다공성 카본 구조를 이용한 리튬 다황화물 셀의 전기화학적 출력 특성에 대한 연구

Abstract

The discharge reaction in lithium-sulfur (Li-S) batteries consists of two stages. The first stage is the conversion reaction of S8 to soluble long-chain polysulfide species (S8↔Li2S4, theoretical capacity of 419 mAh g-1). The second step is the reduction of Li2S4 to form a solid product (Li2S4↔Li2S). The kinetics in this stage is governed by the formation of the Li2S, which is relatively slow compared to the first stage. High rate capability is achieved using a porous carbon gas diffusion layer (PCG) system cycled at various current rates and in a voltage range of 2.2 - 2.8 V. More than 100 cycles were delivered with an average specific capacity of 400 mAh g-1, corresponding to a practical energy density of 320 Wh kg-1 and a power of approximately 7000 W kg-1 at a high C-rate (50 C). This value was higher than that of conventional lithium ion batteries (~200 Wh kg-1), making this battery configuration an attractive alternative for practical applications