discharge and charge. These problems cause early cell death, poor Coulombic efficiency (CE), rapid cycling capacity decay, and catastrophic thermal runaway. [9][10][11][12] To overcome the above thorny issues, extensive endeavors have been revived and a number of strategies have been proposed and practiced. For example, strengthening the solid electrolyte interphase (SEI) films by engineering liquid electrolytes with functional additives (LiNO 3 , Cs + , LiF, etc.) or employing solid electrolytes to prevent the Li dendrites. [13][14][15][16][17][18][19] However, these efforts cannot accommodate the infinite volume changes of Li metal during lithium stripping/plating, which can damage the contact interfaces between the electrolytes and Li anodes for continuous charge/discharge cycling. Porous and conductive scaffolds are expected to simultaneously suppress the Li dendrite growth and minimize the volume changes of Li metal electrodes. [20][21][22][23][24][25][26] Such host materials with a large specific surface area not only lower the local effective current density to form a uniform Li-ion flux but also provide an ample space to accommodate Li. Multifarious porous metal foams, such as 3D porous Cu foils and Cu-Ni core-shell nanowire networks, have behaved as effective hosts of Li. [23,27,28] However, the high mass density of these porous metals dramatically reduces the overall energy density of the composite electrodes, and dissipates the advantages of Li-metal anodes in specific capacity and energy density. In this respect, it is highly desirable to develop lightweight, flexible, conductive, and porous host materials with a lower interfacial energy with lithium.Lightweight porous carbon materials, including carbon nanotube and graphene exhibit distinct advantages over porous metals. [10,[29][30][31][32][33] The appealing characteristics of low mass density, excellent electrical conductivity, and chemical stability render them as promising host materials of Li anodes. [34][35][36][37][38][39][40][41] However, these carbon skeletons are usually lithium-phobic and require Li seed growth or additional lithiophilic surface modification to load Li. [42][43][44][45][46][47] Additionally, conventional porous carbon hosts with relatively large pore size (>10 µm) cannot efficiently dissipate large current densities due to limited surface areas, deteriorating the high rate performance of Limetal anodes. [29,31,36] Technically, it is difficult to efficiently pack 1D carbon nanotube and 2D graphene sheets into a 3D porous structure that can simultaneously achieve high porosity, largeThe key bottlenecks hindering the practical implementations of lithiummetal anodes in high-energy-density rechargeable batteries are the uncontrolled dendrite growth and infinite volume changes during charging and discharging, which lead to short lifespan and catastrophic safety hazards. In principle, these problems can be mitigated or even solved by loading lithium into a high-surface-area, conductive, and lithiophilic porous scaffold. However, ...

The real capacity of graphene and the lithium-storage process in graphite are two currently perplexing problems in the field of lithium ion batteries. Here we demonstrate a three-dimensional bilayer graphene foam with few defects and a predominant Bernal stacking configuration, and systematically investigate its lithium-storage capacity, process, kinetics, and resistances. We clarify that lithium atoms can be stored only in the graphene interlayer and propose the first ever planar lithium-intercalation model for graphenic carbons. Corroborated by theoretical calculations, various physiochemical characterizations of the staged lithium bilayer graphene products further reveal the regular lithium-intercalation phenomena and thus fully illustrate this elementary lithium storage pattern of two-dimension. These findings not only make the commercial graphite the first electrode with clear lithium-storage process, but also guide the development of graphene materials in lithium ion batteries.

Excellent tensile strength and ductility of porous graphene can be realized by 3D bicontinuous nanoarchitecture.

State-of-the-art carbonaceous anodes are approaching their achievable performance limit in Li-ion batteries (LIBs). Silicon has been recognized as one of the most promising anodes for next-generation LIBs because of its advantageous specific capacity and secure working potential. However, the practical implementation of silicon anodes needs to overcome the challenges of substantial volume changes, intrinsic low conductivity, and unstable solid electrolyte interphase (SEI) films. Here, we report an inventive design of a sandwich N-doped graphene@Si@hybrid silicate anode with bicontinuous porous nanoarchitecture, which is expected to simultaneously conquer all these critical issues. In the ingeniously designed hybrid Si anode, the nanoporous N-doped graphene acts as a flexible and conductive support and the amorphous hybrid silicate coating enhances the robustness and suppleness of the electrode and facilitates the formation of stable SEI films. This binder-free and stackable hybrid electrode achieves excellent rate capability and cycling performance (817 mAh/g at 5 C for 10 000 cycles). Paired with LiFePO4 cathodes, more than 100 stable cycles can be readily realized in full batteries.