Cathode for lithium sulfur battery and method for preparing thereof
A technology for lithium-sulfur batteries and positive electrodes, which is applied in the field of positive electrodes for lithium-sulfur batteries and its preparation, and can solve problems such as limitations
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preparation example 1
[0043] In the initial stage of lithium-sulfur batteries, the positive electrode is S (S 8 ) and the anode is lithium metal (Li). When starting to discharge, S 8 Receive Li and generate lithium polysulfide Li 2 S 8 . Li 2 S 8 Participate in the reaction and dissolve in the electrolyte at the same time. At the end of discharge, Li 2 S remains at the positive pole. Relative to the electrolyte (1M LiTFSI in TEGDME), Li 2 S 8 The saturated solubility is about 6M.
[0044] First, in the reaction [42S+6Li 2 S=6Li 2 S 8 ] in the preparation of Li according to the stoichiometric ratio of 6M 2 S 8 (additional active substance) liquid. In TEGDME the solvent was 1M LiTFSI and stirring was carried out at 50°C for 12 hours. Hereinafter, where the dissolved Li 2 S 8 The electrolyte will be referred to as "PS electrolyte".
[0045] If Li is added in an amount of 10 μmol 2 S 8 The liquid is added to the electrolyte (performed in a small cell experiment used to evaluate th...
preparation example 2
[0048] Preparation of 0.25M, 1M and 3M PS (Li 2 S 8 ) electrolyte.
[0049] Mix 10ml of 1M LiTFSI in TEGDME / DIOX (1 / 1) with 0.2MLiNO 3 Li in solution 2 A mixture of S (45.95 g / mol) and S (32.06 g / mol) powders was mixed to provide a stoichiometric composition. The stoichiometric composition is based on the reaction formula (7xS+xLi 2 S=xLi 2 S 8 ). After stirring at 50°C for 12 hours, the powder did not dissolve for the 3M PS electrolyte. The solubility is determined to be lower because DIOX is mixed in the solvent and LiTFSI and LiNO 3 Salt is already dissolved in the electrolyte.
[0050] battery assembly
[0051] Case 1. (Add PS electrolyte, 1M)
[0052] The positive electrode was prepared such that the mixing ratio of fine sulfur powder: VGCF (vapour-grown carbon fiber): PvdF (polyvinylidene fluoride) was 6:2:2 and the sulfur loading was 4.0 mg / cm 2 .
[0053] The diaphragm uses a PE diaphragm and a carbon sheet (conductive structure) and is used as a reaction ...
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