Search for: All records

The significant performance decay in conventional graphite anodes under low‐temperature conditions is attributed to the slow diffusion of alkali metal ions, requiring new strategies to enhance the charge storage kinetics at low temperatures. Here, nitrogen (N)‐doped defective crumpled graphene (NCG) is employed as a promising anode to enable stable low‐temperature operation of alkali metal‐ion storage by exploiting the surface‐controlled charge storage mechanisms. At a low temperature of −40 °C, the NCG anodes maintain high capacities of ≈172 mAh g⁻¹for lithium (Li)‐ion, ≈107 mAh g⁻¹for sodium (Na)‐ion, and ≈118 mAh g⁻¹for potassium (K)‐ion at 0.01 A g⁻¹with outstanding rate‐capability and cycling stability. A combination of density functional theory (DFT) and electrochemical analysis further reveals the role of the N‐functional groups and defect sites in improving the utilization of the surface‐controlled charge storage mechanisms. In addition, the full cell with the NCG anode and a LiFePO₄cathode shows a high capacity of ≈73 mAh g⁻¹at 0.5 °C even at −40 °C. The results highlight the importance of utilizing the surface‐controlled charge storage mechanisms with controlled defect structures and functional groups on the carbon surface to improve the charge storage performance of alkali metal‐ion under low‐temperature conditions.

Redox‐active organic compounds have attracted substantial attention as charge storage materials, owing to their high theoretical capacity. Herein, a two‐dimensional organic electrode material is prepared by using hydrothermally polymerized dopamine molecules on graphene nanosheets. Two‐dimensional polydopamine is employed as a positive electrode for storing alkali metal ions based on the surface redox reaction between oxygen functional groups and alkali ions. The two‐dimensional polydopamine positive electrodes deliver high capacities of 255 mAh g⁻¹in Li cells, 150 mAh g⁻¹in Na cells, and 124 mAh g⁻¹in K cells at 0.1 A g⁻¹, demonstrating a promising organic positive electrode for rechargeable alkali‐ion batteries.

The energy and power performance of lithium (Li)‐ion batteries is significantly reduced at low‐temperature conditions, which is mainly due to the slow diffusion of Li‐ions in graphite anode. Here, it is demonstrated that the effective utilization of the surface‐controlled charge storage mechanism through the transition from layered graphite to 3D crumpled graphene (CG) dramatically improves the Li‐ion charge storage kinetics and structural stability at low‐temperature conditions. The structure‐controlled CG anode prepared via a one‐step aerosol drying process shows a remarkable rate‐capability by delivering ≈206 mAh g^–1at a high current density of 10 A g^–1at room temperature. At an extremely low temperature of −40 °C, CG anode still exhibits a high capacity of ≈154 mAh g^–1at 0.01 A g^–1with excellent rate‐capability and cycling stability. A combination of electrochemical studies and density functional theory (DFT) reveals that the superior performance of CG anode stems from the dominant surface‐controlled charge storage mechanism at various defect sites. This study establishes the effective utilization of the surface‐controlled charge storage mechanism through structure‐controlled graphene as a promising strategy to improve the charge storage kinetics and stability under low‐temperature conditions.