Controllably Enriched Oxygen Vacancies through Polymer Assistance in Titanium Pyrophosphate as a Super Anode for Na/K-Ion Batteries

Abstract

Although sodium-ion batteries (SIBs) and potassiumion batteries (PIBs) are promising prospects for next-generation energy storage devices, their low capacities and inferior kinetics hinder their further application. Among various phosphate-based polyanion materials, titanium pyrophosphate (TiP 2 O 7 ) possesses outstanding ion transferability and electrochemical stability. However, it has rarely been adopted as an anode for SIBs/PIBs due to its poor electronic conductivity and nonreversible phase transitions. Herein, an ultrastable TiP 2 O 7 with enriched oxygen vacancies is prepared as a SIB/PIB anode through P-containing polymer mediation carbonization, which avoids harsh reduction atmospheres or expensive facilities. The introduction of oxygen vacancies effectively increases the pseudocapacitance and diffusivity coefficient and lowers the Na insertion energy barrier. As a result, the TiP 2 O 7 anode with enriched oxygen vacancies exhibits ultrastable Na/K ion storage and superior rate capability. The synthetic protocol proposed here may offer a simple pathway to explore advanced oxygen vacancy-type anode materials for SIBs/PIBs.

Encapsulating Oxygen‐Deficient TiNb24O62 Microspheres by N‐Doped Carbon Nanolayer Boosts Capacity and Stability of Lithium‐Ion Battery

“…Note that the electronically coupled PDA polymers play a crucial role in introducing oxygen deficiencies, which were produced from the direct oxidation of dopamine monomers with extending πconjugated electron systems, bringing oxygen deficiencies into the crystal structure of the TNO, and accompanied with the injection of electrons into its conduction band, possessing high conductivity. [38,54,55] Besides, the high-temperature carbothermal reduction can also generate oxygen deficiencies in the argon atmosphere. Moreover, N-doped carbon is known to processes various defects, for example, the existence of unpaired electrons in pyridinic-N and pyrrolic-N, respectively.…”

“…As a comparison, the DTNO@NC exhibits a significant EPR response signal at around g=2.003, which directly demonstrate the existence of oxygen deficiencies. Note that the electronically coupled PDA polymers play a crucial role in introducing oxygen deficiencies, which were produced from the direct oxidation of dopamine monomers with extending π‐conjugated electron systems, bringing oxygen deficiencies into the crystal structure of the TNO, and accompanied with the injection of electrons into its conduction band, possessing high conductivity [38,54,55] . Besides, the high‐temperature carbothermal reduction can also generate oxygen deficiencies in the argon atmosphere.…”

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.…”

Boosting the Pseudocapacitive and High Mass‐Loaded Lithium/Sodium Storage through Bonding Polyoxometalate Nanoparticles on MXene Nanosheets

“…Then, galvanostatic intermittent titration technique (GITT) was employed to evaluate the diffusion coefficient of Li + ( D Li + ) in the MF POMs/MXenes. [ 47,48 ] The calculated coefficient values were plotted as a function of the potential during charge and discharge, as shown in Figure S7d–f (Supporting Information). The D Li + value remains high and stable, indicative of a very fast diffusion rate of Li + in the framework of MF POMs/MXenes.…”