Synergistic Inorganic–Organic Dual-Additive Electrolytes Enable Practical High-Voltage Lithium-Ion Batteries

Abstract

Severe electrolyte decomposition under high voltage can easily lead to degradation of the performance of lithium-ion batteries, which has become a major obstacle to the practical application of high-energy-density batteries. To solve these problems, a dual-functional electrolyte additive comprising inorganic lithium difluorophosphate (LiDFP) and organic 1,3,6-hexanetrinitrile (HTN) was designed and employed to improve the performance of high-voltage Si@C/LiNi 0.5 Mn 1.5 O 4 full batteries. LiDFP with a lower LUMO energy than the solvent in the electrolyte takes priority in reduction, facilitating the formation of a dense and stable film on the anode, effectively suppressing side reactions of the electrolyte and aiding tolerance to the volume expansion of the Si@C electrode. Additionally, the lower HOMO energy of HTN can improve the oxidation resistance of the electrolyte, with the CN functional group of HTN helping to remove the trace water and the byproduct HF from the electrolyte. The Si@C/LiNi 0.5 Mn 1.5 O 4 full battery with 1 wt % LiDFP and 1 wt % HTN in 1.0 M LiPF 6 traditional electrolyte delivers high capacity retention of 91.57% after 150 cycles at 0.2C, compared to 34.58% capacity retention without any additives. Moreover, the Coulombic efficiency of batteries with electrolyte additives can reach 99.75% on average, compared to their counterparts at ∼96.54%. The synergistic effect of LiDFP and HTN provides a promising strategy for enhancing the performance of high-voltage batteries for practical industrialization.

Integrating SEI into Layered Conductive Polymer Coatings for Ultrastable Silicon Anodes

“…Numerous attempts have been made to stabilize SEI, including the nanostructure engineering, [9][10][11][12][13][14][15][16][17][18][19] surface modification, [20][21][22][23][24] composite design, [25][26][27][28] binder optimization, [19,[29][30][31][32][33][34][35] and electrolyte modulation. [36][37][38][39] Carbon coating is one of the most effective strategies to improve the conductivity, buffer the volume expansion as well as stabilize the SEI. [15,27,[40][41][42] Nevertheless, the carbon coating together with buffer voids for high-capacity silicon anodes (>1000 mAh g −1 ) usually has a low-efficiency "point-to-point" model in terms of ion and electron transport.…”

Phenyl 4-Fluorobenzene Sulfonate as a Versatile Film-Forming Electrolyte Additive for Wide-Temperature-Range NCM811//Graphite Batteries

“…Nevertheless, because of the alkaline nature of these transition metals (TMs) and the oxide-induced intrinsic high pH value, the Ni-rich cathode NMC811 is skewed toward accelerating the side reactions of electrolytes. The cycle stability of the NCM811 cathode is conjointly deteriorated easily, resulting in TM ion dissolution and lattice collapse, and the electrolyte decomposition reactions occur more easily. , Moreover, the TM ions randomly migrate from the cathode and are aimlessly accelerated by the solvent decomposition, which ultimately get deposited on the graphite surface. ,, Subsequently, unremitting electrolyte decomposition on the electrode surface results in an unstable, heterogeneous, and continuously thickened solid electrolyte interphase (SEI) layer, exaggerating the Li + diffusion resistance. ,− Though various strategies have been proposed to solve these issues, selecting multi-functional molecules in the electrolyte to generate a highly stable SEI layer on both NCM and graphite is the most effective and economical method. − To achieve this target, the additives ought to possess a better reduction/oxidation activity than the ester solvents. − In other words, an ideal film-forming additive should ensure the prior disintegration of the molecules on both the cathode and anode.…”

Electrolyte Additive-Controlled Interfacial Models Enabling Stable Antimony Anodes for Lithium-Ion Batteries

“…have been being widely dedicated to stabilizing the alloying anode (e.g., Sb, , Sn, , Bi, , Si , ), the complex synthetic procedures and also the boundaries’ impedance between nanostructures may raise the cost and safety issues in batteries. Alternatively, the electrolyte design including introducing film-forming additives (e.g., FEC, , VC, , LiDFOB, , LiPO 2 F 2 , ), increasing salt concentrations to form a high-concentration electrolyte, , adding a dilute solvent (e.g., HFE, BTFE, OTE) to form a localized high-concentration electrolyte, and changing the kind of solvent (e.g., THF/2-MeTHF, , DME, − SN) have also been widely developed to stabilize the alloying anode. Among them, introducing film-forming additives in the electrolyte is one of the most economic and effective methods to improve the alloying anode performance.…”