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Sn-based materials have been popularly researched as anodes for energy storage due to their high theoretical capacity. However, the sluggish reaction kinetics and unsatisfied cycling stability caused by poor conductivity and dramatic volume expansion are still pivotal barriers for the development of Sn-based materials as anodes. In this work, the binary-metal Mn 2 SnO 4 nanoparticles and Sn encapsulated in N-doped carbon (Sn@Mn 2 SnO 4 -NC) were fabricated by multistep reactions and employed as the anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The coexistence of binary metals (Sn and Mn) can improve intrinsic conductivity. Simultaneously, hollow architecture along with carbon relieves internal stress and prevents structural collapse. A Sn@Mn 2 SnO 4 -NC anode delivers an appealing capacity of 1039.5 mAh g -1 for 100 cycles at 100 mA g -1 and 823.8 mAh g -1 for 600 cycles at 1000 mA g -1 in LIBs. When evaluated as an anode in SIBs, the Sn@Mn 2 SnO 4 -NC anode tolerates up to 7000 cycles at 2000 mA g -1 and maintains a capacity of 185.8 mAh g -1 . Quantified kinetic investigations demonstrate the high contribution of pseudocapacitive effects during the cycle process. Furthermore, density functional theory (DFT) calculations further verify that introduction of the second metal (Mn) improves the conductivity of the material, which is favorable for charge transport. This work is expected to provide a feasible preparation strategy for binary-metal materials to enhance the performance of lithium- and sodium-ion batteries.

Devising novel composite electrodes with particular structural/electrochemical characteristics becomes an efficient strategy to advance the performance of rechargeable battery. Herein, considering the homogeneous transition metal sulfide with N-doped carbon derived from zeolitic imidazolate framework-67 (ZIF-67) and WS 2 with large interlayer spacing, a laurel-leaf-like Co 9 S 8 /WS 2 @N-doped carbon bimetallic sulfide (Co 9 S 8 /WS 2 @NC) is engineered and prepared via a step-by-step method. As an electrode material for sodium ion batteries (SIBs), Co 9 S 8 /WS 2 @NC composite delivers high capacities of 480 and 405 mA h g -1 at 0.1 and 1.0 A g -1 , respectively. As the current density increases from 0.1 to 5.0 A g -1 , it provides specific capacity of 359 mA h g -1 with a capacity retention rate of 78.0%, which is higher than that of Co 9 S 8 @NC (63.5%) and WS 2 (58.6%). The Co 9 S 8 /WS 2 @NC composite anode maintains a stable specific capacity (354 mA h g -1 at 2.0 A g -1 ). It also exhibits a high capacitive contribution ratio of 90.8% at 1.0 mV s -1 . This study provides a new and reliable insight for designing bimetallic sulfide with two-dimensional nanostructure for energy storage., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)