A Versatile Strategy for Achieving Fast‐Charging Batteries via Interfacial Engineering: Pseudocapacitive Potassium Storage without Nanostructuring

Abstract

over the past two decades. [1] In particular, intensive research on the rocking-chair type insertion/extraction behavior of alkali ions into electrodes has expanded the rechargeable battery market from portable electronic devices to electric vehicles (EVs). [2] However, this significant shift in the battery paradigm to high-energy-density applications has resulted in challenges related to charging time. [3] For example, several hours are inevitably required to charge EVs completely using the current battery technology, far the behind practical goal that EVs charge to 80% of state of charge (ΔSOC) within only 10-15 min. [4] Therefore, the fast-charging capability of rechargeable batteries has become an essential requirement in modern society to adopt EVs and future energy systems. [5] Generally, the fast-charging properties of batteries depend on the transport kinetics of alkali ions in electrodes; hence, a short diffusion time of alkali ions in solid-state active material is highly required. [6] The diffusion time (τ) of alkali ions in electrodes is related to the diffusion length (L) and diffusivity (D), as follows: τ = L 2 × D −1 . [7] As the diffusion time is dependent on the values of L and D, approaches to shorten the diffusion length and to increase the diffusivity of alkali ions have been mainly investigated in the design of fast-charging batteries. [8] Recently,The rapid transport of alkali ions in electrodes is a long-time dream for fast-charging batteries. Though electrode nanostructuring has increased the rate-capability, its practical use is limited because of the low tap density and severe irreversible reactions. Therefore, development of a strategy to design fast-charging micron-sized electrodes without nanostructuring is of significant importance. Herein, a simple and versatile strategy to accelerate the alkali ion diffusion behavior in micron-sized electrode is reported. It is demonstrated that the diffusion rate of K + ions is significantly improved at the hetero-interface between orthorhombic Nb 2 O 5 (001) and monoclinic MoO 2 (110) planes. Lattice distortion at the hetero-interface generates an inner space large enough for the facile transport of K + ions, and electron localization near oxygen-vacant sites further enhances the ion diffusion behavior. As a result, the interfacial-engineered micron-sized anode material achieves an outstanding rate capability in potassium-ion batteries (KIBs), even higher than nanostructured orthorhombic Nb 2 O 5 which is famous for fast-charging electrodes. This is the first study to develop an intercalation pseudocapacitive micron-sized anode without nanostructuring for fast-charging and high volumetric energy density KIBs. More interestingly, this strategy is not limited to K + ion, but also applicable to Li + ion, implying the versatility of interfacial engineering for alkali ion batteries.

Enabling intercalation‐type TiNb24O62 anode for sodium‐ and potassium‐ion batteries via a synergetic strategy of oxygen vacancy and carbon incorporation

“…TNO shows a flat line with no prominent EPR signal (Figure 1E), indicating that Ti and Nb are in the highest oxidation state and there are no free electrons in pristine TNO. TNO x /rGO shows a strong signal at a g ‐value close to 1.98, which confirms the presence of OVs 30,46 . As a result, the oxidation states of Nb and Ti reduce, which introduces free electrons for charge compensation, thereby generating EPR signal.…”

“…TNO x /rGO shows a strong signal at a g-value close to 1.98, which confirms the presence of OVs. 30,46 As a result, the oxidation states of Nb and Ti reduce, which introduces free electrons for charge compensation, thereby generating EPR signal. Furthermore, the high resolution Nb 3d X-ray photoelectron spectrometer (XPS) spectrum of TNO (Figure 1F) shows two distinct peaks at 210.2 and 207.4 eV, corresponding to Nb 5+ 3d 3/2 and Nb 3d 5/2 , respectively.…”

Dendrite‐Free and High‐Rate Potassium Metal Batteries Sustained by an Inorganic‐Rich SEI

“…To further evaluate the interfacial charge-transfer properties, Tafel plots and electrochemical impedance spectroscopy (EIS) curves were collected for symmetric cells. [33,34] As shown in Figure S10, Supporting Information, the exchange current density of NG@P-Al is as high as 4.27 × 10 −6 mA cm −2 , indicating the facilitated charge transfer kinetics of Faradaic processes. [35,36] The Nyquist plots of all samples over a temperature range of 10-50 °C displays the lowest impedance of NG@P-Al (Figure S11, Supporting Information).…”

Fe2O3 for stable K-ion storage: mechanism insight into dimensional construction from stress distribution and micro-tomography

“…The micron-scale electrodes are more conducive to the diffusion behavior of potassium ions for the easy transport of potassium ions, the improvement of the multiplicity of performances of potassium ion batteries, as well as the acceleration of battery charging and discharging. 35 The micron-scale Fe 2 O 3 is also convenient for analyzing its failure mechanism using synchrotron radiation. Therefore, we prepared micrometer-scale Fe 2 O 3 .…”