Black Phosphorus Quantum Dot/Ti₃C₂ MXene Nanosheet Composites for Efficient Electrochemical Lithium/Sodium‐Ion Storage

Abstract

The exploration of new and efficient energy storage mechanisms through nanostructured electrode design is crucial for the development of high‐performance rechargeable batteries. Herein, black phosphorus quantum dots (BPQDs) and Ti3C2 nanosheets (TNSs) are employed as battery and pseudocapacitive components, respectively, to construct BPQD/TNS composite anodes with a novel battery‐capacitive dual‐model energy storage (DMES) mechanism for lithium‐ion and sodium‐ion batteries. Specifically, as a battery‐type component, BPQDs anchored on the TNSs are endowed with improved conductivity and relieved stress upon cycling, enabling a high‐capacity and stable energy storage. Meanwhile, the pseudocapacitive TNS component with further atomic charge polarization induced by POTi interfacial bonds between the two components allows enhanced charge adsorption and efficient interfacial electron transfer, contributing a higher pseudocapacitive value and fast energy storage. The DMES mechanism is evidenced by substantial characterizations of X‐ray photoelectron spectroscopy and X‐ray absorption fine structure spectroscopy, density functional theory calculations, and kinetics analyses. Consequently, the composite electrode exhibits superior battery performance, especially for lithium storage, such as high capacity (910 mAh g−1 at 100 mA g−1), long cycling stability (2400 cycles with a capacity retention over 100%), and high rate capability, representing the best comprehensive battery performance in BP‐based anodes to date.

Low‐Temperature Reduction Strategy Synthesized Si/Ti3C2 MXene Composite Anodes for High‐Performance Li‐Ion Batteries

“…Moreover, the proportion of capacitive‐controlled capacity increases with the sweep rate (Figure f), illustrating that the capacitive behavior can be useful for store/release Li + more effectively at higher sweep rate, due to the rapid charge/discharge characteristic of the capacitive storage mechanism. These results indicate that the energy storage process of Ti 3 C 2 /Si nanocomposite anode defers to a battery‐capacitive dual‐model energy storage mechanism (Figure S16, Supporting Information) …”

“…Ti 3 C 2 MXene also has been an attractive candidate for electrode materials of supercapacitors and anodes of LIBs due to the abundant surface redox reaction, which enables Ti 3 C 2 display significant contribution to the capacity rather than only work as conductive matrix. For instance, black phosphorus quantum dot (BPQD)/Ti 3 C 2 MXene nanosheet composites synthesized by an interfacial assembly strategy present a high reversible capacity of 1124 mAh g −1 at 50 mA g −1 when used as anodes of LIBs, which is attributed to the excellent conductivity of Ti 3 C 2 MXene and indispensable synergies of BPQD and Ti 3 C 2 MXene in capacity contribution . Therefore, Ti 3 C 2 MXene is expected to replace graphene to combine with Si as LIBs anodes with more excellent electrochemical performance.…”

Space‐Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium‐Ion Batteries

“…After 1 500 cycles, a high reversible capacity of 837 mAh g −1 remained, giving a capacity retention of nearly 100 %. The capacity increase in the initial 150 cycles is ascribed to a combined activation mechanism induced by carbon activation and Si amorphization . The amorphization of Si NDs upon cycling is observed in the corresponding in situ XRD measurements (Figure S10).…”

Surface Modified MXene‐Based Nanocomposites for Electrochemical Energy Conversion and Storage

“…Recently, Yang and co‐workers have reported a liquid–solid phase assembly approach, which can easily produce the nanocomposite consisting of black phosphorus quantum dots (BPQDs) and HF‐etched Ti 3 C 2 T m MXene . Verified by a series of characterizations and DFT calculation, the authors pointed out that the high affinity of BPQDs for oxygen would result in the strong covalent P–O–Ti interaction, which might contribute to the assembly of BPQDs on the surface of HF‐etched Ti 3 C 2 T m MXene.…”