A MnO@C microcage with a multi-structure and tunable carbon shell was fabricated through a facile bio-inspired synthesis strategy for highly reversible Li storage. Micrometer-sized MnO unit aggregates were covered with a porous carbon shell outside with a thickness of about 0.2 μm, and a graphene-analogous carbon network inside the MnO@C microcages. The carbon shell could be tunable by a graphene-base shell. The unique double-carbon-coating structure of the MnO@C microcages enabled realizing the high Li-storage performance of the MnO particles with a micrometer size. The electrode containing the MnO@C microcages delivered a high reversible capacity of 1450.5 mA h g⁻¹ after 270 cycles at a current density of 0.1 A g⁻¹, good rate capability, and outstanding cycling stability with a retention capacity of 805 mA h g⁻¹ after 2000 cycles at a high current density of 1 A g⁻¹. Quantitative kinetic analysis indicated that around 40% of the charge storage came from the capacitive contribution of the microcage structure. It was found that the tunable graphene-base shell could enhance the Li-ion diffusion rate significantly, and enable a stable ultralong long life cycle performance and enhanced rate performance of the microcages.

中文翻译：

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高性能MnO @ C微笼，具有分级结构和可调碳壳，可实现高效，持久的锂存储†

通过一种易于生物启发的合成策略，以高度可逆的锂存储方式制造了具有多结构和可调碳壳的MnO @ C微笼。微米尺寸的MnO单元聚集体的外部被多孔碳壳覆盖，其厚度约为0.2μm，并且在MnO @ C微笼内部有类似于石墨烯的碳网络。碳壳可以通过石墨烯基壳进行调节。MnO @ C微笼的独特双碳涂层结构使得能够实现微米级MnO颗粒的高储锂性能。含有MnO @ C微笼的电极在270次循环后以0.1 A g ^-1的电流密度提供了1450.5 mA hg ^-1的高可逆容量，良好的倍率性能和优秀的循环稳定性与805毫安Hg的保留容量^-1 2000个循环后，在1所述的g的高电流密度^-1。定量动力学分析表明，约40％的电荷存储来自微笼结构的电容性贡献。结果发现，可调石墨烯基壳层可以显着提高锂离子的扩散速率，并具有稳定的超长寿命周期性能和增强的微笼速率性能。