Unraveling transition metal dissolution of Li1.04Ni1/3Co1/3Mn1/3O2 (NCM 111) in lithium ion full cells by using the total reflection X-ray fluorescence technique

Mn2+ or Mn3+? Investigating transition metal dissolution of manganese species in lithium ion battery electrolytes by capillary electrophoresis

“…Furthermore, it can be noted that the total amount of dissolved manganese (Mn 3+ and Mn 2+ ) increased with lower pH. This was in good agreement with previous results, which reported the accelerated dissolution of manganese under acidic conditions [17, 18, 21, 31, 34, 35]. In contrast to the expected Mn 2+ from disproportionation reaction, the diphosphate led mainly to the formation of Mn 3+ .…”

“…Dissolution experiments with LNMO powder in buffered aqueous diphosphate solutions at defined pH were performed to investigate the formation of manganese species in the presence of a TM‐ion‐scavenging agent. These experiments showed mainly the formation of Mn 3+ with increased concentrations at lower pH, which was in line with previous reported results [17, 18, 21, 31, 34, 35]. Also, the formation of mainly Mn 3+ was in good agreement to a study, in which polymeric aza‐15‐crown‐5 ethers were used for Mn‐ion‐scavenging in LMO‐cells [25].…”

“…In the first charge–discharge cycles, a solid electrolyte interphase (SEI) is formed at the anode surface, protecting the electrolyte from further decomposition [11–14]. During LIB operation, transition metal (TM) ions can dissolve from the cathode, migrate through the electrolyte to the anode, and are subsequently incorporated into the SEI or are reduced to metal [15–19]. These effects eventually lead to increased cell impedance, more side reactions, and finally to reduced life [16, 20, 21].…”

“…Dissolution of manganese was observed for a variety of cathode materials [16, 17, 20, 21, 28–33]. In addition to dissolution mechanisms like corrosion or structural deformation, dissolution by disproportionation reaction of surficial Mn 3+ to Mn 4+ and soluble Mn 2+ is mainly reported in the literature [7, 17, 18, 20, 21, 29, 30, 34–36]. Several more recent studies found dissolved manganese to be mainly in oxidation state +3 not in +2, which is in contradiction to established reports.…”

Minimized Metal Dissolution from High-Energy Nickel Cobalt Manganese Oxide Cathodes with Al2O3 Coating and Its Effects on Electrolyte Decomposition on Graphite Anodes

“…[4][5][6][7] The previous report about the capacity recovery of NCM cathodes collected from full cells suggests the deterioration of anode is the main cause of full cell degradation. 8 Although transition metal dissolution from various cathodes has been studied extensively, [9][10][11][12][13] the effect of transition metal dissolution on the SEI layer of anode has not been well-established due to the large number of different materials investigated. Dissolved transition metal ions accumulate on the anode, where they induce additional side reactions of electrolyte, continuous SEI growth and further the loss of active lithium.…”