Organic/Inorganic Hybrid Block Copolymer Electrolytes with Nanoscale Ion-Conducting Channels for Lithium Ion Batteries

Abstract

A series of organic/inorganic hybrid block and random copolymers were prepared by reversible addition− fragmentation chain transfer (RAFT) polymerization using poly-(ethylene glycol) methyl ether methacrylate (PEGMA) and 3- (3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.1 3,9 .1 5,15 .1 7,13 ]octasiloxane-1-yl)propyl methacrylate (MA-POSS) as monomers in order to study the effect of polymer morphology and POSS content on the properties of polymer electrolytes. Flexible and dimensionally stable free-standing films were made from the hybrid block and random copolymers mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) when the contents of MA-POSS unit were larger than 31 and 16 mol %, respectively. The ionic conductivity of the solid-state block copolymer (PBP) electrolyte was found to be 1 order of magnitude higher than that of the random copolymer (PRP) electrolyte when they had similar MA-POSS content, although their glass transition temperature values of their ion-conducting segments were quite close. Moreover, the ionic conductivity of the PBP electrolyte was not much different from that of the wax state poly(poly(ethylene glycol) methyl ether methacrylate) (P(PEGMA)) electrolyte. For example, the ionic conductivity values for the PBP electrolyte containing 31 mol % of MA-POSS, the PRP electrolyte containing 29 mol % of MA-POSS, and P(PEGMA) electrolyte were 2.05 × 10 −5 , 3.00 × 10 −6 , and 4.23 × 10 −5 S cm −1 , respectively, at 30 °C. The large ionic conductivity value of the block copolymer electrolyte is ascribed to the nanophase separation forming the ion-conducting channels.

Design of a Zwitterion Polymer Electrolyte Based on Poly[poly (ethylene glycol) methacrylate]: The Effect of Sulfobetaine Group on Thermal Properties and Ionic Conduction

“…resulting in a more efficient ion transport. Furthermore the activation energies obtained for pMPS8 and pMPS8/LiPF 6 are low compared to block copolymer electrolytes based on pPEGMA (0.104 and 0.155 eV) . The ionic conductivities obtained for typical mixtures of organic solvents (dimethyl ether, diethyl ether, dimethyl carbonate, diethyl carbonate) used in Li‐ion batteries range approximately 10 −3 S cm −1 at 20 °C .…”

“…The chain interlocking forms cylinders enabling stable coordination with Li + ions, but the ions are trapped into the cylinders at high salt concentration, restricting the mobility of the polymer chains, and consequently the ionic conductivity drops . At low salt concentration, it has been demonstrated that amorphous phases of PEO provide an adequate ionic conduction, whence a number of synthetic strategies have been adopted to prepare primarily amorphous phases, including the synthesis of comb polymers and block copolymers . However, their dimensional properties such as mechanical strength and flexibility were low, whence ion conduction also decreased due to loss of mobility of polymer chains.…”

Solid Polymer Electrolytes Based on Functionalized Tannic Acids from Natural Resources for All‐Solid‐State Lithium‐Ion Batteries

“…[1][2][3] Commercialized liquid electrolytes that comprise lithium salts and carbonatebased organic solvents have safety issues such as leakage and flammability,e specially at elevated temperatures. [5][6][7][8][9][10] However,t he ionic conductivities of SPEs based on PEO are much smaller than those of liquid electrolytesd ue to the intrinsically lowm obility of polymer chains. [5][6][7][8][9][10] However,t he ionic conductivities of SPEs based on PEO are much smaller than those of liquid electrolytesd ue to the intrinsically lowm obility of polymer chains.…”

Cubic Polyhedral Oligomeric Silsesquioxane Based Functional Materials: Synthesis, Assembly, and Applications

“…POSS‐PEG ( 18 )/POSS‐Li ( 19 ) composite electrolyte with O/Li=16:1 exhibited a conductivity of σ=2.5×10 −4 S cm −1 at 30 °C, σ=1.6×10 −3 S cm −1 at 90 °C, and 1.5×10 −5 S cm −1 at 10 °C. Lee et al reported a series of block and random copolymers of flexible ion‐conducting poly(ethylene glycol)methyl ether methacrylate and rigid POSS methyl ether methacrylate ( P3 in Figure ) . Flexible and stable free‐standing films could be fabricated from the block and random copolymers mixed with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (Figure a).…”