High Stable Cycling Performance Research Articles

Regeneration of high-performance Li1.2Mn0.54Ni0.13Co0.13O2 cathode material from mixed spent lithium-ion batteries through selective ammonia leaching

The efficient recycling process of spent lithium-ion batteries (LIBs) to regenerate electrode materials can alleviate the metal resources scarcity and environmental pollution. Here, the Li-rich cathode Li1.2Mn0.54Ni0.13Co0.13O2 (LR) material was successfully re-synthesized via an environment-friendly and impurity-free recycling process combined ammonia leaching with sol-gel process. Compared with the general methods, ammonia leaching is delicately applied to selectively extract valuable metals from spent LiNixCoyMnzO2 materials exclusive of other impurities (Fe, Al). The process facilitates the subsequent recovery without additional purification process. Surprisingly, the leaching efficiency of Li, Ni, and Co elements is up to as high as 99.28%, 99.63%, and 99.76%, respectively. After adding extra metal compounds stoichiometrically, LR with uniform particle size and elements distribution was regenerated from the valuable metals in the lixivium via the sol-gel method. The LR synthesized at 800 °C exhibits a satisfying capacity of 246.5 mAh g−1 at 0.1 C and high-stable cycle performance with a capacity of 163.3 mAh g−1 after 80 cycles at 0.2 C between 2.0 and 4.8 V. The fundamental results provide inspiration for recovery of the complex spent LIBs, which can selectively separate the multiple metal impurities with high-efficient reutilization.

Confined interfacial assembly of controlled Li2Ti3O7 building blocks and Si nanoparticles in Lithium-ion batteries

Most studies combine high-capacity silicon (Si) with high-conductivity carbon materials to overcome the poor electrical connectivity of Si, but the pathway for the Li+ rapid transmission to Si is often ignored. Lithium titanate (LixTiyOz) as a protective additive to improve the transmission speed of Si-based anodes has attracted extensive scientific interest. However, highly reactive titanium precursor imparts great difficulties in precisely controlling the growth of LixTiyOz on the Si surface, resulting in poor secondary particle formation, and severely weakening the advantage of LixTiyOz at the Si-based electrode level. Herein, we propose a confined interfacial assembly method to combine the controlled Li2Ti3O7 building blocks and the Si nanoparticles through the electrostatic interaction and Ostwald-ripening. This facile and reproducible method relies on the surface charge change effect of CTAB, the solvent-confinement effect of glycerol and the crystalline dimension control of ammonia. The Li2Ti3O7 building blocks has a height-adjustable shape (2D-layered, 3D-spherical), size, and controlled coating surface. As a result, the selected hierarchical microcluster has the advantages of rapid 3D interpenetrating electron/Li+ pathways, buffer space and electrolyte barrier, which achieves superior rate capability (1261 mAh g−1 at 5 A g−1) and high stable cycle performance (1080 mAh g−1 after 1000 cycles at 2 A g−1).

MXene-CNT/PANI ternary material with excellent supercapacitive performance driven by synergy

• A simple method has been successfully applied to the preparation of MXene-CNT/PANI ternary composite. • MXene makes the CNT/PANI disperse uniformly, achieving good electrical conductivity and facile ion diffusion pathway. • MXene-CNT/PANI electrode has superior gravimetric capacity and cyclic stability. MXene is considered a promising two-dimensional (2D) material with excellent conductivity, and it has been proved to be a potential material for supercapacitor electrode. However, the supercapacitive performances of the pristine MXene are always not satisfactory due to the innate re-stacking tendency of the MXene nanosheets. In this work, the carbon nanotubes/polyaniline (CNT/PANI) nanocomposite was introduced and obtained MXene-CNT/PANI ternary composite electrode. Thanks to the synergy between each component, MXene-CNT/PANI exhibited enhanced specific capacitance that reached 429.4 F/g at 1A/g, which is completely better than that of any single compound in the ternary material. Besides, this ternary composite electrode holds a high stable cycle performance with over 93% retention after 10,000 cycles. Furthermore, a quantitative analysis was also carried out to prove the relationship between the capacitive contribution and the scan rate of the MXene-CNT/PANI.

Orientated VSe2 nanoparticles anchored on N-doped hollow carbon sphere for high-stable aqueous energy application

Transition metal dichalcogenides (TMDs) have been considered as the promising energy storage materials due to their unique crystalline structure. In this work, the VSe2 nanoparticles are vertically anchored on N-doping carbon (NC) hollow nanosphere (VSe2@NC) for aqueous energy application. The electrochemical measurements indicate that the VSe2@NC electrode exhibits outstanding electrochemical properties with high specific capacitance and excellent cycling life. Moreover, the asymmetric supercapacitor was assembled by using VSe2@NC cathode and activated carbon anode. It shows high energy density of 85.41 Wh Kg−1 at a power density of 701.99 W Kg−1, and high-stable cycling performance of 90% retention after 2000 cycles. The superior properties are attributed to the particular hollow structure design, which accommodates both the high specific capacity of VSe2 and the desired electrical conductivity of N-doping carbon sphere template.

Cobalt nitride nanoparticles embedded in porous carbon nanosheet arrays propelling polysulfides conversion for highly stable lithium–sulfur batteries

Compared with currently mature lithium ion batteries, lithium-sulfur batteries (LSBs) show many remarkable advantages for next-generation electrical energy storage owing to high theoretical specific energy and low cost. However, the shuttle effect, low conductivity of sulfur cathode, and sluggish kinetics are remarkable barriers preventing their realistic application. Herein, we present a facile strategy in which cobalt nitride (Co4N) nanoparticles embedded leaf-like porous carbon nanosheet arrays are grown on flexible carbon cloth as a free-standing cathode for high-performance LSBs. Co4N not only adsorbs the intermediate lithium polysulfides (LiPSs) strongly, but also catalytically promotes the mutual transformation between sulfur and Li2S. Moreover, theoretical simulations reveal the strong interaction between Co4N and sulfur species. The created free-standing cathode exhibits a high capacity of 1121 mAh g-1 after 100 cycles at 0.5 C, a high rate performance (746 mAh g-1 at a high rate of 5 C relative to 1237 mAh g-1 at 0.2 C), and high stable cycle performance (598 mAh g-1 at 5 C over 500 cycles with ultralow 0.035% decay per cycle). Our method provides a new potential avenue for energy conversion and storage devices based on multi-electron redox reactions.

Construction of homogeneously Al3+ doped Ni rich Ni-Co-Mn cathode with high stable cycling performance and storage stability via scalable continuous precipitation

Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode materials have been considered as one of the promising candidates for high energy density lithium-ion battery, but they still suffer from capacity fading and safety caused by structural degradation, insufficient thermal stability and poor storage properties. In the current work, homogeneously Al3+ doped Ni rich cathode with high stable cycling performance and storage stability was constructed via scalable continuous precipitation. With the more homogeneous distribution of Al3+ in the secondary agglomerates, the Ni rich cathode synthesized from Al3+ doped hydroxide precursor showed more perfect sphere, decreased ratio of Ni2+/Ni3+ and Li+/Ni2+ disorder in the internal of agglomerates. The homogeneously Al3+ doped Ni rich LiNi0.8Co0.1Mn0.09Al0.01O2 cathode exhibited much improved cycling performance, with a capacity retention of 78.92% at 1 C rate after 200 cycles, and a capacity retention of 70.0% at 10 C rate after 1000 cycles. Additionally, the homogeneous substitution of Al could significantly prevent the reaction with H2O and CO2 during storage process and improve storage stability.

A new insight into the lithium storage mechanism of sulfurized polyacrylonitrile with no soluble intermediates

Sulfurized polyacrylonitrile (S@pPAN) is a promising cathode material for next-generation batteries due to its high stable cycle performance. However, challenges remain in achieving larger capacity and higher discharge voltage, it is therefore of vital significance to illustrate the electrochemical reaction mechanism of S@pPAN or similar materials. Herein, we present conjugate double-bond lithium-ion storage mechanism by solid-state NMR and XPS. During discharge, besides the reaction between sulfur and lithium, the C=N and C=C groups can also react with lithium to form Li-C-N-Li and Li-C-C-Li and afford capacity, resulting a higher practical discharge capacity than the theoretical capacity of elemental sulfur. This electrochemical reaction mechanism provides a new idea for the new energy materials with high capacity.