) increases oxidation state. During the charging phase, an external power source is used to reverse this reaction, replenishing the electrolytes.
Flow batteries have a very long cycle life and minimal degradation over time because the energy is stored in the electrolyte rather than in the battery cell itself. Another advantage of flow batteries is that they can be left completely discharged for long periods without suffering any damage, which is not the case with many other types of batteries. They also have a quick response time.
Flow batteries have some downsides as well. Their energy density is significantly lower than lithium-ion batteries, meaning they take up more space for the same amount of energy stored. This makes them unsuitable for portable applications, or situations where grid storage is needed in urban or suburban areas. They can also be complex and expensive to manufacture and maintain, as the system involves pumps, sensors, and control units to manage the flow of the electrolyte.
Negative Effects of Lithium-Ion Batteries
Even though they are promoted as a way to mitigate climate change, lithium-ion batteries cause damage to the environment during their manufacturing. For instance, every ton of lithium extracted through hard-rock mining results in 15 metric tons of carbon dioxide emissions. Moreover, the technology uses a narrow set of raw materials — lithium, cobalt, and nickel, among others — controlled by a handful of countries in South America, Asia, and Africa.
This far-flung supply chain not only leads to high transportation costs but also results in a number of environmental and ethical issues:
• Lithium mining has been associated with accelerating drought and displacing Indigenous populations in countries ranging from Chile to Serbia.
• Most of the world’s lithium refining facilities are in China, which is notorious for its abundant use of heavily polluting coal.
• Cobalt mining in the Democratic Republic of Congo is known for exploiting child labor, displacing residents, and damaging the environment.
• Nickel mining in Indonesia has contributed to deforestation, soil erosion, and water pollution.
Lithium-ion batteries also pose significant safety risks. Their organic electrolytes have flash points as low as 60 degrees Celsius, and improper use can cause them to overheat. Before a battery cell in thermal runaway actually catches flame, it vents flammable gases such as hydrogen fluoride and carbon monoxide. These toxic vapors can cause an explosion when they ignite, making Li-ion battery fires especially dangerous, even “safer” chemistries like LFP / LiFePO4.
Alsym’s NFPP+ Sodium-ion Cells
Alsym’s NFPP+ sodium-ion battery cells can be manufactured in the same facilities but at a lower cost than lithium-ion batteries, allowing us to take advantage of existing infrastructure and industry knowledge. While other battery technologies must be produced in costly dry rooms and clean rooms and use toxic solvents that require recovery systems, our batteries can be built with less complexity and increased safety.
NFPP+ is built on sodium, iron, and phosphorus — three of the most abundant elements in the Earth’s crust, none of them critical minerals, and none carrying the mining and refining burden that lithium, cobalt, and nickel do. They are produced at scale in many countries, so sourcing does not depend on a narrow set of deposits or a single refining hub.
We’re working to make low-cost, non-flammable sodium-ion batteries available to all. Contact us to find out more about the future of sodium-ion batteries for energy storage.
