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Poly(ethylene oxide) (PEO)-based electrolyte is considered to be one of the most promising polymer electrolytes for lithium metal batteries. However, a narrow electrochemical stability window and poor compatibility at electrode-electrolyte interfaces restrict the applications of PEO-based electrolyte. An in situ synthetic double-layer polymer electrolyte (DLPE) with polyacrylonitrile (PAN) layer and PEO layer was designed to achieve a stable interface and application in high-energy-density batteries. In this special design, the hydroxy group of PEO-SPE can form an O-H---N hydrogen bond with the cyano group in PAN-SPE, which connects the two layers of DLPE at a microscopic chemical level. A special Li+ conducting mechanism in DLPE provides a uniform Li+ flux and fast Li+ conduction, which achieves a stable electrolyte/electrode interface.LiFePO4/DLPE/Li battery shows superior cycling stability, and the coulombic efficiency remains 99.5% at 0.2 C. Meanwhile, LiNi0.6Co0.2Mn0.2O2/DLPE/Li battery shows high specific discharge capacity of 176.0 mAh g−1 at 0.1 C between 2.8 V to 4.3 V, and the coulombic efficiency remains 95% after 100 cycles. This in situ synthetic strategy represents a big step forward in addressing the interface issues and boosting the development of high-energy-density lithium-metal batteries. [ABSTRACT FROM AUTHOR]

Solid‐state batteries (SSBs) with addition of liquid electrolytes are considered to possibly replace the current lithium‐ion batteries (LIBs) because they combine the advantages of benign interfacial contact and strong barriers for unwanted redox shuttles. However, solid electrolyte and liquid electrolyte are generally (electro)‐chemically incompatible and the resistance of the newly formed solid–liquid electrolyte interphase (SLEI) appears as an additional contribution to the overall battery resistance. Herein, a boron, fluorine‐donating liquid electrolyte (B, F‐LE) is introduced into the interface between the high‐voltage cathode and ultrathin composite solid electrolyte (CSE), which is fabricated by adhering a high content of nanosized Li6.4La3Zr1.4Ta0.6O12 (LLZTO) with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), to generate a low resistance and high stable SLEI in situ, giving a stable high‐voltage output with a reinforced cathode|CSE interface. B, F‐LE, consisting of a highly fluorinated electrolyte with a lithium bis(oxalato)borate additive, exhibits good chemical compatibility with CSE and enables rapid and uniform transportation of Li+, with its electrochemically and chemically stable interface for high‐voltage cathode. Eventually, the B, F‐LE assisted LiNi0.6Co0.2Mn0.2O2|Li battery displays the enhanced rate capability and high voltage cycling stability. The findings provide an interfacial engineering strategy to turn SLEI from a "real culprit" into the "savior" that may pave a brand‐new way to manipulate SLEI chemistry in hybrid solid–liquid devices. [ABSTRACT FROM AUTHOR]

Solid‐state lithium metal batteries incorporating LiNixCoyMnzO2 (NCM) as cathodes are developed to meet the high‐energy‐density requirements of energy storage systems. Nevertheless, the process of plating and stripping of Li‐ions on lithium metal electrodes causes significant volume changes, in which ultimately degrade battery performance. In this study, an elastomeric electrolyte with special latitude‐longitude interwoven structure is designed and synthesized successfully, which is composed of a crosslinked phase as filler and a polymeric phase as skeleton. With the increase of polymeric phase, the electrolyte changes from an irregular wrinkle structure to latitude‐longitude interwoven structure. The optimal electrolyte ATPE‐1 with a predominant latitude feature demonstrates remarkable resilience of 800% stretchability and high room temperature ionic conductivity (1.72 mS cm−1). Therefore, the close contact and excellent compatibility with lithium metal anode enable the lithium symmetric cell with ATPE‐1 as electrolyte to maintain a stable and extended cycle life for over 2000 h. Additionally, the existence of the supramolecular interaction between the polymeric phase and crosslinked phase effectively increases the decomposition voltage of the electrolyte. A Li/ATPE‐1/NCM622 cell delivers superior rate performance under ambient conditions. This innovative elastomeric electrolyte offers a promising potential for the practical application in high‐performance solid‐state lithium metal batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Solid-state polymer electrolytes are outstanding candidates for next-generation lithium metal batteries in the realm of high specific energy densities, high safeties and tight contact with electrodes. However, their applications are still hindered by the limitations that no single polymer is electrochemically stable with the oxidizing high-voltage cathode and the highly reductive Li anode, simultaneously. Herein, a bilayer asymmetric polymer electrolyte (SL-SPE) without accessional interface resistance that using poly (ethylene glycol) diacrylate (PEGDA) as a "bridge" to connect the sulfonyl (O S = O)-contained oxidation-tolerated layer and polyether-derived reduction-tolerated layer (SPE), is proposed and synthesized by sequential two-step UV polymerizations. SL-SPE can provide widened electrochemical stability window up to 5 V, while simultaneously deploying a stable Janus interface property. Eventually, the superior high-voltage (4.4 V) cycling durability can be displayed in LiNi 0.6 Co 0.2 Mn 0.2 O 2 |SL-SPE|Li batteries. This finding provides a bran-new idea for designing multifunctional polymer electrolytes in the application of solid-state batteries. [ABSTRACT FROM AUTHOR]

The development of safe and long-term stable solid polymer electrolytes is a major challenge for all solid-state batteries because good interfacial stability toward electrodes is the main concern. In this paper, a triblock copolymer polystyrene-poly(ethylene glycol)-polystyrene (PS-PEG-PS) is synthesized and investigated as solid polymer electrolyte. This polymer electrolyte exhibits a high ionic conductivity of 1.1 × 10−3 S cm −1 at 70 °C, transference number of 0.17, high degree flexibility, good mechanical strength and thermal stability. The interface stability of the solid-polymer electrolyte is investigated in Li metal cell and the comprehensive electrochemical properties are studied in cells with either LiFePO 4 or LiNi 0.5 Co 0.3 Mn 0.2 O 2 cathode materials. Good rate capability and excellent cyclability of the solid polymer electrolyte is demonstrated, with an electrochemical stability window extending above 4.5 V vs. Li+/Li. Furthermore, constant voltage impedance measurements give evidence of the better interface stability and rate capability of LiNi 0.5 Co 0.3 Mn 0.2 O 2 //Li battery. Meanwhile, molecular orbital energy levels calculated by density functional theory are consistent with experiments. Image 1 • Triblock polystyrene-poly(ethylene glycol)-polystyrene copolymers as SPE. • Enhanced ionic conductivity and high oxidative stability up to 4.5 V. • Excellent interfacial stability with Li metal anode, LiFePO 4 and NMC cathode. • Calculated electrochemical window using density functional theory. [ABSTRACT FROM AUTHOR]

[Display omitted] • The DPPE is obtained by solvent-free in-situ polymerization method. • The DPPE exhibits cross-linked network structure with the thickness of only 20 μm. • Li x BO y F z -rich and LiF-rich CEI layer is generated due to decomposition of LiODFB. • The CEI layer isolate PEO from NCM622 cathode materials. • The CEI layer effectively suppress the decomposition of PEO segments. Poly(ethylene oxide) (PEO)-based solid electrolyte is one of the most promising candidates to be applied in solid-state lithium (Li) metal batteries (SSLMBs), but its poor ionic conductivity at room temperature and incompatibility with LiCoO 2 /LiNi x Mn y Co z O 2 cathode materials impedes the potential application in ambient-temperature and high energy density batteries. Herein, an ultrathin dual-salt PEO based polymer electrolyte (DPPE) with cross-linked network is engineered to tackle these issues. The formed cross-linked networks greatly increase the amorphous region of PEO and the DPPE exhibits high ionic conductivity of 0.57 mS cm−1 at 30 °C. Furthermore, a Li x BO y F z -rich and LiF-rich durable cathode electrolyte interphase (CEI) layer is generated on NCM622 surface on account of preferential decomposition of LiODFB, which isolate PEO based electrolytes from NCM622 cathode materials and effectively suppress the decomposition of PEO segments. Besides, the solvent-free in-situ polymerization method greatly reduces the thickness of DPPE membrane with only 20 μm and contributes to the formation of an optimum DPPE/cathode interface. Improved NCM622|DPPE|Li cell provides prominent cycle performance with a capacity retention of 94.7 % after 100 cycles at 4.2 V under 30 °C. This simple and effective strategy provides a new idea for the practical application of PEO-based solid electrolytes for ambient-temperature high-voltage SSLMB. [ABSTRACT FROM AUTHOR]

Sulfide-based composite solid-state electrolyte has been deemed as "Holy Grail" for unlocking solid-state lithium metal batteries (SSLMBs) with high-energy density, combining the extremely high ionic conductivity of sulfide and machinability of organic polymer. However, this appealing system is hitherto stymied by two hindrances, difficult to synthesize due to the chemical incompatibility of sulfide with moisture and polar solvents, moreover, interfacial instability with lithium (Li) anode inducing severe Li dendrite grown. Herein, by utilizing perfluoropolyethers as bifunctional adjuvant, we initiatively fabricate sulfide-based composite electrolyte, Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li 10 GeP 2 S 12 and assemble SSLMBs. Perfluoropolyethers with low molecular weight facilitate the stable dispersion of Li 10 GeP 2 S 12 in casting solution, ascribed to their strong electronegativity of C–F bonds. In addition, high molecular weight perfluoropolyethers function as interfacial stabilizer, dramatically improving the interfacial compatibility with Li anode by in-situ forming a LiF-rich solid electrolyte interphase layer. This composite electrolyte exhibits high room temperature ionic conductivity (0.18 mS cm−1), outstanding lithium ion transfer number (0.68), good mechanical strength and nonflammability. The solid-state LiFePO 4 ǁLi battery presents superior long-term cycling stability and rate capability. Our study paves a new way for fabricating the sulfide-based composite electrolyte, provides an effective strategy for constructing compatible solid-state electrolyteǁLi interface. Image 1 • PVDF-HFP/Li 10 GeP 2 S 12 electrolyte is prepared by binary solution casting method. • PFPE 500 as dispersing solvents exhibit good chemical compatibility with Li 10 GeP 2 S 12. • A high ion conductivity (σ RT = 10−4 S cm−1) and Li+ transfer number (0.68) are obtained. • PFPEs as interfacial stabilizers enhance the compatibility of Li 10 GeP 2 S 12 with Li. • LiFePO 4 ‖Li battery shows good cycling stability and rate capability. [ABSTRACT FROM AUTHOR]