Highly Cyclable All‐Solid‐State Battery with Deposition‐Type Lithium Metal Anode Based on Thin Carbon Black Layer

A thin carbon black (CB) layer on a metal current collector is used as a substrate of a deposition‐type Li metal anode for a sulfide‐based all‐solid‐state battery (ASSB). In this ASSB, the capacity of the CB layer is set to ≈5–10% of the cathode. Therefore, the anode soon overcharges and a large proportion of the Li ions precipitate as Li metal on the anode during the charging process, thus this precipitated Li works as a Li metal anode. This CB‐based anode effectively suppresses short circuit of the cell, and an ASSB with this anode has shown an excellent cycle property of over 150 cycles with good capacity retention. From measurements involving cross‐sectional scanning electron microscopy, deposited Li metal layer at the CB/Ni interface is observed. It is also found that the addition of metal particles in the CB‐based anode drastically improves cell performance by extending the cycle life. An ASSB with an Ag/CB‐based anode is operated over 700 cycles at 3 mA cm −2 current density (0.5 C) with a capacity retention of ≈86% after 700 cycles.