An official website of the United States government
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+xP3solid 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.
more »
« less
Hard Carbon Derived from Avocado Peels as a High-Capacity, Fast Na + Diffusion Anode Material for Sodium-Ion Batteries
Deriving battery grade materials from natural sources is a key element to establishing sustainable energy storage technologies. In this work, we present the use of avocado peels as a sustainable source for conversion into hard carbon-based anodes for sodium ion batteries. The avocado peels are simply washed and dried then proceeded to a high temperature conversion step. Materials characterization reveals conversion of the avocado peels in high purity, highly porous hard carbon powders. When prepared as anode materials they show to the capability to reversibly store and release sodium ions. The hard carbon-based electrodes exhibit excellent cycling performance, namely, a reversible capacity of 352.55 mAh g−1at 0.05 A g−1, rate capability up to 86 mAh g−1at 3500 mA g−1, capacity retention of >90%, and 99.9% coulombic efficiencies after 500 cycles. Cyclic voltammetry studies indicated that the storage process was diffusion-limited, with diffusion coefficient of 8.62 × 10−8cm2s−1. This study demonstrates avocado derived hard carbon as a sustainable source that can provide excellent electrochemical and battery performance as anodes in sodium ion batteries.
more »
« less
- Award ID(s):
- 1751621
- PAR ID:
- 10370432
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- ECS Advances
- Volume:
- 1
- Issue:
- 3
- ISSN:
- 2754-2734
- Page Range / eLocation ID:
- Article No. 030502
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Lithium‐ion and sodium‐ion batteries (LIBs and SIBs) are crucial in our shift toward sustainable technologies. In this work, the potential of layered boride materials (MoAlB and Mo2AlB2) as novel, high‐performance electrode materials for LIBs and SIBs, is explored. It is discovered that Mo2AlB2shows a higher specific capacity than MoAlB when used as an electrode material for LIBs, with a specific capacity of 593 mAh g−1achieved after 500 cycles at 200 mA g−1. It is also found that surface redox reactions are responsible for Li storage in Mo2AlB2, instead of intercalation or conversion. Moreover, the sodium hydroxide treatment of MoAlB leads to a porous morphology and higher specific capacities exceeding that of pristine MoAlB. When tested in SIBs, Mo2AlB2exhibits a specific capacity of 150 mAh g−1at 20 mA g−1. These findings suggest that layered borides have potential as electrode materials for both LIBs and SIBs, and highlight the importance of surface redox reactions in Li storage mechanisms.more » « less
-
Abstract This study presents a new material, “HxCrS2” (denotes approximate composition) formed by proton‐exchange of NaCrS2which has a measured capacity of 728 mAh g−1with significant improvements to capacity retention, sustaining over 700 mAh g−1during cycling experiments. This is the highest reported capacity for a transition metal sulfide electrode and outperforms the most promising proposed sodium anodes to date. HxCrS2exhibits a biphasic structure featuring alternating crystalline and amorphous lamella on the scale of a few nanometers. This unique structural motif enables reversible access to Cr redox in the material resulting in higher capacities than seen in the parent structure which features only S redox. Pretreatment by proton‐exchange offers a route to materials such as HxCrS2which provide fast diffusion and high capacities for sodium‐ion batteries.more » « less
-
Cobalt telluride anchored to nitrogen-rich carbon dodecahedra (CoTe@NCD) was synthesized by simultaneous pyrolysis-tellurium melt impregnation of ZIF-67 MOFs. The purely thermal method involved no secondary chemicals and no waste byproducts. The result is a microstructure consisting of nanoscale 86 wt% CoTe intermetallic nanoparticles contained within a thin N-rich carbon matrix. During electrochemical cycling, the 21 nm average diameter CoTe provides short diffusion paths for Na + /K + ions, which in conjunction with the electrically conducting carbon matrix allow for rapid potassiation or sodiation. As potassium ion battery (PIB and KIB) and sodium ion battery (NIB and SIB) anodes, CoTe@NCD demonstrates attractive reversible capacity, promising cycling stability, and state-of-the-art rate performance. For example, as a KIB anode, the CoTe@NCD electrode exhibits a reversible capacity of 380 mA h g −1 at 50 mA g −1 and a fast charge capacity of 136 mA h g −1 at 1000 mA g −1 . As a NIB anode, it also displays excellent rate capability achieving 620 mA h g −1 at 50 mA g −1 and 345 mA h g −1 at 1000 mA g −1 .more » « less
-
This work explores a novel approach for improving the sodium-ion battery performance of coal char using flash pyrolysis and an ether-based electrolyte. Coal char is an ultra-low cost hard carbon with promising application as an anode material in sodium-ion batteries. During flash pyrolysis, char is heated at 1000 °C/s in a drop-tube furnace to create a highly-irregular structure. The larger d-spacing and smaller closed micropore diameter of flash-pyrolyzed char increases anode capacity compared to traditional slow-pyrolyzed char electrodes. The sodium-ion battery anode performance of flash-pyrolyzed char is further improved using an ether-based electrolyte in place of the traditional ester-based electrolyte. Performance improvements include greater initial Coulombic efficiency (58% in ester- vs. 64% in ether-based electrolyte) and improved specific capacity in an ether-based electrolyte. Overall, the combination of flash pyrolysis and ether-based electrolyte increases the sodium-ion battery discharge capacity of coal char by over 50%, from 72.5 mAh g−1 (slow-pyrolyzed char in ester-based electrolyte) to 109.4 mAh g−1 (flash-pyrolyzed char in ether-based electrolyte) (50 mA g−1 discharge rate). The results highlight improvements that can be realized through flash pyrolysis of coal char for battery applications and the numerous processing advantages of flash vs. slow pyrolysis.more » « less
