Liu Wen, Luo Chong, Zhang Siwei, Zhang Bin, Ma Jiabin, Wang Xinliang, Liu Wenhua, Li Zejian, Yang Quan-Hong, Lv Wei
Shenzhen Geim Graphene Center, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
ACS Nano. 2021 Apr 27;15(4):7491-7499. doi: 10.1021/acsnano.1c00896. Epub 2021 Apr 9.
Metal sulfides, such as MoS, are widely investigated in lithium-sulfur (Li-S) batteries to suppress the shuttling of lithium polysulfides (LiPSs) due to their chemical adsorption ability and catalytic activity. However, their relatively low conductivity and activity limit the LiPS conversion kinetics. Herein, the Co-doped MoS is proposed to accelerate the catalytic conversion of LiPS as the Co doping can promote the transition from semiconducting 2H phase to metallic 1T phase and introduce the sulfur vacancies in MoS. A one-step hydrothermal process is used to prepare such a Co-doped MoS with more 1T phase and rich sulfur vacancies, which enhances the electron transfer and catalytic activity, thus effectively improving the LiPS adsorption and conversion kinetics. The cathode using the three-dimensional graphene monolith loaded with Co-doped MoS catalyst as the sulfur host shows a high rate capability and long cycling stability. A high capacity of 941 mAh g at 2 C and a low capacity fading of 0.029% per cycle at 1 C over 1000 cycles are achieved, suggesting the effectively suppressed LiPS shuttling and improved sulfur utilization. Good cyclic stability is also maintained under a high sulfur loading indicating the doping is an effective way to optimize the metal sulfide catalysts in Li-S batteries.
金属硫化物，如MoS，因其化学吸附能力和催化活性，在锂硫（Li-S）电池中被广泛研究，以抑制多硫化锂（LiPSs）的穿梭。然而，它们相对较低的电导率和活性限制了LiPS的转化动力学。在此，提出了Co掺杂的MoS来加速LiPS的催化转化，因为Co掺杂可以促进从半导体2H相到金属1T相的转变，并在MoS中引入硫空位。采用一步水热法制备了具有更多1T相和丰富硫空位的Co掺杂MoS，这增强了电子转移和催化活性，从而有效地改善了LiPS的吸附和转化动力学。以负载Co掺杂MoS催化剂的三维石墨烯整体作为硫宿主的阴极表现出高倍率性能和长循环稳定性。在2 C下实现了941 mAh g的高容量，在1 C下1000次循环中每循环的低容量衰减为0.029%，这表明LiPS的穿梭得到了有效抑制，硫利用率得到了提高。在高硫负载下也保持了良好的循环稳定性，表明掺杂是优化Li-S电池中金属硫化物催化剂的有效方法。
