Stable alkali metal anodes enabled by crystallographic optimization – a review

Abstract

Alkali metal anodes have been regarded as the ideal candidate for the next generation high-energy electrode couples due to their ultrahigh specific capacity and the lowest redox potential. However, their...

Porous Heteroatom-Doped Ti3C2Tx MXene Microspheres Enable Strong Adsorption of Sodium Polysulfides for Long-Life Room-Temperature Sodium–Sulfur Batteries

“…Similar results can be found in the previous carbon cathodes. 31 The specific discharge capacity of the N-MXene@MWCNT-MP/S cathode is 980 mAh g −1 in the second cycle, which is higher than that of bare MXene/S sample. At the same time, the N-MXene@MWCNT-MP/S cathode possessed a high reversible capacity of 676.3 mAh g −1 after 500 cycles with a high capacity retention of 68.97% and degradation rate as low as 0.062% per cycle, showing a significantly higher electrochemical reversibility.…”

“…The peaks located at around 180 and 314 cm −1 can be assigned to S 8 − monoanions and the peaks at 284 and 464 cm −1 can be assigned to S 6 − monoanions. 12,31 There were no specific peaks of S 6 − or S 8 − monoanions found in the ex situ Raman results of the bare Ti 3 C 2 T x /S cathode. This confirms that the N-MXene@ MWCNT-MP/S cathode could trap the sodium polysulfides during the discharge process, effectively.…”

“…There is an oxidation peak at a voltage of 2.10 V, which can be attributed to the reaction of short-chain sodium polysulfides (Na 2 S y , 1< y < 3) to longchain sodium polysulfides (Na 2 S x , 4 < x < 8). 31 Compared with the bare MXene/S sample, the N-MXene@MWCNT-MP/S cathode cell shows good repeatability and the difference value of oxidation voltage peak and reduction voltage peak (ΔE) between of N-MXene@MWCNT-MP/S cathode is smaller. 32 This result shows that the N-MXene@MWCNT-MP/S cathode possesses more stable kinetic characteristics.…”

Element‐Doped Mxenes: Mechanism, Synthesis, and Applications

“…It is well known that the doped-MXene is used intensively in the research of battery electrodes, however, plain Li anode materials can not satisfy the storage of Li + . [100][101][102][103][104] Zhao et al proposed that Fe-O bounding formed by Fe substitutes C is so poor that the coordination of unsaturated oxygen is conducive to absorb Li + ions and enhance electrochemical performance. [58] Similar to Fe, Co and Ni possess homologous mechanisms (Figure 4b,c).…”

“…Lithium-Ion Batteries: Among different energy storage systems, batteries have the advantages of small size and high efficiency. [101,[243][244][245] Since the commercial application of lithiumion batteries (LIBs) in 1991, their important advantages such as high voltage, large capacity, long cycle life, and good safety performance have attracted much attention. [246,247] Compared with pristine MXenes, due to the adjustment of the interlayer distance by elemental doping, more abundant active sites are generated, which suppress the performance degradation due to the stacking of sheets and provide better electrochemical adsorption sites.…”