Search

The realization of high performance Ni-rich layered cathodes remains a challenge because of the multiple degradation factors that concurrently operate during battery cycling. In particular, depletion of oxygen charge and consequent lattice-oxygen instability at deep charge state accelerate the subsequent chemomechanical degradation mechanisms. Among the proposed methodologies, doping has proven to be effective in enhancing the cathode cycle life by stabilizing the layered structure. Herein, we achieved the electrochemically stabilized Ni-rich LiNi0.92Co0.04Mn0.04O2 through Zr doping, resulting in a 15% increase of the capacity retention after 100 cycles. In-depth investigations are conducted to unveil the effects of Zr doping on the layered cathode, and in particular, the critical role of Zr doping on the lattice oxygen stability is systematically studied. By combining state-of-the-art magnetometer characterization, X-ray analysis, and first-principles calculation, we reveal that Zr doping positively contributes the to lattice oxygen stability by alleviating the oxygen charge loss at deep charge, thereby improving the cathode electrochemical reversibility. Our findings provide an insight into the Zr doping mechanism and help to design Ni-rich layered oxides for future applications.

Along with great attention to eco-friendly power solutions, sodium ion batteries (SIBs) have stepped into the limelight for electrical vehicles (EVs) and grid-scale energy storage systems (ESSs). SIBs have been perceived as a bright substitute for lithium ion batteries (LIBs) due to abundance on Earth along with the cost-effectiveness of Na resources compared to Li counterparts. Nevertheless, there are still inherent challenges to commercialize SIBs due to the relatively larger ionic radius and sluggish kinetics of Na+ ions than those of Li+ ions. Particularly, exploring novel anode materials is necessary because the conventional graphite anode in LIBs is less active in Na cells and hard carbon anodes exhibit a poor rate capability. Various metal compounds have been examined for high-performance anode materials in SIBs and they exhibit different electrochemical performances depending on their compositions. In this review, we summarize and discuss the correlation between cation and anion compositions of metal compound anodes and their structural features, energy storage mechanisms, working potentials, and electrochemical performances. On top of that, we also present current research progress and numerous strategies for achieving high energy density, power, and excellent cycle stability in anode materials. [ABSTRACT FROM AUTHOR]

Chromium tetraphosphide (CrP4) nanopowder was synthesized via high-energy mechanical milling (HEMM) and introduced as an anode for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). The as-synthesized monoclinic CrP4 nanopowder was slightly agglomerated nanoparticles of 100–200 nm consisting of 10–20 nm-sized nanocrystallite aggregates. The CrP4 electrode underwent conversion reactions with both Li and Na ions by forming Li3P and Cr for LIBs and Na3P and Cr for SIBs and exhibited high initial discharge and charge capacities (1776 and 1540 mA h g−1 for LIBs and 1125 and 881 mA h g−1 for SIBs, respectively), implying its potential as a high energy density anode for both LIBs and SIBs. In addition, the CrP4/carbon (C) nanocomposite was fabricated by mixing the as-synthesized CrP4 nanoparticles and acetylene carbon black to improve the long term cyclability and high rate capability of CrP4. The CrP4/C nanocomposite electrode delivered a specific capacity of 860 mA h g−1 after 100 cycles at a current density of 1000 mA g−1 in LIBs and 369 mA h g−1 after 100 cycles at 500 mA g−1 in SIBs. In particular, the CrP4/C electrode showed outstanding high rate capability compared to other transition metal-based phosphide anodes for LIBs. Furthermore, the CrP4/C electrode showed stable cycling performance even in full cell configuration. [ABSTRACT FROM AUTHOR]

Graphitic carbon‐coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as‐synthesized ZnPS3 bulk to 100–500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon‐coated ZnPS3 electrode exhibits excellent high‐rate capability and long‐term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon‐coated nanoparticles. This study demonstrates that the novel graphitic carbon‐coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides. [ABSTRACT FROM AUTHOR]