Integrating metallic cobalt and N/B heteroatoms into porous carbon nanosheets as efficient sulfur immobilizer for lithium-sulfur batteries

Constructing a multifunctional mesoporous composite of metallic cobalt nanoparticles and nitrogen‐doped reduced graphene oxides for high‐performance lithium–sulfur batteries

“…15-0806) of ( 111), (200), and (220) crystal faces at the 2 theta positions of 44.2°, 51.5°, and 75.9°, respectively. 15,38,44 Under an air atmosphere, the TGA-DSC profiles of Co/NrGO showed two exothermic peaks at 461°C and 498°C, and the corresponding weight losses can be assigned to the calcination of the N-doped rGObased carbonaceous framework and the hightemperature oxidation of nanocrystalline Co, respectively (Figure 3B). If the air-atmosphere transformation of elemental Co into Co 3 O 4 is complete (Figure S4), herein, the Co content in as-obtained Co/NrGO can be calculated to be ~15.8 wt% according to TGA-DSC results.…”

“…According to recent advances in the research on highperformance Li-S batteries, 3,5,22,[24][25][26][27][28][29][30][34][35][36][37][38][39]53,54 porous carbon generally serves as a sulfur host and a second collector in the cathode configuration and as a separator coating to block polysulfide migration, and then due to , the 3rd charge-discharge cycling curves in Figure 4B show a discharge/charge capacity of 1505.8/1482.2 and 1144.8/1101.9 mAh g −1 for Co/NrGO/S and NrGO/S, respectively, comparatively indicating higher sulfur utilization of the former than that of the latter. Aside from this, the relatively long-and-flat discharging/charging plateau of Co/NrGO/S with a smaller value of plateau voltage difference (e.g., Co/NrGO/ S ~0.15 V, NrGO/S ~0.23 V) confirms the relatively high electrode polarization of NrGO/S, as shown in Figure 4A.…”

“…[31][32][33][34][35][36][37] When porous carbon nanosheets modified with metallic Co and heteroatoms N and B (Co-NBC) are selected as sulfur-loading frameworks, the corresponding S/Co-NBC cathode yields an initial discharge capacity of 823 mAh g −1 at 0.5 C and then reaches a reversible value of 440 mAh g −1 after 500 galvanostatic cycles. 38 Another example is the use of Coembedded, N-doping carbon nanotubes (Co@NCNTs) as a host of sulfur, and the corresponding S/Co@NCNT yields a reversible capacity of 658 mAh g −1 at 0.5 A g −1 in the 200th cycle. 39 Aside from the catalytic ability of embedded Co nanoparticles therein, powdered S and nanostructured Co@NCNT/Co-NBC are ground at a mass ratio of 3:1 (i.e., 75 wt% of S), and then a 12-h melting-diffusion of elemental sulfur at 155°C under an inert atmosphere is essential to demonstrating a structure-integral synergistic effect on the enhanced performances of the S-loading composites.…”

Recent Progress of Boron-based Materials in Lithium-sulfur Battery

“…的设计中也扮演了重要的角色。Han 等 [40] 将轻质的 硼掺杂石墨烯涂覆在传统隔膜上构建了功能修饰层， 利用其对多硫化物的吸附和再利用，有效缓解了穿 梭效应并提高活性物质利用率。 鉴于不同掺杂元素的基本性质，及其在碳晶格 结构中不同的作用方式，多元素共掺杂是调控碳材 料表面化学，改善硫电化学反应的重要策略之一 [41][42][43] 。对此，Kuang 课题组 [44] 通过水热法首次合成了 氮、硼共掺杂的石墨烯纳米带(NBCGNs [45] 以硼酸为掺杂剂制备了硼、 氧共掺杂的多壁 碳纳米管宿主材料，所得电池循环 100 圈后比容量 仍保持 937 mAh•g -1 ，显著优于基于普通碳管的电池 性能(428 mAh•g -1 )。 此外，研究人员亦尝试了其他 共掺杂形式，包括硼硅共掺杂石墨烯 [46] 、钴金属和 硼氮共掺杂石墨烯 [47] [38] ；(c) NBCGN/S 充放电过程示意图，不 同元素掺杂碳管/硫的复合电极(d)在 0.2C 下的循环性能以及(e)倍率性能 [44] Fig. 3 [48][49][50][51][52][53][54][55][56] ，可为电化学反应提供快速的电子供应 [57] ； 同时，金属与硼之间存在局域有限的离子键极性结 构， 可为多硫化物提供良好的吸附位点 [58][59] ； 此外， 高负电性的硼和过渡金属合金化后稳定性减弱，更 容易参与氧化还原反应，这使得金属硼化物有可能 通过表面反应作为媒介，参与锂硫电化学反应 [60] 。 图 4 几类金属化合物导电性的对比 [48][49][50][51][52][53][54][55][56] Fig.…”

Review of Cathode in Advanced Li−S Batteries: The Effect of Doping Atoms at Micro Levels

“…prepared N, S, and O tri‐doped porous carbon composites from biomass by chemical activation and verified that the atoms of S, O, N would form strong chemical bonds in the host material due to strong electronegativity, thus enhancing the chemisorption of polysulfides (Figure 7d). Zhang et al [92] . obtained prolonged cycling stability and low‐capacity decay rate under 5 C by using porous carbon nanosheets modified with cobalt metal and non‐metallic nitrogen/boron heteroatoms (Co‐NBC) as the main material for fixing sulfur.…”