Influence of silica aerogel on the properties of polyethylene oxide-based nanocomposite polymer electrolytes for lithium battery

In this study, a series of nanocomposite polymer electrolytes (NCPEs) with high conductivity and lithium ion transference number, PEO/LiClO₄/SAP, were prepared from high molecular weight polyethylene oxide (PEO), LiClO₄ and low content of homemade silica aerogel powder (SAP), which had higher surface area and pore volume than the conventional silica particle. From the SEM images it was found that the SAP nanoparticles were well dispersed in the PEO polymer electrolyte matrix. The characterization and interactions in the CPEs were studied by DSC, XRD, FT-IR and ⁷Li NMR analysis. The ac impedance results showed that the ionic conductivity of the CPE was significantly improved by the addition of the as-prepared SAP. The maximum ambient ionic conductivity obtained from the CPE with EO/Li = 6 and 2 wt.% of SAP (O6A2) was about threefold higher than that of the corresponding polymer electrolyte without SAP (O6). In addition, the lithium ion transference number (t⁺) of O6A2 at 70 °C was as high as 0.67, which was also three times higher than that of O6 and has not been previously reported for the PEO–LiX-based polymer electrolytes.     

Ionic conductivity and electrochemical properties of cross-linked solid polymer electrolyte using star-shaped siloxane acrylate

A star-shaped siloxane acrylate with a different number of repeating units of oligo(ethylene oxide) (EO) was synthesized as a cross-linker of solid polymer electrolytes. The cross-linked solid polymer electrolytes blended with the ionic conducting plasticizers, such as low molecular weight poly(ethylene oxide)dimethyl ether (PEGDME) were prepared by the in situ thermal curing of the star-shaped siloxane acrylate. Different morphologies of the cross-linked polymer electrolytes were observed according to the number of repeating units of EO (n) in the cross-linker. A micro-phase separated solid polymer electrolyte was obtained when the n of cross-linker was 1. When the n of cross-linker was larger than 1, homogeneously blended solid polymer electrolytes were prepared. The ionic conductivity was measured to be 6.3 to 7.8 × 10⁻⁴ S cm⁻¹ with 80 wt.% PEGDME at 30 °C. The ionic conductivity of the micro-phase separated solid polymer electrolyte was slightly higher than that of the homogeneously blended solid polymer electrolyte. The electrochemical stability window of the resulting solid polymer electrolyte could be extended to up to 4.8 V versus Li/Li⁺ reference electrode.     

Lithium electrolytes based on modified imidazolium ionic liquids

In this study, new electrolytes for Li-ion batteries in the form of lithium salt solutions in room temperature imidazolium ionic liquids (RTIL) are reported. The ionic liquids applied, for higher reduction potential stability, were substituted at position C2 with oligooxyethylene groups of various length ([Im nEO]⁺X⁻; where: n = 0, 3, 7, 20 and X = Cl, BF₄, N(CF₃SO₂)₂). It was found that they are good solvents for lithium salts (LiBF₄, LiN(CF₃SO₂)₂, {[CH₃(OCH₂CH₂)₃O]₃BC₄H₉}Li) forming liquid solutions of low glass transition temperature (T_g in the −70 to −40 °C range). Ionic conductivity depends on the length of oxyethylene substituent in Im nEO and on the concentration of the salt applied, for 10 mol%, σ_RT is of the order of 10⁻⁴ S cm⁻¹. On the basis of polarization measurements by the variable-current method, the proportion of lithium cations in electric charge transfer (t₊) has been determined. The values obtained (typical for ionic liquids) are low and depend on n and lithium salt concentration but do not exceed a dozen or so percent.     

Lithium ion transport of solid electrolytes based on PEO/CF3SO3Li and aluminum carboxylate

A homogeneous, composite polymer electrolyte (PE) containing poly(ethylene oxide) (PEO), CF₃SO₃Li and 33 wt.% of aluminum carboxylate [RC(O)OAlEt₂]₂ with an oligooxyethylene group R = CH₂CH₂C(O)O(CH₂CH₂O)_nCH₃ (n = 7) (AlCarb7), characterized by low glass transition temperature T_g = −51.4 °C was prepared. The interaction of aluminum carboxylate with various lithium salts was characterized on the basis of ²⁷Al NMR spectroscopy in CDCl₃ solutions. The bulk conductivity of solid PE with AlCarb7 is of the order of 10⁻⁵ S cm⁻¹ at 60 °C and 10⁻⁴ S cm⁻¹ at 90 °C. Electrochemical tests of Li|PE|Li cells showed a decrease in the R_SEI with temperature, stabilizing at about 10 Ω cm⁻². The lithium ion transference numbers determined by ac–dc polarization experiments range from 0.7 to 0.9. ⁷Li, ¹⁹F and ¹H NMR spectra, the relaxation time and diffusion data were obtained. The calculated lithium transference number t₊ at 50 °C is equal to 0.995, which suggests practically complete immobilization of the triflate salt anions. In the range of high temperatures (130–180 °C) t₊ is equal 0.35–0.39. The dependence of t₊ on temperature should probably be connected with the partial dissociation of the aluminum carboxylate and lithium salt complex.     

New electrolytes for lithium ion batteries using LiF salt and boron based anion receptors

The thermal and electrochemical stability, as well as compatibility with various bench mark cathode and anode materials of two new lithium fluoride salt (LiF) based electrolytes have been studied. These two new electrolytes are formed by using boron-based anion receptors, tris(pentafluorophenyl) borane (TPFPB), or tris(2H-hexafluoroisopropyl) borate (THFPB) as additives, which were designed and synthesized at Brookhaven National Laboratory (BNL), to dissolve the LiF salt in carbonate solvents. The transference number of Li⁺ for these electrolytes is as high as 0.7 and the room-temperature conductivity is around 2 × 10⁻³ S cm⁻¹. The electrolytes containing propylene carbonate (PC) show superior low-temperature conductivity properties. The electrochemical window is approaching 5.0 V. It was also found that the new electrolytes work well with LiCoO₂ or LiMn₂O₄ cathodes. However, when PC containing electrolytes were used, PC co-intercalation is still a problem for graphite anodes. The formation of a stable solid electrolyte interface layer on the surface of anode in this type of electrolyte needs to be studied further.     

Ionic conducting behavior of solvent-free polymer electrolytes prepared from oxetane derivative with nitrile group

Polymer with trimethylene oxide (TMO) units prepared from ring-opening polymerization of an oxetane derivative is a candidate for the matrix of solid polymer electrolytes. We prepare an oxetane derivative with nitrile group, 3-(2-cyanoethoxymethyl)-3-ethyloxetane, CYAMEO. CYAMEO is polymerized by using a cationic initiator system. The structure of the resulted polymer, P(CYAMEO), is confirmed by NMR and FTIR spectroscopic techniques. Inorganic salts, such as lithium salts, can be dissolved in P(CYAMEO) matrix. FTIR and DSC results of P(CYAMEO)-based electrolyte films suggest that lithium ions in the P(CYAMEO) matrix interact with the nitrile side chains, mainly, and not with the oxygen atoms on the main chain of the P(CYAMEO). The conductivity at 30 °C for P(CYAMEO)-based electrolyte films, P(CYAME)10(LiX)1, is 19.6 μS cm⁻¹ (X = LiClO₄), 6.59 μS cm⁻¹ (BF₄), 6.54 μS cm⁻¹ (CF₃SO₃), and 25.0 μS cm⁻¹ (N(CF₃SO₂)₂). The rise in temperature from 30 °C to 70 °C increases their conductivity, about 30-40 times. The conductivity at 70 °C for P(CYAMEO)-based electrolyte films is 0.742 mS cm⁻¹ (X = LiClO₄) and 0.703 mS cm⁻¹ (N(CF₃SO₂)₂). Electrochemical deposition and dissolution of lithium on a nickel plate electrode are observed in the solvent-free three-electrode electrochemical cell with P(CYAMEO)10(LiX)1, (X = ClO₄ or N(CF₃SO₂)₂) electrolyte film at 55 °C.     

Modern generation of polymer electrolytes based on lithium conductive imidazole salts

In this paper the application of completely new generation imidazole-derived salts in a model polymer electrolyte is described. As a polymer matrix, two types of liquid low molecular weight PEO analogues e.g. dimethyl ether of poly(ethylene glycol) of 500 g mol⁻¹ average molar mass (PEGDME500) and methyl ether of poly(ethylene glycol) of 350 g mol⁻¹ average molar mass (PEGME350) were used. Room temperature conductivities measured by electrochemical impedance spectroscopy were found to be as high as 10⁻³-10⁻⁴ S cm⁻¹ in the 0.1-1 mol dm⁻³ range of salt concentrations. Li⁺ transference numbers higher than 0.5 were measured and calculated using the Bruce-Vincent method. For a complete electrochemical characterization the interphase resistance stability over time was carefully monitored for a period of 30 days. Structural analysis and interactions between electrolyte components were done by Raman spectroscopy. Fuoss-Kraus semiempirical method was applied for estimation of free ions and ionic agglomerates showing that fraction of ionic agglomerates for salt concentration of 0.1-1 mol dm⁻³ is much lower than in electrolytes containing LiClO₄ in corresponding concentrations.     

Novel weakly coordinating heterocyclic anions for use in lithium batteries

Ab initio calculations have been performed for a new family of lithium salts based on heterocyclic anions: [CF₃SON₄C_2n]⁻ (0 ≤ n ≤ 4). In total, 10 different anions and their 1:1 ion pairs with lithium ions have been studied. The lithium ion affinity globally decreases with the degree of CN-substitution to the ring. Bidentate lithium ion coordination to the sulfonyl oxygen atom and one additional atom or to two adjacent ring nitrogen atoms is strongly preferred when structurally possible. The extremely low lithium ion affinities of the anions together with an appreciable stability towards oxidation make these salts possible candidates for future lithium battery electrolytes.     

Electrochromic devices employing methacrylate-based polymer electrolytes

Poly(ethyl methacrylate) (PEMA)- and poly(2-ethoxyethyl methacrylate) (PEOEMA)-based polymer gel electrolytes with entrapped solutions of lithium perchlorate in propylene carbonate (PC) were prepared by direct, UV-initiated polymerization. The electrolytes were studied using electrochemical methods and they exhibit good ionic conductivity (up to 0.7 mS cm⁻¹ at 20 °C) as well as electrochemical stability up to 2.5 V vs. Cd/Cd²⁺ (5.1 V vs. Li/Li⁺) on gold electrode. The electrolytes have thermal stability up to 125 °C. The electrolytes were successfully tested as ionic conductors in the electrochromic device FTO/WO₃/Li⁺-electrolyte/V₂O₅/FTO using coupled optoelectrochemical methods to discuss the relationship between the electrolyte composition and parameters such as change of transmittance, response time and stability. The transmittance change Δτ was found to be 30-45% at 634 nm.     

Solvent-free,PYR1ATFSI ionic liquid-based ternary polymer electrolyte systems: I. Electrochemical characterization

The electrical properties of solvent-free, PEO–LiTFSI solid polymer electrolytes (SPEs), incorporating different N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, PYR_1ATFSI, ionic liquids (ILs), are reported. For this purpose, PYR_1ATFSI materials containing side alkyl groups with different chain-length and branching, i.e., n-propyl, sec-propyl, n-butyl, iso-butyl, sec-butyl and n-pentyl, were properly synthesized and homogeneously incorporated into the SPE samples without phase separation. The addition of ILs to PEO–LiTFSI electrolytes results in a large increase of the conductivity and in a decrease of the interfacial resistance with the lithium metal anode. Most of the PEO–LiTFSI–PYR_1ATFSI samples showed similar ionic conductivities (>10⁻⁴ S cm⁻¹ at 20 °C) and stable interfacial resistance values (400 Ω cm² at 40 °C and 3000 Ω cm² at 20 °C) upon several months of storage. Preliminary battery tests have shown that Li/P(EO)₁₀LiTFSI + 0.96 PYR_1ATFSI/LiFePO₄ solid-state cells are capable to deliver a capacity of 125 mAh g⁻¹ and 100 mAh g⁻¹ at 30 °C and 25 °C, respectively.     

Preparation of Li2S-GeSe2-P2S5 electrolytes by a single step ball milling for all-solid-state lithium secondary batteries

Glass-ceramic and glass Li₂S-GeSe₂-P₂S₅ electrolytes were prepared by a single step ball milling (SSBM) process. Various compositions of Li_4−xGe_1−xP_xS_2(1+x)Se_2(1−x) with/without heat treatment (HT) from x = 0.55 to x = 1.00 were systematically investigated. Structural analysis by X-ray diffraction (XRD) showed gradual increase of the lattice constant followed by significant phase change with increasing GeSe₂. HT also affected the crystallinity. Incorporation of GeSe₂ in Li₂S-P₂S₅ kept high conductivity with a maximum value of 1.4 × 10⁻³ S cm⁻¹ at room temperature for x = 0.95 in Li_4−xGe_1−xP_xS_2(1+x)Se_2(1−x) without HT. All-solid-state LiCoO₂/Li cells using Li₂S-GeSe₂-P₂S₅ as solid-state electrolytes (SE) were tested by constant-current constant-voltage (CCCV) charge-discharge cycling at a current density of 50 μA cm⁻² between 2.5 and 4.3 V (vs. Li/Li⁺). In spite of the extremely high conductivity of the SE, LiCoO₂/Li cells showed a large irreversible reaction especially during the first charging cycle. LiCoO₂ with SEs heat-treated at elevated temperature exhibited a capacity over 100 mAh g⁻¹ at the second cycle and consistently improved cycle retention, which is believed to be due to the better interfacial stability.     

Electrospun polymer membrane activated with room temperature ionic liquid: Novel polymer electrolytes for lithium batteries

A new class of polymer electrolytes (PEs) based on an electrospun polymer membrane incorporating a room-temperature ionic liquid (RTIL) has been prepared and evaluated for suitability in lithium cells. The electrospun poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-HFP) membrane is activated with a 0.5 M solution of LiTFSI in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) or a 0.5 M solution of LiBF₄ in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF₄). The resulting PEs have an ionic conductivity of 2.3 × 10⁻³ S cm⁻¹ at 25 °C and anodic stability at >4.5 V versus Li⁺/Li, making them suitable for practical applications in lithium cells. A Li/LiFePO₄ cell with a PE based on BMITFSI delivers high discharge capacities when evaluated at 25 °C at the 0.1C rate (149 mAh g⁻¹) and the 0.5C rate (132 mAh g⁻¹). A very stable cycle performance is also exhibited at these low current densities. The properties decrease at the higher, 1C rate, when operated at 25 °C. Nevertheless, improved properties are obtained at a moderately elevated temperature of operation, i.e. 40 °C. This is attributed to enhanced conductivity of the electrolyte and faster reaction kinetics at higher temperatures. At 40 °C, a reversible capacity of 140 mAh g⁻¹ is obtained at the 1C rate.     

Ion-conducting lithium bis(oxalato)borate-based polymer electrolytes

Poly(2-ethoxyethyl methacrylate) polymer gel electrolytes containing immobilised lithium bis(oxalato)borate in aprotic carbonates: propylene carbonate (PC), propylene carbonate–ethylene carbonate (PC–EC 50:50 vol.%) and diethyl carbonate–ethylene carbonate (DEC–EC 50:50 vol.%) were prepared by a direct radical polymerisation. The electrolyte composition was optimised to achieve suitable ionic conductivity 0.5 and 2.4 mS cm⁻¹ at 25 and 70 °C respectively along with good mechanical properties. The electrochemical stability up to 5.1 V vs. Li/Li⁺ was determined on gold electrode by voltammetrical measurements. The polymer electrolytes with high-boiling solvents (PC and PC/EC) showed higher thermal stability (up to 110–120 °C) compared to the liquid electrolytes. The proposed area of application is in the lithium-ion batteries with cathodes operating at elevated temperatures of 70 °C, where higher electrochemical stability of the polymer electrolytes is employed.     

Dye-sensitized, nano-porous TiO2 solar cell with poly(acrylonitrile): MgI2 plasticized electrolyte

Dye-sensitized solar cells are promising candidates as supplementary power sources; the dominance in the photovoltaic field of inorganic solid-state junction devices is in fact now being challenged by the third generation of solar cells based on dye-sensitized, nano-porous photo-electrodes and polymer electrolytes. Polymer electrolytes are actually very favorable for photo-electrochemical solar cells and in this study poly(acrylonitrile)-MgI₂ based complexes are used. As ambient temperature conductivity of poly(acrylonitrile)-salt complexes are in general low, a conductivity enhancement is attained by blending with the plasticizers ethylene carbonate and propylene carbonate. At 20 °C the optimum ionic conductivity of 1.9 × 10⁻³ S cm⁻¹ is obtained for the (PAN)₁₀(MgI₂)_n(I₂)_n/10(EC)₂₀(PC)₂₀ electrolyte where n = 1.5. The predominantly ionic nature of the electrolyte is seen from the DC polarization data. Differential scanning calorimetric thermograms of electrolyte samples with different MgI₂ concentrations were studied and glass transition temperatures were determined. Further, in this study, a dye-sensitized solar cell structure was fabricated with the configuration Glass/FTO/TiO₂/Dye/Electrolyte/Pt/FTO/Glass and an overall energy conversion efficiency of 2.5% was achieved under solar irradiation of 600 W m⁻². The I-V characteristics curves revealed that the short-circuit current, open-circuit voltage and fill factor of the cell are 3.87 mA, 659 mV and 59.0%, respectively.     

LBDOB, a new lithium salt with benzenediolato and oxalato complexes of boron for lithium battery electrolytes

A new unsymmetrical lithium salt containing C₆H₄O₂²⁻[dianion of 1,2-benzenediol] and C₂O₄²⁻[dianion of oxalic acid], lithium [1,2-benzenediolato(2-)-O,O′ oxalato]borate (LBDOB), is synthesized and characterized. The thermal characteristics of it, lithium bis[1,2-benzenediolato(2-)-O,O′]borate (LBBB) and lithium bis(oxalate)borate (LiBOB) are examined by thermogravimetric (TG) analysis. The thermal decomposition in Ar begins at 250, 256, and 302 °C for LBBB, LBDOB, and LBOB, respectively. The order of the stability toward oxidation of these organoborates is LBOB > LBDOB > LBBB, which is in the same order of the thermal stability. The cyclic voltammetry study shows that the LBDOB solution in PC is stable up to 3.7 V vs. Li⁺/Li. They are soluble in common organic solvents. Ionic dissociation properties of LBDOB and its derivatives are examined by conductivity measurements in PC, PC + DME, EC + DME, PC + THF, EC + THF (molar ratio 1:1) solutions. The conductivity values of the 0.10 mold m⁻³ LBDOB electrolyte in PC, PC + DME, EC + DME, PC + THF, EC + THF solutions are higher than those of LBBB, but lower than those of LBOB electrolytes.     

Nano-sponge ionic liquid-polymer composite electrolytes for solid-state lithium power sources

Solid polymer gel electrolytes composed of 75 wt.% of the ionic liquid, 1-n-butyl-2,3-dimethylimidazolium bis-trifluoromethanesulfonylimide with 1.0 M lithium bis-trifluoromethanesulfonylimide and 25 wt.% poly(vinylidenedifluoro-hexafluoropropene) are characterized as the electrolyte/separator in solid-state lithium batteries. The ionic conductivity of these gels ranges from 1.5 to 2.0 mS cm⁻¹, which is several orders of magnitude more conductive than any of the more commonly used solid polymers, and comparable to the best solid gel electrolytes currently used in industry. TGA indicates that these polymer gel electrolytes are thermally stable to over 280 °C, and do not begin to thermally decompose until over 300 °C; exhibiting a significant advancement in the safety of lithium batteries. Atomic force microscopy images of these solid thin films indicate that these polymer gel electrolytes have the structure of nano-sponges, with a sub-micron pore size. For these thin film batteries, 150 charge-discharge cycles are run for Li_xCoO₂ where x is cycled between 0.95 down to 0.55. Minimal internal resistance effects are observed over the charging cycles, indicating the high ionic conductivity of the ionic liquid solid polymer gel electrolyte. The overall cell efficiency is approximately 98%, and no significant loss in battery efficiency is observed over the 150 cycles.     

New covalent salts of the 4+ V class for Li batteries

There is urgent action required for replacing LiPF₆ as a solute for Li-ion batteries electrolytes. This salt, prone to highly Lewis acidic PF₅ release and hydrolysis to HF is responsible for deleterious reaction on carbonate solvents, corrosion of electrode materials leading to safety problems then release to toxic chemicals. A major advantage of LiPF₆ is that it passivates aluminium. Most attempts to replace LiPF₆ with hydrolytically-stable salts have been unsuccessful because of Al corrosion.We present here two “Hückel” type salts, namely lithium (2-fluoroalkyl-4,5-dicyano-imidazolate); fluoroalkyle = CF₃ (TDI), C₂F₅ (PDI) with high charge delocalization. These thermally stable salts give both appreciably conductive solutions in EC/DMC (>6 mS cm⁻¹ at 20 °C) with a lower decrease with temperature than LiPF₆. Non fluorinated lithium (4,5-dicyano-1,2,3-triazolate) is comparatively less than half as conductive. The lithium transference number T₊ measured by PFG-NMR is also higher. Voltammetry scans with either platinum or aluminium electrodes show an oxidation wall at 4.6 V versus Li⁺:Li°. These two salts are thus the first examples of strictly covalent, non-corroding salts allowing 4+ V electrode material operation. This is demonstrated with experimental Li/LiMn₂O₄ cells as beyond the third cycles, the fade of the three electrolytes were quasi-identical, though LiPF₆ had a sharper initial decrease.     

A new lithium salt with dihydroxybenzene and lithium tetrafluoroborate for lithium battery electrolytes

A new unsymmetrical lithium salt containing F⁻, C₆H₄O₂²⁻ [dianion of 1,2-benzenediol], lithium difluoro(1,2-benzene-diolato(2-)-o,o′)borate (LDFBDB) is synthesized and characterized. Its thermal decomposition in nitrogen begins at 170 °C. The cyclic voltammetry study shows that the LDFBDB solution in propylene carbonate (PC) is stable up to 3.7 V versus Li⁺/Li. It is soluble in common organic solvents. The ionic dissociation properties of LDFBDB are examined by conductivity measurements in PC, PC+ ethyl methyl carbonate (EMC), PC + dimethyl ether (DME), PC + ethylene carbonate (EC) + EMC solutions. The conductivity values of the 0.564 mol dm⁻³ LDFBDB electrolyte in PC + DME solution is 3.90 mS cm⁻¹. All these properties of the new lithium salt including the thermal characteristics, electrochemical stabilities, solubilities, ionic dissociation properties are studied and compared with those of its derivatives, lithium difluoro(3-fluoro-1,2-benzene-diolato(2-)-o,o′)borate (FLDFBDB), lithium [3-fluoro-1,2-benzenediolato(2-)-o,o′ oxalato]borate (FLBDOB), and lithium bis(oxalate)borate (LBOB).     

Preparation and electrochemical characterization of gel polymer electrolyte based on electrospun polyacrylonitrile nonwoven membranes for lithium batteries

Electrospun membranes of polyacrylonitrile are prepared, and the electrospinning parameters are optimized to get fibrous membranes with uniform bead-free morphology. The polymer solution of 16 wt.% in N,N-dimethylformamide at an applied voltage of 20 kV results in the nanofibrous membrane with average fiber diameter of 350 nm and narrow fiber diameter distribution. Gel polymer electrolytes are prepared by activating the nonwoven membranes with different liquid electrolytes. The nanometer level fiber diameter and fully interconnected pore structure of the host polymer membranes facilitate easy penetration of the liquid electrolyte. The gel polymer electrolytes show high electrolyte uptake (>390%) and high ionic conductivity (>2 × 10⁻³ S cm⁻¹). The cell fabricated with the gel polymer electrolytes shows good interfacial stability and oxidation stability >4.7 V. Prototype coin cells with gel polymer electrolytes based on a membrane activated with 1 M LiPF₆ in ethylene carbonate/dimethyl carbonate or propylene carbonate are evaluated for discharge capacity and cycle property in Li/LiFePO₄ cells at room temperature. The cells show remarkably good cycle performance with high initial discharge properties and low capacity fade under continuous cycling.     

Performance improvement of polyethylene-supported poly(methyl methacrylate-vinyl acetate)-co-poly(ethylene glycol) diacrylate based gel polymer electrolyte by doping nano-Al2O3

Polyethylene (PE)-supported poly(methyl methacrylate-vinyl acetate)-co-poly(ethylene glycol) diacrylate with and without doping nano-Al₂O₃, namely P(MMA-VAc)-co-PEGDA/PE and P(MMA-VAc)-co-PEGDA/Al₂O₃/PE, are prepared and their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by mechanical test, scanning electron microscopy, thermogravimetric analyzer, electrochemical impedance spectroscopy, cyclic voltammetry, and charge/discharge test. It is found that the doping of nano-Al₂O₃ in the P(MMA-VAc)-co-PEGDA/PE improves the comprehensive performances of the GPE and thus the rate performance and cyclic stability of the battery. With doping nano-Al₂O₃, the mechanical and thermal stability of the polymer and the ionic conductivity of the corresponding GPE increases slightly, while the battery exhibits better cyclic stability. The mechanical strength and the decomposition temperature of the polymer increase from 15.9 MPa to 16.2 MPa and from 410 °C to 420 °C, respectively. The ionic conductivity of the GPE is from 3.4 × 10⁻³ S cm⁻¹ to 3.8 × 10⁻³ S cm⁻¹. The discharge capacity of the battery using the GPE with doping nano-Al₂O₃ keeps 90.9% of its initial capacity after 100 cycles and shows good C-rate performance.