锂-硒电池因其超高的体积能量密度和硒的高电导率而被认为是一种极具有发展前景的锂离子电池.然而,循环过程中电极严重的体积膨胀和多硒化物溶解,以及硒的低负载,阻碍了锂-硒电池应用的发展.解决这三个问题的一种行之有效的方法是将硒限制在具有丰富孔体积的碳基质中,并同时增强硒与碳的界面相互作用.通过将Se浸入酒石酸盐衍生的蜂窝状三维多孔炭中,合成出了一种具有Se―C键的蜂窝状三维多孔炭@硒(HPC@Se)的新型正极材料用于锂-Se电池.得到的蜂窝状三维多孔炭的孔体积可达 1.794 cm3g?1,能够均匀包封 65%硒.此外,硒与碳之间的强化学键有利于稳定硒,从而进一步缓解其巨大的体积膨胀和多硒化物的溶解,还可促进循环过程中的电荷转移.该HPC@Se正极呈现出极好的循环性能和倍率性能.在 0.2 C的电流密度下,经 200次循环后,其比容量可保持在 561 mAhg?1(为理论比容量的 83%),每次循环的比容量衰减率仅为 0.058%.此外,在 5 C的高电流密度下,HPC@Se正极还可以达到 472.8 mAhg?1 的可观容量.
Li-Se batteries have risen to prominence as promising lithium-ion batteries thanks to their ultrahigh volumetric energy density and the high electrical conductivity of Se.However,the use of Li-Se batteries is limited not only by the large volume expan-sion and dissolution of polyselenides in the cathodes during cycling,but also the low selenium loading.A highly effective and cur-rently feasible approach to simultaneously tackle these problems is to position the selenium in a carbon matrix with a sufficient pore volume to accommodate the expansion while increasing the interfacial interaction between the selenium and carbon.We have syn-thesized a novel cathode material(Se@HPC)for Li-Se batteries of a honeycomb 3D porous carbon derived from a tartrate salt,that was impregnated with Se to produce Se-C bonds.The pore volume of the honeycomb 3D porous carbon was as high as 1.794 cm3 g?1,which allowed 65 wt%selenium to be uniformly encapsulated.Moreover,the strong chemical bonds between seleni-um and carbon stabilize the selenium,thus inhibiting its huge volume expansion and the dissolution of polyselenides,and promoting charge transfer during cycling.As expected,a Se@HCP cathode has excellent cyclability and a good rate performance.After 200 cycles at 0.2 C,its specific capacity remains at 561 mA h g?1,83%of the theoretical value,and decays by only 0.058%per cycle.It also has a large capacity of 472.8 mA h g?1 under a high current density of 5 C.