Lithium–sulfur (Li–S) batteries are receiving intense interest because their promise for low-cost and high-energy electrochemical storage [1]. Sulfur has a high theoretical specific capacity (1675 mAh g⁻¹) and energy density (2600 Wh kg⁻¹). In addition, it is abundant, inexpensive and nontoxic. Despite these advantages Li-S batteries have not been commercially produced. Major drawbacks are the insulating nature of orthorhombic sulfur and its discharge product (Li₂S), the dissolution of lithium polysulfide formed during the electrochemical process in organic liquid electrolyte, and the large volumetric expansion of sulfur during lithiation. These factors result in a low utilization of active material and poor cycle life [2]. Furthermore this kind of battery must use lithium metal as the anode. Fully-lithiated lithium sulfide (Li₂S) is more desirable than sulfur as a high capacity cathode material because it allows the use of a variety of lithium-free anode materials. Recently, a number of studies on Li₂S with promising results have emerged. Some authors ball-milled commercial Li₂S to get different particle sizes, and the resulting particles are mostly micrometer-sized [3-4]. Furthermore, high-energy ball milling was also used for the preparation of compounds with improved chemical properties. Iio et al. [5] have synthesized lithium ion conducting materials in the system Li₃N-SiS₂ by mechanical milling at room temperature using Li₃N as a lithium source. In the present study we synthesized Li₂S by high energy ball milling using elemental sulfur and Li₃N. To identify crystalline phases of samples, X-ray diffraction measurements (Rigaku Miniflex diffractometer) were performed for powdered samples after mechanical milling for a given period of time. In the figure below is showed the X-ray diffraction patterns of the sample obtained after 1 h of ball milling. It is possible to observe that the sulfur was completely converted into Li₂S. The Scherrer's formula was used to evaluate the crystal size of the crystallite: d = k*λ/B*cosθ where d is the size of the crystallites, k is a constant that depends on the shape of the crystallites, λ is the wavelength of the radiation used, B is the peak width at half height and θ is the angle of diffraction of the peak. The value of the crystallite size calculated with the Sherrer’s formula was about 17-18 nm. The so obtained material was used to produce an electrode and the electrochemical properties were evaluated in a two electrodes lithium cell. LiClO₄ dissolved in a mixture of ethylene glycol dimethyl ether and  diethylene glycol dimethyl ether 50:50 was used as the electrolyte. We found that lithium can be electrochemically extracted and reversible reinserted into the material.  The capacity was limited to about 180 mAh g^-1 with a good capacity retention with cyclation . Further study will be addressed to increase the specific capacity of the material and to couple the electrode with suitable anode materials to obtain a full lithium-ion cell.

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2. M. Helen, M. Anji Reddy, T. Diemant, U. Golla-Schindler, R. J. Behm, U. Kaiser, and M. Fichtner. Scient. Rep. 20015, 5, 12146.
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