Institute of Chemistry of New Materials, Center of Physics and Chemistry of New Materials, University of Osnabrück , Barbarastr. 7, Osnabrück D-49069 Germany.
ACS Nano. 2017 Sep 26;11(9):8730-8740. doi: 10.1021/acsnano.7b02310. Epub 2017 Aug 28.
Four linear poly(viologens) (PV1, PV2: phenylic, PV3: benzylic, and PV4: aliphatic) in tight molecular contact with reduced graphene oxide (rGO), that is, PV@rGO, were prepared and used as anodic battery materials. These composites show exceptionally high, areal, volumetric, and current densities, for example, PV1@rGO composites (with 15 wt % rGO, corresponding to 137 mAh g) show 13.3 mAh cm at 460 μm and 288 mAh cm with 98% Coulombic efficiency at current densities up to 1000 A g, better than any reported organic materials. These remarkable performances are based on (i) molecular self-assembling of PVs on individual GO sheets yielding colloidal PV@GO and (ii) efficient GO/rGO transformation electrocatalyzed by PVs. Ion breathing during charging/discharging was studied by electrochemical quartz crystal microbalance and electrochemical atomic force microscopy revealing an absolute reversible and strongly anisotropic thickness oscillation of PV1@rGO at a right angle to the macroscopic current collector. It is proposed that such stress-free breathing is the key property for good cyclability of the battery material. The anisotropy is related to a puff paste architecture of rGO sheets parallel to the macroscopic current collector. A thin graphite sheet electrode with an areal capacity of 1.23 mAh cm is stable over 200 bending cycles, making the material applicable for wearable electronics. The polymer acts as a lubricant between the rGO layers if shearing forces are active.
四种线性聚（紫精）（PV1、PV2：苯基，PV3：苄基，和 PV4：脂肪族）与还原氧化石墨烯（rGO）紧密分子接触，即 PV@rGO，被制备并用作阳极电池材料。这些复合材料表现出异常高的面、体和电流密度，例如，PV1@rGO 复合材料（含有 15wt%rGO，对应 137mAhg）在 460μm 时显示 13.3mAhcm，在高达 1000Ag 的电流密度下具有 98%的库仑效率，优于任何报道的有机材料。这些显著的性能基于：（i）PVs 在单个 GO 片上的分子自组装，产生胶体 PV@GO；（ii）PV 电催化有效地将 GO/rGO 转化。通过电化学石英晶体微天平和电化学原子力显微镜研究了充电/放电过程中的离子呼吸，揭示了在宏观电流收集器上呈直角的 PV1@rGO 的绝对可逆和强烈各向异性厚度振荡。提出这种无应力呼吸是电池材料良好循环性能的关键特性。各向异性与 rGO 片平行于宏观电流收集器的蓬松糊剂结构有关。具有 1.23mAhcm2 的面容量的薄石墨片电极在 200 次弯曲循环中稳定，使该材料适用于可穿戴电子设备。如果剪切力起作用，聚合物在 rGO 层之间充当润滑剂。
