Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

Abstract

The development of metallic lithium anode is restrained by lithium dendrite growth during cycling. The solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite growth. To prepare the high‐performance solid polymer electrolyte, the environment‐friendly and cheap bacterial cellulose (BC) is used as filler incorporating with PEO‐based electrolyte owing to good mechanical properties and Li salts compatibility. PEO/LiTFSI/BC composite solid polymer electrolytes (CSPE) are prepared easily by aqueous mixing in water. The lithium ion transference number of PEO/LiTFSI/BC CSPE is 0.57, which is higher than PEO/LiTFSI solid polymer electrolyte (SPE) (0.409). The PEO/LiTFSI/BC CSPE exhibits larger tensile strength (4.43 MPa) than PEO/LiTFSI SPE (1.34 MPa). The electrochemical window of composite electrolyte is widened 1.43 V by adding BC. Density functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed, suggesting the enhanced lithium ion conductivity. Frontier molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite electrolyte. All solid‐state Li metal battery with PEO/LiTFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/LiTFSI SPE battery (50 cycles). Li symmetrical battery using PEO/LiTFSI/BC CSPE could be stable for 1160 h.

Recyclable, Self‐Healing Solid Polymer Electrolytes by Soy Protein‐Based Dynamic Network

“…Thus, the SPEs based on the the ionic conductivity and stress of SPI-3Li to other polymer electrolytes reported in the literature. (Poly(styrene trifluoromethanesulphonylimide of lithium)-poly(ethylene oxide)-poly(styrene trifluoromethanesulphonylimide of lithium) (P(STFSILi)-PEO-P(STFSILi)), [38] poly(ethylene oxide)lithium bis(trifluoromethanesulfonyl)-10%vermiculite sheets (PEO/LiTFSI/10%VS), [9] P(EO) 15 LiTFSI-0.2Li 7 La 3 Zr 2 O 12 -1.1ethylene carbonate (PLLE-3), [36] PEO+LiTFSI(EO:Li = 15:1)+halloysite nanotube(10%) (HNT), [39] metal-organic frameworks-tetrakis (3-mercaptopropionic acid) pentaerythritolpoly(ethylene glycol) diacrylate (M-S-PEGDA), [40] crosslinked poly(tetrahydrofuran)-N,N-dimethylformamide solid polymer electrolytes (xPTHF5DMF2:1 SPE), [41] poly(ethylene glycol)-polyhedral oligomeric silsesquio-xanes(PEG250), [45] PEO/LiTFSI/bacterial cellulose(PEO/LiTFSI/BC), [42] porous polyimide-Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 -poly(vinylidene fluoride) (PI-LLZTO/ PVDF), [43] supramolecular lithium ion conductor (SLIC). [44] ) imine bond dynamic network of SPI is a promising platform for recyclable and repairable electrolytes.…”

“…[36] It is also worth noting that SPI-3Li has higher strength and ionic conductivity than traditional PEO-based polymer electrolytes (Figure 5g). [9,36,[38][39][40][41][42][43][44]…”

Accurate redox potentials for solvents in Li‐metal batteries and assessment of density functionals

“…The electrolyte containing fluorinated solvents delivers superior oxidation potential even up to 6.5–6.8 V [11, 12], and contributes to a stable and LiF‐enriched SEI to regulate the Li‐deposition behaviors, suggesting that fluorinated solvents are promising candidates to substitute organic carbonates for high anodic stability of LMBs [1]. Very recently, density functional theory (DFT) [13–15] has been emerging for virtual screening of fluorinated solvents in LMBs, and many studies have employed DFT to provide insight into the electrochemical performances of fluorinated solvents from the perspective of their electronic structures, including the energies of molecular orbitals [4, 10, 16], interfacial model predictions [17], structure‐optimizations [18, 19], and redox potentials [20]. For example, Zhang et al [11] and Yoo et al [21] calculated oxidation/reduction potentials and highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) of fluorinated carbonates with the B3LYP functional to find promising fluorinated electrolytes for high‐performance LMBs.…”

A Stretchable Ionic Conductive Elastomer for High‐Areal‐Capacity Lithium‐Metal Batteries

“…[10][11][12][13] Nevertheless, the wide applications of Li-metal anode in secondary batteries are still hindered by the uncontrolled lithium dendrite growth and the poor reversibility, especially when the commercial carbonate electrolytes are used. [14][15][16] Up till now, a string of methods is proposed to cope with these challenges, such as creating three-dimensional (3D) Li hosts to alleviate the uneven local current density, [17] substituting solid-state electrolyte for conventional liquid electrolytes to prevent lithium dendrite penetration, [18][19][20] introducing additives to the electrolyte to stabilize the solid electrolyte interface (SEI) films of the Li anodes, [16] constructing robust protective layers [21][22] to reduce the side reactions between the electrolyte and Li anodes, and so on. [23][24][25][26][27][28] Although these countermeasures suppress the formation/growth of the Li dendrites and reduce the side reactions between Li metal and liquid electrolytes, it remains challenging to realize the dendrite-free and high-efficiency Li depositions under high-areal-capacity conditions in conventional carbonate electrolytes, [29][30][31][32] which is one of the most critical and urgent challenges for the practical realization of Limetal batteries.…”