Rechargeable lithium batteries using lithium metal as a negative electrode are attractive candidates for high energy density power sources, because the lithium metal offers a high specific capacity and possesses a low electrochemical potential.^1,2 However, the development of rechargeable lithium metal batteries has been hindered for several decades by the high reactivity of lithium metal toward liquid electrolytes and the occurrence of dendrite growth during charge and discharge cycles. The formation and growth of lithium dendrites result in safety and cycle life problems. Additionally, continuous generation of the new solid electrolyte interphase (SEI) layer on lithium metal causes uncontrolled reductive decomposition of the organic electrolyte and gradual loss in capacity and cycling efficiency with repeated cycling. Therefore, protection of lithium metal and the formation of a stable SEI layer on the lithium electrode are very important for developing lithium metal batteries with good capacity retention and enhanced safety. In this work, a prospective approach for protecting a lithium metal is presented by spray coating with a conductive poly(3,4-ethylenedioxythiohene)-co-poly(ethylene glycol) (PEDOT-co-PEG) and inorganic particles (AlF₃), which allows for lithium ion diffusion and restricts the access of the reactive solvents to the lithium surface. The protective composite layer played a positive role in reducing the reductive decomposition of the electrolyte and suppressing the dendrite growth of lithium during cycling. As a result, the surface modification of lithium electrode with PEDOT-co-PEG and AlF₃ significantly improved the cycling stability of the lithium metal batteries.

 

References

1. J.M.Tarascon and M.Armand, Nature, 539, 414 (2001).

2. D.Linden and T.B.Reddy, Handbook of Batteries, 3rd Edition, McGraw-Hill, New York (2003).