Practical 4.7 V solid-state 18650 cylindrical lithium metal batteries with in-situ fabricated localized high-concentration polymer electrolytes

Abstract In-situ fabricated gel polymer electrolytes (GPEs), characterized with superior interfacial properties and large-scale processibility, represent a promising electrolyte system for high-performance lithium metal batteries (LMBs). Herein, we propose an in-situ fabricated high-voltage GPE featuring a localized high-concentration solvation structure (LHCE-GPE). This tailored special solvation structure within polymer matrix promotes the formation of an electrochemically robust electrode–electrolyte interphase. Furthermore, employing LHCE-GPE, Li||Li1.2Ni0.13Co0.13Mn0.54O2 cells operating at 4.8 V demonstrate a high specific capacity of 248 mAh g−1, and 4.5 V Li||LiNi0.8Co0.1Mn0.1O2 cells achieve a remarkable cycling stability over 1000 cycles. Significantly, our LHCE-GPE allows for the operation of practical solid-state 18 650 cylindrical LMBs at 4.7 V and industrial Li-ion batteries at 4.6 V, achieving high energy densities of 250 and 283 Wh kg−1, respectively (excluding packaging), while also demonstrating robust safety during rigorous nail-penetration tests. Our LHCE-GPE design presents a practical and powerful strategy for realizing solid-state LMBs with high energy density and high safety.