Non-negligible Influence of Oxygen in Hard Carbon as an Anode Material for Potassium-Ion Batteries

Abstract

The development of potassium-ion batteries (PIBs) has been impeded by the lack of an appropriate carbon anode material that could accommodate K+ with a large ionic radius. Hard carbon with low cost and larger interlayer spacing is a promising anode material for PIBs. However, the impact of oxygen-containing functional groups in hard carbon (HC) is less reported. Herein, a hypercrosslinked polymer (HCLP) is prepared and used for the synthesis of microporous hard carbons with superior structural stability and abundant oxygen-containing functional groups and defects, in which the crosslinking agent provided copious oxygen atoms. It is found that a large number of CO groups and micropores provide more storage sites for K+. The surface-controlled process is dominated by the reversible reaction of CO + K+ + e– ↔ C–O–K, which directly increases the capacity contribution. The HCs obtained at 600 °C exhibit good cycling and rate performance with an initial specific capacity of about 254.3 mAh g–1 and the capacity retention of 83.2% after 200 cycles at 50 mA g–1. The capacity reached up to 121 mAh g–1 at 2 A g–1. A possible capacitive-adsorption mechanism is proposed by kinetic analysis. The redox reaction mechanism between CO and K+ at the HC is clearly also revealed.

An oriented tube array porous carbon anode prepared using a self-blowing mold of salt templates for high-rate potassium storage

“…3e). 41 Notably, the CvO content of TAPC (74.4%) is much higher than that of SPC (42.8%) (Fig. S9 †).…”

“…4e). 28,29,34,41,[46][47][48][49][50][51] Fig. 4f presents the plot that shows the TAPC electrode maintains a capacity of 375 mA h g −1 after 100 cycles at 0.1 A g −1 , which is better than that of the SPC electrode.…”

Homogeneous Adsorption of Multiple Potassiation Products of Red Phosphorus Anode toward Stable Potassium Storage

“…Figure b presents the cyclic voltammetry (CV) curve of FePc@RP/C at a 0.2 mV s –1 scanning rate. During the first cathodic scanning cycle, a broad irreversible cathodic peak appears at 0.67 V due to electrolyte decomposition and the formation of SEI, but the peak disappears in subsequent cycles. − Upon comparing the cathodic peak widths at 0.67 V in the CV curves (Figure S6a–c) of the four samples, it is evident that FePc@RP/C < CoPc@RP/C < NiPc@RP/C < RP/C, which suggests that the formation of a stable SEI from RP/C requires the consumption of more electrolyte. The results also indicate that the SEI formed in MPc@RP/C composites can reduce the direct contact between RP and electrolyte, thereby inhibiting the occurrence of side reactions .…”

Graphene Oxide Block Derived Edge‐Nitrogen Doped Quasi‐Graphite for High K+ Intercalation Capacity and Excellent Rate Performance

“…(Figure 3h). [14,15,18,[53][54][55][57][58][59][60]71,[73][74][75][76][77][78][79] Electrochemical performance of NQG-800 and NQG-1200 with different graphitization degrees and nitrogen content were also measured. According to CV curves and GCD patterns, NQG-800 exhibits broad redox peaks owing to the absence of graphite domains (Figure S26a, Supporting Information).…”