Vacant Manganese-Based Perovskite Fluorides@Reduced Graphene Oxides for Na-Ion Storage with Pseudocapacitive Conversion/Insertion Dual Mechanisms.

Na-ion capacitors (NICs) and Na-based dual-ion batteries (Na-DIBs) have been considered to be promising alternatives to traditional lithium-ion batteries (LIBs) because of the abundance and low cost of the Na-ion, but their energy density, power density and life cycle are limited. Herein, dual-vacancy (including K+ and F- vacancies) perovskite fluoride K0.86 MnF2.69 @reduced graphene oxide (rGO; recorded as Mn-G) as anode for NICs and Na-DIBs has been developed. The special conversion/intercalation dual Na-ion energy storage mechanism and pseudocapacitive dynamics are analyzed in detail. The Mn-G//AC NICs and Mn-G//KS6 Na-DIBs delivered a maximum energy density of 92.7 and 187.6 W h kg-1 , a maximum power density of 20.2 and 21.12 kW kg-1 , and long cycle performance of 61.3 and 68.4 % after 1000 cycles at 5 A g-1 , respectively. Moreover, Mn-G//AC NICs and Mn-G//KS6 Na-DIBs can work well over a wide range of temperatures (-20 to 40 °C). These results make it competitive in Na-ion storage applications with high energy/power density over a wide temperature range.

Conversion/Alloying Pseudocapacitance-Dominated Perovskite KZnF3 Anode for Advanced Lithium-Based Dual-Ion Batteries.

Cost-competitive perovskite fluoride KZnF3 has been introduced for the first time as an advanced anode for high-performance lithium-based dual-ion batteries, exhibiting conversion/alloying hybrid mechanisms and dominated pseudocapacitive kinetics for Li-ion storage.

Pseudocapacitive trimetallic NiCoMn-111 perovskite fluorides for advanced Li-ion supercabatteries.

Exploring advanced electrochemical energy storage systems and clarifying their charge storage mechanisms are key scientific frontiers presenting a great challenge. Herein, we demonstrate a novel concept of Li-ion supercabatteries (i.e., Li-ion capacitors/batteries, LICBs), which were realized using a novel trimetallic Ni-Co-Mn perovskite fluoride (K0.97Ni0.31Co0.34Mn0.35F2.98, denoted as KNCMF-111 (8#)) anode and a high-performance activated carbon/LiFePO4 (AC/LFP) cathode, which makes the boundary between LICs and LIBs less distinctive. Thanks to the pseudocapacitive conversion mechanism of the KNCMF-111 (8#) anode with superior kinetics and the enhanced capacity of the capacitor/battery hybrid AC/LFP cathode, the designed KNCMF-111 (8#)//AC/LFP LICBs, integrating the synergistic superiority of pseudocapacitive, capacitive and faradaic characteristics, exhibit remarkable energy/power densities and a long cycle life, indicating a high-efficiency energy storage application. Overall, this work provides new insights into exploring advanced Li-ion supercabatteries and clarifying their charge storage mechanisms based on trimetallic Ni-Co-Mn perovskite fluoride electrode materials, which sheds light on the development of advanced electrochemical energy storage systems and in-depth understanding of their charge storage mechanisms.

A conversion and pseudocapacitance-featuring cost-effective perovskite fluoride KCuF3 for advanced lithium-ion capacitors and lithium-dual-ion batteries.

A cost-effective perovskite fluoride KCuF3 material has been introduced as an advanced anode for lithium-ion capacitors (LICs) and lithium-dual-ion batteries (Li-DIBs), showing a conversion mechanism and pseudocapacitive kinetics for Li ion storage.

Conversion-type NiCoMn triple perovskite fluorides for advanced aqueous supercapacitors, batteries and supercapatteries.

Conversion-type NiCoMn triple perovskite fluorides (KNCMF-622) have been explored for advanced aqueous supercapacitors (ASCs), batteries (ABs) and supercapatteries (i.e., ASC/Bs). The ASC/Bs outperform the ASCs and ABs, owing to the synergistic effect of capacitive, pseudocapacitive and faradaic characteristics, showing great significance in developing energy storage devices.

A F-deficient and high-Mn ternary perovskite fluoride anode with a dominant conversion mechanism for advanced Li-ion batteries.

A F-deficient and high-Mn ternary perovskite fluoride anode (K1.00Ni0.06Co0.14Mn0.80F2.92, KNCMF-3#) has been explored for advanced Li-ion batteries (LIBs), showing a dominant conversion mechanism. Notably, the KNCMF-3#//LiFePO4 (LFP) LIBs furnish an ultra-high performance of 270.5-35.9 W h kg-1/0.63-11.6 kW kg-1/71% retention/5000 cycles/5 A g-1.

A vacancy-rich perovskite fluoride K0.79Ni0.25Co0.36Mn0.39F2.83@rGO anode for advanced Na-based dual-ion batteries.

A novel concept of Na-based dual-ion batteries (Na-DIBs) has been designed via a perovskite K0.79Ni0.25Co0.36Mn0.39F2.83@reduced graphene oxide (KNCMF@rGO) hetero-nanocrystal anode, showing surface conversion and insertion hybrid mechanisms. The KNCMF@rGO//graphite (KS6) DIBs deliver superior energy/power densities and cycling stability and have a significant impact on developing energy storage devices.

Trimetallic NiCoMo/graphene multifunctional electrocatalysts with moderate structural/electronic effects for highly efficient alkaline urea oxidation reaction.

Trimetallic NiCoMo/graphene (NCM/G 811) multifunctional electrocatalysts demonstrate remarkable catalytic activity, fast kinetics, a low onset potential and high stability towards alkaline urea oxidation reaction (UOR). Moderate structural/electronic effects among Ni, Co and Mo species are responsible for the outstanding catalytic behavior.

Engineering doping-vacancy double defects and insights into the conversion mechanisms of an Mn-O-F ultrafine nanowire anode for enhanced Li/Na-ion storage and hybrid capacitors.

The behavior of Li/Na-ion capacitors (LICs/NICs) is largely limited by the low number of electroactive sites in conventional insertion-type anodes. In this work, we demonstrated a novel doping-vacancy double-defective and conversion-type Mn-O-F ultrafine nanowire (denoted as MnF2-E) anode to boost the number of electroactive sites for enhanced LICs/NICs. Owing to the unique hetero oxygen-doping and intrinsic fluorine-vacancy double defects, the Mn-O-F nanowires exhibited superior electroactive sites and thus dramatically enhanced Li/Na-ion storage capability than pristine MnF2 micro/nano-crystals. Both the optimal MnF2 screened by orthogonal experiments and derived Mn-O-F anodes and commercial activated carbon (AC) cathode were used to construct MnF2//AC and MnF2-E//AC LICs/NICs, which were optimized by tuning the active mass ratios of the cathode/anode and the working voltage windows of the hybrid capacitors. The LICs/NICs based on the Mn-O-F anode demonstrated a considerably superior performance than the devices based on the MnF2 anode under the optimal voltages of 0-4 V and 0-4.3 V. The Mn-O-F anode exhibited dominant diffusion/surface-controlled kinetics for Li/Na-ion storage, respectively, showing a major conversion mechanism for the charge storage processes. This work provides a new concept of double-defective and conversion-type electrode materials to improve the Li/Na-ion storage capability and will have a significant impact on the relevant fields.

Vacancy defective perovskite Na0.85Ni0.45Co0.55F3.56 nanocrystal anodes for advanced lithium-ion storage driven by surface conversion and insertion hybrid mechanisms.

A vacancy defective perovskite Na0.85Ni0.45Co0.55F3.56 nanocrystal (NNCF) has been introduced as an advanced anode for Li-ion capacitors (LICs), Li-ion batteries (LIBs) and Li-dual-ion batteries (Li-DIBs), exhibiting the surface conversion and insertion hybrid mechanisms for Li-ion storage.