锂-硫电池是在现有锂离子电池基础上最可能实现储能密度大幅提升的实用二次电池体系. 然而，这一电池体系的电化学利用率与循环稳定性仍然难以满足应用要求. 造成锂-硫电池性能不稳定的原因在于硫正极和锂负极的材料结构和反应环境始终处于变化之中，如在充放电过程中，硫-碳反应界面的电化学阻塞、中间产物的溶解流失、正负极之间的穿梭效应等副反应导致正极与负极均难形成稳定的电化学反应界面。针对这些特殊问题，本文简要分析了影响能量利用率和循环稳定性的化学与电化学机制，并提出了构建稳定锂负极与高效硫正极的若干可行性技术.
Rechargeable Li-S batteries are a promising power source with realizable energy densities several times higher than current Li-ion batteries. However, the capacity utilization and cycling stability of the existing Li-S technologies are still insufficient for battery applications. The causes for the electrochemical instability of this redox system arise probably from the changes in the surface structures and electrochemical microenvironments of the Li anode and sulfur cathode during charge-discharge reactions, which includes the frustrated electron transfer in the sulfur-carbon interface, the dissoluble diffusion of the polysulfide intermediates, and the shuttle reaction inbetween the sulfur and Li electrodes. To deal with these problems, this paper tries to reveal the underlying chemistry affecting the charge-discharge stability of Li-S system and describe possible strategies to construct electrochemically stable Li anode and sulfur cathode, so as to achieve high efficiency Li-S batteries.
[1] Rauh R D, Abraham K M, Pearson G F, et al. A lithium/dissolved sulfur battery with an organic electrolyte[J]. Journal of the Electrochemical Society, 1979, 126 (4): 523-527.
[2] Shim J, Striebel K A, Cairns E J. The lithium/sulfur rechargeable cell, effects of electrode composition and solvent on cell performance[J]. Journal of the Electrochemical Society, 2002, 149 (10): A1321-A1325.
[3] Cheo S E, Ko K S, Cho J H, et al. Rechargeable lithium sulfur battery, i. structural change of sulfur cathode during discharge and charge[J]. Journal of the Electrochemical Society, 2003, 150(6): A796-A799.
[4] Mikhaylik Y V, Akridge J R. Polysulfide shuttle study in the Li/S battery system[J]. Journal of the Electrochemical Society, 2004, 151(11): A1969-A1976.
[5] Lai C, Gao X P, Zhang B, et al. Synthesis and electrochemical performance of sulfur/highly porous carbon composites, Journal of Physical Chemistry C, 2009, 113 (11): 4712-4716.
[6] Ji X L, Lee K T, Nazar L F. A highly ordered nanostructured carbon-sulphur cathode for lithium-sulphur batteries[J]. Nature Materials, 2009, 8(6): 500-506.
[7] Liang C D, Dudney N J, Howe J Y. Hierarchically structured sulfur/carbon nanocomposite material for high-energy lithium battery[J]. Chemistry of Materials, 2009, 21(19): 4724-4730.
[8] Wang X M, Nishina T, Uchida I. Application of the microelectrode technique to the kinetic study of lithium deposition/dissolution and alloying in organic solutions[J]. Journal of Power Sources, 1997, 68(2): 483-486.
[9] Kolosnitsyn V S, Karaseva E V, Ivanov A L. Electrochemistry of a lithium electrode in lithium polysulfide solutions[J]. Russian Journal of Electrochemistry, 2008, 44(5): 564-569.
[10] Lee Y M, Choi N S, Park J H, et al. Electrochemical performance of lithium/sulfur batteries with protected Li anodes, Journal of Power Sources, 2003, 119-121: 964-972.
[11] Mikhaylik Y V. Electrolytes for lithium sulfur cells: US, 0147891[P]. 2005.
[12] Han D H, Kim B S, Choi S J, et al. Time-resolved in situ spectroelectrochemical study on reduction of sulfur in N,N?-Dimethylformamide[J]. Journal of the Electrochemical Society, 2004, 151(9): E283-E290.
[13] Ji X L, Nazar L F. Advances in Li-S batteries[J]. Journal of Materials Chemistry, 2010, 20(44): 9821-9826.
[14] Hayashi A, Ohtomo T, Mizuno F, et al. All-solid-state Li/S batteries with highly conductive glass-ceramic electrolytes[J]. Electrochemistry Communications, 2003, 5(8):701-705.
[15] Ji X L, Evers S，Black R, et al. Stabilizing lithium-sulphur cathodes using polysulphide reservoirs, Nature communications[J]. 2011, 2(Article No. 325).
[16] Aurbach D, Pollak E, Elazari R, et al, On the surface chemical aspects of very high energy density, rechargeable Li-sulfur batteries[J]. Journal of the Electrochemical Society, 2009, 156(8): A694-A702.
