Investigation on the Copolymer Electrolyte of Poly(1,3‐dioxolane‐co‐formaldehyde)

Abstract

have been found in preventing the pen etration of Li dendrites. [15][16][17] However, the excessive interfacial resistance and the complex processing art of inorganic SSEs limit their practical application. [18][19][20] Solid polymer electrolytes (SPEs), on the other hand, can offer good flexibility and stable contact between the electrodes and electrolytes. [20][21][22][23] Several types of polymer matrices have been developed, such as poly(ethyleneoxide) (PEO), [24][25][26] poly carbonate, [27][28][29] and polysiloxane. [30][31][32] SPEs are prepared by mixing polymer matrices with Li salts. PEO is the most popular and deeply studied polymer matrix, [33] and the ethylene oxide chain segments in PEO can dissolve Li salts as well as form complexes with Li + and dis sociated Li salts. [34] Li + is conducted by repeatedly carrying out a "decomplexa tion-recomplexation" process through the movement of chain segments in an amorphous polymer region. [35] The movement of chain segments in an amorphous polymer region is affected by the glass transition temperature (T g ) and crystallinity. Low T g and crystallinity are beneficial for the move ment of chain segments as well as the ionic conductivity. Due to the high crystallinity of PEO, PEObased SPEs have a low ionic conductivity (10 −8 -10 −7 S cm −1 ) at room temperature, which does not meet the requirement for ionic conductivity (>10 −4 S cm −1 at room temperature) of electrolytes with prom ising applications. [33,36,37] Many strategies, such as adding inorganic nanoparticles, [38][39][40] blending, [41] copolymerization, [42] and crosslinking [43][44][45] have been adopted to effectively sup press the crystallization of PEO and improve the ionic conduc tivity of PEObased SPEs. Coat et al. [46] reported the synthesis of poly(diethylene oxidealtoxymethylene) (P(2EOMO)) as a polymer matrix for SPE, which has higher T g than that of PEO in the electrolyte. They found the P(2EOMO)/LiTFSI electro lyte exhibits a slightly lower ionic conductivity due to higher T g , but much higher Li ion transference number can be obtained in P(2EOMO)/LiTFSI electrolyte (0.36) than that in PEO/ LiTFSI (0.19). So tailoring the main chain structure is the most feasible way to optimize the performance of SPEs.Recently, the strategy of in situ polymerizing SPEs in the batteries has attracted extensive attention due to the ability to construct stable ionic conduction networks inside the electrodes to reduce the interfacial resistance, the biggest challenge faced by most SSEs. Cui et al. [13] in situ prepared A series of copolymers are prepared via cationic ring-opening polymerization with 1,3-dioxolane (DOL) and trioxymethylene (TOM) as monomers. The crystallization behaviors of the copolymers can be suppressed by adjusting the ratio of DOL/TOM. With LiBF 4 as a source for a BF 3 initiator, copolymer electrolytes (CPEs) can be prepared in situ inside cells without needing nonelectrolyte catalysts or initiators. The ionic conductivities and Li + diffusion coefficients (D Li + ) of the CPEs inc...

Designing Polymer‐in‐Salt Electrolyte and Fully Infiltrated 3D Electrode for Integrated Solid‐State Lithium Batteries

“…Unfortunately, the ionic conductivity of SPEs at room temperature (RT) is generally low [14, 15] . Considering that the ionic transport in SPEs is completed by the local relaxation and segmental motion of amorphous regions in polymer chains (Figure 1 a), [16–18] various approaches, including cross‐linking, [19, 20] forming copolymer, [21] and introducing inorganic fillers, [22] have been implemented to expand the proportion of amorphous regions to promote ionic conductivity. Alternatively, polymer‐in‐salt solid electrolyte (PISSE: the content of the lithium salt exceeding 50 wt.…”

Low‐Cost Regulating Lithium Deposition Behaviors by Transition Metal Oxide Coating on Separator

“…[ 2b,29 ] The in situ polymerized DOL/trioxymethylene copolymer was adopted as a GPE here, since this GPE had been demonstrated owning good stability with Li metal anode. [ 30 ] Combined with the GPE, the sheet‐like Li@Cu||LFP cell shows stable capacity and high CE (>99.0%) for more than 150 cycles (Figure 9a,b) which are both better than the liquid DOL/DME electrolyte, demonstrating a synergistic effect of sheet‐like Li@Cu anode and GPE. These improved electrochemical performances indicate that the electrochemical deposition method with the in situ creation of Li 2 O containing SEI layer is an efficient solution for the preparation of in situ SEI protected ultrathin lithium metal anodes, which is highly expected for the development of LMBs.…”

Advances in host selection and interface regulation of polymer electrolytes

“…When the DOL/TXE ratio was set to 8/2, the corresponding PE delivers the highest ionic conductivity and t Li+ , and its good interfacial compatibility with lithium metal provides a uniform lithium plating/stripping process for 1200 h (entry 6). This study reveals that copolymerization is an efficient strategy for the fabrication of high‐performance PEs beyond PEO 38 …”