A transformative study released in Nano-Micro Letters unveils an “enhanced regional electric potential difference” (EREPD) design that propels composite polymer solid electrolytes (CPSEs) to record-high performance. Led by Chao Jiang, Kaihang Wang and Ning Wang from Shandong University, the work introduces methoxy-substituted graphdiyne (OGDY) as a 2D nanofiller that simultaneously boosts ionic conductivity to 1.1 × 10 -3 S cm -1 , raises the Li + transference number to 0.71 and suppresses dendrites in flexible, quasi-solid-state lithium cells.
Why This Research Matters
• Overcoming Low Ionic Conductivity: Conventional PEO-based solid electrolytes suffer from sluggish Li + transport (≈10 -4 S cm -1 ) and limited transference numbers (<0.3), hindering room-temperature operation of solid-state batteries. The EREPD strategy creates continuous potential gradients that slash activation energy to 0.42 eV—0.06 eV lower than pristine PEO—enabling safe, high-rate, long-life power sources.
• Enabling Flexible, High-Energy Devices: From wearable sensors to EV battery packs, applications demand thin, bendable electrolytes that withstand mechanical abuse. OGDY/PEO films retain 1280 % elongation, sustain 850 h of Li||Li cycling and power 42-LED arrays even after cutting, folding and bending, demonstrating real-world viability.
Innovative Design and Mechanisms
• Asymmetric Substitution & Periodic EREPD: Bottom-up Glaser–Hay coupling installs methoxy groups at three meta positions of the GDY benzene ring, generating alternating electron-rich (ERR) and electron-deficient (EDR) regions. NPA charge analysis reveals localized differences up to 0.94 e; the resulting 0.44 eV EREPD between ERR and EDR sites steers Li + along low-barrier pathways.
• Dual Lewis Acid–Base Function: ERRs act as Lewis bases, weakening Li + –PEO binding (−1.29 to −2.52 eV vs −4.16 eV in PEO) and accelerating segmental motion. EDRs function as Lewis acids, anchoring TFSI - (BE > 4.7 eV) to liberate free Li + and suppress ion clusters. Raman shows 82.5 % free TFSI - versus 76.2 % in PEO.
• Crystallinity Suppression & Mechanical Robustness: The 2D lamellar OGDY imposes steric hindrance and electrostatic attraction (−1.61 kcal mol -1 ) that cut PEO crystallinity, lower Tg to −54.9 °C and triple ionic mobility while maintaining film flexibility.
Applications and Future Outlook
• Record Symmetric-Cell Lifespan: Li||OGDY/PEO||Li cells cycle 850 h at 0.1 mA cm -2 /0.1 mAh cm -2 , nine times longer than PEO (90 h). SEM reveals flat Li deposits and a 7.5 µm SEI versus 10.3 µm dendritic layers in PEO. Critical current density rises from 0.75 to 1.0 mA cm -2 .
• Full-Cell & Pouch-Cell Performance: LFP||OGDY/PEO||Li delivers 158.7 mAh g -1 at 0.5 C, 91.4 % capacity retention after 205 cycles and retains 118 mAh g⁻¹ at 2 C. A 2 cm × 2 cm pouch survives bending, folding and cutting while continuously lighting LEDs, proving mechanical integrity and safety.
• Scalable Synthesis & Universal Design: Solution-processable OGDY is compatible with roll-to-roll coating and can be extended to Na + , K + and Zn 2+ systems. Future work will tailor substituent patterns and integrate OGDY with high-voltage cathodes for >400 Wh kg -1 solid-state packs.
Conclusions
By orchestrating asymmetric methoxy substitution to create periodic EREPDs, this study transforms graphdiyne from a passive filler into an active Li + highway. The resulting OGDY/PEO electrolyte simultaneously achieves high conductivity, high transference and dendrite suppression, charting a practical route toward flexible, safe and energy-dense all-solid-state lithium batteries.
Nano-Micro Letters
Experimental study
Enhanced Regional Electric Potential Difference of Graphdiyne Through Asymmetric Substitution Strategy Boosts Li+ Migration in Composite Polymer Solid-State Electrolyte
21-May-2025