Hierarchical porous biomass activated carbon for hybrid battery capacitors derived from persimmon branches

Abstract

Activated carbon materials are used in hybrid battery capacitors. They reduce energy density of devices, and can greatly improve the cycle life and power density. Herein, we used fast-growing persimmon branches in Shaanxi as a biomass carbon source. The persimmon branch activated carbon (PB-AC850) material was found to exhibit abundant graded pore structure similar to graphite structure after KOH activation. The macro/mesoporous structure in PB-AC850 facilitated the ions (solvated PF-6 ) transport, resulting in much better rate capability as compared to commercial activated carbon. It was moreover found from preparation of the hybrid battery capacitor that the addition of activated carbon reduced resistance and polarization of the device. LFP+PB-AC850 exhibited excellent cycle stability with high to 93.4% capacity reservation after 500 cycles at 5C.

Hierarchical Porous Electrode Impedance Model Based on Diffusion Dynamics and the Electrode Morphology and Prediction of Electric Double-Layer Structures

“…Supercapacitors (SCs) are considered to be promising electrical energy storage devices, which can bridge the power/energy difference that exists between dielectric capacitors with high power output and batteries/fuel cells with high energy storage. , This advantage makes it not only used as single energy or power equipment but also can be combined with other energy storage devices to improve the application value of a single device . In recent years, hierarchical porous carbon (HPC) has been considered as a promising electrode material for SCs, as it has advantages of a high specific surface area, high conductivity, and low cost. , Moreover, the hierarchical structure composed of macropores (>50 nm) and mesopores (2–50 nm) could facilitate electrolytic transportation inside the electrode, shortening the transport paths for both charges and ions. , Additionally, the micropores (<2 nm) could also increase the reversible storage capacity. , The energy storage/release of SCs depends on the electric double-layer (EDL) storage/reorganization inside the framework composed of hierarchical porous structures. , Therefore, exploring the effect of microscopic changes of porous and electrolytic characteristics on the internal ionic mechanism of the EDL is the basis for improving the performance of SCs, and relevant experiments need to be carried out under the support of theoretical models.…”

Electrochemical performances of a LiFePO4-based heat-treated activated carbon electrode

“…8 According to Peng et al , the larger the specific surface area of the activated carbon added, the better the rate capability of LiFePO 4 . 9 In these studies, the power of the composite electrodes was improved because the activated carbon pores present around the LiFePO 4 particles served as storage for the electrolyte or improved tortuosity in the electrode, allowing the smooth supply of Li ions to LiFePO 4 . Most of the aforementioned studies discuss the transport properties of Li ions through activated carbon pores, but few have reported on the effect of the electrical conductivity of activated carbon on the power characteristics of composite electrodes.…”

Porous Activity of Biomass-Activated Carbon Enhanced by Nitrogen-Dopant Towards High-Performance Lithium Ion Hybrid Battery-Supercapacitor

“…Over the past few years, biomass carbon materials have gained immense attention because of their environmentally friendliness and unique three-dimensional structure. 7,8 After carbonization activation, this three-dimensional structure becomes more stable because of the discharge of the volatile components, and the porous carbon material skeleton forms a rich pore structure with a large specific surface area. When used as an electrode material, porous carbon can promote the mass storage and rapid transportation of electrolyte ions.…”