Mn‐Substituted Tunnel‐Type Polyantimonic Acid Confined in a Multidimensional Integrated Architecture Enabling Superfast‐Charging Lithium‐Ion Battery Anodes

Abstract

Given the inherent features of open tunnel‐like pyrochlore crystal frameworks and pentavalent antimony species, polyantimonic acid (PAA) is an appealing conversion/alloying‐type anode material with fast solid‐phase ionic diffusion and multielectron reactions for lithium‐ion batteries. Yet, enhancing the electronic conductivity and structural stability are two key issues in exploiting high‐rate and long‐life PAA‐based electrodes. Herein, these challenges are addressed by engineering a novel multidimensional integrated architecture, which consists of 0D Mn‐substituted PAA nanocrystals embedded in 1D tubular graphene scrolls that are co‐assembled with 2D N‐doped graphene sheets. The integrated advantages of each subunit synergistically establish a robust and conductive 3D electrode framework with omnidirectional electron/ion transport network. Computational simulations combined with experiments reveal that the partial‐substitution of H3O+ by Mn2+ into the tunnel sites of PAA can regulate its electronic structure to narrow the bandgap with increased intrinsic electronic conductivity and reduce the Li+ diffusion barrier. All above merits enable improved reaction kinetics, adaptive volume expansion, and relieved dissolution of active Mn2+/Sb5+ species in the electrode materials, thus exhibiting ultrahigh rate capacity (238 mAh g−1 at 30.0 A g−1), superfast‐charging capability (fully charged with 56% initial capacity for ≈17 s at 80.0 A g−1) and durable cycling performance (over 1000 cycles).

Unveiling the Role and Mechanism of Nb Doping and In Situ Carbon Coating on Improving Lithium‐Ion Storage Characteristics of Rod‐Like Morphology FeF3·0.33H2O

“…Values of b between 0.5 and 1.0 indicate that the electrode behavior is compatible with both diffusioncontrolled and capacitance-controlled mechanisms. [38] The O1 and R1 peaks represent the deintercalation and intercalation of Li + in N3F, with b values of 0.898 and 0.992, respectively, demonstrating that this process is dominated by surface-controlled capacitive behavior. The O2 and R2 peaks correspond to the conversion process and their b values are calculated as 0.72 and 0.523, respectively, revealing diffusion-controlled faradaic storage.…”

“…As shown in Figure 3i and Figure S5 (Supporting Information), the adsorption curve is inconsistent with the corresponding desorption curve, and a hysteresis loop appears, indicating the IV-type characteristics, which derives from the mesoporous generation of solids. [38] The pore size and specific surface area of N0F are ≈16 nm and 81 m 2 g −1 . Although the pore size (13 nm) and specific surface area (72 m 2 g −1 ) of N3F are slightly reduced due to the introduction of Nb, it still has mesoporous structure and a relatively large specific surface area, which is favorable for fast transport of Li + and penetration of the electrolyte.…”

“…With N3F, when the rate returned to 0.1 C, the capacity rapidly recovered to 471.0 mAh g −1 , demonstrating the acceptable rate capacity, fast Li + storage capability, and good structural stability of this electrode. [38] The charge/discharge curves of N0F (Figure 4e) and N3F (Figure 4f) were also compared in the third cycle at each rate. As the rate was increased from 0.1 to 5.0 C, their charge and discharge capacities showed a downward trend.…”

Synergy of diffraction and spectroscopic techniques to unveil the crystal structure of antimonic acid

“…One of the long-standing chemical identity issues is that corresponding to the so-called ‘antimonic acid’ (hereafter: AA), also referred to as hydrated antimony pentoxide (frequently termed HAP), antimony oxide hydrates, and Sb(V) hydroxide. This material has proven useful for a variety of applications due to its distinctive proton-conducting nature 1 – 4 , ionic exchangeability 5 – 10 , and radiation resistance 7 , serving as potential candidate for photocatalyst 11 , 12 , fuel cells electrolyte 13 , 14 , heavy metals remover 15 , 16 , and for its application in electrochromic displays 3 or as precursor of several useful derivatives 7 , 11 , 17 – 19 , among others. This enigmatic substance was already described by J.J. Berzelius.…”

Unveiling the crystal structure of ‘antimonic acid’: short- and long-range perspectives

“…One of the long-standing chemical identity issues is that corresponding to the so-called "antimonic acid" (hereafter: AA), also referred to as hydrated antimony pentoxide (HAP), antimony oxide hydrates, and Sb(V) hydroxide. This material has proven useful for a variety of applications due to its distinctive proton-conducting nature [1][2][3][4] , ionic exchangeability [5][6][7][8][9][10] , and radiation resistance 7 , serving as potential candidate for photocatalyst 11,12 , fuel cells electrolyte 13,14 , heavy metals remover 15,16 , and for its application in electrochromic displays 3 or as precursor of several useful derivatives 7,11,[17][18][19] , among others. This enigmatic substance was already described by J.J. Berzelius.…”