EnerVenue, an American battery tech startup founded in 2020, develops nickel-hydrogen batteries for large-scale renewable and storage applications. Over decades, nickel-hydrogen batteries have proven to be simple, safe, and maintenance-free energy storage devices. They are also safer and less finicky than lithium-ion batteries in addition to being durable, efficient, and recyclable. The company has raised $112M to accelerate clean energy and their battery systems are expected to last about 30 years and 30,000 cycles with very little maintenance required.
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Challenges: lithium battery
Today, more and more solar cells and wind turbines are being utilized to generate clean electricity. To store their electrical energy, rechargeable batteries have been deployed to increase the efficiency and reliability of these intermittent renewable energy technologies.
Lithium-ion batteries are a mature technology. They have been used to store energy on the grid that is integrated with intermittent solar and wind energy. However, the high cost and undesirable lifetime of lithium-ion batteries prevents their widespread use to store energy on the grid. Additionally, it is reported that several dozens of lithium-ion energy storage systems have resulted in explosions or fires.
Nickel(II) hydroxide-hydrogen rechargeable batteries show robust stability, and they have been applied extensively in satellites and aircraft with service life of more than three decades.
However, the use of expensive platinum (Pt) catalysts in the nickel(II) hydroxide-hydrogen battery impedes its widespread applications. It is necessary to explore advanced nickel(II) hydroxide-hydrogen batteries or other metal compound-hydrogen batteries to achieve the United States Department of Energy (DOE) target of $100 kWh⁻¹ for grid storage, which is highly desirable yet very challenging.
This book Nickel-Hydrogen Batteries provides an in-depth view of nickel-hydrogen cell technology: how it was developed, how and why it works, how to implement it and realize its ultimate capability, and what can go wrong if it is not properly managed. (see on Amazon)
EnerVenue develops low-cost bi-functional catalysts for nickel(II) hydroxide-hydrogen batteries that exhibit performance comparable to the battery based on the costly platinum catalyst. Additionally, EnerVenue develops a variety of cathode materials for high-performance metal compound-hydrogen batteries. Their batteries cost less than $100 kWh⁻¹.
EnerVenue nickel hydrogen batteries
Nickel hydrogen battery structure
The nickel(II) hydroxide-hydrogen battery, as depicted in the figure below, consists of a nickel(II) hydroxide (Ni(OH)₂) cathode, porous polymer separator, bi-functional catalyst anode, and electrolyte.
To make the cathode, micrometer-sized nickel(II) hydroxide spheres are heavily coated in nickel foam to form a compact electrode. Due to the high density of the nickel(II) hydroxide microspheres, the cathode has a tap density of 2.6 g cm⁻³, which corresponds to a high mass loading of 182 mg cm⁻². The nickel(II) hydroxide electrode’s large thickness, high mass loading, and tap density are comparable to industry levels, allowing nickel(II) hydroxide-hydrogen batteries into practical energy storage applications.
The bi-functional catalyst consists of ruthenium-containing compounds, such as ruthenium phosphide (RuP₂). The catalyst may also be a nickel-molybdenum-cobalt (NiMoCo) alloy. They are nanoparticles deposited on the surface of nickel foam to create the anode. The bi-functional catalyst is capable of catalyzing both hydrogen evolution and hydrogen oxidation reactions. The nickel foam skeletons are interconnected virtually free-of-junction, ensuring high electrical conductivity of the electrodes for efficient battery operation.
Depending on the bi-functional nanoparticle catalysts, the electrolyte is aqueous alkaline, neutral, or acid solution. The electrolyte may be pH-universal if the bi-functional catalyst is ruthenium phosphide. If nickel-molybdenum-cobalt (NiMoCo) alloy is used as a catalyst, the alkaline electrolyte composed of 30% potassium hydroxide is typically used.
In between the cathode and the anode is the separator. This film is porous, water-absorbent, and insulating. It is composed of either cellulose or glass fiber.
How EnerVenue nickel hydrogen batteries work
During charging, nickel(II) hydroxide on the cathode is oxidized to nickel(III) oxide hydroxide (NiOOH), while hydrogen gas is evolved from the electrolyte on the anode through the ruthenium phosphide or NiMoCo-catalyzed hydrogen evolution reaction.
During discharging, nickel(III) oxide hydroxide on the cathode is reduced back to nickel(II) hydroxide and hydrogen gas is oxidized on the anode via the ruthenium phosphide or NiMoCo-catalyzed hydrogen oxidation reaction. The redox reactions of the nickel(II) hydroxide-hydrogen battery during charging and discharging can be described as:
Cathode: Ni(OH)₂ + OH⁻ ⇄ NiOOH + H₂O + e⁻
Anode: H₂O + e⁻ ⇄ ½H₂ + OH⁻
Overall: Ni(OH)₂ ⇄ NiOOH + ½H₂
The nickel(II) hydroxide-hydrogen rechargeable battery with a ruthenium phosphide anode has an operating potential of 1.3 V, a capacity of 200 mAh g⁻¹, and a cycle life of greater than 1,000 cycles.
The nickel(II) hydroxide-hydrogen rechargeable battery with a NiMoCo alloy anode has an operating potential of 1.3 V, a capacity of 195 mAh g⁻¹, and a cycle life greater than 1,500 cycles.
EnerVenue metal hydrogen batteries
EnerVenue also develops rechargeable metal compound-hydrogen batteries based on the ruthenium phosphide anode and other types of cathode, such as lead(IV) oxide (PbO₂), manganese(IV) oxide (MnO₂), lithium manganese oxide (LiMn₂O₄ (LMO)).
Lead hydrogen battery
In this battery, the cathode is composed of lead(IV) oxide, the anode is composed of ruthenium phosphide, and the electrolyte is typical 4.5 M sulfuric acid (H₂SO₄) aqueous solution. The redox reactions of the lead(IV) oxide-hydrogen rechargeable battery during charging and discharging can be described as:
Cathode: PbO₂ + 4H⁺ + SO₄²⁻ + 2e⁻ ⇄ PbSO₄ + 2H₂O
Anode: 2H⁺ + 2e⁻ ⇄ H₂
Overall: PbO₂ + H₂SO₄ + H₂ ⇄ PbSO₄ + 2H₂O
The lead(IV) oxide-hydrogen rechargeable battery with a ruthenium phosphide anode has an operating potential of 1.75 V, a capacity of 200 mAh g⁻¹, a cycle life greater than 3,000 cycles, and kinetics greater than 100 C.
Manganese hydrogen battery
In this battery, the cathode is composed of manganese(IV) oxide (MnO₂), the anode is composed of ruthenium phosphide, and the electrolyte is typical 3 M manganese(II) sulfate (MnSO₄) aqueous solution. The redox reactions of the manganese(IV) oxide-hydrogen rechargeable battery during charging and discharging can be described as:
Cathode: MnO₂ + 4H⁺ + 2e⁻ ⇄ Mn²⁺ + 2H₂O
Anode: 2H⁺ + 2e⁻ ⇄ H₂
Overall: MnO₂ + 2H⁺ + H₂ ⇄ Mn²⁺ + 2H₂O
The manganese(IV) oxide-hydrogen rechargeable battery with a ruthenium phosphide anode has an operating potential of 1.3 V, a capacity of 125 Ah L⁻¹, a cycle life greater than 5,000 cycles, and kinetics greater than 50 C.
LMO hydrogen battery
In this battery, the cathode is lithium manganese oxide (LiMn₂O₄ (LMO)), the anode is ruthenium phosphide, and the electrolyte is typical 1 M lithium sulfate (Li₂SO₄) aqueous solution. The redox reactions of the LMO-hydrogen rechargeable battery during charging and discharging can be described as:
Cathode: 2MnO₂ + Li⁺ ⇄ LiMn₂O₄
Anode: 2H⁺ + 2e⁻ ⇄ H₂
Overall: 2MnO₂ + ½H₂ + Li⁺ ⇄ LiMn₂O₄ + H⁺
The LMO-hydrogen rechargeable battery with a ruthenium phosphide anode has an operating potentials 1.3 V and a capacity of 108 mAh g⁻¹.
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EnerVenue nickel hydrogen battery applications
Renewable Energy Storage
EnerVenue’s batteries are used for grid-scale energy storage, providing long-duration and cost-effective solutions.
High Caliber Energy will use 25 MWh of EnerVenue Energy Storage Vessels.
EnerVenue’s nickel hydrogen batteries can be used to power satellites, the International Space Station, and the Hubble Telescope.
The EnerVenue’s rechargeable hydrogen battery is shown in the figure below. The battery operates in -40 to 60 ºC ambient temperatures. It is durable and has a 30 year lifespan. It shows excellent overcharge, over discharge, and deep-cycle capabilities.
Currently, the EnerVenue’s battery system is big and heavy, as shown in the figure below. The battery system is used for stationary energy storages.
EnerVenue is funded by 4 investors, including
Yi Cui is Co-Founder.
Jorg Heinemann is CEO.