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Abstract Manganese (Mn)‐based redox flow batteries (RFBs) have emerged as promising candidates for large‐scale energy storage owing to their high redox potential (Mn 2+ /Mn 3+ : 1.58 V vs SHE), cost‐effectiveness, and sustainability. Nevertheless, Mn‐based RFBs face a critical challenge: the undesired formation of crystalline MnO 2 through Mn 3+ disproportionation and irreversibility of MnO 2 deposits on electrode surfaces severely diminish accessible reaction sites and restrict achievable areal capacity. Herein, it is demonstrated that ligand chelation‐mediated structural transformation of MnO 2 by sodium diphosphate (Na 4 P 2 O 7 , PPi) modulates MnO 2 deposition behavior. The PPi coordinate with Mn 2+ to form a stable Mn(HPO 4 ) 2 (H 2 O) 2 2− chelate, which facilitates the incorporation of defective O and P into the evolving MnO 2 structure, effectively disrupting its crystallographic ordering and converting MnO 2 from crystalline to amorphous configuration. The amorphous MnO 2 tends to flow into the electrolyte instead of depositing on the electrode due to the electrostatic interplay, thereby resulting in a breakthrough areal capacity of 91.5 mAh cm −2 (300 cycles @ 99.7% CE) and 141.8 mAh cm −2 (150 cycles @ 98.2% CE, the highest reported values), representing a 10‐fold enhancement compared to additive‐free counterparts. The ligand chelation modification of MnO 2 provides a new pathway for developing high‐areal‐capacity Mn‐based RFBs.
Liu et al. (Sat,) studied this question.