In Situ Revealing the Electroactivity of PO and PC Bonds in Hard Carbon for High‐Capacity and Long‐Life Li/K‐Ion Batteries

Abstract

The low capacity and unsatisfactory rate capability of hard carbon still restricts its practical application for Li/K‐ion batteries. Herein, a low‐cost and large‐scale method is developed to fabricate phosphorus‐doped hard carbon (PHC‐700) by crosslinking phosphoric acid and epoxy resin and followed by annealing at 700 °C. H3PO4 acts not only as a crosslinker to solidify epoxy resin for promoting the degree of graphitization and lowering the specific surface area, but also as phosphorus source for forming PC and PO bonds, thus providing more active sites for Li/K storage. As a result, the PHC‐700 electrode delivers a highly reversible capacity of 1294.8 mA h g−1 at 0.1 A g−1 and a capacity of 214 mA h g−1 after 10 000 cycles at 10 A g−1. As for potassium‐ion batteries, PHC‐700 exhibits a reversible capacity of 381.9 mA h g−1 at 0.1 A g−1 and a capacity of 260 mA h g−1 after 1000 cycles at 0.2 A g−1. In situ Raman and in situ NMR measurements reveal that the P‐containing bonds can enhance the adsorption to alkali metal ions, and the PC bond can participate in electrochemical redox reaction by forming Lix PCy . Additionally, P‐doped hard carbon shows better structural/interfacial stability for improved long‐term cycling stability.

Pushing the Energy Output and Cycling Lifespan of Potassium‐Ion Capacitor to High Level through Metal–Organic Framework Derived Porous Carbon Microsheets Anode

“…According to the equation (La (nm) = (2.4 × 10 −10 )λ 4 (I D /I G ) −1 ), [27] the average domain size (La) of MDPC is calculated to be ≈13.42 nm, which is close to other reports on MOFs derived carbons with amorphous structure or heteroatom doping. [15,17,[19][20][21][22]28] The surface area and pore-size characterizations of as-prepared MDPC sample were performed by N 2 adsorption/desorption isotherms. A isotherm, as shown in Figure 2c, reveals the details of a high nitrogen uptake at the low-pressure region in which micropores filling occurs, as well as a hysteresis like type H4, at the middle and high-pressure region, which is indicative of the presence of large mesopores with broad size distribution embedded in a carbon matrix.…”

“…[17,19] Although the role of heteroatom doping in carbonaceous materials is currently not fully understand, lots of experiments confirmed that heteroatoms dopants, including O, S, N, P, are considered as one of most efficient strategy to boost the potassium storage capacity of carbonaceous materials. [18][19][20][21][22] In this regard, well-designed carbonaceous material with an enlarged interlayer spacing, highly porous structure, and optimal heteroatom dopants is highly desired to overcome the limitations from the kinetics and capacity, and thus could boost the performance of PICs.…”

Metal chalcogenides for potassium storage

“…The first step toward achieving high‐performance K + ‐based energy storage technologies is to exploit host materials that have superior potassium storage capability and sufficient structural stability to withstand the repeated K + ‐ion insertion and extraction processes . For PIBs, the most representative K + ‐based rechargeable energy storage system, the aforementioned target indicates that developing efficient anode materials with the favorable features of high specific capacities, excellent cycling stabilities, and fast diffusion/reaction kinetics is urgently required to advance the progress of current PIBs toward practical applications . Inspired by the existing pioneering work involving graphite, tremendous efforts have been devoted to this area of research.…”

Multiscale Hierarchically Engineered Carbon Nanosheets Derived from Covalent Organic Framework for Potassium‐Ion Batteries

“…F might fully emit into the gaseous phase without being doped into the carbon work during thermal decomposition possibly due to the reactive and volatile nature of fluorine species. Some recent works [ 12 ] also show the difficulty of doping F into carbon while doping N and P is relatively easy. As a result, no F element can be identified.…”