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

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 VS 4 /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 V 2+ present as instead of partial V 4+ 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, K 0.20 VS 4 /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. • K + is pre-intercalated into VS 4 /N-TG as cathode of MIBs via electrochemical method. • Enlarged interchain spacing and induced V 2+ is obtained via K + pre-intercalation. • Multi-electron reaction occurs in intercalation type cathode by K + pre-intercalation. • Coordination mechanism of multi-electron reaction and cycling stability is realized. • K 0.20 VS 4 /N-TG owns high specific capacity, cyclic property, and rate capability.