ABSTRACT This study reports a high-performance tin (Sn)-coated vertically aligned carbon nanofiber array anode for lithium-ion batteries. The array electrodes have been prepared by coaxial sputter-coating of tin (Sn) shells on vertically aligned carbon nanofiber (VACNF) cores. The robust brush-like highly conductive VACNFs effectively connect high-capacity Sn shells for lithium-ion storage. A high specific capacity of 815 mAh g -1 of Sn was obtained at C/20 rate, reaching toward the maximum value of Sn. However, the electrode shows poor cycling performance with conventional LiPF 6 based organic electrolyte. The addition of fluoroethylene carbonate (FEC) improve the performance significantly and the Sn-coated VACNFs anode shows stable cycling performance. The Sn-coated VACNF array anodes exhibit outstanding capacity retention in the half-cell tests with electrolyte containing 10 wt.% FEC and could deliver a reversible capacity of 480 mAh g -1 after 50 cycles at C/3 rate.
more »
« less
Improved Electrochemical Properties of Li4Ti5O12 Nanopowders (NPs) via Addition of LiAlO2 and Li6SiON Polymer Electrolytes, Derived from Agricultural Waste
Li4Ti5O12 (LTO) has received considerable interest as an alternate anode material for high power density batteries for large scale applications. However, LTO suffers from poor Li+ diffusivity and poor electronic conductivity, resulting in capacity loss and poor rate performance. Here we demonstrate a facile synthesis of LTO NPs using liquid-feed flame spray pyrolysis (LF-FSP) which provides high surface area (∼38 m2/g) spinel structure LTO NPs with average particle sizes (APSs) of 45 ± 0.3 nm. Pristine LTO-Li half-cells exhibit reversible capacity of 70 mAh/g at 10 C. In this study, we show that mixing LiAlO2 NPs (5 wt %) and Li6SiON polymer precursor (10 wt %) with pristine LTO via ball-milling and ultrasonication followed by tape casting enhances the LTO rate performance
providing reversible capacity of ∼217 mAh/g at 5 C over 500 cycles. The Li6SiON polymer electrolyte is synthesized from rice hull ash (RHA), an agricultural waste,
providing a green synthetic approach to electrode coating materials. CV and EIS
studies indicate that adding the solid and polymer electrolytes reduces charge-transfer resistance and electrode polarization, enhancing both reversibility and the LTO Li+ diffusion coefficient from 4.6 × 10−14 to 2.7 × 10−12 cm2/s.
more »
« less
- Award ID(s):
- 1926199
- NSF-PAR ID:
- 10357009
- Date Published:
- Journal Name:
- ACS applied energy materials
- Volume:
- 4
- ISSN:
- 2574-0962
- Page Range / eLocation ID:
- 1894−1905
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract Layered transition metal oxides are appealing cathodes for sodium‐ion batteries due to their overall advantages in energy density and cost. But their stabilities are usually compromised by the complicated phase transition and the oxygen redox, particularly when operating at high voltages, leading to poor structural stability and substantial capacity loss. Here an integrated strategy combing the high‐entropy design with the superlattice‐stabilization to extend the cycle life and enhance the rate capability of layered cathodes is reported. It is shown that the as‐prepared high‐entropy Na2/3Li1/6Fe1/6Co1/6Ni1/6Mn1/3O2cathode enables a superlattice structure with Li/transition metal ordering and delivers excellent electrochemical performance that is not affected by the presence of phase transition and oxygen redox. It achieves a high reversible capacity (171.2 mAh g−1at 0.1 C), a high energy density (531 Wh kg−1), extended cycling stability (89.3% capacity retention at 1 C for 90 cycles and 63.7% capacity retention at 5 C after 300 cycles), and excellent fast‐charging capability (78 mAh g−1at 10 C). This strategy would inspire more rational designs that can be leveraged to improve the reliability of layered cathodes for secondary‐ion batteries.
-
more » « less
Abstract Si‐based anodes with a stiff diamond structure usually suffer from sluggish lithiation/delithiation reaction due to low Li‐ion and electronic conductivity. Here, a novel ternary compound ZnSi2P3with a cation‐disordered sphalerite structure, prepared by a facile mechanochemical method, is reported, demonstrating faster Li‐ion and electron transport and greater tolerance to volume change during cycling than the existing Si‐based anodes. A composite electrode consisting of ZnSi2P3and carbon achieves a high initial Coulombic efficiency (92%) and excellent rate capability (950 mAh g−1at 10 A g−1) while maintaining superior cycling stability (1955 mAh g−1after 500 cycles at 300 mA g−1), surpassing the performance of most Si‐ and P‐based anodes ever reported. The remarkable electrochemical performance is attributed to the sphalerite structure that allows fast ion and electron transport and the reversible Li‐storage mechanism involving intercalation and conversion reactions. Moreover, the cation‐disordered sphalerite structure is flexible to ionic substitutions, allowing extension to a family of Zn(Cu)Si2+
x P3solid solution anodes (x = 0, 2, 5, 10) with large capacity, high initial Coulombic efficiency, and tunable working potentials, representing attractive anode candidates for next‐generation, high‐performance, and low‐cost Li‐ion batteries. -
Transition metal dichalcogenides (TMDs) such as the WS2 have been widely studied as potential electrode materials for lithium-ion batteries (LIB) owing to TMDs’ layered morphology and reversible conversion reaction with the alkali metals between 0 to 2 V (v/s Li/Li+) potentials. However, works involving TMD materials as electrodes for sodium- (NIBs) and potassium-ion batteries (KIBs) are relatively few, mainly due to poor electrode performance arising from significant volume changes and pulverization by the larger size alkali-metal ions. Here, we show that Na+ and K+ cyclability in WS2 TMD is improved by introducing WS2 nanosheets in a chemically and mechanically robust matrix comprising precursor-derived ceramic (PDC) silicon oxycarbide (SiOC) material. The WS2/SiOC composite in fibermat morphology was achieved via electrospinning followed by thermolysis of a polymer solution consisting of a polysiloxane (precursor to SiOC) dispersed with exfoliated WS2 nanosheets. The composite electrode was successfully tested in Na-ion and K-ion half-cells as a working electrode, which rendered the first cycle charge capacity of 474.88 mAh g−1 and 218.91 mAh g−1, respectively. The synergistic effect of the composite electrode leads to higher capacity and improved coulombic efficiency compared to the neat WS2 and neat SiOC materials in these cells.more » « less
-
more » « less
Abstract Low temperature rechargeable batteries are important to life in cold climates, polar/deep‐sea expeditions, and space explorations. Here, this work reports 3.5–4 V rechargeable lithium/chlorine (Li/Cl2) batteries operating down to −80 °C, employing Li metal negative electrode, a novel carbon dioxide (CO2) activated porous carbon (KJCO2) as the positive electrode, and a high ionic conductivity (≈5–20 mS cm−1from −80 °C to room‐temperature) electrolyte comprised of aluminum chloride (AlCl3), lithium chloride (LiCl), and lithium bis(fluorosulfonyl)imide (LiFSI) in low‐melting‐point (−104.5 °C) thionyl chloride (SOCl2). Between room‐temperature and −80 °C, the Li/Cl2battery delivers up to ≈29 100–4500 mAh g−1first discharge capacity (based on carbon mass) and a 1200–5000 mAh g−1reversible capacity over up to 130 charge–discharge cycles. Mass spectrometry and X‐ray photoelectron spectroscopy probe Cl2trapped in the porous carbon upon LiCl electro‐oxidation during charging. At −80 °C, Cl2/SCl2/S2Cl2generated by electro‐oxidation in the charging step are trapped in porous KJCO2carbon, allowing for reversible reduction to afford a high discharge voltage plateau near ≈4 V with up to ≈1000 mAh g−1capacity for SCl2/S2Cl2reduction and up to ≈4000 mAh g−1capacity at ≈3.1 V plateau for Cl2reduction.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/doi.org/10.1021/acsaem.0c02994
