LiNO3 and TMP enabled high voltage room-temperature solid-state lithium metal battery

The poor interfacial contact and notorious instability issues between solid electrolyte and electrodes seriously handicap the practical applications of solid-state lithium metal batteries (LMBs). In-situ polymerization is a considerable choice to upgrade the interfacial transport properties by directly curing the liquid precursor inside the cell. Herein, a ∼ 17 μm poly(ethylene glycol) methyl ether methacrylate (PEGMEA) based solid polymer electrolyte (SPE) is prepared by this method. Trimethyl phosphate (TMP) and LiNO 3 are introduced to promote the ion transport as well as enhance the electrodes/electrolyte interfacial stability. Interestingly, although LiNO 3 increases the electrolyte’s glass transition temperature thus hinders the anion transport, while higher Li + conductivity is obtained due to the weakened interaction between Li + and its ligands, ethylene oxide (EO) and TMP. The optimal electrolyte (PTLiN1) shows an acceptable ionic conductivity of 1.2 × 10 -4 S cm −1 at 55°C and lithium ion transference number ( t L i + ) of 0.46, which enables the Li||Li symmetric cells to run stability within 1500 h (0.2 mA cm −2 , 0.4 mAh cm −2 ) at 55°C and 1000 h (0.1 mA cm −2 , 0.2 mAh cm −2 ) at 25°C. Meanwhile, the LiFePO 4 ||Li cell with PTLiN1 shows superior long cycle lifetime with a high capacity retention of 88.4% over 300 cycles at 0.5 C. The cells coupled with LiCoO 2 can even work stably under room temperature in the voltage range of 3.0 ∼ 4.3 V. Pouch cells based on PTLiN1 are also prepared and show outstanding flexibility and high security, which provides new idea for the development of economical and convenient solid-state batteries.