Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

Andrei Dolocan,Hugo Celio,Arumugam Manthiram,Pilgun Oh,Jaephil Cho,Suhyeon Park,Wangda Li

doi:10.1038/ncomms14589

Abstract

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.

Highlights

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries
Potential candidates include Ni-rich layered oxides[6,7,8] (LiNi1-xMxO2 with M 1⁄4 metal B4.5 V), Li-rich layered oxides[9,10,11] (Li1 þ xM1-xO2 with B4.7 V), high-voltage spinel oxides[12,13] (LiNi0.5Mn1.5O4 with B4.8 V) and high-voltage polyanionic compounds[14,15,16]. These cathodes suffer from limited service life due to aggressive electrochemical degradation initiated at the electrode–electrolyte interface
By applying ROI analysis on the TOF-SIMS spectra, we show that this in situ generated cathode-electrolyte interphase (CEI) originates from the mutual exchange of interphasial species between the active cathode particles and carbon (Fig. 6)

Summary

Introduction

Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Considerable interest has been directed towards the development of reliable, low-cost, high-energy-density rechargeable Li-ion batteries to meet the demands of multiple emerging fields, such as advanced robotics, electric vehicles and grid storage[1,2,3,4,5] This has motivated extensive investigation of cathode materials with higher operating voltages B4.2 V vths anLi/cLoinþv)enttoionmalaxLimiCiozeO2en(eurpgpye-rstocruatgoeff voltage of capabilities. As the quest for alternative, non-reacting electrolyte combinations is a formidable task, most efforts tackling the unsatisfactory cycle life of these high-voltage cathodes attempt to enhance the electrode–electrolyte interface stability with the formation of a stable, robust passivation film, similar to the solid-electrolyte interphase formed on graphite[2,4,17,24] This is achieved ex situ by coating or doping of active cathode particles[25,26,27], or in situ by employing electrolyte additives[28,29]. The understanding of interphases formed on cathode materials in existing cell configurations is rather limited as well, in part due to complex influences of the ‘inactive’

Methods

Results

Conclusion