<p>Solid-state
batteries (SSBs) with alkali metal anodes hold great promise as energetically
dense and safe alternatives to conventional Li-ion cells. Whilst, in principle,
SSBs have the additional advantage of offering virtually unlimited plating
current densities, fast charges have so far only been achieved through sophisticated
interface engineering strategies. Here, we reveal that such interface
engineering can be easily achieved by tuning the chemistry of NaSICON solid
electrolytes (Na<sub>3.4</sub>Zr<sub>2</sub>Si<sub>2.4</sub>P<sub>0.6</sub>O<sub>12</sub>)
and taking advantage of the thermodynamic
stabilization of a Na<sub>3</sub>PO<sub>4</sub> layer on their surface upon
thermal activation. The optimized planar Na|NZSP interfaces are characterized
by their exceptionally low interface resistances (down to 0.1 Ω cm<sup>2 </sup>at room temperature) and, more
importantly, by their tolerance to large plating current densities (up to 10 mA
cm<sup>-2</sup>) even for extended cycling periods of 30 minutes (corresponding
to an areal capacity 5 mAh cm<sup>-2</sup>).</p>
The role of NaSICON surface chemistry in stabilizing fast-charging Na metal solid-state batteries
