Sn-based submicron-particles encapsulated in porous reduced graphene oxide network: Advanced anodes for high-rate and long life potassium-ion batteries

Potassium-ion batteries (PIBs) have been identified as the possible alternatives to lithium-ion batteries (LIBs) due to the abundant reserve, low price, and low potential of potassium (-2.936 V vs. standard hydrogen electrode). However, there is still a challenge to achieve high energy density and long cycle life to promote its practical application. A simple synthesis strategy is reported in this paper to make the submicron metallic tin (Sn) particles encapsulated in the reduced graphene oxide (RGO) network, which is used as the electrode materials for PIBs. Sn-based particles are homogeneously distributed in the RGO network, abundant structural defects and a high Brunauer-Emmett-Teller (BET) surface area (136.5 m(2)/g), which enhance potassium ion storage of Sn@RGO anode. The Sn@RGO anode exhibits exhibiting a high charge capacity of 200 mAh g(-1) after 50 cycles at 100 mA g(-1) and an excellent rate capability of 67.1 mAh g(-1) at 2000 mA g(-1), while the pure Sn anode holds limited capacity and rate capability. Cyclic voltammogram measurements are conducted to verify the contributions of surface-dominated K-storage, demonstrating the high surface area having crucial effect on the capacity improvement. Meanwhile, the alloying phases are observed by in ex-situ XRD analysis at the fully depotassiation state. Consequently, this work shows a promising development of Sn-based anode materials with superior cost-effectiveness and sustainability for PIBs. (C) 2019 Elsevier Ltd. All rights reserved.