Development of cathode-electrolyte-interphase for safer lithium batteries

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The growing demand for sustainable energy storage devices requires rechargeable lithium‐ion batteries (LIBs) with higher specific capacity and stricter safety standards. Ni‐rich layered transition metal oxides outperform other cathode materials and have attracted much attention in both academia and industry. Lithium‐ion batteries composed of Ni‐rich layered cathodes and graphite anodes (or Li‐metal anodes) are suitable to meet the energy requirements of the next generation of rechargeable batteries. However, the instability of Ni‐rich cathodes poses serious challenges to large‐scale commercialization. This paper reviews various degradation processes occurring at the cathode, anode, and electrolyte in Ni‐rich cathode‐based LIBs. It highlights the recent achievements in developing new stabilization strategies for the various battery components in future Ni‐rich cathode‐based LIBs.

Section: Degradation Mechanismsmentioning

confidence: 99%

A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

Jiang

Danilov

Eichel

et al. 2021

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180

“…Meanwhile, the construction of robust electrode‐electrolyte interface (EEI) has been regarded as a fascinating strategy to relieve these above‐mentioned safety concerns and enhance the electrochemical properties. [ 29–36 ] The robust EEI can significantly mitigate the release of oxygen, and suppress the interfacial side reactions. Moreover, the formation approach is perfectly compatible with the current battery technology for industrial manufacture.…”

Section: Introductionmentioning

confidence: 99%

High‐Voltage and High‐Safety Practical Lithium Batteries with Ethylene Carbonate‐Free Electrolyte

Ren

Liu

et al. 2021

Self Cite

Serious safety issues are impeding the widespread adoption of high‐energy lithium‐ion batteries for transportation electrification and large‐scale grid storage. Herein, a triple‐salt ethylene carbonate (EC) free electrolyte for high‐safety and high‐energy pouch‐type LiNi0.8Mn0.1Co0.1O2|graphite (NMC811|Gr) cells is reported. This EC‐free electrolyte can effectively stabilize the NMC811 surface under high potential (up to 4.5 V), as well as generate a stable interphase to achieve a superior compatibility with the Gr anode. The electrolyte strategy enables significantly enhanced intrinsic safety (trigger temperature of thermal runaway (TR) increased by 67.0 °C), excellent electrochemical properties (4.2V, ≈100% after 200 cycles), and superior high voltage stability (4.5 V, 82.1% after 200 cycles). The work opens up a new avenue for developing novel electrolyte systems to build safer high‐energy batteries for practical applications.

“…[5] Similarly, LCO suffers from serious electrolyte decomposition and irreversible phase transformation, especially when the cut-off voltage was increased to 4.6 V. [6] Two different strategies have been developed to fabricate a favorable cathode-electrolyte-interphase (CEI), usually nanometer-scale in thickness, either from the active material side or from the electrolytes' side. [7] The former strategy includes various surface coatings on Ni-rich NCM and LCO cathodes, such as Al 2 O 3 , [8] AlF 3 , [9] Li 2 ZrO 3 , [2b,10] SiO 2 , [11] etc. However, the introduced metal oxide coatings usually require a high-temperature sintering process, which may damage the cathode lattice structure.…”

Section: Introductionmentioning

confidence: 99%

Electrolytes Polymerization‐Induced Cathode‐Electrolyte‐Interphase for High Voltage Lithium‐Ion Batteries

Yang

Liu

Wang

et al. 2021

Self Cite

However, the cycling stability of NCM cathodes cannot meet the commercial requirement, especially with increased Ni contents or charge cut-off voltage. [1c,d] The interfacial instability is especially critical for the nickel-rich NCM cathodes (for example, LiNi 0.8 Co 0.1 Mn 0.1 O 2 , NCM811) since the NiO bond on the surface is easy to be attacked by acid components in the electrolytes. The surface Ni 4+ intermediate induced by the simultaneous metal-to-ligand electron transfer can further oxidize the organic ingredients in the electrolytes, leading to gas generation and impedance increase. [2] The in situ Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) results confirmed that ethylene carbonate (EC), which was believed to be stable up to 4.8 V on Pt surfaces, could be decomposed on the NCM811 surface at a much lower voltage of 3.8 V. [3] Moreover, the Ni 4+ cations suffer from migration after most of the lithium is extracted from the lattice, thus resulting in a layered-spinel-rock salt phase transformation. [4] Another commercial cathode material, lithium cobalt oxide (LCO), with a similar layer crystal structure, has a higher volumetric energy density than NCM cathodes due Lithium-ion batteries (LIBs) based on LiNi x Co y Mn 1-x-y O 2 (NCM) cathode materials have been widely commercialized, because of their high energy density, favorable rate performance, and relatively low cost. However, with increased Ni content to further increase their energy density, their cycling stability deteriorates dramatically and thus fails to meet the commercial application requirements. The artificial cathode-electrolyte-interphase (CEI) is a promising approach to solve this problem. Here, a robust CEI is fabricated through in situ polymerization of ethylene carbonate induced by aluminum isopropoxide (AIP). By adding 1 wt.% AIP in a commercial electrolyte, the capacity retention of LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||Li cell at 1 C rate has been significantly increased from 80.8% to 97.8% with a highly reversible capacity of 176 mA h g -1 after 200 cycles. AIP can be also used as an additive during the slurry-making process, enabling a reversible capacity of 170 mA h g -1 for LiCoO 2 after 200 cycles even at a high charge cut-off voltage of 4.6 V. It is confirmed that the in situ formed CEI layer can prevent the cathodes from cracking and reduce the irreversible phase transformation.