A Temperature‐Tolerant Magnesium‐Ion Battery Using Ball Cactus‐like MgV2O4 as High‐Performance Cathode

Abstract Safe and high‐performance secondary batteries using for all‐climate conditions with different temperatures are highly required. Here, we develop a three‐dimensional ball cactus‐like MgV 2 O 4 as cathode material for magnesium‐ion (Mg‐ion) batteries. After cycling 300 times, the capacity maintains 111.7 mAh g −1 , while Coulombic efficiency stabilizes at about 100 %. Under temperatures of 45 °C and −5 °C, the capacities remain stable after 200 cycles. After three rounds of rate‐performance tests, the capacity keeps quite stable. It is ascribed to the ball cactus‐like morphology buffers the volumetric change during Mg 2+ insertion/extraction, and provides sufficient pathways for ion diffusion, which has been verified by constant‐current intermittent titration technology. It is believed that the good performance enables the Mg‐ion batteries to have a all‐climate capability.