High-Performance Li-Metal-Free Sulfur Battery Employing a Lithiated Anatase TiO<sub>2</sub> Anode and a Freestanding Li<sub>2</sub>S–Carbon Aerogel Cathode
Ravindra Kumar Bhardwaj, Homen Lahan, V. Sekkar, Bibin John, Aninda J. Bhattacharyya
Abstract
Lithium–sulfur (Li–S) batteries have emerged as promising alternatives to Li-ion batteries. The commercial feasibility of Li–S batteries is still in question due to the usage of a highly reactive Li-metal anode and complex electrochemistry of the sulfur cathode. We demonstrate here a sulfur battery that is free of both the lithium-metal anode and sulfur-element (S8) cathode. Instead of a carbonaceous material, a lithiated anatase titanium dioxide (TiO2) nanoparticle is chosen here as the anode. A freestanding pellet of lithium sulfide and carbon aerogel (Li2S/CA) is used as the cathode in the Li-metal-free sulfur battery. Activation of Li2S and its conversion to S8 are confirmed by in operando Raman spectroscopy. UV–vis spectroscopy clearly shows high retention of intermediate polysulfides inside the Li2S/CA pellet. The cell with the freestanding Li2S/CA cathode (Li2S-loading ≈ 10 mg cm–2) and the TiO2 anode shows remarkable electrochemical performance at current rates varying from 0.1C (1st cycle: 565 mAh g–1; 200th cycle: 370 mAh g–1) to 1C (≈200 mAh g–1). The Li2S/CA also performed remarkably well with the Li-metal anode in the current rate range from 0.1C (1st cycle: 955 mAh g–1; 200th cycle: 855 mAh g–1) to 2C (average specific capacity@1C ≈ 380 mAh g–1).