Revealing An Intercalation‐Conversion‐Heterogeneity Hybrid Lithium‐Ion Storage Mechanism in Transition Metal Nitrides Electrodes with Jointly Fast Charging Capability and High Energy Output

Abstract

The performance of electrode materials depends intensively on the lithium (Li)-ion storage mechanisms correlating ultimately with the Coulombic efficiency, reversible capacity, and morphology variation of electrode material upon cycling. Transition metal nitrides anode materials have exhibited high-energy density and superior rate capability; however, the intrinsic mechanism is largely unexplored and still unclear. Here, a typical 3D porous Fe 2 N micro-coral anode is prepared and, an intercalation-conversion-heterogeneity hybrid Li-ion storage mechanism that is beyond the conventional intercalation or conversion reaction is revealed through various characterization techniques and thermodynamic analysis. Interestingly, using advanced in situ magnetometry, the ratio (ca. 24.4%) of the part where conversion reaction occurs to the entire Fe 2 N can further be quantified. By rationally constructing a Li-ion capacitor comprising 3D porous Fe 2 N micro-corals anode and commercial AC cathode, the hybrid full device delivers a high energy-density (157 Wh kg −1 ) and high power-density (20 000 W kg −1 ), as well as outstanding cycling stability (93.5% capacitance retention after 5000 cycles). This research provides an original and insightful method to confirm the reaction mechanism of material related to transition metals and a fundamental basis for emerging fast charging electrode materials to be efficiently explored for a next-generation battery.

Facilely Fabricating F-Doped Fe3N Nanoellipsoids Grown on 3D N-Doped Porous Carbon Framework as a Preeminent Negative Material

“…The peak located at 0.25 V vanishes in the later discharging processes, which could stem from the formation of an SEI film [ 42 ]. For the later discharging processes, two reduction peaks shift to a relatively high potential of 1.40 and 0.81 V. In the foremost charging process, the F-Fe 3 N/NPCF negative electrode only gives an evident oxidation peak located at 1.87 V, which corresponds to the release of lithium ion from the Li 3 N and the conversion of iron elemental to Fe 3 N [ 43 ]. For the later charging processes, the oxidation peak shifts to a relatively high potential of 1.91 V. Comparing the next four cyclic curves, it is uncomplicated to find that they have barely changed, thus validating the salient electrochemical reversibility of the F-Fe 3 N/NPCF negative electrode.…”

Voltage Hysteresis in Transition Metal Oxide Cathodes for Li/Na‐Ion Batteries

“…In particular, the magnetism of electrodes based on transition metals and their compounds is sensitive to electron transfer during the charge storage process, either on the surface of the material or in the bulk. Thus, our group [180][181][182][183][184] used in situ magnetometry to investigate the interface charge storage behaviour of TM-based anodes, and made good progress. For this reason, the charge compensation mechanism revealed in situ magnetometry can be generalized to a broad range of TM oxide cathodes.…”

An ecofriendly and universal strategy to balance the active sites and electrical conductivity of biomass-derived carbon for superior lithium storage

“…4,5 In this regard, a series of material candidates have been tested as anodes for LIBs, including carbonaceous materials, metallic/non-metallic alloys, and transition metal oxides/phosphide/sulfides/selenides/ nitrides. [6][7][8][9][10][11][12][13] Among them, hard or non-graphitizable carbons, especially those carbons derived from biomass, have received enormous attention because of their naturally formed diffusion channels, numerous active adsorption sites, vast availability, and cost-effectiveness. 14,15 However, there is a contradiction between the active sites and the conductivity of biomass-derived carbon which hinders its use in large-scale applications.…”