Layered Heterostructure Ionogel Electrolytes for High‐Performance Solid‐State Lithium‐Ion Batteries

Abstract

Ionogel electrolytes based on ionic liquids and gelling matrices offer several advantages for solid‐state lithium‐ion batteries, including nonflammability, wide processing compatibility, and favorable electrochemical and thermal properties. However, the absence of ionic liquids that are concurrently stable at low and high potentials constrains the electrochemical windows of ionogel electrolytes and thus their high‐energy‐density applications. Here, ionogel electrolytes with a layered heterostructure are introduced, combining high‐potential (anodic stability: >5 V vs Li/Li+) and low‐potential (cathodic stability: <0 V vs Li/Li+) imidazolium ionic liquids in a hexagonal boron nitride nanoplatelet matrix. These layered heterostructure ionogel electrolytes lead to extended electrochemical windows, while preserving high ionic conductivity (>1 mS cm−1 at room temperature). Using the layered heterostructure ionogel electrolytes, full‐cell solid‐state lithium‐ion batteries with a nickel manganese cobalt oxide cathode and a graphite anode are demonstrated, exhibiting voltages that are unachievable with either the high‐potential or low‐potential ionic liquid alone. Compared to ionogel electrolytes based on mixed ionic liquids, the layered heterostructure ionogel electrolytes enable higher stability operation of full‐cell lithium‐ion batteries, resulting in significantly enhanced cycling performance.

Ionic Liquid-Based Gels for Applications in Electrochemical Energy Storage and Conversion Devices: A Review of Recent Progress and Future Prospects

“…Similarly, by using in situ photopolymerization, Ming’s group reported the synthesis of a transparent, stretchable, phase-transformable 1,3-dimethyl imidazolium bis(trifluorosufonylmethane imide) (MMITFSI)-based IL-based gel for long-storage capacitors from a precursor solution consisting of butyl acrylate and fluorinated butyl acrylate as monomers, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) as the photoinitiator, and 1,6-hexandiol diacrylate (HDDA) as the cross-linker [ 43 ]. Meanwhile, Hyun et al illustrated the development of layered heterostructure IL-based gel electrolytes based on EMIMTFSI and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI) containing 1 M LiTFSI salt using hexagonal boron nitride (hBN) nanoplatelets as the gelling matrix [ 44 ]. The designed layered heterostructure IL-based gels hold high ionic conductivity of >1 mS cm −1 at room temperature.…”

“…Playing with widely developed materials, Ravi et al [ 50 , 51 , 52 ] studied the composition dependency of LiTFSI and P(VDF-HFP) and Pyr 13 TFSI and found the maximal ionic conductivity of these electrolytes. A new introduction was also made this year by Hyun et al to replace IL-based gel electrolytes using IL mixtures in the form of layered heterostructures because they can extend the window while maintaining high ionic conductivity [ 44 ]. This is a potential new development for further research.…”

“… ( a ) Synthesis HP-A and IL-based gel from HP-A by photopolymerization [ 44 ] and ( b ) basic overview of polymer/inorganic hybrid electrolyte (HE) [ 34 ]. …”

Long-chain fluorocarbon-driven hybrid solid polymer electrolyte for lithium metal batteries

“…The urgent demand for high-performance energy storage devices has triggered a new upsurge in research on high-energy-density lithium-ion batteries. 1–3 Nevertheless, due to the potential safety hazards and low theoretical energy densities of conventional lithium-ion batteries consisting of flammable liquid electrolyte (LE) and graphite anodes, researchers have begun to pursue superior alternatives. 4–6 Combining a non-volatile and non-inflammable solid electrolyte with Li metal anodes that have high capacity and low electrochemical potential provides a feasible solution.…”

Functional additives for solid polymer electrolytes in flexible and high‐energy‐density solid‐state lithium‐ion batteries

“…Generally, an ideal SPE should simultaneously possess some desired properties, including high ionic conductivity along with high ion transference number, low interfacial resistance, excellent thermal, mechanical, and electrochemical stability, and so forth. 20 Some strategies have been proposed to achieve high-performance SPEs, including molecular structure design, [21][22][23][24][25] anion chemistry, [26][27][28][29] interfacial engineering, [30][31][32] and so on. Among these methods, the incorporation of functional additives into polymeric matrices is a facile but effective route to improve the comprehensive performance of SPEs and has created some historical milestones in boosting the development of SPEs.…”