Solids that simultaneously conduct electrons and ions are key elements for the mass transfer and storage required in battery electrodes. Single-phase materials with a high electronic and high ionic conductivity at room temperature are hard to come by, and therefore multiphase systems with separate ion and electron channels have been put forward instead. Here we report on bilayer graphene as a single-phase mixed conductor that demonstrates Li diffusion faster than in graphite and even surpassing the diffusion of sodium chloride in liquid water. To measure Li diffusion, we have developed an on-chip electrochemical cell architecture in which the redox reaction that forces Li intercalation is localized only at a protrusion of the device so that the graphene bilayer remains unperturbed from the electrolyte during operation. We performed time-dependent Hall measurements across spatially displaced Hall probes to monitor the in-plane Li diffusion kinetics within the graphene bilayer and measured a diffusion coefficient as high as 7 × 10^–5 cm² s^–1.

中文翻译：

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锂在双层石墨烯中的超快速扩散

同时传导电子和离子的固体是电池电极中所需质量传递和存储的关键元素。在室温下很难获得具有高电子和高离子电导率的单相材料，因此提出了具有分开的离子和电子通道的多相系统。在这里，我们报道双层石墨烯作为单相混合导体，它证明了Li的扩散比石墨快，甚至超过了氯化钠在液态水中的扩散。为了测量Li的扩散，我们开发了一种片上电化学电池体系结构，其中迫使Li嵌入的氧化还原反应仅位于器件的突起处，因此石墨烯双层在操作过程中不会受到电解质的干扰。 ×  10 ^–5  cm ² s ^–1。