Structure engineering of Mn2SiO4/C architecture improving the potential window boosting aqueous Li-ion storage

Abstract

Aqueous Li-ion batteries (ALIBs) hold the significant superiorities of nonflammability and low cost, which can address the challenges related to conventional LIBs. However, the promotion of ALIBs has been severely restricted due to the lack of selectable cathode materials. Structure engineering of materials with novel architecture represents the state-of-art cathode materials’ design for advanced batteries. Herein, as a new type cathode material based on manganese silicate for ALIBs, multilayer rGO@Mn2SiO4@ZIF-8-C is rationally designed by a layer-by-layer assembly method, and this structure engineering is an effective tool to address the deficiencies directed at Mn2SiO4 of electroconductibility and durability. With the integrated layer-by-layer structure, the rGO@Mn2SiO4@ZIF-8-C electrode can ensure the Li-ion transfer kinetics and inhibit Mn2SiO4 dissolution during the electrochemical reaction. As for the application in ALIBs, rGO@Mn2SiO4@ZIF-8-C electrode shows the work potential window of 2.0 V and displays the peak discharge capacity of 450, 296 and 254 mAh·g−1 at 0.1, 0.2 and 0.5 A·g−1, respectively. The possible Li-ion storage mechanism during charge–discharge process for rGO@Mn2SiO4@ZIF-8-C electrode is discussed in detail. When rGO@Mn2SiO4@ZIF-8-C cathode is assembled with an NaTi2(PO4)3@C anode into an ALIB full cell, an ultra-wide voltage window for 2.1 V is obtained. The full cell shows the initial discharge capacity of 165 mAh·g−1 and possesses 112 mAh·g−1 over 50 cycles at 0.1 A·g−1. This designed rGO@Mn2SiO4@ZIF-8-C architecture can serve as a good choice for ALIBs cathode materials and extend the cathode material category of ALIBs. The unique layer-by-layer assembly method provides important insight for electrodes’ structure engineering concept which would be achieved in other related materials.