Hierarchical N-doped porous carbon hosts for stabilizing tellurium in promoting Al-Te batteries

Abstract

Aluminum batteries are attractive in electrochemical energy storage due to high energy density and low-cost aluminum, while the energy density is limited for the lack of favorable positive electrode materials to match aluminum negative electrodes. Tellurium positive electrode is intrinsically electrically conductive among chalcogen and holds high theoretical specific capacity (1260.27 mAh g−1) and discharge voltage plateau (~1.5 V). However, the chemical and electrochemical dissolution of Te active materials results in the low material utilization and poor cycling stability. To enhance the electrochemical performance, herein a nitrogen doped porous carbon (N-PC) is derived from zeolite imidazolate framework (ZIF-67) as an effective tellurium host to suppress the undesired shuttle effect. In order to inhibit the volume expansion of N-PC during the charge/discharge process, the reduced graphene oxide (rGO) nanosheets are introduced to form a stable host materials (N-PC-rGO) for stabilizing Te. The physical encapsulation and chemical confinement to soluble tellurium species are achieved. N-PC-rGO-Te positive electrode exhibits an improved initial specific capacity and long-term cycling performance at a current density of 500 mA g−1 (initial specific capacity: 935.5 mAh g−1; after 150 cycles: 467.5 mAh g−1), highlighting a promising design strategy for inhibiting chemical and electrochemical dissolution of Te.