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Solid polymer electrolytes (SPEs) are considered to be the key to solve the safety hazards and cycling performance of liquid high‐voltage lithium metal batteries (HVLMBs), but still suffer from low conductivity and poor interfacial compatibility. Here, polyvinylidene fluoride–polyvinyl acetate‐based (PVDF–PVAC) rigid–flexible coupling SPE selectively wetted by a tetramethylene sulfone (TMS) is prepared for high‐performance and superior‐safety HVLMBs. The intermolecular interactions in such SPE significantly facilitate lithium‐ion conductivity and electrolyte/electrode interface wettability. Moreover, PVAC selectively wetted with the TMS enhances interface compatibility with Li anodes and high‐voltage LiCoO2 cathodes. As a result, the as‐assembled LiCoO2/lithium‐metal solid‐state batteries present excellent cyclability with 85% capacity retention after 200 cycles between 3.0 and 4.5 V at room temperature. Furthermore, pouch cells with the as‐prepared SPE exhibit brilliant safety and superior interfacial compatibility. This study offers a promising and general selectively wetted design strategy to handle the compatibility and safety issues in HVLMBs. [ABSTRACT FROM AUTHOR]

High‐voltage all‐solid‐state lithium batteries (HVASSLBs) are considered attractive systems for portable electronics and electric vehicles, due to their theoretically high energy density and safety. However, realization of HVASSLBs with sulfide solid electrolytes (SEs) is hindered by their limited electrochemical stability, resulting in sluggish interphase dynamics. Here, a bidirectionally compatible buffering layer design scheme is proposed to overcome the interfacial challenges of sulfide‐based HVASSLBs. As a proof of concept, it is found that NASICON‐type LixZr2(PO4)3 surprisingly exhibit great compatibility with both 4.5 V LiCoO2 and Li6PS5Cl, based on the results of first‐principles calculations and various in situ/ex situ characterizations. This compatibility significantly restrains the interface reactivity and boosts interfacial Li‐ion transport. Therefore, 4.5 V sulfide‐based HVASSLBs can exhibit remarkably enhanced initial discharge capacity (143.3 vs 125.9 mAh·g−1 at 0.2C), capacity retention (95.53% vs 74.74% after 100 cycles), and rate performance (97 vs 45 mAh·g−1 at 2C). This work sheds light on the great prospects of sulfide‐based HVASSLBs with high‐rate characteristics, and constitutes a crucial step toward the rational design of interface and interphase chemistry for high‐performance sulfide‐based HVASSLBs. [ABSTRACT FROM AUTHOR]

It is demonstrated that a novel eutectic solution including 1,3,5‐trioxane (TXE) and succinonitrile (SN) can be converted into solid‐state polymer electrolyte (SPE) via in situ polymerization triggered by lithium difluoro(oxalato)borate (LiDFOB). It is worth noting that all the precursors (LiDFOB, TXE, and SN) of this novel SPE are totally solid and nonvolatile at room temperature, where, LiDFOB works as a lithium salt and an initiator simultaneously to avoid the introduction of impurity. It is noted that such SPE presents a considerable ionic conductivity of 1.14 × 10−4 S cm−1 and a sufficiently wide electrochemical window of 4.5 V, which is significant for supporting the high‐energy lithium batteries. In addition, this dedicatedly designed in situ polymerization is powerful to build kinetically favorable polymer‐based protective layers on LiCoO2 cathode and Li metal anode simultaneously, guaranteeing outstanding cycling stability (capacity retention of 88% after 200 cycles) of 4.3 V LiCoO2/lithium metal batteries at room temperature. More intriguingly, soft packed LiCoO2/SPE/Li metal batteries can still light a blue light emitting diode (LED) under the harsh conditions of being bent, cut, and stroked by a hammer, demonstrating excellent safety characteristics. [ABSTRACT FROM AUTHOR]