A Temperature-Tolerant Magnesium-Ion Battery Using Ball Cactus-like MgV 2 O 4 as High-Performance Cathode.

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.