Double Conductor Coating to Improve the Structural Stability and Electrochemical Performance of LiNi_0.8Co_0.1Mn_0.1O₂ Cathode Material

Abstract

LiNi x Co y Mn1–x–y O2 (NCM) is identified as the most typical cathode material on account of high specific capacity, cheaper cost, and good security. Nevertheless, the storage environment of NCM is inferior, whose surface lithium compounds could cause side reactions and corrode the electrode. Herein, we propose a strategy to synergistically modify the NCM cathode material with the ionic conductor (LiBO2) and electronic conductor [poly­(3,4-ethylenedioxythiophene), PEDOT], whose mechanism was comprehensively investigated in detail using material characterizations and electrochemical measurements. Benefiting from the multiple effects of the dual conductor, surface residual alkali and impurities of NCM were significantly reduced, and the corresponding side reactions was effectively inhibited, which further improved the interfacial stability and slowed down the formation of rock salt impurity phases. As a consequence, the modified sample exhibited an outstanding electrochemical property with a retention of 95.44% at 1 C after 100 cycles, which provides a new understanding for the modification strategy and efficient service of nickel-rich cathode materials for lithium-ion batteries.

Recent progress in Co‐free, Ni‐rich cathode materials for lithium‐ion batteries

“…Thus, research has focused on this kind of NCM surface coating strategy, and it is well known for its success in improving battery performance. 72,[93][94][95][96][97] Additionally, layered NCM cathodes substituted with metal ions (e.g., Mg, Zr, Y, La, Ti, and Nb) also solved problems that occurred during continuous cyclability tests. The partial substitution of metal ions has a significant effect on preventing cation mixing, electrolyte catalytic reactions, and multiphase transitions, and it often results in improved electrochemical performance.…”

“…The NCM@Li 2 MnO 3 cathode maintained ~80% capacity retention after 500 cycles, which was significantly greater than the bare NCM (~63%) cathode material, resulting in improved cycling stability (Figure 2c). Thus, research has focused on this kind of NCM surface coating strategy, and it is well known for its success in improving battery performance 72,93–97 …”

One Stone Three Birds: Na–Zr Co-Doping and Li6Zr2O7 Coating Enhance the Structural Stability and Electrochemical Performance of the LiNi0.8Co0.1Mn0.1O2 Cathode Material

“…14−16 Coating is a common means of forming a coating on the surface of the cathode material by a dry or wet method. The role of the coating layer has the following points: (1) restrain surface side reactions; (2) slow dissolution of transition metals; and (3) form thinner CEI films to reduce the precipitation of oxygen atoms. 17 Common coating materials are metal oxides, 18 lithium salts, 19 rare earth compounds, 20 fluoride, 21 and nitride.…”

“…Since Sony introduced the lithium-ion battery (LIB) to the public in the 1990s, LIB research has continued to progress . The core units of the battery contain cathode material, anode material, diaphragm, and electrolyte, where the proportion of cathode material is about 1/3. – It is the most critical material in LIBs. Ni–Co–Mn ternary cathode materials are considered to be very foreground cathode material because of their high working voltage, remarkably cycle stability, fair price, and large specific capacity.…”

Chemical Cross‐linked Electrode–Electrolyte Interface Boosting the Structural Integrity of High Nickel Cathode Materials

“…[12][13][14][15][16][17][18][19][20][21][22] Surface coating is a traditional modification strategy to enhance the interface stability of NCM, whose key mechanism is that the coating layer serves as a shield barrier between NCM and electrolyte, enhancing the interfacial chemical properties, and mitigating the occurrence of side reactions. [23][24][25][26] However, no matter how the high-nickel cathode materials are modified, the adverse side reactions always ultimately occur at the electrode side. Therefore, it is crucial to construct a stable and robust electrode-electrolyte interface (CEI).…”