| Izvleček: | <p>All-solid-state batteries (SSBs) based on sulfide solid electrolytes (SEs) have the potential to increase safety and provide greater energy density compared to lithium-ion batteries (LIBs). To match the high capacity of metallic anodes, SSBs require high energy density, long-lasting composite cathodes such as those based on lithium Ni-Mn-Co (NMC) oxide mixed with a solid-state electrolyte (SE). However in practice, cathode capacity typically fades due to NMC cracking and increasing NMC/SE interface debonding because of NMC pulverization. Using smart processing protocols, a single-crystal particulate LiNi0.83Mn0.06Co0.11O2 and Li6PS5Cl SE composite cathode was fabricated with outstanding discharge capacity of 210 mA h g−1 and high areal capacity of 8.7 mA h cm−2 at 30 °C. A first cycle coulombic efficiency of >85%, and >99% thereafter, was achieved despite a 5.5% volume change during cycling.</p>
<p>Many battery applications target fast charging that increase the state of charge (SOC) to at least 80% in <15 min. However, most SSBs take several hours to reach >80% SOC and a typical specific energy of 400 Wh kg−1 cell. This arises because of current density limitations at the anode and high interfacial resistances in the cathode, leading to high overpotentials even at elevated temperature. The fast-charging capability of a low resistance sulfide based single crystal NMC all-solid-state cathode was investigated using a 3-electrode arrangement that allowed differentiation between anodic and cathodic contributions. At 30 °C and charging at 15 mA cm−2, a specific capacity of 150 mA h g−1 in ∼8 min was achieved, with 80% capacity retention after 3000 cycles. There was a low void formation rate during cycling highlighting the importance of optimized cathode fabrication. At 80 °C, a current density of 50 mA cm−2 charged a cathode areal capacity of 8 mA h cm−2 in only 10 min, suggesting SSB cathodes for fast charging at 400 W h kg−1 cell may be within reach.</p>
<p>Although there has been steady improvements in the performance of SSBs, most research has focused on small (∼10 mm diameter) and thick (up to a 1 mm or more) pellet-type cells that are based on non-scalable manufacturing routes. Inevitably, these approaches lead to a low energy density at the cell scale. Practical applications require higher energy densities (typically 1000 W h L−1 cell) and therefore thinner and larger area sheet-type cells made by scalable techniques. A scalable layer-by-layer spray printing approach has been explored for the manufacture of sheet-type SSB components, including the SE separator, cathode, and anode. Sprayed sulfide SE separators with a low thickness of 10 μm and high ionic conductivity of 1 mS cm −1 were fabricated. A sprayed cathode was demonstrated and cycled for 800 cycles with a capacity retention of 63%. The high potential for process integration of the spraying approach was highlighted by the fabrication of a Li metal-free cell consisting of a sprayed Ag-C layer and a sprayed SE layer.</p>
|
|---|