Insight into the coordinating mechanism of multi-electron reaction and structural stability induced by K+ pre-intercalation for magnesium ions batteries

Abstract

Multi-electron reaction as the appealing alternative can offer higher specific capacity, however, it delivers a tendency to collapse the structure causing cycling instability. Herein, K+ pre-intercalation strategy is applied to modify VS4/N-TG as cathode for MIBs. As opposed to the structural breakdown caused by multi-electron reaction, pre-intercalated K+ not only modulate electronic state, making V2+ present as instead of partial V4+ achieving multi-electron reaction, but also act as pillar ions for coordinating the interaction of guest-ions with adjacent host ions to strengthen the framework to maintain structural stability, therefore, K0.20VS4/N-TG delivers high specific capacity of 190 mAh g–1, and excellent cycling stability with about near 100% capacity retention after 2000 cycles. This finding gives insights into enabling multi-electron transfer reaction while achieving high structural stability via K+ pre-intercalation, shed light on designing viable multi-electron reaction in intercalation type cathode without destroying stable structure for high performance magnesium ions batteries.