Direct-ink-writing of all-solid-state batteries with solvent-free, non-flammable electrolytes toward wearable electronics

Abstract

As demand for customized wearable electronics grows, free-form Li-ion batteries (LIBs) are attracting significant attention. Although substantial advancements have been made in printed LIBs for shape-versatile electronics, the development of printable solid-state electrolytes remains challenging due to the difficulty of simultaneously achieving desirable rheological properties and ionic conductivity. In this study, a solvent-free, non-flammable solid polymer electrolyte (SPE) is designed as a novel three-dimensional (3D) printable electrolyte via direct ink writing (DIW) for all-solid-state batteries (ASSBs). The solvent-free nature of this SPE eliminates post-annealing steps, enhancing safety by mitigating risks of leakage, short-circuiting, and fire. Additionally, precise control over polymer molecular weight and electrolyte composition enables high printing resolution (~100 μm), high ionic conductivity (0.705 mS cm^–1 at 25°C), and intrinsic non-flammability. A 3D-printed ASSB, featuring a LiFePO₄ cathode and Li₄Ti₅O₁₂ anode with a mass loading of 7 mg cm^–2, achieves a high areal capacity of 1.14 mAh cm^–2, surpassing all previously reported directly printed ASSBs. This SPE facilitates scalable production of fully DIW-printed ASSBs with superior design flexibility and space efficiency, enabling printing onto customized targets such as flexible substrates and advancing the development of next-generation wearable electronics.

Keywords

3D printing / direct ink writing / printed batteries / solid polymer electrolytes / wearable power sources

References

[1] Zhou G, Li F, Cheng H-M. Progress in flexible lithium batteries and future prospects. Energy Environ Sci. 2014; 7(4): 1307-1338.

[2] Lee K-H, Ahn DB, Kim J-H, Lee J-W, Lee S-Y. Printed built-in power sources. Matter. 2020; 2(2): 345-359.

[3] Yan J, Huang S, Lim YV, et al. Direct-ink writing 3D printed energy storage devices: from material selectivity, design and optimization strategies to diverse applications. Mater Today. 2022; 54: 110-121.

[4] Kumar R, Johnson KM, Williams NX, Subramanian V. Scaling printable Zn-Ag₂O batteries for integrated electronics. Adv Energy Mater. 2019; 9(13): 1803645.

[5] Koo M, Park K-I, Lee S, et al. Bendable inorganic thin-film battery for fully flexible electronic systems. Nano Lett. 2012; 12(8): 4810-4816.

[6] Wei L, Liu ST, Balaish M, et al. Customizable solid-state batteries toward shape-conformal and structural power supplies. Mater Today. 2022; 58: 297-312.

[7] Huo S, Sheng L, Xue W, et al. 3D printing manufacturing of lithium batteries: prospects and challenges toward practical applications. Adv Mater. 2024; 36(8): 2310396.

[8] Fan L-Z, He H, Nan C-W. Tailoring inorganic-polymer composites for the mass production of solid-state batteries. Nat Rev Mater. 2021; 6(11): 1003-1020.

[9] Zhang Y, Zheng S, Zhou F, et al. Multi-layer printable lithium ion micro-batteries with remarkable areal energy density and flexibility for wearable smart electronics. Small. 2022; 18(5): 2104506.

[10] Zhang X, Hu L, Zhou K, et al. Fully printed and sweat-activated micro-batteries with lattice-match Zn/MoS₂ anode for long-duration wearables. Adv Mater. 2024; 36(48): 2412844.

[11] Fu K, Wang Y, Yan C, et al. Graphene oxide-based electrode inks for 3D-printed lithium-ion batteries. Adv Mater. 2016; 28(13): 2587-2594.

[12] Bae J, Oh S, Lee B, et al. High-performance, printable quasi-solid-state electrolytes toward all 3D direct ink writing of shape-versatile Li-ion batteries. Energy Storage Mater. 2023; 57: 277-288.

[13] Lee S-S, Kim S-H, Ahn DB, et al. All-direct-ink-writing of artistic supercapacitors: toward on-demand embodied power sources. Adv Funct Mater. 2022; 32(34): 2202901.

[14] Hodaei A, Subramanian V. Additive fabrication of fully-integrated high-performance millimeter-scale microsupercapacitors: fine-tuning chemistry to maximize performance. J Power Sources. 2023; 588: 233738.

[15] Song Y, Tay RY, Li J, et al. 3D-printed epifluidic electronic skin for machine learning-powered multimodal health surveillance. Sci Adv. 2023; 9(37): eadi6492.

[16] Tay RY, Song Y, Yao DR, Gao W. Direct-ink-writing 3D-printed bioelectronics. Mater Today. 2023; 71: 135-151.

[17] Lee B, Cho H, Moon S, et al. Omnidirectional printing of elastic conductors for three-dimensional stretchable electronics. Nat Electron. 2023; 6(4): 307-318.

[18] M'Barki A, Bocquet L, Stevenson A. Linking rheology and printability for dense and strong ceramics by direct ink writing. Sci Rep. 2017; 7(1): 6017.

[19] Cheng M, Jiang Y, Yao W, et al. Elevated-temperature 3D printing of hybrid solid-state electrolyte for Li-ion batteries. Adv Mater. 2018; 30(35): 1800615.

[20] Zhang Y, Shi G, Qin J, et al. Recent progress of direct ink writing of electronic components for advanced wearable devices. ACS Appl Electron Mater. 2019; 1(9): 1718-1734.

[21] Ahn DB, Lee S-S, Lee K-H, Kim J-H, Lee J-W, Lee S-Y. Form factor-free, printed power sources. Energy Storage Mater. 2020; 29: 92-112.

[22] Wang J, Sun Q, Gao X, et al. Toward high areal energy and power density electrode for Li-ion batteries via optimized 3D printing approach. ACS Appl Mater Interfaces. 2018; 10(45): 39794-39801.

[23] Xu K, Zhao N, Li Y, et al. 3D printing of ultrathick natural graphite anodes for high-performance interdigitated three-dimensional lithium-ion batteries. Electrochem Commun. 2022; 139: 107312.

[24] Li X, Ling S, Zeng L, He H, Liu X, Zhang C. Directional freezing-assisted 3D printing to solve a flexible battery dilemma: ultrahigh energy/power density and uncompromised mechanical compliance. Adv Energy Mater. 2022; 12(14): 2200233.

[25] Kong D, Li W, Chu N, et al. 3D printed ordered hierarchically porous electrodes for developing high-performance quasi-solid-state aqueous nickel-iron batteries. Adv Funct Mater. 2024; 35(7): 2415480.

[26] He Y, Chen S, Nie L, Sun Z, Wu X, Liu W. Stereolithography three-dimensional printing solid polymer electrolytes for all-solid-state lithium metal batteries. Nano Lett. 2020; 20(10): 7136-7143.

[27] Cheng M, Ramasubramanian A, Rasul MG, et al. Direct ink writing of polymer composite electrolytes with enhanced thermal conductivities. Adv Funct Mater. 2021; 31(4): 2006683.

[28] Ma H, Tian X, Fan J, et al. 3D printing of solid-state zinc-ion microbatteries with ultrahigh capacity and high reversibility for wearable integration design. J Power Sources. 2022; 550: 232152.

[29] Li L, Meng J, Bao X, et al. Direct-ink-write 3D printing of programmable micro-supercapacitors from MXene-regulating conducting polymer inks. Adv Energy Mater. 2023; 13(1): 2203683.

[30] Lu X, Wang Y, Xu X, Yan B, Wu T, Lu L. Polymer-based solid-state electrolytes for high-energy-density lithium-ion batteries—review. Adv Energy Mater. 2023; 13(38): 2301746.

[31] Kim E, Jamal H, Jeon I, Khan F, Chun S-E, Kim JH. Functionality of 1-butyl-2,3-dimethylimidazolium bromide (BMI-Br) as a solid plasticizer in PEO-based polymer electrolyte for highly reliable lithium metal batteries. Adv Energy Mater. 2023; 13(47): 2301674.

[32] Lim H, Chae MS, Jamal H, et al. Triple-layered noncombustible PEO-based solid electrolyte for highly safe lithium-metal batteries. Small. 2024; 21(14): 2406200.

[33] Pan J, Zhang Y, Wang J, et al. A quasi-double-layer solid electrolyte with adjustable interphases enabling high-voltage solid-state batteries. Adv Mater. 2022; 34(10): 2107183.

[34] Liu D, Wang Z, Qian Q, et al. Customizable supercapacitors via 3D printed gel electrolyte. Adv Funct Mater. 2023; 33(20): 2214301.

[35] Zhao J, Feng X, Pang Q, et al. Battery safety: machine learning-based prognostics. Prog Energy Combust Sci. 2024; 102: 101142.

[36] Huang J, Li C, Jiang D, et al. Solid-state electrolytes for lithium metal batteries: state-of-the-art and perspectives. Adv Funct Mater. 2024; 35(1): 2411171.

[37] Ma C, Cui W, Liu X, Ding Y, Wang Y. In situ preparation of gel polymer electrolyte for lithium batteries: progress and perspectives. InfoMat. 2021; 4(2): e12232.

[38] Han L, Liao C, Liu Y, et al. Non-flammable sandwich-structured TPU gel polymer electrolyte without flame retardant addition for high-performance lithium-ion batteries. Energy Storage Mater. 2022; 52: 562-572.

[39] Zhu G-R, Zhang Q, Liu Q-S, et al. Non-flammable solvent-free liquid polymer electrolyte for lithium metal batteries. Nat Commun. 2023; 14(1): 4617.

[40] Echeverri M, Kim N, Kyu T. Ionic conductivity in relation to ternary phase diagram of poly(ethylene oxide), succinonitrile, and lithium bis(trifluoromethane)sulfonimide blends. Macromolecules. 2012; 45(15): 6068-6077.

[41] Echeverri M, Hamad C, Kyu T. Highly conductive, completely amorphous polymer electrolyte membranes fabricated through photo-polymerization of poly(ethylene glycol diacrylate) in mixtures of solid plasticizer and lithium salt. Solid State Ion. 2014; 254: 92-100.

[42] Li S, Chen Y-M, Liang W, et al. A superionic conductive, electrochemically stable dual-salt polymer electrolyte. Joule. 2018; 2(9): 1838-1856.

[43] Ha H-J, Kil E-H, Kwon YH, Kim JY, Lee CK, Lee S-Y. UV-curable semi-interpenetrating polymer network-integrated, highly bendable plastic crystal composite electrolytes for shape-conformable all-solid-state lithium-ion batteries. Energy Environ Sci. 2012; 5(5): 6491-6499.

[44] Kwon S-J, Kim D-G, Shim J, Lee JH, Baik J-H, Lee J-C. Preparation of organic/inorganic hybrid semi-interpenetrating network polymer electrolytes based on poly(ethylene oxide-co-ethylene carbonate) for all-solid-state lithium batteries at elevated temperatures. Polymer. 2014; 55(12): 2799-2808.

[45] Kim SH, Choi KH, Cho SJ, Yoo JT, Lee SS, Lee SY. Flexible/shape-versatile, bipolar all-solid-state lithium-ion batteries prepared by multistage printing. Energy Environ Sci. 2018; 11(2): 321-330.

[46] Jiang J, Pan H, Lin W, Tu W, Zhang H. UV-induced semi-interpenetrating polymer electrolyte membrane for elevated-temperature all-solid-state lithium-ion batteries. Mater Chem Phys. 2019; 236: 121781.

[47] Kim Y, Park C, Im S, Kim JH. Design of intrinsically stretchable and highly conductive polymers for fully stretchable electrochromic devices. Sci Rep. 2020; 10(1): 16488.

[48] Alarco P-J, Abu-Lebdeh Y, Abouimrane A, Armand M. The plastic-crystalline phase of succinonitrile as a universal matrix for solid-state ionic conductors. Nat Mater. 2004; 3(7): 476-481.

[49] Fan L-Z, Hu Y-S, Bhattacharyya AJ, Maier J. Succinonitrile as a versatile additive for polymer electrolytes. Adv Funct Mater. 2007; 17(15): 2800-2807.

[50] Fan LZ, Wang XL, Long F, Wang X. Enhanced ionic conductivities in composite polymer electrolytes by using succinonitrile as a plasticizer. Solid State Ion. 2008; 179(27): 1772-1775.

[51] Xu S, Sun Z, Sun C, et al. Homogeneous and fast ion conduction of PEO-based solid-state electrolyte at low temperature. Adv Funct Mater. 2020; 30(51): 2007172.

[52] Bai C, Wu Z, Xiang W, et al. Poly(ethylene oxide)/poly(vinylidene fluoride)/Li_6.4La₃Zr_1.4Ta_0.6O₁₂ composite electrolyte with a stable interface for high-performance solid-state lithium metal batteries. J Power Sources. 2020; 472: 228461.

[53] Ha H-J, Kwon YH, Kim JY, Lee S-Y. A self-standing, UV-cured polymer networks-reinforced plastic crystal composite electrolyte for a lithium-ion battery. Electrochim Acta.2011; 57: 40-45.

[54] Wen P, Lu P, Shi X, et al. Photopolymerized gel electrolyte with unprecedented room-temperature ionic conductivity for high-energy-density solid-state sodium metal batteries. Adv Energy Mater.2021; 11(6): 2002930.

[55] Devaux D, Bouchet R, Glé D, Denoyel R. Mechanism of ion transport in PEO/LiTFSI complexes: effect of temperature, molecular weight and end groups. Solid State Ion.2012; 227: 119-127.

[56] Zhang H, Liu C, Zheng L, et al. Lithium bis(fluorosulfonyl)imide/poly(ethylene oxide) polymer electrolyte. Electrochim Acta.2014; 133: 529-538.

[57] Jiang Y, Guo N, Dong F, Xie H, Liu J. Semi-interpenetrating-network PEO-based polymer electrolytes with fast Li-ion conduction for solid Li-metal batteries. J Energy Storage.2023; 73: 108809.

[58] Wen J, Zhao Q, Jiang X, et al. Graphene oxide enabled flexible PEO-based solid polymer electrolyte for all-solid-state lithium metal battery. ACS Appl Energy Mater.2021b; 4(4): 3660-3669.

[59] Khan K, Hanif MB, Xin H, et al. PEO-based solid composite polymer electrolyte for high capacity retention all-solid-state lithium metal battery. Small.2024; 20(4): 2305772.

[60] McOwen DW, Seo DM, Borodin O, Vatamanu J, Boyle PD, Henderson WA. Concentrated electrolytes: decrypting electrolyte properties and reassessing Al corrosion mechanisms. Energy Environ Sci.2014; 7(2): 416-426.

[61] Emilsson S, Albuquerque M, Öberg P, Brandell D, and Johansson M. Understanding ion transport in alkyl dicarbonates: an experimental and computational study. ACS Phys Chem Au. 2025; 5(1): 80-91.

[62] He R, Echeverri M, Ward D, Zhu Y, Kyu T. Highly conductive solvent-free polymer electrolyte membrane for lithium-ion batteries: effect of prepolymer molecular weight. J Membr Sci.2016; 498: 208-217.

[63] Zhang Z, Huang Y, Zhang G, Chao L. Three-dimensional fiber network reinforced polymer electrolyte for dendrite-free all-solid-state lithium metal batteries. Energy Storage Mater.2021; 41: 631-641.

[64] Lu P, Liu L, Wang S, et al. Superior all-solid-state batteries enabled by a gas-phase-synthesized sulfide electrolyte with ultrahigh moisture stability and ionic conductivity. Adv Mater.2021; 33(32): 2100921.

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