Sthyr Energy Aims To Tame $169 Bn Energy Storage Market By Switching From Lithium To Zinc

Storing energy is no less important than harnessing it. In fact, stored energy is a raincheck for the days when the sun doesn’t shine and the wind doesn’t blow. 

The domain began boiling with major global economies vowing to go net zero as stored energy helps achieve flexibility, enhance grid reliability, and scale up renewable energy. But unabated geopolitical turmoil has kept the $169 Bn energy storage market volatile by making it increasingly harder to source rare earth elements that are crucial in storage devices.

What the market needs desperately is stability. A Bengaluru startup named itself Sthyr Energy, from the Sanskrit word sthir, to bring in stability to such an edgy market.   

It has developed mechanically rechargeable zinc-air battery systems that are designed for long-duration and seasonal energy storage across solar and wind farms and for powering the microgrids. This is designed to replace lithium (Li), often referred to as white gold due to its high demand in the electric mobility sector, in storage devices. 

“The zinc-based technology can store electricity for months or even years at low cost. The cathode here is not made of lithium and other metals. Instead, zinc is the primary ingredient here,” said Akhil Kongara, one of the three founders of Sthyr Energy. Being the fourth most-produced metal and the 23rd most abundant element in the world, there’s also no fear of running out of zinc reserves in the near term.  

Metals Malady And Hunt For Alternatives  

As the world accelerates its efforts to rapidly electrify vehicles and store renewable energy, the demand for lithium-ion batteries is expected to grow from 700 GWh in 2022 to 1,700 GWh in 2025 and is projected to surpass 4,000 GWh in the next five years.

The mining of lithium, various critical materials such as nickel, cobalt, graphite, copper, and the extraction of rare earth elements that are critical in the manufacturing of Li-ion batteries has, however, come under two major concerns around the world. Besides environmental and humanitarian crises, there’s a looming threat of supply chain snag because of the world’s over-dependence on certain geopolitically sensitive regions.

As the hunt for an alternative went full throttle to keep up the momentum in EVs, smartphones, and consumer electronic goods, sodium-ion batteries and metal-air batteries like zinc-air and aluminium-air came to the fore, but none were ideal replacements for Li-ion batteries. 

With the rough waves hitting the Indian shores, its 3 Lakh-unit EV industry’s target to claim 30% of the Indian passenger vehicle sales is lost in a cloud of uncertainty. The hurdles are steeper because of the country’s perennial tension with neighbouring China, which treasures the world’s largest reserves of critical materials and rare earth elements. 

India has the fifth-largest reserve of rare earth elements, yet it ranks low when it comes to meeting its industrial needs. There is a tough choice ahead of India – mine its own resources, even at the cost of environmental damage, or scale its battery recycling facilities, or bet big on alternatives. If the country has to power its clean energy ecosystem beyond EVs, it has to focus on more innovation in battery chemistry.

The Right Chemistry Out Of An Idea 

Back in 2018, Akhil Kongara was doing his PhD research at IIT Madras to find out an alternative cell chemistry for EVs that could be safer and stable than Li-ion batteries. Gunjan Kapadia and Muhammed Hamdan joined him a year later, and the trio began working together on zinc as a substitute for lithium in batteries.   

After the initial testing phases and building a prototype, the team realised that their zinc-air battery technology could not cater to all categories of EVs, while Li-ion was a clear winner there. 

But they stumbled upon an interesting fact. The lithium cells could outsmart their zinc peers, but the Li-ion batteries couldn’t store power for long durations, where zinc-air cells had a clear edge. For comparison, Sthyr claims to be able to provide up to 100 hours of energy storage while Li-ion batteries can store energy for a maximum of eight hours. In 2022, they decided to pivot the target application of their zinc-air battery technology from EVs to long-duration energy storage and started building the products.

After almost two years of testing and R&D at IIT Madras, the team set up Sthyr Energy in August 2024 and began preparing for commercialising its products. Sthyr’s product is at a stage between TRL (technology readiness level) 4 and 5, where its first product – a 3.2 kWh battery module – is ready, but it is yet to be tested in the real-world environment. 

The company reached out to deeptech-focussed VC firm Speciale Invest towards the end of last year. Speciale Invest and Antares Ventures pumped $1 Mn into the seed stage startup a few months later. 

“They had been working for years on a problem that most startups don’t dare touch: how to build a battery that can store clean energy for weeks or even months, safely and affordably. They were not just experimenting in the lab. They had built an operational prototype, secured patents, published in top journals, and begun conversations with industrial partners. Their goal wasn’t just to publish – it was to commercialise,” Speciale Invest wrote about the Sthyr founders.

Zinc-based battery technologies started catching the attention of the private sector and the governments alike in recent days as the world aims to store 442 GWh of renewable energy by 2030. As against lithium, which is more than four times costlier, zinc offers an affordable solution with superior performance. 

Zinc-air batteries also have more energy density and they can function more stably under extreme weather conditions, where Li-ion batteries fail to deliver. Hindustan Zinc and IIT Madras last year announced a collaboration to develop electrically rechargeable zinc-air batteries. Godrej, too, has developed a zinc-manganese dioxide battery technology. 

Sthyr Energy, with three granted patents in its kitty, aims to challenge legacy battery companies and startups in Li-ion and lead-acid battery markets, which are dominated by the likes of Exide and Amara Raja in India.

It’s The Core That Makes The Difference 

Just like the core of a cell, which determines its character and performance, there are three guiding principles that give Sthyr the stability it stands for: safety, scalability, and cost-efficiency. 

Metal-air batteries are not new to the world. In fact, the zinc-air battery itself is almost a 150-year-old technology. Italian physicist Alessandro Volta, known as the inventor of the battery, used zinc as an anode in a cell in 1796. The technology has evolved down the centuries.

A zinc-air battery consists of a zinc metal anode and a porous air cathode, separated by a water-based electrolyte. It also has a gas diffusion electrode. During discharge of the battery, oxygen must enter the cathode through the semi-permeable membrane or the electrode. This membrane plays a crucial role in the functioning of these batteries and decides the cost and performance as well.

Sthyr’s cofounder Kapadia said that the reason why the zinc-air battery technology has changed for over two centuries is not because the chemistry had to be perfected, but because not everyone could crack the technology of perfecting this membrane. “Most companies fail in building this technology because of the electrode. We took almost five years to perfect this technology before announcing or deploying anything in the market,” he said.

Sthyr’s rise in zinc-air battery technology reminds us of the dead-end nanotechnology startup Log9 Materials has hit. It had bet big on aluminium-air cells that were expected to cost 30-40% lower than Li-ion batteries. Despite multiple attempts, it failed to scale any of its chemistries. 

Unlike others developing electrically rechargeable zinc-air batteries for smaller applications like hearing aids, patient monitors and some EVs, Sthyr has developed a mechanically rechargeable system. This essentially involves decoupling energy and power components to make charging flexible and enabling deployments of battery modules or battery storage systems at various scales.

Solar panels, for example, typically generate excess power during the summer. Sthyr’s technology helps retain this excess energy by converting zinc oxide to zinc plates, which can be stored for months and years. When needed, these zinc plates can be put back in the batteries to convert stored chemical into electricity, producing zinc oxide as a residue. 

The amount of zinc used in making one battery module is recycled to make it work in multiple cycles, reducing the need for excess mining. Its batteries are also designed to provide a power backup for over 100 hours.

Sthyr claims that the capex on its battery systems stands at $70 per kWh, which it will bring down to $30-40 in two years. In comparison, Li-ion batteries start from $150 per kWh. 

Speciale managing partner Vishesh Rajaram told Inc42 that while many companies often claim to have developed metal-air batteries, they are all in concept stages. “Sthyr has actually shown significantly large prototypes of its technology, even though they don’t have commercial deployments yet,” he said.

Storing Energy To Power The Future  

 The Sthyr founders believe that the time they have invested in developing the technology and the money it will invest in making it more robust will pay off in the long run. Its direct customers will be the energy companies, asset managers, and independent power producers. In defence, its batteries can replace diesel generators for power supply in remote locations, while it also sees huge demand from the surge in data centres. 

The primary market for long-duration energy storage startup lies in Europe, Canada, and Australia, which are more dependent on renewable power sources and have a scarcity of daylight. Sthyr believes that a major chunk of its revenue after commercialisation will come from England, Scotland, and the Scandinavian regions.

For the home turf, the startup plans to find the right applications gradually. Sthyr competes with the likes of e-Zinc, ABOUND Energy in Indian markets.  Sthyr plans to set up another 2-3 GWh manufacturing facility in India by 2028-29.

Sthyr has so far tested its batteries for 2,000 hours of continuous operation. It aims to increase it to 5,000 hours. Depending on applications, the startup will deploy its battery stacks separately or the fully-equipped energy storage systems.

The startup is setting up a manufacturing and R&D facility in Chennai with 30 MWh per year capacity, expanding the team, and readying itself for deploying the pilot products within a year-and-a-half. Sthyr will develop multiple 300 kWh systems in this pilot facility, test them with potential customers, and then go for full-fledged commercial production after three years.

The global energy storage market almost tripled in 2023, maintaining a pace of 21% until 2030, when solar and wind markets are expected to surge by 9% and 7%, respectively. Lower power storage costs will be key to supporting more economic deployment of the technology. 

Sthyr Energy has positioned itself to ride on this global momentum. Only time will tell how it has galvanised its zinc-air battery technology to remain stable in the long run.

[Edited By Kumar Chatterjee]