Li-H Batteries Could Revolutionise Renewable Energy Storage

The global push to shift to clean and renewable energy necessitates the development of more advanced and high-performance batteries.

Renewable energy sources are intermittent, meaning they don’t always generate power when needed. This requires batteries to store excess energy generated during peak times and release it when demand is high or renewable energy sources aren’t producing enough.

Effectively integrating renewable energy into the grid and making it more accessible means higher energy capacity—how much energy it can store—and energy efficiency batteries—how well they can store and release energy without significant loss. This is needed to ensure that energy is reliable and available for longer periods and also reduces dependence on fossil fuel-based backup power.

A study conducted by the University of Science and Technology of China, titled “Rechargeable lithium‐hydrogen gas hybrid batteries,” published in November 2024, reveals the latest innovation in hydrogen battery that has the potential to significantly improve renewable energy storage for the grid, electric vehicles, and other applications.

Researchers propose a new approach in which hydrogen gas is used as the cathode in a rechargeable battery alongside a lithium (Li) metal anode. This combination shows excellent potential for higher energy density and voltage.

Despite recent advances in Li-air and Li-S batteries, challenges remain, such as issues with the air cathode’s redox performance and polysulfide shuttling in Li-S batteries. Pairing Li metal with other cathodes, such as H2O or SOCl2, can offer high energy density, but these are primary batteries and lack the recharging ability of rechargeable batteries. Additionally, directly using Li metal anodes raises cost and safety concerns.

Hydrogen gas (H2) is an attractive alternative due to its potential as a renewable resource. Because of its favourable redox potential and long-term stability, H2 can be used as an electrode with an electrocatalyst.

Rechargeable hydrogen gas batteries, such as those used in nickel-hydrogen chemistry, have been around since the 1960s and have been successfully used in aerospace by NASA. More recently, other hydrogen gas battery systems have shown promise for large-scale energy storage. However, previous hydrogen gas-based batteries had limited voltage (0.8-1.4 V) and low energy density (less than 139 Wh/kg).

The new idea proposed in the study, where hydrogen gas is used as the cathode in a rechargeable battery, combined with a lithium metal anode, shows higher energy and voltage potential. The set-up achieves a high theoretical energy capacity of up to 2630 Wh/kg and demonstrates versatility with different hydrogen gas cathode catalysts and electrolytes. Using a low-cost phosphoric acid electrolyte and a well-established Pt/C catalyst, the battery shows a practical, theoretical energy of 766 Wh/kg with a working voltage of 3.04 V.

Additionally, the battery exhibited long-term stability for over 1900 hours, a high capacity of more than 20 mAh per square centimetre, and the ability to operate within a wide temperature range of -20 to 80°C. These results are competitive with other advanced gas electrode batteries. Researchers also demonstrated that this battery could function without a traditional anode by utilising lithium metal derived from affordable lithium salts. This makes the Li-H battery a promising option for future energy storage needs.

While there are concerns about the safety of hydrogen (H2) in transportation and storage, the study indicates that safety can be ensured with proper containment in a high-pressure vessel. This approach is similar to that used with other battery types, such as nickel-hydrogen (Ni-H) batteries.

The pressure of H2 gas in this battery is much lower than in hydrogen-oxygen fuel cells, which have been safely utilised for years in aerospace and other applications. Although the pressure vessel may slightly reduce the battery’s energy density, it is expected to remain within an acceptable weight range. In the future, in hydrogen-rich environments such as certain planets, the lithium-hydrogen (Li-H) battery could be an excellent option for energy storage.

Its potential applications extend to large-scale energy storage, but further materials science and engineering advancements are necessary to enhance its capabilities. Future improvements will focus on solid electrolytes, catalysts, gas electrodes, lithium salts, and innovative designs.

Implications of the study

The findings of this study could significantly transform the performance and efficiency of renewable energy systems, long-range electric transportation, and next-generation aviation. The Li-H system offers improved energy density and efficiency compared to traditional nickel-hydrogen batteries.

It stands out as a strong candidate for the next generation of power storage systems as the world increasingly moves toward electrification and decarbonisation. The anode-free version has shown promise in paving the way for more affordable and scalable hydrogen-based batteries.

Learn more about the study: Rechargeable Lithium-Hydrogen Gas Batteries.