Abstract
Lithium metal is the ideal anode for the next generation of high-energy-density batteries. Nevertheless, dendrite growth, side reactions and infinite relative volume change have prevented it from practical applications. Here, we demonstrate a promising metallic lithium anode design by infusing molten lithium into a polymeric matrix. The electrospun polyimide employed is stable against highly reactive molten lithium and, via a conformal layer of zinc oxide coating to render the surface lithiophilic, molten lithium can be drawn into the matrix, affording a nano-porous lithium electrode. Importantly, the polymeric backbone enables uniform lithium stripping/plating, which successfully confines lithium within the matrix, realizing minimum volume change and effective dendrite suppression. The porous electrode reduces the effective current density; thus, flat voltage profiles and stable cycling of more than 100 cycles is achieved even at a high current density of 5 mA cm−2 in both carbonate and ether electrolyte. The advantages of the porous, polymeric matrix provide important insights into the design principles of lithium metal anodes.
Highlights
Lithium metal is the ideal anode for the generation of high-energy-density batteries
Two key factors contributed to the excellent electrochemical performance of the Li-coated PI matrix, namely, the porous nature of the electrode and the non-conducting nature of the exposed matrix surface after Li stripping
The high porosity can be further confirmed by the fast electrolyte uptake during cell assembly (Supplementary Fig. 15)
Summary
Lithium metal is the ideal anode for the generation of high-energy-density batteries. A promising nanoscale interfacial engineering approach has been demonstrated recently based on interconnected hollow carbon nanospheres, ultrathin two-dimensional boron nitride or oxidized polyacrylonitrile fibres to control the dendrite growth and improve the cycling CE34–36 All these studies adopted the galvanostatic Li plating/stripping approach on a current collector, which is still unable to address the issue of infinite volume change since the electrodes expand during Li plating and shrink during stripping. The electrically insulating surface after Li stripping effectively prevents the direct plating of Li on the top surface of the matrix in the subsequent cycle, bringing about a well-confined, dendrite-free Li stripping/plating behaviour that successfully addresses the problem of infinite volume change present in all the previous designs. The obtained electrode is highly porous so that the reduced effective current density results in flat voltage profiles and stable cycling of at least 100 cycles in both carbonate- and ether-based electrolytes even at a high current density of 5 mA cm À 2, which stands in stark contrast to the fluctuated and unstable cycling profile of bare Li foil electrodes
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