TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The electrolyte further comprises a compound that is polymerizable with the diacrylamide compound. The gel polymer electrolyte contains a polymerization initiator, electrolyte (plasticizer) and a lithium salt.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: The device is fabricated by a process involving: installing an electrode assembly in a battery case; injecting a mixture of a cross-linking polymerizable precursor material, a polymerization initiator, electrolyte and lithium salt into the battery case, followed by sealing; and polymerizing the cross-linking polymerizable precursor material; or further involving: formation for activation of the battery and aging for stabilization of the activated battery.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The crosslinked polymer is formed by cross-linking of a diacrylamide monomer and/or oligomer. The diacrylamide compound (1-10 wt.%) is a monomer of formula CH2=CH-C(O)-N(R1)-(CH2)n-N(R2)-C(O)-CH=CH2 (I) or its oligomer (preferably 1-(4-acryloyl-piperazin-1-yl)-propenone (II), CH2=C(O)-NH-CH2CH2-NH-C(O)-CH=CH2 (III) or CH2=C(R3)-C(O)-(O-CH(R5-CH2)m-O-C(O)-C(R4)=CH2 or their oligomers). The polymerizable compound is at least one selected from a (meth)acrylic ester compound, unsaturated carboxylic compound, vinyl compound and their mixtures. The (meth)acrylic ester compound is a (meth)acrylate compound containing at least two acrylate groups in the molecular structure; diacrylate compound. The (meth)acrylic ester compound is at least one selected from diethylene glycol diacrylate (Di(EG)DA), diethylene glycol dimethacrylate (Di(EG)DM), ethylene glycol dimethacrylate (EGDM), dipropylene glycol diacrylate (Di(PG)DA), dipropylene glycol dimethacrylate (Di(PG)DM), ethylene glycol divinyl ether (EGDVE), ethoxylated(6)trimethylolpropane triacrylate (ETMPTA), diethylene glycol divinyl ether (Di(EG)DVE), triethylene glycol dimethacrylate (Tri(EG)DM), dipentaerythritol pentaacrylate (DpentA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTM), propoxylated(3)trimethylolpropane triacrylate (PO(3)TMPTA), propoxylated(6)trimethylolpropane triacrylate(PO(6)TMPTA), poly(ethylene glycol)diacrylate(PA1) and/or poly(ethylene glycol)dimethacrylate.R1,R2=H, or 1-6 alkyl (optionally substituted);R1+R2=optionally saturated ring;n=0-4;R3-R5=H or 1-4C alkyl (optionally substituted);m=1-20.Provided, a direct bond is formed when n is 0. EXAMPLE - Non-Aqueous Electrolyte Containing Lithium Salt was prepared as follows: LiPF6 (1M) was added to a non-aqueous electrolyte solvent composed of a mixture of ethylene carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) (4:3:3, wt./wt.%). Based on the weight of the electrolyte, vinylene carbonate (VC) (1.5 wt.%), propylene sulfone (PS) (0.5 wt.%), azodiisobytyronitrile (AIBN) (2 mol.%) as a polymerization initiator, and ethylene diacrylamide of formula CH2=C(O)-NH-CH2CH2-NH-C(O)-CH=CH2 (2 wt.%) was added to the resulting mixture to obtain non-aqueous electrolyte. Cathode was fabricated as follows: Using LiCoO2 as a cathode active material, cathode slurry was prepared by adding a cathode mix composed of LiCoO2 (95.4 wt.%) having a particle diameter of 18 mu m, Super-P (RTM: (conductive material) (1.6 wt.%) and PVDF (binder) (3 wt.%) to NMP (N-methyl-2-pyrrolidone) as a solvent. Then, the resulting cathode slurry was coated on an aluminum current collector to thereby fabricate a cathode. Anode was fabricated as follows: Graphite as an anode active material and polyvinylidene fluoride (PVDF) (3.5 wt.%) were added to NMP to prepare an anode slurry. Then, the resulting anode slurry was coated on a copper current collector to thereby fabricate an anode. Lithium-Ion Polymer Secondary Cell (test) was fabricated as follows: A separator was disposed between the thus-fabricated cathode and anode to fabricate an electrode assembly. Then, the electrode assembly was mounted into a prismatic can to which the mixture (2 g) was then injected via an inlet, thus fabricating a 523450 prismatic battery. Then, cross-linking polymerization was carried out by heating the resulting prismatic battery in an oven purged with nitrogen gas, at a temperature of 60degrees C for 4-12 hours. A comparative secondary battery was fabricated in the same manner as in the test secondary battery except that polyethylene glycol diacrylate was added, instead of ethylene diacrylamide. The test fabricated secondary battery/comparative fabricated secondary battery were charged to 4.2 V at a charge rate of IC, 50 mA (cut off), and discharged to 3 V (cut off) at a discharge rate of IC. These charge/discharge cycles were repeated 500 times at room temperature. Meanwhile, for checking the capacity of the batteries, the fabricated batteries were aged for 5 days at room temperature after their fabrication. Immediately after the examination of battery capacity, cycle tests were carried out. Changes in the charge capacity and battery thickness for 300-500 cycles were measured, respectively. Thus the test battery exhibited a significant reduction of thickness swelling, as compared to the comparative lithium-ion polymer battery.