Batteries are only more "efficient" than hydrogen when their duty cycle is relatively high. For seasonal balancing (with a duty cycle of ~1/year), hydrogen is significantly cheaper because of the lower storage costs.

For example this study:

>For storage durations longer than approximately 36 h, technologies with very low storage costs, such as geologic hydrogen storage and natural gas with CCS, offer the least-cost options for LDES and low-emission power generation capacity.

>These results share some similarities with those of previous studies while also offering unique insights. Schmidt et al.11 similarly demonstrated that hydrogen storage and CAES have the lowest costs for seasonal storage in the near term, with hydrogen becoming the least-cost technology for seasonal storage in the future. The present analysis, however, introduces a lower-cost HDV-PEM fuel cell system compared with the stationary fuel cell system considered in Schmidt et al.11 The HDV-PEM system in this analysis provides both a lower power capital cost by using the HDV-PEM fuel cell as well as a lower energy storage capital cost by using a salt cavern. These cost reductions are slightly offset by the lower capacity factor modeled for HDV-PEM systems because of their lower round-trip efficiency, but the results still indicate that HDV-PEM|Salt systems achieve the lowest LCOE at durations as low as 36 h in the future scenario, much lower than the duration estimated by Schmidt et al.11 when including all technologies.