Lithium metal is regarded as a “Holy Grail” anode material because of its high theoretical specific capacity and uniquely low reduction potential. However, its low Coulombic efficiency and hazards caused by uncontrolled lithium dendrite growth have hindered its practical application in anodes for many years. In this work, we design a novel boron-containing single-ion conducting polymer electrolyte that eliminates the large electric field that Chazalviel has identified as the cause of lithium dendrite growth. The ability to inhibit lithium dendrite growth is demonstrated via galvanostatic cycling tests of Li/Electrolyte/Li cells. In addition, the boron-containing single-ion conducting polymer electrolyte exhibits excellent ionic conductivity (2.23 mS cm^?1) and an extremely high lithium-ion transference number (0.71). Moreover, the LiFePO 4 /Electrolyte/Li cell exhibits an outstanding specific capacity of more than 130 mAh g ^?1 and excellent capacity retention (90% of the highest capacity was retained after 100 cycles). This excellent performance indicates a promising strategy for development of safe, long-life lithium metal batteries.