During our Top Innovators of 2021 Forum in Renewables & Energy Storage we asked our clients which topics would they like us to focus on in our research on 2022. Here are the results:

Figure 1.Poll results from Top Innovators of 2021 Forum in Renewables & Energy Storage.

With new battery chemistries at the top of the list and still some months until our Forum on the topic, we have gone ahead and listed the innovators that are gaining traction due to their development and implementation of new battery chemistries. These technologies make use of cheaper, more abundant, and safer materials than li-ion, but will likely not replace li-ion batteries in the short-term.

To get a full picture of these technologies you can also take a quick look at our framework on these new battery chemistries:

Figure 2.New battery Chemistries Framework. Click here for full version.

If you want to dive deeper into this area, here is a breakdown of the basics of each of these technologies:

Metal-ion Batteries

As with lithium-ion batteries, sodium-ion & zinc-ion batteries utilize the same ion storage principle, using the alkali ions only as charge carriers while energy is reversibly stored and released in intercalation and/or conversion electrodes. Since they utilize similar electrochemical principles to lithium-ion batteries, the sodium-ion & zinc-ion battery technology can track and adopt most of the knowledge gained through the extended and in-depth studies conducted with lithium-ion battery technology. They would also be able to be manufactured making use of li-ion batteries’ manufacturing infrastructure. In this sense, the similarity of these technologies with li-ion is a good starting point for the implementation of advanced production of sodium-ion & zinc-ion batteries, substantially lowering their cost.

The low price and unlimited available resources are the major advantages of these technologies. In fact, especially if shortage of supplies or peaking prices of lithium and cobalt will occur, sodium-ion & zinc-ion batteries could serve as an affordable complementary device. Specifically for sodium-ion, their renaissance is not only because of the remarkably higher natural abundance of sodium compared to lithium, but also the ease availability even from seawater.

Still, the relatively lower energy density of these batteries compared to their Li-ion counterparts cannot be overcome. Therefore, the possible fields of application are narrowed to those where energy densities (both gravimetric and volumetric) are not the main requirements.

Sodium-ion Batteries

The abundance of resources, relatively low cost, and the possibility of employing bio-waste materials from the production of the active electrode materials might compensate for the intrinsic low energy density of Na-ion batteries, enabling their market penetration as a cost-effective, more sustainable technology. However, to establish these performances, researchers in the Na-ion battery field must find new electrolytes enabling lower costs and higher safety. Sodium-ion batteries have been already commercialized for grid-scale applications, but its cost is in the range of $445–555/kWh.

Zinc-based batteries

Metallic zinc has been regarded as a promising anode material for various primary and secondary batteries, due to its high specific volumetric capacity (5855 mAh cm⁻³), high abundance, and intrinsic benignity.

Zinc-ion

As commented in the previous section, zinc-ion batteries (ZIBs) are considered among the most promising systems for large-scale energy storage, due to their similar principle to lithium-ion batteries and advanced research. Enerpoly is developing this technology, starting the pilot programs mid of 2022, and their batteries being tested by a third party in Q3.

Zinc-bromine

Zinc-bromine batteries are often related to flow batteries, but there are two companies who have been making innovative strides with this chemistry. Gelion (Australia) and EOS Energy Enterprises (USA) are developing and commercializing their non-flow zinc-bromine batteries. Both flow and non-flow zinc-bromine batteries share many advantages over incumbent lithium-ion storage systems:

• 100% depth of discharge capability on a daily basis. • Little capacity degradation enabling 5000+ cycles. • Low fire risk as electrolyte is non-flammable. • No need for cooling systems. • Use of low cost and readily available battery materials. • Easy of end-of-life recycling using existing processes.

They also share some disadvantages: • Lower energy density than li-ion batteries. • Lower Round Trip Efficiency than li-ion (although this can be partially offset by the energy drawn from li-ion installations to run cooling systems). • The need to be fully discharged every few days to prevent zinc dendrites that can puncture the separator. • Lower charge and discharge rates than Li-ion.

In September 2021, Gelion announced its partnership with one of Australia’s lead-acid battery manufacturers, Battery Energy Power Solutions allowing Gelion to manufacture batteries in Battery Energy’s facility in Fairfield, Sydney. Targeting semi commercial applications for 2022-2024 for projects between 10kWh and 1MWh. The company is pursuing a commercial product cost of just $100 per kWh, which is highly competitive. Obviously, since cost is hugely dependent on volume, the company’s strategy is to tolerate a loss in its first few years while production scales up. Maschmeyer estimates the company should be able to break even and cover its costs by 2023 or 2024.

EOS is commercialising their Zyneth “zinc hybrid cathode” battery and targeting 4 semi commercial applications for 2022 for projects between 10kWh and 1MWh. As of November 2021, EOS has secured a 300MWhr order from Pine Gate Renewables with installation planned for 2022. To date, they have 12 projects - 11 pilot projects, relatively small projects 1MW or smaller for 4 hours, and they are commissioning an additional project of 3MW/74MWh in California. In the last year, they received $137 million (USD) in orders.

Alkaline batteries

The alkaline Zn–MnO₂ use metallic Zn as an anode and conversion-type cathode. However, challenges remain in the rechargeability of zinc anode in alkaline electrolyte and the development of electrode materials. These challenges include dendrite formation, non-uniform zinc dissolution, and limited solubility in electrolytes.

Companies like Sunergy or UEP have been able to develop these chemistries making zinc-based batteries rechargeable. UEP attained two significant breakthroughs that pushed ZnMnO₂ technology forward: • Developing a fully rechargeable manganese dioxide cathode that can maintain capacity without significant degradation during cycling, and • Controlling zinc behavior through key additives and separator materials.

In January 2022, they will be energizing their biggest project of 1 MW in San Diego and are working with two small solar developers near New York. UEP's technology has been commercialized to result in a battery that costs approximately $160/kWh which will be manufactured in 2021 at their pilot scale production levels, with a roadmap to reach $20/kWh by 2025 through increasing the utilization of active materials while maintaining performance and cycle life. Still, the main issue hampering their wide implementation is the low cycle life, mostly due to instability of the MnO₂ cathode.

On the other hand, Sunergy is developing all kinds of zinc-based batteries (Zn-air, ZnMnO₂ & Ni-Zn).

Metal-air Batteries

The metal–air battery is composed of a metal anode, an air electrode, an ion conducting electrolyte, and a separator. Unlike the conventional metal-ion batteries, metal–air batteries function through the redox reaction between the metal anode and oxygen at the air cathode, with theoretical specific energies and energy densities (based on the metal anode) exceeding Li-ion batteries (up to 1000 Wh kg⁻¹ and 5000 Wh L⁻¹ at a material level). Among these metal–air battery technologies, Zn–air and Fe–air possess the most promising electrochemical performance due to their potential to offer a better electrical rechargeability. Other aqueous metal–air batteries, such as aluminum, silicon, and magnesium are also highly prone to corrosion, which limits these batteries only to primary applications with low utilization efficiencies.

Today, the overall performances of metal–air batteries is not satisfactory - so far. Therefore, it would be quite optimistic to state that metal–air batteries could be the major energy storage devices in the future.

Zinc-air

Zinc–air batteries have higher energy density than many other types of battery because atmospheric air is one of the battery reactants, in contrast to battery types that require a material such as manganese dioxide in combination with zinc. A key innovation here is the mechanical recharge. The benefits of mechanical recharging systems over rechargeable batteries include the decoupling of energy and power components, and providing design flexibility for different charge rate, discharge rate, and energy capacity requirements.

Companies working around this are e-zinc and Zinc8. E-zinc is already in stage 7 TRL, was awarded a $1.3 million grant by the California Energy Commission for Long Duration Non-Lithium Energy Storage Systems in September 2020, and have already started working in their first commercial project out of 3 lined up for 2022.

Iron-air

Rechargeable Fe–air batteries differ from other metal–air systems by requiring a critical formation process (for carbonyl iron electrodes) after which the electrodes could provide a stable discharge capacity. The main challenges related to Fe–air technologies have to do with anode originated problems such as corrosion.

Iron–air rechargeable batteries are an attractive technology with the potential of grid-scale energy storage. In July 2021, Form Energy announced the chemistry of their battery would be iron-air. The basic principle of operation of the iron-air battery is reversible rusting. While discharging, the battery breathes in oxygen from the air and converts iron metal to rust. While charging, the application of an electrical current converts the rust back to iron and the battery breathes out oxygen.

There has been a lot of expectations on Form’s Technology, as among its main investors are Jeff Bezos and Bill Gates, and it was co-founded by Tesla's former Vice President: Mateo Jaramillo. The company received $240 million in funding last year, but still little is known about their technology, and their commercialization timeline is 5 years out.

Nickel-based batteries

Nickel-Cadmium

Where energy density is important, Ni–Cd batteries are now at a disadvantage compared with nickel–metal hydride and lithium-ion batteries. However, they still present some advantages: • They are useful in applications requiring high discharge rates as this will not cause damage or loss of capacity. • They tolerate deep discharge for long periods. In fact, Ni–Cd batteries in long-term storage are typically stored fully discharged • Ni–Cd batteries typically last longer, in terms of number of charge/discharge cycles, than other rechargeable batteries such as lead/acid batteries.

Still, the primary trade-off with Ni–Cd batteries is their higher cost and the use of cadmium. This heavy metal is an environmental hazard, and is highly toxic to all higher forms of life. This means they would require special care during battery disposal, thereby increasing costs.

Another of its biggest disadvantages is that the battery exhibits a very marked negative temperature coefficient. This means that as the cell temperature rises, the internal resistance falls, which can pose considerable charging problems. Lastly, they may suffer from a "memory effect" if they are discharged and recharged to the same state of charge hundreds of times. The apparent symptom is that the battery "remembers" the point in its discharge cycle where recharging began and during subsequent use suffers a sudden drop in voltage at that point, as if the battery had been discharged.

Nickel.metal hydride

Nickel–metal hydride (NiMH) batteries are the newest, and most similar, competitor to Ni–Cd batteries. Compared to Ni–Cd batteries, they have a higher capacity and are less toxic, and are now more cost effective. Originally, a Ni–Cd battery had a lower self-discharge rate (for example, 20% per month for a Ni–Cd battery, versus 30% per month for a traditional NiMH under identical conditions), but now low self-discharge ("LSD") NiMH batteries are available, which have substantially lower self-discharge than either Ni–Cd or traditional NiMH batteries.

Nickel–zinc

NiZn batteries do not use mercury, lead, or cadmium, or metal hydrides, all of which can be difficult to recycle. Both nickel and zinc are commonly occurring elements in nature, and can be fully recycled. NiZn cells use no flammable active materials or organic electrolytes, and the newest models use polymeric separators which reduce the dendrite formation problem.

The company developing this technology is Zincfive (formerly PowerGenix). Zincfive manufactures cell and monobloc nickel-zinc batteries, delivers nickel-zinc battery-based uninterruptible power supplies for mission critical applications in Data Centers and Intelligent Transportation, and offers batteries for stationary, motive and start-stop applications. With 95 patents awarded, ZincFive leverages nickel-zinc chemistry within its solutions to provide high power density and performance simultaneous with superior safety and environmental advantages.

As of 2018, Zincfive has commercially available products using nickel-zinc batteries in the intelligent transportation and mission critical IT/data center markets in the form of uninterruptible power supplies. Also available are nickel-zinc batteries for stationary, motive, and start-stop applications.

Li resources are still sufficient for at least 25 years of battery production but this gives enough time to intensify the research on the more abundant, safer and potentially easier recyclable multivalent battery systems. All of the mentioned technologies, and many more further away from commercialization, are being studied and tested. Still, in the short-term, all of these new chemistries will not be replacing Li-ion batteries but competing side-by-side with them, depending on each novel battery's characteristics and costs.

You can find more information on all of the companies addressed and the remaining ones presented on the framework by accessing their Storefronts on Darcy Connect.