Integrating high ionic conductive PDOL solid/gel composite electrolyte for enhancement of interface combination and lithium dentrite inhibition of solid-state lithium battery

Gel Polymer Electrolytes for Lithium Batteries: Advantages, Challenges, and Perspectives

The increasing demand for high-energy-density and safe lithium batteries has driven significant advancements in electrolyte technology. Among the various options, gel polymer electrolytes (GPEs) have emerged as a promising solution, combining the high ionic conductivity of liquid electrolytes with the structural integrity of solid-state (polymer) electrolytes. GPEs possess a hybrid structure composed of a polymer matrix, lithium salts, one or more solvents or plasticizers, and often functional additives, offering exceptional flexibility, adaptability, and performance for advanced energy storage systems. This review provides a comprehensive analysis of GPE technology for lithium batteries, covering fabrication methods, advantages, and challenges, while emphasizing potential application scenarios and the underlying mechanisms. Finally, future research directions are outlined to provide valuable insights and guidelines for advancing GPE technology.

An initiator loaded separator triggering in situ polymerization of a poly(1,3-dioxolane) quasi-solid electrolyte for lithium metal batteries

An in situ polymerization strategy is regarded as a promising approach to fabricate gel polymer electrolytes (GPEs) and improve interface contact between the electrolyte and electrodes, in which the initiator is initially dissolved in the precursor solution. Herein, aluminum trifluoromethanesulfonate (Al(OTf)3) is preloaded onto a separator sheet as the initiator to trigger the ring-opening reaction of 1,3-dioxolane (DOL). The polymer matrix near the separator has a higher crystallization degree than that far away from the separator. Fluoroethyl carbonate (FEC) is further introduced as a liquid plasticizer to produce an amorphous GPE for enhanced ionic conductivity and interfacial stability. As a result, the as-synthesized FEC based GPE exhibits a substantial ionic conductivity of 1.5 × 10-4 S cm-1 at room temperature, an expanded electrochemical window of 4.8 V, and a high Li+ transference number of 0.63. The symmetric Li|Li cell exhibits a stable lifespan for 650 h at 1 mA cm-2 and 1 mA h cm-2. Moreover, the LiFePO4 full cell exhibits stable cycling for 300 cycles at 1C with a capacity retention of 94.5%. This work provides a novel idea for the in situ synthesis of advanced GPEs toward practical application of solid-state lithium metal batteries.

PDOL-Based Solid Electrolyte Toward Practical Application: Opportunities and Challenges

Polymer solid-state lithium batteries (SSLB) are regarded as a promising energy storage technology to meet growing demand due to their high energy density and safety. Ion conductivity, interface stability and battery assembly process are still the main challenges to hurdle the commercialization of SSLB. As the main component of SSLB, poly(1,3-dioxolane) (PDOL)-based solid polymer electrolytes polymerized in-situ are becoming a promising candidate solid electrolyte, for their high ion conductivity at room temperature, good battery electrochemical performances, and simple assembly process. This review analyzes opportunities and challenges of PDOL electrolytes toward practical application for polymer SSLB. The focuses include exploring the polymerization mechanism of DOL, the performance of PDOL composite electrolytes, and the application of PDOL. Furthermore, we provide a perspective on future research directions that need to be emphasized for commercialization of PDOL-based electrolytes in SSLB. The exploration of these schemes facilitates a comprehensive and profound understanding of PDOL-based polymer electrolyte and provides new research ideas to boost them toward practical application in solid-state batteries.

Engineering and regulating the interfacial stability between Li1.3Al0.3Ti1.7(PO4)3-based solid electrolytes and lithium metal anodes for solid-state lithium batteries

InCl3@Li1.3Al0.3Ti1.7(PO4)3-F (InCl3@LATP-F) solid electrolyte powders are designed and fabricated by coating a uniform InCl3 layer on the surface of F--doped Li1.3Al0.3Ti1.7(PO4)3 (LATP-F) solid powders via a feasible wet-chemical technique. The assembled Li/InCl3@LATP-F/Li cell can undergo longer cycles of 2500 h at 0.4 mA cm-2 without obvious increases in the overvoltage compared to 1837 h for the Li/LATP-F/Li cell, and the interfacial resistance demonstrates a sharp decrease from 3428 to 436 Ω for the Li/InCl3@LATP-F/Li cell during the first 500 h. Importantly, the assembled LiCoO2/InCl3@LATP-F/Li cell delivers a high discharge specific capacity of 126.4 mAh g-1 with a 95.42% capacity retention ratio after 100 cycles at 0.5 C, and the value easily returns to 112.9 mAh g-1 when the current density is abruptly set back to 0.1 C after different rate cycles. These improved results can be mainly attributed to the fact that the InCl3 layer with a lithiophilic nature can react with lithium metal to form a Li-In alloy, which can guarantee homogeneous lithium ion flux to avoid the accumulation of ions/electrons across the interface and suppress the growth of lithium dendrites. Moreover, the InCl3 layer can prevent direct contact of the LATP-F solid electrolyte and lithium metal to effectively alleviate the reduction reaction of Ti4+ and preserve the structural stability of the composite electrolyte. Therefore, this work may provide an effective strategy to engineer and regulate the interfacial stability between LATP solid electrolytes and lithium metal anodes for LATP-type solid-state lithium batteries.

Enhanced ion-electron mixing interface for high energy solid-state lithium metal batteries

Solid-state Li metal batteries (SSLMBs) are famous for superior security and excellent energy density. Nevertheless, the poor interfacial contact between solid lithium and electrode is one key problem in the development of SSLMBs, resulting in high impedance and growth of lithium dendrites along the grain boundaries. Herein, an innovative and accessible approach has been applied to SSLMBs, which introduces an ion-electron mixing (IEM) interface on the surface of Li1.3Al0.3Ti1.7(PO4)3 (LATP). The IEM interlayer generates LixSn/LiI of fast lithium-ion conductor through an in-situ reaction. The existence of LiI would promote the quick transmission of Li+ at the interface and inhibit the electronic conduction, thus restraining the growth of lithium dendrites. The batteries with IEM@LATP electrolyte could stably cycle more than 1000 h at high current density of 0.1 mA cm-2. Even increasing the current density to 3.0 mA cm-2, the batteries still could work normally. This novel and viable approach offers a robust basis for the practical application of SSLMBs and has some general applicability to other solid-state batteries.

Engineering the interface of organic/inorganic composite solid-state electrolyte by amino effect for all-solid-state lithium batteries

Composite solid-state electrolyte (CSSE) with integrated strengths avoids the weaknesses of organic and inorganic electrolytes, and thus become a better choice for all-solid-state lithium battery (ASSLB). However, the poor dispersion of inorganic fillers and the organic/inorganic nature difference leads to their interface incompatibility, which greatly destroys the performance of CSSE and ASSLB. Herein, silane coupling agent (SCA) aminopropyl triethoxysilane (ATS) is introduced to tailor the organic/inorganic interfaces in CSSE by the common chemical bridging effect of SCA and the special amino effect (hydrogen bond and lone pair electron effects). It is found that the hydrogen bond interaction between -NH₂ and polyethylene oxide (PEO) enhances their interface interaction. And the lone pair electrons on nitrogen atom allow it to react with solvent acetonitrile and promote the uniform dispersion of ceramic fillers. Moreover, the lone pair electrons can complex with Li⁺, which promotes the dissociation of Li salts, uniforms Li⁺ diffusion and inhibits the Li dendrite. Thanks to the above merits, the interface compatibility and stability of organic/inorganic CSSE are much enhanced by innovatively introducing ATS, showing high ionic conductivity and superior mechanical/thermal stability. The ASSLB with this modified CSSE exhibits excellent electrochemical performance with a reversible capacity of 140.9 mAh g^-1 and a capacity retention of 94.4% after 280 cycles. These achievements offer a new insight into improving the stability of organic/inorganic CSSE interface and promoting their applicability into ASSLB.