Bidirectional catalysis of Co0.4Ni1.6P for Li2S1–2 deposition/decomposition reactions in Li-S batteries

To improve the electrochemical activity of S electrodes in Li-S batteries, the synergistic electrocatalysis mechanism of Co 0.4 Ni 1.6 P with Ni and Co bimetal interactions is clarified. The alternating crystal structure of Co and Ni regulates the adsorption and decomposition energy of Co 0.4 Ni 1.6 P to polysulfides and has the bidirectional catalysis for the Li 2 S 1–2 deposition/decomposition process. Co 0.4 Ni 1.6 P can promote the breaking of the S-S bond of Li 2 S 4 and decrease the decomposition energy barrier of Li 2 S. This regulation accelerates the discharge/charge reaction between S, polysulfides, and Li 2 S and improves the kinetics of the S electrodes. The 1 st , 100 th , and 200 th discharge capacity densities at 0.1 mA cm −2 of the S electrodes with a high sulfur loading were 1,405, 987.2, and 828.4 mAh g S −1 , respectively. The bidirectional catalytic mechanism is a novel idea for improving the electrochemical performance of Li-S batteries.