Fluorinated Solvent‐Coupled Anion‐Derived Interphase to Stabilize Silicon Microparticle Anodes for High‐Energy‐Density Batteries

Abstract

Si microparticle (SiMP) anodes feature much lower production cost and higher tap density compared to their nanosized counterparts, which hold great promise for high‐energy‐density lithium‐ion batteries, yet they suffer from unavoidable particle pulverization during repeated cycling, thus making their practical application extremely challenging. Herein, a non‐flammable localized high‐concentration electrolyte (LHCE) is rationally formulated using a fluorinated solvent, 2,2,2‐trifluoroethyl methyl carbonate (FEMC), to induce fluorinated solvent‐coupled anion‐derived interfacial chemistry. Unlike other LHCEs, the FEMC‐based LHCE is demonstrated to build a highly robust and stable F‐rich inorganic–organic bilayer solid–electrolyte interphase on SiMP anode, which endows stable cycling of SiMP anode (≈3.4 mAh cm−2) with an ultrahigh Coulombic efficiency of ≈99.7%. Coupled with its high anodic stability, the FEMC‐based LHCE endows unprecedented cycling stability for high‐energy‐density batteries containing high‐capacity SiMP anodes with Ni‐rich LiNi8Mn1Co1O2 or 5 V‐class LiNi0.5Mn1.5O4 cathodes. Remarkably, a 1.0 Ah‐level SiMP||LiNi8Mn1Co1O2 pouch‐cell stably operates for more than 200 cycles, representing the pioneering report in pouch cells containing SiMP anodes.

Lithium metal batteries with in situ copolymerized fluorinated polyether electrolytes

“…18–20 Nevertheless, most fluorinated solvents suffer from a decline in Li-ion conductivity due to their weakened Li-ion solvation. 15,21–23 It was demonstrated that when small molecule ether solvents were partially fluorinated via introducing –CF 2 – in the middle of the ether chain, the coordination/dissociation of Li ions in these solvents becomes easy, leading to good Li-ion conductivity and high oxidation stability, as reported by Cui and colleagues. 24–26 Ali Coskun et al modified the ether solvent into a cyclic structure with –CF 3 as the substituent groups, which could achieve a high voltage stability and retain the solvation ability of oxygen atoms.…”

In Situ Integration of a Flame Retardant Quasisolid Gel Polymer Electrolyte with a Si-Based Anode for High-Energy Li-Ion Batteries

“…On the other hand, the O 1s spectrum in Figure S20b reveals oxygen-rich organic SEI components, such as the carbonyl group (C�O), RCO 2 Li, and polyether carbon (−(CH 2 − CH 2 −O) n −), on the silicon anode in the LE, which may mainly arise from the solvent decomposition. In addition, some S-containing species, such as Li 2 S, Li x S, S−N, SO 2 F, and RSO 3 , 56 and the B-containing species like B−O and B−F species exist in the SEI of Si electrodes cycled in the QSGPE or in the LE. Figure 6c shows a schematic representation of the SEI related to the QSGPE with the F, N-rich inorganic/organic hybrid structure, mainly including polymers, LiF, and Li 3 N as well as small amounts of S-and B-based compounds.…”

Electrolyte Engineering Toward High Performance High Nickel (Ni ≥ 80%) Lithium‐Ion Batteries

“…The first class of novel electrolytes is formulated by LiPF 6 and high voltage stable solvents with different functional groups (Scheme 2 and Table 2), such as sulfolane (SL), [97] FEC, [97,[99][100][101][102][103][104][105][106][107] 2,2,2-trifluoroethyl acetate (TFA), [98,106] acetonitrile (AN), [99][100] methyl difluoroacetate (MDFA), [102] ethoxypentafluoro-cyclotriphosphazene (PFPN), [102] 2,2,2-trifluoroethyl methyl carbonate (FEMC), [103][104][105] 1,1,2,2-tetrafluoroethyl-2′,2′,2′trifluoroethyl ether (HFE). [103][104] Solvents with different functional groups endow novel electrolytes with various characteristics.…”