Interconnected hollow carbon nanospheres for stable lithium metal anodes

Abstract

For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼ 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

A Review of Solid Electrolyte Interphases on Lithium Metal Anode

“…Limited by the resolution of optical microscopy, the hyperfine structure of SEI layer cannot be obtained. To further understand the SEI morphology and investigate the layer in nanometer scale, transmission electron microscopy (TEM) experiments are employed 65, 66. Tu and co‐workers67 employed TEM to investigate the ex situ Li 3 N film on Li metal.…”

“…Cui and co‐workers innovatively created an artificial SEI with a monolayer of nanostructured and interconnected amorphous hollow carbon nanospheres to protect the Li metal anode ( Figure 11 ). 66 The artificial SEI was with a conductivity of ≈7.5 S m −1 , effectively inhibiting the electron delivery through SEI. Large pores cannot be found on the artificial SEI, avoiding electrolyte leakage into the Li surface 135.…”

“…Dendrite‐free Li metal anode with hollow carbon nanospheres coating 66. a) Fabrication of Cu electrode with carbon nanospheres.…”

“…The red dashed line is the trace of the curvature of bending. Reproduced with permission 66. Copyright 2014, Nature Publishing Group.…”

Recent Advances in Designing High‐Capacity Anode Nanomaterials for Li‐Ion Batteries and Their Atomic‐Scale Storage Mechanism Studies

“…E) Comparison of cycling performances of the hollow carbon nanosphere‐modified electrode (solid symbols) and the control Cu electrode (hollow symbols) at different current rates. Reproduced with permission 166. Copyright 2014, Nature.…”