Abstract
Lithium (Li) metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries. However, the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites, resulting in poor cycling stability and severe safety issues. Herein, vertical graphene (VG) film grown on graphite paper (GP) as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites. The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients, thus regulating the Li deposition to suppress the dendrite growth. The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal, which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential. As a result, the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5 mA cm−2 in half cells and a small hysteresis of 50 mV at 1 mA cm−2 in symmetric cells. This work provides an efficient strategy for the rational design of highly stable Li metal anodes.
Highlights
The commercial lithium-ion batteries cannot meet the demand for the fast development of electric vehicles and electronic devices due to their low energy density [1, 2]
The surface chemistry of the vertical graphene (VG)@graphite paper (GP) film is analyzed by X-ray photoelectron spectroscopy (XPS)
We demonstrate an all-carbon current collector, which is a graphite paper with vertical graphenes grown on its surface, realizing the stable Li deposition
Summary
The commercial lithium-ion batteries cannot meet the demand for the fast development of electric vehicles and electronic devices due to their low energy density [1, 2]. The unstable solid electrolyte interphase (SEI) on the Li surface cracks due to the volume changes and reforms during the Li plating/stripping processes which continuously consumes the Li-ions and electrolytes, resulting in fast capacity fading and low Coulombic efficiency [9,10,11] All these drawbacks impede the practical applications of LMA. To solve the above problems, we design a hybrid carbon structure that the vertical graphene (VG) array with a height less than 2 μm grown on graphite paper (GP) (VG@GP) to enable uniform Li nucleation and deposition In this structure, the VG structure provides a comprehensive contact with the electrolyte through their large surface area and effectively reduces the local current density. Stable cycling performance with high CE is obtained in the full cells by using VG@GP Li anode
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