Heterostructure ZnSe-CoSe2 embedded with yolk-shell conductive dodecahedral as Two-in-one hosts for cathode and anode protection of Lithium–Sulfur full batteries

Abstract

Simultaneously realizing the cathode and anode protection is critical for developing practical lithium sulfur (Li-S) batteries. Currently, many efforts have been devoted to solving problems related to either shuttle effect on sulfur cathode or dendrite growth on lithium anode. However, dual side protection is rarely reported. Herein, we rationally designed and synthesized yolk-shell nitrogen doped carbon frameworks embedded with heterostructures ZnSe-CoSe2 (ZnSe-CoSe2@NC), working as “two-in-one” hosts for both the sulfur cathode and lithium anode protection. As an anode host, the in situ formed Li2Se phase contributes to the Li+ transfer. Co and Zn guides a homogenous growth of Li within the 3D framework, thus effectively suppressing Li dendrite growth. Meanwhile, the heterostructure ZnSe-CoSe2 endows the cathode host with superior electronic conductivity, strong polysulfide chemisorption and efficient catalytic activity for polysulfide redox when compared with single metal selenides. Combined with these advantages, this Li-S full cell exhibits ultralong cycle life over 1000 cycles at 2 C. Even with a high sulfur loading (6.08 mg cm−2) and lean electrolyte (4.1 µL mg−1), the full cell achieves a high areal capacity of 4.16 mA h cm−2 after 100 cycles at 0.2 C. This work not only provides a new approach for the structure design of Li-S full battery, but also improves the utilization of active electrode materials.