Jiang Yushan, Deng Yaqian, Zhang Bin, Hua Wuxing, Wang Xinliang, Qi Qi, Lin Qiaowei, Lv Wei
Shenzhen Key Laboratory for Graphene-based Materials, Engineering Laboratory for Functionalized Carbon Materials, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Nanoyang Group, State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China.
Nanoscale. 2020 Jun 18;12(23):12308-12316. doi: 10.1039/d0nr02607g.
The shuttling of lithium polysulfides (LiPSs) in lithium-sulfur (Li-S) batteries results in low sulfur utilization and fast capacity decay, hindering their practical applications. Constructing an interlayer is an efficient way to block the LiPS shuttling, but maintaining a low Li ion diffusion resistance with such an interlayer is hard to achieve. Herein, a thin porous carbon nanosheet embedded with TiO2 nanoparticles (denoted PCNS-TiO2) was used to fabricate an interlayer on the separator, which effectively solves the above problem. The PCNS-TiO2 was prepared by using the Ti3C2Tx MXene as the two-dimensional (2D) template directing the porous carbon sheet formation, and the Ti3C2Tx transformed into TiO2 nanoparticles embedded in the PCNS. The decomposition of the MXene eliminates the ion blocking effect by the 2D nanosheet structure. The thin and hierarchical porous structure allows fast Li ion diffusion across the interlayer, and at the same time, the porous structure and the strong adsorption ability of TiO2 effectively block the polysulfide diffusion. Thus, the Li-S battery with this interlayer shows good rate performance with a high capacity of 627 mA h g-1 at 2 C. Meanwhile, stable cycling performance is also achieved, showing a low capacity decay of 0.063% per cycle after 300 cycles at 0.5 C.
锂硫（Li-S）电池中多硫化锂（LiPSs）的穿梭导致硫利用率低和容量快速衰减，阻碍了它们的实际应用。构建中间层是阻止LiPS穿梭的有效方法，但要使这种中间层保持低锂离子扩散电阻却很难实现。在此，一种嵌入TiO₂纳米颗粒的薄多孔碳纳米片（表示为PCNS-TiO₂）被用于在隔膜上制备中间层，这有效地解决了上述问题。PCNS-TiO₂是通过使用Ti₃C₂Tx MXene作为二维（2D）模板来指导多孔碳片的形成而制备的，并且Ti₃C₂Tx转化为嵌入PCNS中的TiO₂纳米颗粒。MXene的分解消除了二维纳米片结构对离子的阻挡作用。薄且分层的多孔结构允许锂离子快速穿过中间层扩散，同时，多孔结构和TiO₂的强吸附能力有效地阻止了多硫化物的扩散。因此，具有这种中间层的Li-S电池表现出良好的倍率性能，在2 C时具有627 mA h g⁻¹的高容量。同时，也实现了稳定的循环性能，在0.5 C下300次循环后，每循环的容量衰减低至0.063%。
