Against the backdrop of China’s “dual-carbon” goals, building a new power system dominated by renewable energy has become the cornerstone of the nation’s energy transition. Today, the levelized cost of electricity (LCOE) from solar PV and wind has fallen well below that of coal; however, their inherent intermittency and volatility pose a serious threat to grid stability. Safe, long-duration and low-cost energy storage is therefore the key to large-scale renewable integration and reliable grid operation.

Among the many storage technologies, flow batteries—thanks to their intrinsic safety and ultra-long cycle life—are regarded as one of the most promising solutions for large-scale, long-duration applications. Among them, the sulfide–iron flow battery (SIFB) has recently attracted wide academic and industrial attention because of its abundant raw materials, low cost and environmental friendliness.

Since 2021, ZH Energy has joined forces with Central South University in a deep industry–university–research program, focusing on critical material optimization, system integration and engineering validation to accelerate technology iteration. After continuous R&D, ZH Energy is now the global front-runner in SIFB commercialization and has achieved breakthroughs in several core areas:

Technical development: the SIFB has realized stable operation at a high current density of 120 mA / cm² with an energy efficiency exceeding 73 %—performance that stands at the global frontier and underscores the company’s technical leadership.

Substantial project milestones

2024: In partnership with State Grid, ZH Energy successfully grid-connected the world’s first SIFB technology-validation project, whose system efficiency and cycling stability have reached world-leading levels, proving the technology’s feasibility and reliability.

2025: the company is advancing the construction of a megawatt-hour first-of-its-kind demonstration system; its completion will further test scalability and real-world adaptability.

2026: commercial standard module products are scheduled for market release, marking the transition of SIFB into large-scale deployment.

Economics

Once deployed at scale, SIFB systems are expected to achieve an initial installed cost below 1 ¥ / Wh and a lifetime LCOE as low as 0.1 ¥ / kWh—dramatically improving the economics of renewable-plus-storage on the generation side. Notably, unlike all-vanadium flow batteries (where electrolyte accounts for >50 % of total cost), electrolyte in SIFB represents <15 % of system cost, while the stack contributes >50 %. This cost structure indicates that SIFB cost reductions will be driven mainly by stack technology advances, whereas vanadium systems must rely more heavily on electrolyte scale effects or process improvements.

Product Series：

Flow Battery Test Platform