Rational design of 3D ordered macro-microporous TiN/carbon architectures for high-energy and stable rocking-chair aqueous Mn-ion batteries

Abstract

Rechargeable aqueous manganese-ion batteries (MIBs) have emerged as promising candidates for grid-scale energy storage due to their intrinsic safety, cost-effectiveness, and high energy density. However, their widespread adoption is hindered by the large ionic radius of Mn²⁺ ions and the limited availability of electrode materials that can efficiently accommodate Mn²⁺ ion storage. To address these issues, this study introduces a novel insertion-type anode material, consisting of a three-dimensional ordered macro-microporous TiN/C composite (3DOM-TiN/C), synthesized from Ti-MOF (MIL-125(Ti)). This material features a hierarchical macro-microporous architecture, an enhanced specific surface area, excellent electronic conductivity, and robust mechanical stability, which collectively facilitate efficient and reversible Mn²⁺ ion insertion and deinsertion processes. Additionally, the 3DOM-TiN/C composite serves as an optimal framework for anchoring redox-active MnO₂ material through in-situ chemical bath deposition, resulting in the formation of a 3DOM-TiN/C@MnO₂ cathode electrode. When assembled into a coin cell configuration (3DOM-TiN/C||3DOM-TiN/C@MnO₂), the MIBs exhibit exceptional electrochemical performance, achieving ultrahigh energy and power densities of 274.2 Wh kg⁻¹ and 18.05 kW kg⁻¹, respectively. Moreover, pouch cell configurations demonstrate significant potential for practical applications. These findings underscore the promise of Ti-based insertion-type materials as a groundbreaking class of anode materials for rechargeable aqueous MIBs.