Challengers emerge: alternatives to lithium-ion batteries

As the energy sector pivots toward renewable mass storage options, new or at least improved technologies will be required to service global energy needs into the future.

Lithium-Ion batteries were an amazing technological breakthrough. Dually tackling the main weaknesses of alkaline batteries – rechargeability and mass energy storage – lithium-ion technology truly revolutionised the energy storage industry.

First discovered by American chemist Gilbert Lewis in 1912, lithium-ion technology has since come to dominate the battery market, with the global lithium-ion market valued at US$53.6 billion in 2020, expected to grow at a compound annual growth rate (CAGR) of 19.0% from 2020 to 2028.

In this article:

• What is a lithium-ion battery?
• New kids on the block: lithium-ion alternatives
• Dual carbon
• Sodium-ion
• Zinc-ion
• Honourable mention: redox flow batteries
• Battery technology driving a cleaner, greener future

Lightweight with high energy density and low lifetime cost in comparison with traditional alkaline-based batteries, lithium-ion batteries are essential to the booming electric vehicle industry.

Unfortunately, demand will likely soon far outstrip supply, and projections of earth’s total lithium stores indicate that the resource may soon be depleted – as early as 2040 by some estimates.

As the energy sector pivots toward renewable mass storage options, new or at least improved technologies will be required to service global energy needs into the future.

The issue is further complicated by the markets’ heavy investment in lithium-ion manufacturing, requiring emerging technologies to adopt standardised manufacturing processes that will allow for low cost, rapid scale-up and conversion using existing infrastructure.

What is a lithium-ion battery?

Lithium-ion batteries are a type of intercalation battery, which means the same ion is reacting at both the anode and cathode, travelling between the two through a liquid electrolyte.

As the battery discharges, the lithium ion is released from the anode, travels through the liquid electrolyte, and is absorbed by the cathode. Recharging reverses the process.

Lithium-ion batteries have an energy density of anywhere from 100-265 watt-hours per litre, much higher than most other types of batteries.

They are not without their downsides, however, requiring expensive cathode and anode materials in the form of cobalt, nickel, manganese and aluminium.

They are also unstable in some environments, namely when overheated or when the internal battery is exposed to water or air.

They have been known to cause dramatic exothermic reactions under the wrong circumstances, which led airlines to ban batteries with more than 160 watt-hours from being carried onto flights as personal baggage.

Similarly, lithium-ion batteries must be kept within careful charging and discharging cycles and voltages, lest they degrade or combust.

Finally, lithium-ion batteries have a set lifespan of 2,000 to 3,000 cycles and will slowly deteriorate over time even when not in use, just like alkaline or nickel-cadmium batteries.

Current models are expected to last 10 to 20 years in the right temperature conditions, with a slow but progressive decline in energy storage capacity as they’re charged and recharged.

So, given lithium-ion's limitations and supply concerns, what are the alternatives?

New kids on the block: lithium-ion alternatives

New battery types are in research and development already, representing dozens of different universities, companies and state initiatives all working toward alternatives to lithium-ion batteries.

There has been considerable success in identifying potential new materials to base these batteries on, with everything from sulphur to vanadium to graphite coming under the microscope.

The bar for entry is high, as lithium-ion represents a major step up from any previous commercial battery technology. An interloper would need to match, if not beat, lithium-ion’s energy density, rechargeability, raw material and manufacturing costs, safety and scalability.

Considering the amount of capital already invested in lithium-ion manufacturing, a challenger would also likely need to be compatible with, and preferably simplify the lithium-ion manufacturing process.

Dual carbon

Also called the Ryden battery, dual carbon battery technology was originally based on the work of Professor Tastumi Ishihara at Kyushu University in Japan but has since been adopted by Power Japan Plus to be developed on a commercial level.

Perhaps the frontrunner in the race to replace lithium-ion, this technology uses carbon at both the anode and cathode of the battery, offering energy density comparable to lithium-ion but over a longer potential functional lifetime with improved safety and much cheaper raw materials.

Dual carbon batteries also charge as much as 20 times faster than traditional Lithium-ion and can utilise existing manufacturing lines.

Power Japan has already moved to commercialise dual carbon batteries, releasing the first generation in August 2021.

Dual carbon is well-placed as a comparable, already commercial technology capable of using existing lithium-ion manufacturing infrastructure.

There are very little downsides to the Ryden battery, which offers full recyclability (being purely carbon) and eliminates the need for complex, expensive cooling systems with its completely temperature-stable operation.

In fact, the only real ‘problem’ the Ryden battery has is that Power Japan intends to sell the units directly to only satellite communications and medical device segments despite already being electric vehicle compatible. Others will have to wait for it to become commercially available.

Sodium-ion

In December 2020, scientists from the Tokyo University of Science, Japan, found an energy-efficient method to fabricate a hard carbon electrode with very high sodium storage capacity.

Made with inexpensive and abundant materials, with a potentially higher energy density than lithium-ion, multiple companies and research teams have now invested capital in researching and developing sodium-ion batteries.

Contemporary Amperex Technology (CATL), a Chinese battery manufacturer and technology company, has already released its first generation of sodium-ion batteries.

The energy density of CATL’s sodium-ion battery cell can achieve up to 160 watt-hours per litre, and the battery can charge in 15 minutes to 80% capacity at room temperature, much faster than lithium-ion. CATL is targeting 200 watt-hours for the next generation of these batteries.

Zinc-ion

Zinc-ion batteries are another intercalation-style battery that uses zinc anodes and cathodes. The technology uses a water-based electrolyte that vastly improves on safety – zinc being another fairly stable element when compared with lithium – and does not react with oxygen.

Salient Energy announced its zinc-ion battery in early 2021, touted as the ‘future of the energy storage industry.’

Zinc-ion batteries will be heavier than equivalent lithium-ion, one of the few drawbacks for the much cheaper technology.

Offering similar performance in terms of energy density, Zinc-ion will have a lifespan of potentially 15-20 years with four-hour charge/discharging cycles and similarly sized battery packs.

Recent attempts to produce a metal oxide cathode Zinc-ion battery resulted in a much more energy-dense battery, offering an energy density of 450 watt-hours per litre with half as many recharge cycles.

Honourable mention: redox flow batteries

Vanadium redox flow batteries (VRFB) are structural batteries with a vanadium base, a type of rechargeable flow battery that uses vanadium’s ability to exist in four different oxidation states to produce energy from a single electroactive element.

Unfortunately, due to the structural nature of these aqueous batteries, they are bulky and heavy, with a much larger spatial footprint when compared with lithium-ion batteries.

They are quickly becoming a front-runner for grid stabilisation however, with a lifespan of over 20 years, no degradation over time, a life cycle of 15,000 to 20,000 charges and discharges, no limit on energy capacity per unit and a very low production cost, making them an attractive option in structural applications.

South Australia has already bought into the technology, commissioning Australia’s first-ever utility-scale vanadium flow battery to be installed in regional South Australia with the goal of providing scalable, flexible, medium-duration energy storage.

Considering the global push toward renewable energy and carbon neutrality, such batteries may eventually support our energy grids as we make the transition to green power sources.

Battery technology driving a cleaner, greener future

This article is by no means an exhaustive review of lithium-ion battery alternatives, with new technologies emerging constantly even as ‘old’ technologies are innovated and improved upon.

While it’s impossible to predict which carbon-neutral, renewable power source will carry us into the future, it’s obvious that the global energy storage industry will only grow from here.

It will require progressively more efficient, cheaper, and more sustainable options as the world transitions away from fossil fuels and hydrocarbon-based energy storage and into green energy and sustainable storage solutions.

Many of these batteries already rival lithium-ion in capabilities, but are lagging in capital investiture and manufacturing infrastructure, playing catch-up with an already established sector of the industry.

Lithium-ion batteries are certainly here to stay, at least for now, but the energy storage sector will no doubt be an exciting industry to watch evolve over the next few decades.

Stay tuned for part two, where we’ll explore players in the lithium-ion alternative battery space.