Lithium ion batteries (LIBs) have been successfully used as the efficient energy storage equipment for the consumable electronic devicesand electric vehicles in the past decades. However, the conventionalLIBs which use the organic flammable liquid electrolytes can cause somesafety and environmental problems. All-solid-state lithium ion batteries which use non-flammable solid electrolytes have received increasing attention recently for their performances are superior than theconventional LIBs especially in the safety issues [5–7]. As the key component of all-solid-state LIBs, solid electrolytes should possess high ionicconductivity and ion transference number, good mechanical strength,chemical compatibility with the electrodes and wide electrochemicalwindow [5,8]. Therefore, the main issue right now is to design solid electrolytes with better comprehensive performance.Currently, various of solid electrolytes include solid oxide-basedelectrolytes (i.e. LLZO [9] and LAGP [10]), solid sulfide-based electrolytes (i.e. LGPS [11]) and solid polymer electrolytes (SPEs) have beenextensively developed and successfully applied to the all-solid-stateLIBs. However, the oxide-based electrolytes exhibit great stability inair but show a large interfacial resistance between the electrode andsolid electrolyte [12]. Solid sulfide-based electrolytes possess highionic conductivity at room temperature but they are very unstable inair and polar solvents [13]. Compared to inorganic solid electrolytes,SPEs possess several advantages like flexibility, light weight, wellinterface contact between electrode and electrolyte and easy to fabricateon a large scale [5,14]. These features make SPEs the most promising candidate electrolytes for all-solid-state LIBs. SPEs are usually comprised ofpolymer matrix and lithium salt. Various polymer materials such as poly(ethylene oxide) (PEO)[15,16], polycarbonate [17], polyphosphazenes[18], polymethacrylate [19], polysiloxane [20], single-ion polyelectrolyte[21] and polyurethane [22] have been investigated as polymer matrix.However, looking for new polymer matrix to improve comprehensiveperformance of SPEs is still an important issue for all-solid-state LIBs. Furthermore, the fabrication of SPEs is usually use solution casting method,which requires the usage of toxic and volatile organic solvent such as dimethyl formamide (DMF) and acetonitrile (ACN) to dissolve the polymer[23]. This process will lead to a considerable release of volatile organiccompounds (VOCs) which is harmful to the environment.Environmentally friendly waterborne polyurethane (WPU) hasattracted increasing attention recently and has been widely used asbinder, coating, ink and so on in the field of industrial applications[24,25]. WPU is a colloidal system in which the polyurethane particlesare dispersed in water without any VOCs [26]. Polyurethane showsrubbery behavior and their properties can be designed by adjustingthe interaction of soft and hard segments [27]. Benefit from these characteristics, polyurethane has been considered to be used as binder [28],separator [29] and polymer electrolyte [30] in lithium batteries. Li et al.[31] reported a WPU-based gel polymer electrolyte which showed goodionic conductivity at room temperature, however it contained organicsolvent in the electrolytes. As for SPEs, Liu et al. [32] reported series ofcationic PU-based SPEs and Mustapa et al. [33] reported a Jatropha oilbased PU used as SPEs recently. Although these polyurethane basedSPEs possess excellent mechanical properties and high ionic conductivities, the organic solvent are inevitably involved in the preparation ofthese SPEs, which may cause serious environmental problems. In addition, the performance of all-solid-state LIBs used these PU based SPEshave not been tested.In this work, a waterborne polyurethane (WPU) was synthesized aspolymer matrix for SPEs by polymerization of polyethylene glycol(PEG), hexamethylene diisocyanate (HDI), diethylene glycol (DEG)and dimethylol propionic acid (DMPA). The SPEs were prepared bycomplexing the WPU with various concentration of LiTFSI and usedwater as the solvent during the environmentally friendly fabrication. Itwas demonstrated that such WPU-based SPEs achieved high ionicconductivity around 10−4 and 10−3 S cm−1 at 60 and 80 °C. TheLiFePO4/SPE/Li all-solid-state batteries were assembled and characterized with the WPU-based SPEs. It's found that the WPU-based SPEsexhibited better discharge capacity and cycle performance than thepristine PEO electrolyte and other polymer electrolyte reported recently(Table S1, Supporting Information). These WPU-based SPEs may become a promising environmentally friendly candidate for all-solidstate LIBs.