Research On MOS₂@CC As The Interlayer And Cathode Matrix Material Of Lithium-sulfur Batteries

Lithium-sulfur(Li-S)batteries are one of the most promising energy storage devices with great potential in high energy density,low cost and non-toxicity.However,a series of problems,such as the huge volume change,the low conductivity of sulfur,the dissolution and shuttle of lithium polysulfides(LIPS),restricted the practical utilization of Li-S batteries.To solve the above matters,commercial carbon cloth(CC)as the matrix,and the molybdenum disulfide(MoS2)nanosheets were grown on CC by a simple hydrothermal method,the MoS2@CC composite was obtained.CC took some advantages in high conductivity and stable performance.Meanwhile,the three-dimensional network structure can avoid agglomeration of MoS2 nanosheets and expose more active sites,leading to inhibiting the shuttle problem of LIPS.In addition,the preparation process of commercial CC is guaranteed and stable,so it is more conducive to the industrialization of Li-S batteries.The main research contents of this paper are as follows:(1)T300 CC acted as the matrix to investigate the micromorphology and phase of MoS2 nanosheets grown on CC under different hydrothermal reaction times and temperatures,and synthesized two kinds of crystal MoS2(1T and 2H).Moreover,the 1T or 2H phase MoS2 can be prepared by directly adjusting the hydrothermal temperature,without further annealing treatment.In general,the metal-stated 1T-MoS2 was more conducive than the 2H-MoS2 in semiconductor state,and the former had good conductivity(81.0 S/cm)and more defect structure,which was more contribute to transporting ions and anchoring LIPS.(2)The interlayer of Li-S batteries was inserted by MoS2@CC between cathode and separator.The results showed the cells with the 1T-MoS2@CC interlayer performed the initial discharge specific capacity of 1007.1 mAh/g at 0.2 C,and remained at 640.3 mAh/g after 100 cycles.In addition,it delivered an excellent stability of 513.0 mAh/g over 350 cycles at 0.5 C.It was also proved by uv-vis absorption spectrum that MoS2 had strong ability binding with LIPS,which improved the absorption of LIPS.(3)Based on the previous research,MoS2@CC was directly used as cathode matrix material of Li-S battery.Then the active slurry,which was obtained by dimethyl sulfoxide mixed with sulfur,binder and conductive agent,were dropped to the MoS2@CC to realize molybdenum disulfide@carbon cloth-sulfur(MoS2@CC-S)composite cathode.The capacity of 1T-MoS2@CC-S still maintained 834.2 mAh/g after 200 cycles at 0.2 C,the initial capacity can reach 720.4 mAh/g at 0.5 C,and it still be kept at 362.2 mAh/g after 450 cycles.Under high sulfur loadings of 2.5 and 4.0 mg/cm2,the cell achieved 957.7 and 632.1 mAh/g after 100 cycles at 0.1 C,which confirmed excellent cycle performance.It was further indicated that 1T-MoS2@CC,as a cathode matrix,can inhibit the dissolution and diffusion of LIPS,so it was feasible to prepare cathode material by this newly sulfur-loaded method.