Lattice-Coupled Si/MXene Confined by Hard Carbon for Fast Sodium-Ion Conduction

Abstract

Silicon (Si) has been ascertained as one of the most desirable anode candidates for sodium-ion batteries (SIBs), ascribed to its sizeable theoretical capacity and abundant resource. However, the inherent electrochemical inertness of crystalline Si against sodium impedes its practical use. Herein, lattice-coupled Si nanoparticles are uniformly distributed onto delaminated MXene (d-MXene) and further tightly confined by hard carbon (HC), consequently forming a 3D cross-linked (Si/d-MXene)@HC architecture as an anode material for SIBs. Coupling a carboncoated Si anode with a conductive d-MXene matrix through the local lattice overlapping not only vastly enables the alloying reactivity of Si with Na, but also provides fast-transfer portholes for Na + and electrons because of the capacitive-like behavior of d-MXene, thus increasing the capacity and achieving fast ion conduction. The Si/d-MXene bonded with HC, constructing a robust architecture, can effectively stabilize the whole electrode structure and accommodate the volume expansion of Si upon cycling and increase capacitive-like contributions, resulting in an enhanced capacity and excellent cycle performance as anodes for SIBs. The developed electrode thus harvests favorable electrochemical performance compared to pure Si and d-MXene electrodes, such as high initial discharge capacity (370 mAh g −1 ), long cycling stability (a capacity retention above 80% after 500 cycles), and superior rate performance. The protocol to enable the sodium storage performance of Si/MXene anodes by adopting the capacitive-battery dual model would inspire rather far-ranging investigations on other advanced battery systems.

Functional Group Regulated Ni/Ti3C2Tx (Tx = F, −OH) Holding Bimolecular Activation Tunnel for Enhanced Ammonia Borane Hydrolysis

“…The binding energies of C 1s peaks appeared at 281.7 and 284.8 eV belong to TiC and CC, respectively. Besides, peaks emerged at 286.1 and 288.5 eV are assigned to COH and HOCO, respectively (Figure d). , The emergence of F 1s HRXPS spectrum also verified that F was successfully introduced into the catalyst after etching by HF (Figure e). The binding energies of Ni 2p 1/2 and Ni 2p 3/2 located at 873.9 and 856.0 eV, respectively, indicating the Ni (0) chemical state.…”

“…Besides, peaks emerged at 286.1 and 288.5 eV are assigned to COH and HOCO, respectively (Figure 2d). 35,36 The emergence of F 1s HRXPS spectrum also verified that F was successfully introduced into the catalyst after etching by HF (Figure 2e). 2f).…”

Richly electron-deficient BCxO3−x anodes with enhanced reaction kinetics for sodium/potassium-ion batteries

“…On the basis of the cell voltage linearly proportional to τ 1/2 (Fig. 5e), it can be calculated according to the equation, 6,16 in which m B , M B and V M are the mass, molar mass and molar volume, τ is the pulse duration, and S is the active surface area of the electrode, respectively. The parameters of Δ E S and Δ E τ are derived from the GITT curves (Fig.…”

“…On the basis of the cell voltage linearly proportional to t 1/2 (Fig. 5e), it can be calculated according to the equation, 6,16…”

“…Increasing concerns regarding the carbon emission peak and carbon neutrality targets have propelled researchers to seek out inexpensive and resourceful energy storage devices. [1][2][3][4][5][6] Currently, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) for large-scale grid energy systems appear to be promising alternatives to traditional lithium-ion batteries (LIBs) owing to their merits of natural abundance, low price and high energy density. [7][8][9][10] Both metallic sodium and potassium have a similar redox potential and reaction mechanisms to lithium.…”