Experimental insight into the structure-property relationship and lithium storage mechanism of hydroxyl chloride anchored in the 3D porous conductive matrix

Hydroxyl chloride has attracted extensive attention in recent years due to its outstanding performance relative to other similar anode materials. In this paper, Co₂(OH)₃Cl was introduced into graphene aerogels by a one hot-pot method to fabricate a Co₂(OH)₃Cl/graphene aerogels composite (Co₂(OH)₃Cl/GA) with a 3D loose-porous structure. The Co₂(OH)₃Cl particles are evenly dispersed and independently wrapped within the 3D graphene network, preventing particle agglomeration and alleviating the volume effect while also providing a more convenient multi-dimensional channel for electron transmission. Hence, Co₂(OH)₃Cl/GA electrode delivered a superior cycling capacity of 615 mAh g⁻¹ at 1.6 A g⁻¹ after 150 cycles. Furthermore, due to the high conductivity and superior mechanical flexibility of the 3D porous matrix, Co₂(OH)₃Cl/GA composite could also achieve good performance even as a free-standing electrode without additives and metal foil. More importantly, the lithium storage mechanism of Co₂(OH)₃Cl/GA free-standing electrode during charge-discharging progress could be detected more clearly by ex situ XRD and XANES because the interferences of metal foil and additives were avoided. The mechanism research results reveal that the reversible lithiation/de-lithiation progress of Co₂(OH)₃Cl/GA is mainly attributed to the reversible reaction of Co(OH)₂ + 2Li⁺ + 2e⁻ ⇌ Co⁰ + 2LiOH. The collected evidence also suggests that the chlorine element may participate in the formation of solid-electrolyte-interface (SEI) film, which is conducive to enhancing the electrode stability.