High-voltage Li Metal Batteries Research Articles

Dendrite-free reversible Li plating/stripping in adiponitrile-based electrolytes for high-voltage Li metal batteries

In this study, we describe how incompatible adiponitrile is made compatible with lithium by forming a stable LiF enriched porous Li2O coating, which enables reversible Li plating/stripping with no dendrites.

Polymer matrix mediated solvation of LiNO3 in carbonate electrolytes for quasi-solid high-voltage lithium metal batteries

Lithium (Li) metal is one of the most promising anodes for next-generation energy storage systems. However, the Li dendrite formation and unstable solid-electrolyte interface (SEI) have hindered its further application. Lithium nitrate (LiNO3) is extensively used as an effective electrolyte additive in ether-based electrolytes to improve the stability of lithium metal. Nevertheless, it is rarely utilized in carbonate electrolytes due to its low solubility. Here, a novel gel polymer electrolyte (GPE) consisting of poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO) with LiNO3 additive is proposed to solve this issue. In this GPE, polyether-based PEO serves as a matrix for dissolving LiNO3 which can be decomposed into a fast Li-ion conductor (Li3N) in conventional carbonate electrolytes to enhance the stability and Li+ conductivity of the SEI film. As a result, dendrite formation is effectively suppressed, and a significantly improved average Coulombic efficiency (CE) of 97.2% in Li-Cu cell is achieved. By using this novel GPE coupled with Li anode and LiNi0.5Mn0.3Co0.2O2 (NMC532), excellent capacity retention of 94.1% and high average CE of over 99.2% are obtained after 200 cycles at 0.5 C. This work presents fresh insight into practical modification strategies on high-voltage Li metal batteries.

(Invited) Localized High Concentration Electrolytes for Li Metal and Li Ion Batteries

It is well known that a stable and high efficiency Li metal anode (LMA) is critical for rechargeable Li metal batteries (LMBs). Although LMA is kinetically unstable with non-aqueous electrolyte, Localized High Concentration Electrolytes (LHCEs) can largely minimize the side reaction between LMA and electrolyte, therefore enable a dynamically stable LMA for long term cycling of li metal batteries. In this work, we report a series of LHCEs we developed recently that are highly stable with both LMA and high voltage cathode such as Ni rich LiNixCoyMn1-x-yO2 (x ≥ 0.6), LiCoO2 etc. These LHCEs not only exhibit the advantage of high concentration electrolyte, but also exhibit low viscosity, low cost of the low concentration electrolytes. Furthermore, these electrolytes can be tailored to be non-flammable and stable at low temperature. With appropriate additives, these LHCEs can also largely improve the stability of Si based Li ion batteries. The excellent performance of these batteries are mainly due to the formation of inorganic rich (such as LiF and Li2O) solid electrolyte interphase (SEI) on LMA and cathode electrolyte interphase (CEI) in these electrolytes. The monolithic solid electrolyte interphase (SEI) generated in some of these electrolytes is largely different with those of mosaic- or multilayer-type SEIs reported before. These electrolytes not only can improve the stability of LMA, but also greatly suppresses the phase transformation (from layer structure to rock salt) of the cathode and prevent dissolution of transition metal element in bulk cathode. Therefore, excellent cell performances in terms of long-term cycling stability and high rate capability is realized in high voltage LMBs together with reduced safety concerns. The fundamental mechanism behind the stability of these electrolytes to both LMA and high voltage cathode will also be discussed.

High-performance lithium metal batteries with ultraconformal interfacial contacts of quasi-solid electrolyte to electrodes

We report an in-situ strategy initiating polymerization of liquid electrolytes in electrochemical cells to produce quasi-solid electrolytes with cross-linked structure; with such a strategy, ultraconformal interfacial contacts between cathode/electrolyte and electrolyte/anode are created. The solid electrolyte exhibits a high ionic conductivity of 4.3 ​mS ​cm−1, a Li-ion transference number of 0.55 ​at room temperature and a wide electrochemical window of 5.2 ​V. The robust LiF-rich solid electrolyte interphase (SEI) layer on the Li anode effectively prevents the dendrite growth and the pulverization of the Li anode. By applying the quasi-solid electrolyte in Li–LiNi0.85Co0.05Al0.1O2 (NCA), Li–LiNi0.6Co0.2Mn0.2O2 (NCM622) batteries, high specific discharge capacities and long cycling lifetime are achieved at large current densities. This work demonstrates the tremendous potential of the in-situ strategy in promoting the application of high-voltage Li metal batteries.

An All-Fluorinated Ester Electrolyte for Stable High-Voltage Li Metal Batteries Capable of Ultra-Low-Temperature Operation

Improving the energy output of batteries at sub-zero temperatures is crucial to the long-term application of advanced electronics in extreme environments. This can generally be accomplished by empl...

Synergistic effect of organic plasticizer and lepidolite filler on polymer electrolytes for all-solid high-voltage Li–metal batteries

Synergistic effect of organic plasticizer and lepidolite filler on polymer electrolytes enables high performance all-solid high-voltage Li–metal batteries.

Stable cycling of high-voltage lithium metal batteries in ether electrolytes

The key to enabling long-term cycling stability of high-voltage lithium (Li) metal batteries is the development of functional electrolytes that are stable against both Li anodes and high-voltage (above 4 V versus Li/Li+) cathodes. Due to their limited oxidative stability ( 90% over 300 cycles and ~80% over 500 cycles with a charge cut-off voltage of 4.3 V. This study offers a promising approach to enable ether-based electrolytes for high-voltage Li metal battery applications. Ether-based electrolytes offer many advantages compared to other electrolyte systems, but they are not stable in Li metal batteries when operating at high voltages. Here, the authors develop a concentrated ether electrolyte that enables long-term cycling stability of high-voltage Li metal batteries.