Dual-Defect Engineering Strategy Enables High-Durability Rechargeable Magnesium-Metal Batteries

Rechargeable magnesium-metal batteries(RMMBs)are promising next-generation secondary batteries;however,their development is inhibited by the low capacity and short cycle lifespan of cathodes.Although various strategies have been devised to enhance the Mg^(2+)migration kinetics and structural stability of cathodes,they fail to improve electronic conductivity,rendering the cathodes incompatible with magnesium-metal anodes.Herein,we propose a dual-defect engineering strategy,namely,the incorporation of Mg^(2+)pre-intercalation defect(P-Mgd)and oxygen defect(Od),to simultaneously improve the Mg^(2+)migration kinetics,structural stability,and electronic conductivity of the cathodes of RMMBs.Using lamellar V_(2)O_(5)·nH_(2)O as a demo cathode material,we prepare a cathode comprising Mg_(0.07)V_(2)O_(5)·1.4H_(2)O nanobelts composited with reduced graphene oxide(MVOH/rGO)with P-Mgd and Od.The Od enlarges interlayer spacing,accelerates Mg^(2+)migration kinetics,and prevents structural collapse,while the P-Mgd stabilizes the lamellar structure and increases electronic conductivity.Consequently,the MVOH/rGO cathode exhibits a high capacity of 197 mAh g^(−1),and the developed Mg foil//MVOH/rGO full cell demonstrates an incredible lifespan of 850 cycles at 0.1 A g^(−1),capable of powering a light-emitting diode.The proposed dual-defect engineering strategy provides new insights into developing high-durability,high-capacity cathodes,advancing the practical application of RMMBs,and other new secondary batteries.

Interfacial chemistry of anode/electrolyte interface for rechargeable magnesium batteries

Rechargeable magnesium batteries(RMBs),as a low-cost,high-safety and high-energy storage technology,have attracted tremendous attention in large-scale energy storage applications.However,the key anode/electrolyte interfacial issues,including surface passivation,uneven Mg plating/stripping,and pulverization after cycling still result in a large overpotential,short cycling life,poor power density,and possible safety hazards of cells,severely impeding the commercial development of RMBs.In this review,a concise overview of recently advanced strategies to address these anode/electroyte interfacial issues is systematically classified and summarized.The design of magnesiophilic substrates,construction of artificial SEI layers,and modification of electrolyte are important and effective strategies to improve the uniformity/kinetics of Mg plating/stripping and achieve the stable anode/electrolyte interface.The key opportunities and challenges in this field are advisedly put forward,and the insights into future directions for stabilizing Mg metal anodes and the anode/electrolyte interface are highlighted.This review provides important references fordeveloping the high-performance and high-safety RMBs.

Self-standing oxygen-deficient a-MoO_(3-x)nanoflake arrays as 3D cathode for advanced all-solid-state thin film lithium batteries

Compared with the planar two-dimensional(2D)all-solid-state thin film batteries(TFBs),threedimensional(3D)all-solid-state TFBs with interdigitated contact between electrode and electrolyte possess great advantage in achieving both high energy and power densities.Herein,we report a facile fabrication of vertically aligned oxygen-deficient a-MoO3-x nanoflake arrays(3D MO_(x))using metal Mo target by direct current(DC)magnetron sputtering.By utilizing the 3D MO_(x)cathode,amorphous lithium phosphorus oxynitride solid electrolyte,and lithium thin film anode,3D solid-state TFBs have been successfully fabricated,exhibiting high specific capacity(266 mAh g^(-1)at 50 mA g^(-1)),good rate performance(110 mAh g^(-1)at 1000mA g^(-1)),and excellent cycle performance(92.7%capacity retention after 1000 cycles)in comparison with the 2D TFBs using the planar MO_(x)thin film as cathode.The superior electrochemical performance of the 3D TFBs can be attributed to the 3D architecture of the cathode,maximizing the cathode/electrolyte interface while retaining the short Lit diffusion length.The charge/discharge measurements of the 3D MO_(x)cathode in liquid electrolyte,however,exhibit fast capacity fading,demonstrating the advantage of using transition metal oxide as cathode in solid-state batteries.