Ashby David S, Horner Jeffrey S, Whang Grace, Lapp Aliya S, Roberts Scott A, Dunn Bruce, Kolesnichenko Igor V, Lambert Timothy N, Talin A Alec
Sandia National Laboratories, Livermore, California 94550, United States.
Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
ACS Appl Mater Interfaces. 2022 Jun 15;14(23):26604-26611. doi: 10.1021/acsami.2c01021. Epub 2022 Jun 6.
Conversion cathodes represent a viable route to improve rechargeable Li battery energy densities, but their poor electrochemical stability and power density have impeded their practical implementation. Here, we explore the impact cell fabrication, electrolyte interaction, and current density have on the electrochemical performance of FeS/Li cells by deconvoluting the contributions of the various conversion and intercalation reactions to the overall capacity. By varying the slurry composition and applied pressure, we determine that the capacity loss is primarily due to the large volume changes during (de)lithiation, leading to a degradation of the conductive matrix. Through the application of an external pressure, the loss is minimized by maintaining the conductive matrix. We further determine that polysulfide loss can be minimized by increasing the current density (>C/10), thus reducing the sulfur formation period. Analysis of the kinetics determines that the conversion reactions are rate-limiting, specifically the formation of metallic iron at rates above C/8. While focused on FeS, our findings on the influence of pressure, electrolyte interaction, and kinetics are broadly applicable to other conversion cathode systems.
转换型阴极是提高可充电锂电池能量密度的一条可行途径，但其较差的电化学稳定性和功率密度阻碍了其实际应用。在此，我们通过剖析各种转换和嵌入反应对总容量的贡献，来探究电池制备、电解质相互作用和电流密度对FeS/Li电池电化学性能的影响。通过改变浆料组成和施加压力，我们确定容量损失主要是由于（脱）锂过程中的大体积变化，导致导电基体降解。通过施加外部压力，通过维持导电基体可使损失最小化。我们进一步确定，通过提高电流密度（>C/10）可使多硫化物损失最小化，从而缩短硫形成期。动力学分析确定转换反应是限速步骤，特别是在高于C/8的速率下金属铁的形成。虽然我们的研究重点是FeS，但我们关于压力、电解质相互作用和动力学影响的发现广泛适用于其他转换型阴极系统。
