RESUMEN
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.
RESUMEN
In-situ-polymerized solid-state electrolytes can significantly improve the interfacial compatibility of Li metal batteries. Typically, in-situ-polymerized 1,3-dioxolane electrolyte (PDOL) exhibits good compatibility with Li metal. However, it still suffers from the narrow electrochemical window (4.1 V), limiting the application of high-voltage cathodes. Herein, a novel modified PDOL (PDOL-F/S) electrolyte with an expanded electrochemical window of 4.43 V and a considerable ionic conductivity of 1.95 × 10-4 S cm-1 is developed by introducing high-voltage stable plasticizers (fluoroethylene carbonate and succinonitrile) to its polymer network. The space-confined plasticizers are beneficial to construct a high-quality cathode-electrolyte interphase, hindering the decomposition of lithium salts and polymers in electrolytes at high voltage. The as-assembled Li|PDOL-F/S|LiCoO2 battery delivers superior cycling stability (capacity retention of 80% after 400 cycles) at 4.3 V, superior to that of pristine PDOL (3% after 120 cycles). This work provides new insights into the design and application of high-voltage solid-state lithium metal batteries by in situ polymerization.