Abstract
Selenium cathodes have attracted considerable attention due to high electronic conductivity and volumetric capacity comparable to sulphur cathodes. However, practical development of lithium-selenium batteries has been hindered by the low selenium reaction activity with lithium, high volume changes and rapid capacity fading caused by the shuttle effect of polyselenides. Recently, single atom catalysts have attracted extensive interests in electrochemical energy conversion and storage because of unique electronic and structural properties, maximum atom-utilization efficiency, and outstanding catalytic performances. In this work, we developed a facile route to synthesize cobalt single atoms/nitrogen-doped hollow porous carbon (CoSA-HC). The cobalt single atoms can activate selenium reactivity and immobilize selenium and polyselenides. The as-prepared selenium-carbon (Se@CoSA-HC) cathodes deliver a high discharge capacity, a superior rate capability, and excellent cycling stability with a Coulombic efficiency of ~100%. This work could open an avenue for achieving long cycle life and high-power lithium-selenium batteries.
Highlights
Selenium cathodes have attracted considerable attention due to high electronic conductivity and volumetric capacity comparable to sulphur cathodes
After mixing the PVP-modified PS spheres with zinc nitrate, cobalt nitrate, and 2methyl-imidazolate successively in methanol solution at room temperature, PS@Zeolitic Imidazolate Framework (ZIF) particles and small ZnCo-ZIFs clusters are formed on the surface of the PS spheres
Single-atom catalysts were achieved through various strategies, including wet impregnation and coprecipitation methods[61], atomic layer deposition[62], pyrolysis[63] and photodeposition[64]
Summary
Selenium cathodes have attracted considerable attention due to high electronic conductivity and volumetric capacity comparable to sulphur cathodes. This work could open an avenue for achieving long cycle life and high-power lithium-selenium batteries. Rechargeable lithium-ion batteries (LIBs) are considered to be the promising candidates towards sustainable energy storage devices due to its long cycle life, high specific power and energy density[1,2]. The development of Li–S batteries still suffers from the inherent issues of low electronic conductivity of sulfur and the shuttle effect of polysulfides. The Se cathodes have a dissolution issue associated with high-order lithium selenides (Li2Sex, x > 4) and large volume expansion during the charge/discharge process, resulting in a low Se utilization, inferior capacity and short cycle life[7,8,9]. For Se/porous carbon composite materials, the charge transfer resistance can be decreased and the shuttle effect of polyselenides can be suppressed because of the high conductivity of carbon matrix and the strong affinity of porous carbon for Se particles[7]
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