Observation of High‐Capacity Monoclinic B‐Nb₂O₅ with Ultrafast Lithium Storage

Abstract

Apart from Li4Ti5O12, there are few anode substitutes that can be used in commercial high‐power lithium‐ion batteries. Orthorhombic T‐Nb2O5 has recently been proven to be another substitute anode. However, monoclinic B‐Nb2O5 of same chemistry is essentially inert for lithium storage, but the underlying reasons are unclear. In order to activate the “inert” B‐Nb2O5, herein, nanoporous pseudocrystals to achieve a larger specific capacity of 243 mAh g−1 than Li4Ti5O12 (theoretical capacity: 175 mAh g−1) are proposed. These pseudocrystals are rationally synthesized via a “shape‐keep” topological microcorrosion process from LiNbO3 precursor. Compared to pristine B‐Nb2O5, experimental investigations reveal that B‐Nb2O5−x delivers ≈3000 times higher electronic conductivity and tenfold enhanced Li+ diffusion coefficient. An ≈30% reduction of energy barrier for Li‐ion migration is also confirmed by the theoretical calculations. The nanoporous B‐Nb2O5−x delivers unique ion/electron transport channels to proliferate the reversible and deeper lithiation, which activate the “inert” B‐Nb2O5. The capacitive‐like behavior is observed to endow B‐Nb2O5−x ultrafast lithium storage ability, harvesting 136 mAh g−1 at 100 C and 72 mAh g−1 even at 250 C, superior to Li4Ti5O12. Pouch‐type full cells exhibit the energy density of ≈251 Wh kg−1 and ultrahigh power density up to ≈35 kW kg−1.

Upgrading Polyvinyl Chloride by ZnO-Assisted Solvothermal Dehalogenation

“…With the increase of ZnO amount, the carbon skeleton of ZPCs has a larger interlayer distance and better electron conductivity, which allows a faster kinetic rate of the Faraday reaction and promotes the diffusion of solid ions between layers. 27,35,37,38 All of these results suggest that faster kinetics is favored by the developed lamellar structure and the improved electron conductivity.…”

“…The smaller semicircle in the high-frequency region of the ZPC-1/2/4 electrodes suggests that ZPC-1/2/4 provides more improved electronic conductivity than ZPC-0, which matches the results of previous conductivity measurements and the retention of CC in ZPC-1/2/4. With the increase of ZnO amount, the carbon skeleton of ZPCs has a larger interlayer distance and better electron conductivity, which allows a faster kinetic rate of the Faraday reaction and promotes the diffusion of solid ions between layers. ,,, All of these results suggest that faster kinetics is favored by the developed lamellar structure and the improved electron conductivity.…”