锂电池用正极材料多硫代苯的电化学性能

Electrochemical Performance of a Novel Cathode Material Phenyl Polysulfide for Lithium Batteries

采用多硫化钠与六氯代苯为原料,制备了一系列具有网状交联结构的不同硫含量的多硫代苯作为锂电池正极材料,并对其电化学性能进行了研究.结果表明,提高硫含量有利于提高材料的放电容量,但易加剧充放电循环中的容量衰减.硫含量为91.99%的样品,首放容量达到756mAh·g-1,20次循环容量保持367mAh·g-1.讨论了多硫代苯的放电机理,循环容量衰减和充放电效率较低的原因.

A novel orgnaosulfur cathode material named phenyl polysulfide(PPS) for lithium batteries was studied. The highly crosslinked stucture of this material with phenyl repeat units covalently linked by - S-x - moieties (x greater than or equal to 2) was designed to reduce the generation of small molecule during discharging which was one of the main reasons for its cycling capacity fade. A series of PPS with different sulfur contents were prepared through the reaction between hexachlorobenzene and Na2Sx (x greater than or equal to 2). Galvanostatic cycling and cyclic voltammetry were used to investigate the electrochemical characteristics of this material. The results demonstrated that higher sulfur content of the material led to higher discharge capacity but more serious capacity fade during cycling. The sample PPS-10 containing 91.99% sulfur exhibited high capacity up to 756 mAh (.) g(-1) in the initial cycle and a stable reversible capacity 367 mAh (.) g(-1) after 20 cycles. The discharge mechanism, the reason for capacity fade during cycling and poor coulomb efficiency of the materials were also discussed.