Porous skeleton-stabilized Co/N–C coated separator for boosting lithium-ion batteries stability and safety

Abstract

Commercial separators still show poor wettability and thermal stability. In this work, the zeolitic imidazolate framework-67 (ZIF-67) derived Co/N–C is successfully coated onto the commercial separator. In comparison to ZIF-67, the Co/N–C modified separators show higher wettability (contact angle: 20.4°) and electrolyte absorption (140%). Interestingly, at 150 °C the thermal shrinkage of Co/N–C modified separators is only 6.6% (Pristine: 33.3%, ZIF-67 modified: 13.3%). The ionic conductivity of Co/N–C modified separator batteries increases to 1.501 ms cm−1 (Pristine: 0.918 ms cm−1, ZIF-67 modified: 1.476 ms cm−1), and its decomposition potential increases to 4.91 V (Pristine: 4.48 V, ZIF-67 modified: 4.80 V). It is revealed that the significantly enhanced safety and electrochemical performance of Co/N–C modified separator batteries are mainly attributed to the well-defined morphology of Co/N–C particles, the hierarchical porous structure with high porosity, and the unique metallic Co and N-doped C component. Particularly, the Co/N–C modified separators provide significantly enhanced cycling stability with a capacity retention rate of as high as 95.3% at 1C after 100 cycles. This study provides an effective strategy to enhance the separator performance and then improve stability and safety of battery.