namely natural graphite (NG) and artificial graphite. NG originates from organics rich in carbon under long-term hightemperature and high-pressure geological environments, while artificial graphite is obtained by artificial carbonization and graphitization of organics under high temperature. The main types of NG include flake graphite (FG) and microcrystalline graphite (MG). NG, such as flake FG, delivers high capacity owing to its larger anisotropic crystalline domains, while the artificial graphite with higher purity and larger fraction of edge planes caused by smaller crystalline size presents excellent electrochemical kinetics, long cycle life, but low initial Coulombic efficiency (ICE). [9,10] NG has drawn great attention as anode material in LIBs due to the outstanding features such as high energy density, excellent processability, and low cost. [11,12] By 2020, NG accounted for 39% of the anode material market compared with 58% of artificial graphite. [13] It should be noted that the market share of NG will continue to grow due to the requirements for reducing CO 2 emission and environmental footprint since the production of artificial graphite is energy-intensive, high cost, and time consuming. [14] China is rich in resources of NG and is the world's largest exporter of NG. [15] FG shows a typical layered and anisotropic structure in which large graphite crystals stack together within orientation. [16] When used as an anode material, FG presents high specific capacity and ICE, but poor cyclic stability due to the structure destruction caused by volume expansion. [17,18] MG presents isotropic structure, consisting of graphitic microcrystals randomly stacked together. The MG anode presents better cyclic stability and outstanding rate performance due to the small volume expansion and shortened lithium ion (Li + ) diffusion distance, but low ICE owing to the large surface area. [16] It should be noted that our group invented NG-based materials as early as 1992, [19][20][21] and introduced such low-cost materials in many aspects of applications, and finally into LIBs as commercial anodes in 1997. [22][23][24] To improve its electrochemical performance, surface modification such as carbon coating is essential for NG to form a stable solid electrolyte interface (SEI) layer, which can reduce the initial irreversible capacity, enhance the cyclability, and improve the low-temperature as well as thermal stability. [25] Besides, the NG can be hybridized with other carbon materials, including carbon nanotube (CNT), [26][27][28] Graphite, commonly including artificial graphite and natural graphite (NG), possesses a relatively high theoretical capacity of 372 mA h g -1 and appropriate lithiation/de-lithiation potential, and has been extensively used as the anode of lithium-ion batteries (LIBs). With the requirements of reducing CO 2 emission to achieve carbon neutral, the market share of NG anode will continue to grow due to its excellent processability and low production energy consumption. NG, which is abundant in Chi...

Constructing robust nucleation sites with an ultrafine size in a confined environment is essential toward simultaneously achieving superior utilization, high capacity, and long-term durability in Na metal-based energy storage, yet remains largely unexplored. Here, we report a previously unexplored design of spatially confined atomic Sn in hollow carbon spheres for homogeneous nucleation and dendrite-free growth. The designed architecture maximizes Sn utilization, prevents agglomeration, mitigates volume variation, and allows complete alloying-dealloying with high-affinity Sn as persistent nucleation sites, contrary to conventional spatially exposed large-size ones without dealloying. Thus, conformal deposition is achieved, rendering an exceptional capacity of 16 mAh cm −2 in half-cells and long cycling over 7000 hours in symmetric cells. Moreover, the well-known paradox is surmounted, delivering record-high Na utilization (e.g., 85%) and large capacity (e.g., 8 mAh cm −2 ) while maintaining extraordinary durability over 5000 hours, representing an important breakthrough for stabilizing Na anode.

We have demonstrated an ingenious one-pot aqueous domino-driven synthesis toward hollow hybrid spheres with ultrafine metal nitrides/oxides in hollow carbon cavity. The micelle-interfacial copolymerization is applied for shell formation, while the copolymerization-generated H + spontaneously triggers oxometallate condensation for encapsulation. By regulating the synthetic conditions, the encapsulated metal species can be well tailored with different sizes/contents (nanocluster to several nanometers) and compositions (VN, VO, MoN, WN, bimetal-based nitrides). The ultrafine VN confined in hollow carbon exhibits excellent potassium storage performance.

Development of highly porous carbons with abundant surface functionalities and well-defined nanostructure is of significance for many important electrochemical energy storage systems. However, porous carbons suffer from a compromise between porosity, doped functionality, and nanostructure that have thus far restricted their performances. Here, we report the design of highly porous, nitrogenenriched hollow carbon nanospheres (PN-HCNs) by an interfacial copolymerization strategy followed by NH 3 -assisted carbonization, and further demonstrate their significance and effectiveness in enhancing the electrochemical performances. The PN-HCN simultaneously delivers a large surface area (1237 m 2 g −1 ) and high N functionalities (6.25 atom %) with a remarkable efficiency of the surface area increase to N loss ratio enabled by NH 3 treatment while inheriting the hollow nanospherical structure. Accordingly, owing to the enhanced surface area and retained N doping, the prepared PN-HCN demonstrates outstanding electrochemical performances as a cathode host in lithium−sulfur batteries, including a near-to-theoretical capacity of 1620 mAh g −1 , high rate capability and good cycling stability (789 mAh g −1 at 0.5C after 200 cycles). These results are superior to those of HCN without NH 3 treatment. Also, PN-HCN exhibits superior capacitances (203 F g −1 ) and fast ion transport ability in supercapacitors. Our finding shows the simultaneous achievement of both highly porous structures and sufficient N functionalities for high-performance applications.