Self-Deprotonation of LDHs toward Aqueous Multi-Ion Battery Cathode

Layered double hydroxides (LDHs) have emerged as promising cathode materials for rechargeable aqueous multi-ion batteries. However, the cation (de)intercalation process in Co-containing LDHs typically requires a predeprotonation step in alkaline solutions. Even after predeprotonation, the achievable capacity remains limited. In this study, we report for the first time a self-deprotonation phenomenon in a Mn-based LDH in the initial charging process in a neutral solution. Specifically, the terminal hydrogen atoms are removed from the hydroxyl groups in the Mn-based LDH layers, exposing active oxygen sites that facilitate cation intercalation, even without predeprotonation. The Mn-based LDH demonstrates remarkable multi-ion storage capabilities, delivering an average capacity that surpasses Co-based LDH by 280%, Ni-based LDH by 480%, and deprotonated Co-based LDH by 150%. Furthermore, the performance of the Mn-based LDH is comparable to that of predeprotonated Mn-based LDH, highlighting its potential as a high-performance cathode material. Furthermore, nanostructured Mn-based LDH demonstrates high capacity across diverse electrolytes (Li+, Na+, K+, Ca2+, Mg2+, and Zn2+) with specific capacities of 289.5, 174.7, 158.6, 417.1, 410.6, and 98.4 mAh g–1, respectively. This work not only demonstrates the feasibility of activating LDHs for cathode applications but also provides valuable insights into the design of high-performance LDH-based materials.