Original Article:
Exploring the synergetic electrochemical performance of cobalt sulfide/cobalt phosphate composites for supercapattery devices with high-energy and rate capability
Muhammad Zahir Iqbal, et al.
Electrochimica Acta 384 (2021): 138358.
10.1016/j.electacta.2021.138358
Supercapattery devices combine battery-grade properties with those of electric double-layer capacitors (EDLCs), employing two different charge storage mechanisms (Faradic due to battery-level merging and non- Faradic due to intercalation of capacitive material), thereby exhibit high specific power as well as impressive specific energy, excellent stability potential, rate capability, and durability. In the study of supercapattery devices, the selection of active materials with excellent electrochemical performance is a very important factor. In this work, the researchers propose a method for combining cobalt sulfide and cobalt phosphate to provide synergistic electrochemical performance. This novel approach enables electrode materials with self-supporting electrochemical worth for high-performance energy storage applications.
How can cobalt sulfide/cobalt phosphate improve the performance of super batteries?
- Metal sulfides (MS) exhibit multiple valence states with possible stoichiometric compositions, nanocrystalline morphologies, and crystal structures. These advantages endow them with greater electrochemical activity.
- Compared with other electrode materials, MS has better mechanical and thermal stability. Among different transition metal sulfides, cobalt sulfide has rich redox chemistry and better charge storage capacity than many electrode materials.
- Transition metal phosphates (MPs) have high electrochemical activity and good chemical stability. Many MPs exhibit better electrical conductivity and flexibility to tune the electrochemical performance of nano- and mesostructured materials.
- Compared with conductive polymers, MPs have higher cycle stability potential. Among transition metal phosphates, cobalt phosphate has good electrochemical potential and possible synergistic effects.
Based on the aforementioned mechanism, the combination of cobalt sulfide/cobalt phosphate is expected to provide synergistic redox activity while maintaining stability for flash electrochemical performance.
Preparation of Cobalt Sulfide/Cobalt Phosphate Composite Electrodes
1. First, cobalt sulfide and cobalt phosphate nanomaterials were synthesized through sonochemical pathways.
2. Synthetic cobalt sulfide and cobalt phosphate composites with different wt% were prepared by physical blending.
3. Prepare a homogeneous slurry by adding 75 wt% cobalt sulfide/cobalt phosphate composite, 10 wt% PVDF binder, and 15 wt% conductive acetylene black (to overcome the influence of the binder).
4. Finally, the prepared slurry was deposited on nickel foam as working electrodes.
Supercapattery Performance Optimized by Cobalt Sulfide/Cobalt Phosphate
- Composite cobalt sulfide 75%/cobalt phosphate 25% showed excellent performance with a specific capacity value of 451.3 C/g at 3 mV/s and 436.9 C/g at 0.6 A/g operation.
- Using cobalt sulfide/cobalt phosphate composite as the positive electrode material and activated carbon as the negative electrode material, an asymmetric supercapattery device was assembled.
- The device delivered a remarkable specific energy of 63.93 Wh/kg and specific power of 850 W/kg at a current of 1 A/g. The supercapattery also exhibited an astonishing specific power of 13,600 W/kg while still delivering an impressive energy density of 34.68 Wh/kg at 16 A/g.
Chemicals Related in the Paper:
| Catalog Number | Product Name | Structure | CAS Number | Price |
|---|---|---|---|---|
| ACM10294505 | Cobalt(ii)phosphate octahydrate |  |
10294-50-5 | Price |
| ACM12013104-1 | Cobalt(iv)sulfide |  |
12013-10-4 | Price |
