Biomass Template Derived Boron/Oxygen Co‐Doped Carbon Particles as Advanced Anodes for Potassium‐Ion Batteries

Abstract

Potassium-ion batteries (KIBs) have shown increasingly attractive potential for practical applications in terms of the resource enrichness and cost-effectiveness. [1][2][3] In comparison with the congener, lithium-ion battery (LIB), one specific merit of KIBs is that K + (3.6 Å) has smaller solvated radius in propylene carbonate electrolytes as compared to Li + (4.8 Å) and lower desolvation energy, which corresponds to higher diffusion kinetics and conductivity of ions. [4,5] In addition, the standard redox potential of K is similar to or even lower than that of Li in nonaqueous electrolyte, consequently guaranteeing advanced energy density. Nevertheless, one of the main challenges for KIBs lies in the much bigger radius of K + (1.38 Å) as compared to Li + (0.76 Å), making it difficult to insert/extract into/from the anodes. [4,6] This would inevitably lead to an irreversible distortion of the electrodes and hence incur the capacity attenuation upon long-term cycling. In this sense, it is a priority to design appropriate anode materials to advance the KIB technology.To date, there has been a plethora of material candidates attempted as anodes for KIBs, including carbonaceous materials, metal alloys, and transition metal oxides/sulfides/selenides/carbides. [2,7] Among these, carbon-based anodes have readily stimulated widespread interests due to its satisfying conductivity and wide availability. [8] Graphite, the commercial anode material for LIB, could also be used as anode for KIB because of their similar cell structure and working mechanism. [9] Despite the fact that graphite has excellent electrochemical activity benefiting from its low and stable voltage plateau, it still suffers from unsatisfactory capacity (with a theoretical value of 279 mAh g −1 ). Furthermore, inferior cycling stability and poor Coulombic efficiency also hinder the performance of graphite anodes for KIBs. [9,10] In this sense, designing innovative carbon architectures harnessing heteroatom doping, appropriate surface area, and sufficient active sites are highly desirable for boosting the performance of anodes. [11][12][13][14][15] In particular, the introduction of heteroatom dopants into carbon frameworks has been proven an effective way to modify the crystal structure and intrinsic electronic/ionic states, which is beneficial to enhancing the adsorption of K ions and boosting

Boron-Doped Pine-Cone Carbon With 3D Interconnected Porosity for Use as an Anode for Potassium-Ion Batteries With Long Life Cycle

“…Supplementary Figure S8a,b showed CV curves for BZPC (0.2-2 mV s −1 ) and ZPC (0.01-3 V), respectively. The CV curves for ZPC and BZPC between 1.25 and 3 V were rectangular, indicating the capacitive behaviour of the potassium-ion storage process (Lian et al, 2022), in agreement with the results of the charge-discharge curves. It is well known that the relationship between current and potential scan rate in CV can be expressed by log(i) = blog(v)+log(a), where i is the peak current, v is the scan rate, and a and b are fitting constants (Wang et al, 2018a;Lian et al, 2022).…”

“…The CV curves for ZPC and BZPC between 1.25 and 3 V were rectangular, indicating the capacitive behaviour of the potassium-ion storage process (Lian et al, 2022), in agreement with the results of the charge-discharge curves. It is well known that the relationship between current and potential scan rate in CV can be expressed by log(i) = blog(v)+log(a), where i is the peak current, v is the scan rate, and a and b are fitting constants (Wang et al, 2018a;Lian et al, 2022). Based on this relationship, the b values of the cathodic peaks were calculated as 0.9014 and 0.9445 for ZPC and BZPC, respectively; these values are between 0.5 and 1, indicating that potassium storage in these materials involves both diffusion-controlled and surfacecontrolled processes (Li et al, 2017;Liu et al, 2020).…”

“…The corresponding anodic peak was broad (over a wide voltage window), which is attributed to the adsorption behaviour of abundant large-radius potassium ions at the active/defect sites of the electrode material and the slow electrochemical reaction kinetics (Ruan et al, 2019;Deng et al, 2021). Furthermore, an irreversible reduction peak near 0.5 V was observed for ZPC and BZPC in the first cycle of the CV curve, which was not observed in subsequent scans, corresponding to the decomposition of the electrolyte on the electrode surface to form a solid electrolyte interphase (SEI) film and the irreversible insertion of K ions (Ruan et al, 2019;Deng et al, 2021;Lian et al, 2022). Additionally, compared to ZPC, the weak irreversible peak of BZPC indicated that B doping increased the Coulombic efficiency.…”

O-Doping Configurations Reduce the Adsorption Energy Barrier of K-Ions to Improve the Electrochemical Performance of Biomass-Derived Carbon

“…Figure 1 f shows the high-resolution C 1s XPS spectra of OPDC, which mainly appears in three configurations. The C-C group in the defect-free graphite lattice is located at 284.8 eV, and the peaks at 285.7 and 288.9 eV are attributed to the C-O group in the defective graphite lattice and C=O group [ 28 ]. It is noteworthy that no characteristic peak indicating a π–π interaction is detected in the spectra, indicating that only a small amount of microcrystalline pseudo-graphite isstacked together [ 29 ].…”

Fast-Charging Nonaqueous Potassium-Ion Batteries Enabled by Rational Construction of Oxygen-Rich Porous Nanofiber Anodes

“…In the subsequent cycles, the charge–discharge curve of O-C600 shows a sloping characteristic, similar to the previously reported soft carbon materials, , indicating a main capacity contribution from the adsorption behavior. The reason for this phenomenon is that the high content of oxygen functional groups in O-C600 provide more active sites for K + adsorption on the surface or near the surface, , resulting in enhanced potassium storage kinetics. At a current density of 0.5 A g –1 , the O-C600 electrode delivers a high reversible capacity of 226 mAh g –1 and can operate stably over 5000 cycles with the Coulombic efficiency near 100% (Figure c).…”