Superior Fast‐Charging Lithium‐Ion Batteries Enabled by the High‐Speed Solid‐State Lithium Transport of an Intermetallic Cu6Sn5 Network

Superior fast charging is a desirable capability of lithium‐ion batteries, which can make electric vehicles a strong competition to traditional fuel vehicles. However, the slow transport of solvated lithium ions in liquid electrolytes is a limiting factor. Here, a LixCu6Sn5 intermetallic network is reported to address this issue. Based on electrochemical analysis and X‐ray photoelectron spectroscopy mapping, it is demonstrated that the reported intermetallic network can form a high‐speed solid‐state lithium transport matrix throughout the electrode, which largely reduces the lithium‐ion‐concentration polarization effect in the graphite anode. Employing this design, superior fast‐charging graphite/lithium cobalt oxide full cells are fabricated and tested under strict electrode conditions. At the charging rate of 6 C, the fabricated full cells show a capacity of 145 mAh g−1 with an extraordinary capacity retention of 96.6%. In addition, the full cell also exhibits good electrochemical stability at a high charging rate of 2 C over 100 cycles (96.0% of capacity retention) in comparison to traditional graphite‐anode‐based cells (86.1% of capacity retention). This work presents a new strategy for fast‐charging lithium‐ion batteries on the basis of high‐speed solid‐state lithium transport in intermetallic alloy hosts. A high‐speed solid‐state lithium‐transport matrix throughout the electrode is built up by a LixCu6Sn5 intermetallic network, which largely reduces the polarization effect in the graphite anode and realizes superior fast‐charging graphite/lithium cobalt oxide full cells under strict electrode conditions (areal capacity >3 mAh cm−2, porosity < 35%).