In Situ Reaction Fabrication of a Mixed‐Ion/Electron‐Conducting Skeleton Toward Stable Lithium Metal Anodes

Abstract

Lithium metal batteries are emerging as a strong candidate in the future energy storage market due to its extremely high energy density. However, the uncontrollable lithium dendrites and volume change of lithium metal anodes severely hinder its application. In this work, the porous Cu skeleton modified with Cu6Sn5 layer is prepared via dealloying brass foil following a facile electroless process. The porous Cu skeleton with large specific surface area and high electronic conductivity effectively reduces the local current density. The Cu6Sn5 can react with lithium during the discharge process to form lithiophilic Li7Sn2 in situ to promote Li‐ions transport and reduce the nucleation energy barrier of lithium to guide the uniform lithium deposition. Therefore, more than 300 cycles at 1 mA cm−2 are achieved in the half‐cell with an average Coulombic efficiency of 97.5%. The symmetric cell shows a superior cycle life of more than 1000 h at 1 mA cm−2 with a small average hysteresis voltage of 16 mV. When coupled with LiFePO4 cathode, the full cell also maintains excellent cycling and rate performance.

Extrusion 3D Printing of Patterned Cu Current Collectors for Advanced Lithium Metal Anodes

“…A preferential Li‐ion adsorption and an increased number of nucleation sites can be obtained thanks to rougher Cu surface. The porous structure can also induce the Li plating in the internal cavities providing a better metal accommodation and distribution along the current collector [26] . The result is an enhanced local current density that boosts the electron transfer process (expressed in terms of an increased exchange current density) [27] .…”

“…This hypothesis has been further consolidated in literature by ab‐initio molecular dynamics, which indicated significantly lower nucleation energy barriers and consequently faster transport for Li ions for those substrates or current collectors which provided improved stripping and plating performances. Such lower activation energy for diffusion prevents gathering of ions and favours more homogeneous ionic flux, consequently hindering the generation of lithium dendrites [26] …”

“…Such lower activation energy for diffusion prevents gathering of ions and favours more homogeneous ionic flux, consequently hindering the generation of lithium dendrites. [26] Average Coulombic efficiency higher than 95 % is observed for all the investigated Li@3DCu anodes. The P4 sample shows stripping/plating efficiencies of about 100 % for all the explored cycling ranges.…”

“…The porous structure can also induce the Li plating in the internal cavities providing a better metal accommodation and distribution along the current collector. [26] The result is an enhanced local current density that boosts the electron transfer process (expressed in terms of an increased exchange current density). [27] Additionally, the huge storage space provided by the 3D pattern can mitigate the typical volume deformation of the lithium anode that is responsible for cycling instability and severe cell failure.…”