The big challenge for practical lithium metal batteries is how to make full and reversible utilization of lithium anode. The preformed three-dimensional (3D) porous framework with numerous lithium nucleation sites is able to guide the lithium deposition in the cavity of 3D framework, suppressing the dendrite growth and dimensional change. Herein, we design a nanocapsule structure for lithium metal anodes consisting of 3D graphene with Mg_xLi_y seeds inside. The 3D composite anode not only can be prepared in a simple and scalable process, but also can meet the requirements for both high energy density and long cycle life in the practical cells. During the observation of lithium deposition by transmission electron microscope, it was found that lithium metal was mainly deposited around the Mg_xLi_y seeds within 3D graphene. Thereafter, when the composite anodes are well paired with the commercial LiFePO₄ cathodes in coil cells and NCM811 (LiNi_0.8Co_0.1Mn_0.1O₂) cathodes in pouch batteries, they are able to deliver the energy density exceeding 350 Wh·kg⁻¹ and long cycle life (>150 cycles) with high energy retention (>85%). The 3D lithium metal/graphene composite anode in the present work provides a promising new avenue for the fabrication of high energy density Li-metal batteries.

对于实用的锂金属电池来说，最大的挑战是如何充分，可逆地利用锂阳极。具有许多锂成核位点的预制三维（3D）多孔骨架能够引导锂沉积在3D骨架的空腔中，从而抑制枝晶生长和尺寸变化。在这里，我们设计了一种用于3D石墨烯和Mg _x Li _y组成的锂金属阳极的纳米胶囊结构。里面的种子。3D复合阳极不仅可以通过简单且可扩展的方法制备，还可以满足实际电池中高能量密度和长循环寿命的要求。在通过透射电子显微镜观察锂沉积的过程中，发现锂金属主要沉积在3D石墨烯内的Mg _x Li _y晶种周围。此后，当复合阳极与线圈单元中的商用LiFePO ₄阴极以及袋装电池中的NCM811（LiNi _0.8 Co _0.1 Mn _0.1 O ₂）阴极很好地配对时，它们能够提供超过350 Wh·kg ^-1的能量密度循环寿命长（> 150个循环），能量保持率高（> 85％）。当前工作中的3D锂金属/石墨烯复合阳极为高能量密度锂金属电池的制造提供了有希望的新途径。