Supercritical CO₂‐Assisted SiO_x/Carbon Multi‐Layer Coating on Si Anode for Lithium‐Ion Batteries

Abstract

Supercritical CO2 (SCCO2), characterized by gas‐like diffusivity, low surface tension, and excellent mass transfer properties, is applied to create a SiOx/carbon multi‐layer coating on Si particles. Interaction of SCCO2 with Si produces a continuous SiOx layer, which can buffer Si volume change during lithiation/delithiation. In addition, a conformal carbon film is deposited around the Si@SiOx core. Compared to the carbon film produced via a conventional wet‐chemical method, the SCCO2‐deposited carbon has significantly fewer oxygen‐containing functional groups and thus higher electronic conductivity. Three types of carbon precursors, namely, glucose, sucrose, and citric acid, in the SCCO2 syntheses are compared. An eco‐friendly, cost‐effective, and scalable SCCO2 process is thus developed for the single‐step production of a unique Si@SiOx@C anode for Li‐ion batteries. The sample prepared using the glucose precursor shows the highest tap density, the lowest charge transfer resistance, and the best Li+ transport kinetics among the electrodes, resulting in a high specific capacity of 918 mAh g−1 at 5 A g−1. After 300 charge–discharge cycles, the electrode retains its integrity and the accumulation of the solid electrolyte interphase is low. The great potential of the proposed SCCO2 synthesis and composite anode for Li‐ion battery applications is demonstrated.

Dual‐Design of Nanoporous to Compact Interface via Atomic/Molecular Layer Deposition Enabling a Long‐Life Silicon Anode

“…Both are harmful to the cycling performance. [4] The long-term cycling test of the MLD/ALD dual-film coated silicon anodes at a current density of 1 and 2 A g −1 is performed as shown in Figure 4e; Figure S8, Supporting Information. Prior to the test, a small current density of 0.2 A g −1 is applied to the two electrodes for initial three cycles, followed by using 1 or 2 A g −1 in subsequent cycles.…”

Supercritical carbon dioxide assisted formation of crystalline materials for various energetic applications

“…Supercritical CO 2 was recently applied by the Chang group to create a SiO x /carbon multi-layer coating on Si particles. 56 The SiO x shell surface oxidation was attained by treating Si particles with scCO 2 fluid. Then, external carbon shells were obtained from glucose, sucrose, and citric acid via calcination at 850 °C under Ar atmosphere for 5 h. The composite prepared with the glucose precursor showed the highest tap density, the lowest charge transfer resistance, and the best Li + transport kinetics among the electrodes, resulting in a high specific capacity of 918 mA h g −1 at 5 A g −1 .…”

Charge–Discharge Mechanism of High‐Entropy Co‐Free Spinel Oxide Toward Li+ Storage Examined Using Operando Quick‐Scanning X‐Ray Absorption Spectroscopy

“…Many approaches have been proposed for improving LIB performance. [ 1 , 2 , 3 , 4 ] Increases in the specific capacity and rate capability of anode materials are particularly desirable for next‐generation LIBs because the conventional graphite electrode has a limited capacity and unsatisfactory high‐rate performance. [ 5 ] Lithium (Li) metal is an appealing candidate anode material due to its low potential and extremely high capacity (theoretically 3860 mAh g −1 ).…”