Crossover Effects in Batteries with High‐Nickel Cathodes and Lithium‐Metal Anodes

Abstract

It is well understood that cathode‐to‐anode crossover, especially of transition‐metal ions, can significantly impact the long‐term cycling of lithium‐ion batteries. The dissolved transition‐metal ions in lithium‐ion cells deposit on the graphite anode, disrupt the solid‐electrolyte interphase (SEI), and catalyze further side reactions. Meanwhile, crossover effects in lithium‐metal batteries have rarely been studied. This study is the first to investigate crossover effects in lithium‐metal batteries with high‐nickel layered‐oxide cathodes. It is shown that the crossover of transition‐metal ions from LiNi0.9Mn0.05Co0.05O2 has minimal effect on the lithium‐metal anode (LMA) due to the following reasons. The catalytic transition metals 1) have less effect on an inherently reactive LMA, 2) are diluted in a thicker SEI, and 3) are produced in overall lower quantity due to the limited cycle life of the LMA. Conversely, the LMA generates soluble decomposition products that cross over to the cathode even during early cycling. This crossover accelerates impedance growth and capacity fade at the cathode and is partially responsible for the mismatch between the performance of half and full‐cells with layered‐oxide cathodes. This study highlights the need for better battery design with LMA, potentially including electrolyte or cell modifications.

The influence of electrochemical cycling protocols on capacity loss in nickel-rich lithium-ion batteries

“…3,4,6,45,51,52 However, electrolyte degradation products formed at the reactive lithium metal surface can cross the separator and react at the NMC surface (termed cross-talk) leading to degradation that is not representative of the full cell chemistry. 53,54 Others have built and cycled full cells with an electrochemically pre-lithiated graphite anode, 55 Using DVA we also detect a high voltage NMC degradation mechanism leading to capacity loss at potentials >4.1 V vs Li/Li + (Figure 3e, f). The post-test half-cell experiments with aged NMC811 cathodes (Figure 5c) also provide support for this aging process.…”

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

“…The crossover effect in batteries with a Ni‐rich cathode and Li‐metal anode (LiNi 0.9 Mn 0.05 Co 0.05 O 2 /Li) has been thoroughly investigated by Langdon and Manthiram. [ 83 ] Figure 17d shows optical and SEM images of cycled Li‐metal anodes from disassembled cells. Gradually dark and rough surfaces with spatial inhomogeneities can clearly be observed with increasing cycle number, suggesting the formation of a brittle SEI film at the Li‐metal anode.…”

A Self‐Healable Sulfide/Polymer Composite Electrolyte for Long‐Life, Low‐Lithium‐Excess Lithium‐Metal Batteries

“…High-Nickel Cathode: LiNi 0.9 Mn 0.05 Co 0.05 O 2 (NMC) was synthesized with a coprecipitation method in-house. [69] Typically, stoichiometric amounts of the transition-metal salts (NiSO 4 •6H 2 O, MnSO 4 •H 2 O, and CoSO 4 •7H 2 O) were added together to deionized water. Separately, a solution of NH 4 OH and KOH was controllably added to the salt solution into a stirred tank reactor.…”