High Cut-off Voltage Research Articles

Effect of Fluoroethylene Carbonate Electrolyte Additives on the Electrochemical Performance of Nickel-Rich NCM Ternary Cathodes

It has been well established recently that fluorinated electrolyte additives such as fluoroethylene carbonate (FEC) could promote the formation of LiF-based solid electrolyte interphases that can stabilize lithium metal anodes. Meanwhile, the impact of FEC additives on the cathode side, particularly for the high energy density nickel-rich LiNi1–x–yCoxMnyO2 (NCM) ternary cathodes, remains unclear. In this study, we investigated the structural and chemical composition of a cathode electrolyte interphase (CEI) and its electrochemical performance to elucidate the effect of FEC additives on the LiNi0.9Co0.05Mn0.05O2 (NCM90) cathode for high energy lithium-ion batteries. It is discovered that the FEC additive in carbonate electrolyte (BE-FEC) can produce a LiF-based CEI, which could stabilize the NCM90 surface and improve the cycle performance at low cut-off voltage. The formation of a thick LiF layer under high cut-off voltage and high rate has been observed to result in increased polarization and slower Li+ transport kinetics, ultimately leading to a deterioration in battery performance. On the other hand, in a carbonate electrolyte (BE) and under low voltage, the unstable Li2CO3-based CEI components on the NCM90 surface with an intermediate rock salt phase in between contribute to poor long-term performance and reduced reliability. While under high voltage, the BE sample shows superior electrochemical performance due to the formation of a thin LiF layer from the decomposition of LiPF6. Our work provides a comprehensive understanding of the role of FEC in the CEI of nickel-rich cathodes, offering practical guidance for the design of electrolytes for high-energy high-voltage nickel-rich cathodes.

Electrochemical Aging Protocol Governed Capacity Losses and Structure Degradations in Layered LiNi0.8 Co0.1 Mn0.1 O2 Oxides.

The comparatively poor endurance of Ni-rich cathode materials restricts their application in high-energy lithium-ion batteries. A thorough understanding of the degradation characteristics of such materials under complex electrochemical aging protocols is required to further improve their reliability. In this work, the irreversible capacity losses of LiNi0.8 Mn0.1 Co0.1 O2 under different electrochemical aging protocols are quantitatively evaluated via a well-designed experiment. In addition, it is discovered that the origin of irreversible capacity losses is highly related to electrochemical cycling parameters and can be divided into two types. Type I is heterogeneous degradation caused by low C-rate or high upper cut-off voltage cycling and features abundant capacity loss during H2-H3 phase transition. Such capacity loss is attributed to the irreversible surface phase transition that limits the accessible state of charge during the H2-H3 phase transition stage via the pinning effect. Type II is fast charging/discharging induced homogeneous capacity loss that occurs consistently throughout the whole phase transition time. This degradation pathway shows a distinctive surface crystal structure, which is dominated by a bending layered structure rather than a typical rock-salt phase structure. This work offers detailed insight into the failure mechanism of Ni-rich cathodes and provides guidance on designing long-cycle life, high-reliability electrode materials.

LiMgPO4 -Coating-Induced Phosphate Shell and Bulk Mg-Doping Enables Stable Ultra-High-Voltage Cycling of LiCoO2 Cathode.

Stable cycling of LiCoO2 (LCO) cathode at high voltage is extremely challenging due to the notable structural instability in deeply delithiated states. Here, using the sol-gel coating method, LCO materials (LMP-LCO) are obtained with bulk Mg-doping and surface LiMgPO4 /Li3 PO4 (LMP/LPO) coating. The experimental results suggest that the simultaneous modification in the bulk and at the surface is demonstrated to be highly effective in improving the high-voltage performance of LCO. LMP-LCO cathodes deliver 149.8mAhg-1 @4.60 V and 146.1mAhg-1 @4.65 V after 200 cycles at 1C. For higher cut-off voltages, 4.70 and 4.80V, LMP-LCO cathodes still achieve 144.9mAhg-1 after 150 cycles and 136.8mAhg-1 after 100 cycles at 1C, respectively. Bulk Mg-dopants enhance the ionicity of CoO bond by tailoring the band centers of Co 3d and O 2p, promoting stable redox on O2- , and thus enhancing stable cycling at high cut-off voltages. Meanwhile, LMP/LPO surface coating suppresses detrimental surface side reactions while allowing facile Li-ion diffusion. The mechanism of high-voltage cycling stability is investigated by combining experimental characterizations and theoretical calculations. This study proposes a strategy of surface-to-bulk simultaneous modification to achieve superior structural stability at high voltages.

High-voltage electrolyte design for a Ni-rich layered oxide cathode for lithium-ion batteries

LiNi0.8Co0.1Mn0.1O2 (NCM811) is one of the most promising cathode materials in high-energy-density Li-ion batteries (LIBs) because of its high capacity and low cost. However, it still suffers from irreversible capacity fading at high cut-off voltages. This is mainly because high voltage accelerates the hydrolysis reaction of lithium hexafluorophosphate with trace water to generate byproducts such as highly corrosive hydrogen fluoride (HF) resulting in an unstable cathode–electrolyte interface and continuous irreversible phase transitions. Here, we modify a conventional electrolyte by adding the dual additives of tetrabutyl titanate (TBT) and lithium difluoroxalate borate (LiDFOB) to form a stable Ti-, B-, and F-rich interfacial layer to eliminate the unfavorable cathode-electrolyte side reactions and suppress deleterious phase transitions. Additionally, TBT can stabilize the electrolyte by removing H2O/HF. With the synergistic effect of the dual additives, the cycling stability of NCM811 at high voltages is enhanced considerably. The Li∣NCM811 cell with dual additives exhibits a high capacity retention rate of 86% after 200 cycles at 1 C and a high cut-off voltage of 4.5 V. This strategy provides a reference for designing high-voltage electrolytes for LIBs.

Electrochemical performance enhancement of LiNi0.6Co0.2Mn0.2O2 at high cut-off voltage by aluminum-doped polypyrrole coating

LiNi0.6Co0.2Mn0.2O2 (NCM622) is a kind of high nickel ternary cathode materials for lithium-ion batteries with high energy density and high discharge platform. However, the insufficient electron/ion conductivities and corrosion of hydrofluoric acid have limited its practical usage. In overcoming the challenges, it is particularly important to find a method that can improve both electronic and ionic conductivities of such a material. In this study, aluminum (Al)-doped polypyrrole (Al@PPy) is used to coat NCM to improve its rate and cycling performance. Compared with the uncoated NCM, Al@PPy-NCM has more electron/ion transport channels and much better cycling stability. It has an initial capacity of 224.3 mAh/g at a current density of 20 mA/g, and a capacity retention rate of 91.6% after 100 cycles in voltage range of 3.0–4.5 V. At a current density of 200 mA/g, the initial capacity can still be 185.1 mAh/g, and the capacity retention rate can maintain at 88.1% after 200 cycles.

High-Performance Dual-Ion Battery Based on Silicon-Graphene Composite Anode and Expanded Graphite Cathode.

Dual-ion batteries (DIBs) are a new kind of energy storage device that store energy involving the intercalation of both anions and cations on the cathode and anode simultaneously. They feature high output voltage, low cost, and good safety. Graphite was usually used as the cathode electrode because it could accommodate the intercalation of anions (i.e., PF6-, BF4-, ClO4-) at high cut-off voltages (up to 5.2 V vs. Li+/Li). The alloying-type anode of Si can react with cations and boost an extreme theoretic storage capacity of 4200 mAh g-1. Therefore, it is an efficient method to improve the energy density of DIBs by combining graphite cathodes with high-capacity silicon anodes. However, the huge volume expansion and poor electrical conductivity of Si hinders its practical application. Up to now, there have been only a few reports about exploring Si as an anode in DIBs. Herein, we prepared a strongly coupled silicon and graphene composite (Si@G) anode through in-situ electrostatic self-assembly and a post-annealing reduction process and investigated it as an anode in full DIBs together with home-made expanded graphite (EG) as a fast kinetic cathode. Half-cell tests showed that the as-prepared Si@G anode could retain a maximum specific capacity of 1182.4 mAh g-1 after 100 cycles, whereas the bare Si anode only maintained 435.8 mAh g-1. Moreover, the full Si@G//EG DIBs achieved a high energy density of 367.84 Wh kg-1 at a power density of 855.43 W kg-1. The impressed electrochemical performances could be ascribed to the controlled volume expansion and improved conductivity as well as matched kinetics between the anode and cathode. Thus, this work offers a promising exploration for high energy DIBs.

Effect of the PrPO4 modification on the structure and electrochemical performance of LiCoO2

Increasing interest in LiCoO2 as a cathode material for Li-ion batteries has recently arisen due to its high operating voltage, high energy density and long cycle life. However, irreversible structural damage and severe side reactions at high cut-off voltages severely deteriorate the electrochemical performance of LiCoO2 materials, resulting in a series of safety issues when used in batteries. In this work, PrPO4, Li2CO3 and Co3O4 are mixed and then treated at a high temperature to obtain PrPO4-modified LiCoO2 with improved electrochemical performance at 4.55 V. XRD and Rietveld refinement results confirm that the modified LiCoO2 materials exhibit well-ordered structures with compact unit cells. PrPO4 is not incorporated into the crystal lattice of LiCoO2 but converted by Li2O and Co3O4 into PrCoO3 and Li3PO4 phases during the reaction. Additionally, these two phases are well-incorporated into the LiCoO2 particle. Electrochemical tests indicate that the irreversible capacity during cycling is significantly reduced by PrPO4 modification. Benefiting from the enhanced interface stability induced by Li3PO4 and PrCoO3, the 1 mol% PrPO4-modified LiCoO2 sample exhibits an initial discharge capacity of 185 mAhg−1 at 0.5C with a capacity retention of 92.4% after 100 cycles, as well as an excellent rate capability with a capacity of 128 mAhg−1 even at 5C.

Comparative Study of High-Temperature Cycling and Thermal Stability of LLOs and NCMs under Medium–High Voltage

Lithium-rich layered oxides (LLOs) are considered as one of the most potential layered cathode materials due to their high discharge specific capacity, low cost, and environmental friendliness. However, the decomposition of electrolytes at high voltages (4.7 V) limits the commercial application of LLOs. Furthermore, to meet the demand for high energy density, lithium nickel cobalt manganese oxides (NCMs) need to improve their working voltage. In limited conditions, all LLOs and NCMs need to be used under the medium–high (4.4–4.6 V) cutoff voltage. Herein, we compare the performance of LLOs and NCMs in the voltage window with a medium–high cutoff voltage. Results show that after 100 cycles at high temperature (45 °C), the capacity retention rate of LLO is 98.68%, while that of NCMs is 78.15–96.93%. Differential scanning calorimetry reveals that the exothermic temperature of LLO is increased by 60–100 °C, and thermal release is reduced by 33–93%. LLOs have obvious advantages under medium–high voltages and a promising application prospect. This work systematically analyzes and compares LLOs and NCMs under medium–high voltage, providing guidance for the industrialization of LLOs.

Armor-like Inorganic-rich Cathode Electrolyte Interphase Enabled by the Pentafluorophenylboronic Acid Additive for High-voltage Li||NCM622 Batteries.

Lithium metal batteries (LMBs) comprising Li metal anode and high-voltage nickel-rich cathode could potentially realize high capacity and power density. However, suitable electrolytes to tolerate the oxidation on the cathode at high cut-off voltage are urgently needed. Herein, we present an armor-like inorganic-rich cathode electrolyte interphase (CEI) strategy for exploring oxidation-resistant electrolytes for sustaining 4.8 V Li||LiNi0.6 Co0.2 Mn0.2 O2 (NCM622) batteries with pentafluorophenylboronic acid (PFPBA) as the additive. In such CEI, the armored lithium borate surrounded by CEI up-layer represses the dissolution of inner CEI moieties and also improves the Li+ conductivity of CEI while abundant LiF is distributed over whole CEI to enhance the mechanical stability and Li+ conductivity compared with polymer moieties. With such robust Li+ conductive CEI, the Li||NCM622 battery delivered excellent stability at 4.6 V cut-off voltage with 91.2 % capacity retention after 400 cycles. The excellent cycling performance was also obtained even at 4.8 V cut-off voltage.

Ultra-high voltage solid-state Li metal batteries enabled by in-situ construction of cathode electrolyte interphase through synergistic dual-anion decomposition

Due to their high operating voltages, energy densities and safety performance, all solid-state Li metal batteries (ASSLMB) share a bright application prospect. However, the poor ion transport and contact issue at cathode electrolyte interphase (CEI) will easily lead to severe capacity degradation at high operating voltages, which remained as the bottleneck problem for ASSLMB. In this work, a CEI layer consisting of LiF and LixBOyFz was in-situly constructed through the synergistic decomposition of DFOB− and TFSI− from ionic liquids. At high operating voltages, this stable and thin CEI layer could not only protect the ionic liquid-based electrolytes by suppressing the polarizations and side reactions on the cathodic surfaces, but also facilitate the transfer of interfacial lithium ions. When tested at 0.1C and 60 °C with a high cut-off voltage of 4.5 V, this ASSLMB possessed an initial specific capacity of 190.7 mA h g − 1 and an 80% capacity retention after 100 cycles. Our findings provide a promising approach to realize ionic liquid-based electrolytes in high-voltage ASSLMBs.

In Situ Formed Heterostructure Interface and Well-Tuned Electronic Structure Ensuring Long Cycle Stability for 4.9 V High-Voltage Li-Rich Layered Oxide Cathodes

High-voltage lithium-rich manganese-based layered oxides (LMLOs) are considered as the most competitive cathode materials for next-generation high-energy-density lithium-ion batteries (LIBs). However, LMLOs still suffer from irreversible lattice oxygen release, uncontrollable interface side reactions, and surface structural degradation. Herein, we propose an integration strategy combining La/Al codoping and LixCoPO4 nanocoating to improve the electrochemical performance of LMLOs comprehensively. La/Al codoping regulates the electronic structure to enhance the redox activity of anions and cations and inhibit structural degradation. The LixCoPO4 nanocoating formed by in situ reaction with the surface residual lithium can not only promote Li-ion migration but also reduce interfacial side reactions. The induced Layered@Rocksalt@LixCoPO4 heterostructure suppresses lattice volume variation and structural degradation during cycling. Under the synergistic effect of the heterostructure interface and well-tuned electronic structure, the capacity retention rate of comodified LMLO materials reaches 80.06% after 500 cycles (2.0-4.65 V) and 75.1% after 340 cycles at 1C under a high cut-off voltage of 4.9 V.

Extending the high-voltage operation of Graphite/NCM811 cells by constructing a robust electrode/electrolyte interphase layer

The cycling life of layered Ni-rich LiNi1-x-yCoxMnyO2 (NCM, 1-x-y ≥ 0.8) is typically extended by restricting the upper cut-off voltage during cycling to below 4.2 V, sacrificing, however, the untapped additional capacity above the cut-off voltage. To make this additional capacity available, we investigate graphite/LiNi0·8Co0·1Mn0·1O2 cells cycled to high upper cut-off voltages up to 4.5 V at high electrode areal capacities of 4.8 mAh/cm2 in a standard electrolyte consisting of 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate and ethylene methyl carbonate (ethylene carbonate:ethylene methyl carbonate = 3:7 vol% + 2% vinylene carbonate). Although the initial capacity reaches 190 mAh/g, the capacity retention after 300 cycles to 4.5 V is only 66%. Employing a combination of tris(trimethylsilyl)phosphite and lithium difluoro(oxalato)borate as electrolyte additives, we demonstrate excellent capacity retention of 85% after 300 cycles to 4.5 V. Moreover, graphite/LiNi0·8Co0·1Mn0·1O2 cells with additives show improved capacity retention also at elevated temperatures of 60 °C. A detailed post-mortem analysis reveals the formation of a compact and LiF-rich and B-containing cathode/electrolyte interphase layer on the LiNi0·8Co0·1Mn0·1O2 particles cycled with tris(trimethylsilyl)phosphite and lithium difluoro(oxalato)borate additives, substantially suppressing the transition metal dissolution and the cation-disordered layer formation on the exposed particles' surface.

Synergistic structure of LiFeO2 and Fe2O3 layers with electrostatic shielding effect to suppress surface lattice oxygen release of Ni-rich cathode

The Ni-rich cathodes used for lithium-ion batteries (LIBs) suffer from severe surface side reactions, slow kinetics, and microcracks during long-term cycling. To address these problems, a dual-modified protective coating consisting of LiFeO2&Fe2O3 layers (denoted as LFO) was fabricated on the surface of the cathode material LiNi0.8Co0.1Mn0.1O2 (NCM811) by capturing the lithium impurities in the electrolyte solution using an electric field. The LiFeO2 layer acts as an ionic conductor, accelerating interfacial Li+ transport, and exhibits a synergistic effect with the bulk material during the charging/discharging process. The Fe2O3 layer, which contains abundant oxygen vacancies, acts as an electrostatic shielding layer and effectively inhibits the outward migration of Oα− (α < 2), thus improving the structural stability. Hence, the interface-protected NCM@LFO3 cathode showed excellent cycling stability (capacity retention of 82.4% after 600 cycles at 1 C) and even at a high cut-off voltage of 4.5 V (capacity retention of 88.9 % after 200 cycles at 1 C).

Probing the particle size dependence of nonhomogeneous degradation in nickel-rich cathodes for high-energy lithium-ion batteries

Increasing the loading and calendering density of Ni-rich cathodes by adopting a mixture of small to large particles is a practical way to create high-energy lithium-ion batteries. However, high-energy lithium-ion batteries using this type of Ni-rich electrode still suffer from rapid capacity degradation. In this work, the nonhomogeneous degradation of a Ni-rich cathode is characterized by particle size using a commercial 320 Wh kg−1 pouch cell. The correlation between the volume change (ΔV) and state-of-charge (SOC) of the cathode particles with different diameters (D) is determined using in situ transmission X-ray diffraction and numerical simulations. At 0.2 C, minor differences occur in the SOC between the small (D = 5 μm) and large (D = 25 μm) particles. However, at 3 C, the SOC and ΔV of the small particles are 1.03 and 1.11 times higher than those of the large particles, respectively. This work demonstrates that size-dependent nonhomogeneity is undesirable because it promotes the performance decay of Ni-rich cathodes, especially at high cutoff voltages and rates.

Weakly Solvating Cyclic Ether Electrolyte for High-Voltage Lithium Metal Batteries

The commercialization of high-voltage lithium (Li) metal batteries (LMBs) has been severely hindered due to the lack of advanced electrolytes that can simultaneously support a stable lithium metal anode (LMA) and high-voltage cathode (>4 V vs Li+/Li). Here, we propose a tetrahydropyran (THP)-based weakly solvating electrolyte (WSE) to regulate Li+ solvation structures and interfacial behaviors. The anion-rich Li+ solvation in THP-based WSE effectively promotes the formation of inorganic-rich solid electrolyte interphase (SEI) layers, firm cathode electrolyte interphase (CEI) films, and protective passivation films on an Al current collector. The optimized interfacial behaviors contribute to the highly compact Li deposition, high-voltage stability, and inhibition of transition metal ion dissolution and Al corrosion. Finally, the Li||LiNi0.5Co0.2Mn0.3O2 full cell delivered stable cycling performance at high cutoff voltages of 4.3 and even 4.5 V. This study demonstrates an exciting approach to enable ether-based electrolytes for high-voltage LMBs and could be developed for other battery systems.

A smart polymer electrolyte coordinates the trade-off between thermal safety and energy density of lithium batteries

In this article, we develop a smart polymer electrolyte through in-situ radical random polymerization of the cyclic carbonate urethane methacrylate monomer and the 2-isocyanatoethyl methacrylate monomer, which coordinates the trade-off between thermal safety and energy density of lithium batteries. It is demonstrated that the as-developed polymer electrolyte can incur the battery thermal shutdown before reaching the thermal runaway temperature. This originates from the highly crosslinking network caused by the nucleophilic addition of carbamate to isocyanate in the polymer matrix under the elevated temperature exceeding 170 °C. Besides, superior cycle performance of 4.5 V-class LiNi0.6Co0.2Mn0.2O2/Li batteries can be achieved, with a capacity retention of 80% after 200 cycles at 0.5 C and 30 °C, owing to enhanced interface compatibility of this polymer electrolyte. Noting that this polymer electrolyte possesses a superior water-scavenging ability, which helps improve the moisture resistance and battery cycle performance. Impressively, this polymer electrolyte can achieve improved energy density and superior safety characteristic of lithium batteries under high cut-off voltage.

Synergistic-effect of diluent to reinforce anion-solvation-derived interfacial chemistry for 4.5 V−class Li||LiCoO2 batteries

Electrolyte engineering-controlled interfacial chemistries on both lithium metal anode (LMA) and high-voltage cathode are key to stable lithium-metal batteries (LMBs). Here, we demonstrate that a kind of local high concentrated electrolyte (LHCE) by introducing an active difluoroethylene carbonate (DFEC) co-solvent can contribute to excellent interfacial chemistries. Unlike the conventional LHCEs, DFEC with lower LUMO energy serves as both additive and diluent, and reinforces the anion-solvation-derived interfacial layers, leading to the suppression of side reactions/dendrite lithium growth and the acceleration of Li+ desolvation/transfer kinetics. Consequently, the assembled high-capacity Li||LiCoO2 full cell (1.836 mAh cm−2) holds a high retention of > 80% over 1000 cycles at 0.3 C under a high cut-off voltage of 4.5 V. More impressively, the addition of DFEC leads to a significant improvement of cycle stability for ∼265 mAh Li||LiCoO2 pouch cells. Designing functional diluent with a synergistic effect that heightens interfacial chemistries to control anion-solvation is very promising and paves a bright way to develop rechargeable LMBs.

Improved Li‐Ion Conduction and (Electro)Chemical Stability at Garnet‐Polymer Interface through Metal‐Nitrogen Bonding

AbstractOrganic‐inorganic composite solid electrolytes consisting of garnet fillers dispersed in polyvinylidene difluoride (PVDF) frameworks have shown promise to enable high‐energy solid‐state Li‐metal batteries. However, the air‐sensitive garnets easily form poorly‐conductive residues, which hinders fast Li‐ion exchange at the garnet‐polymer interface and results in low ionic conductivity. The highly alkaline residues trigger instant dehydrofluorination of PVDF to form unsaturated CC bonds, which are unstable against high‐voltage cathode materials. Here it is shown that, by applying a 10‐nm polydopamine coating on the residue‐removed garnet surface, the modified garnet filler becomes air‐stable and does not generate alkaline residues, so PVDF remains an intact structure. Surface characterizations reveal substantial metal‐nitrogen bonding between the La atoms of garnet and the amino groups of polydopamine, which can invite stronger adsorption of Li ions at the heterointerface. A new interparticle Li‐ion conduction mechanism is disclosed for the composite electrolyte, in which Li ions preferably migrate through the garnet‐polydopamine interface, forming an efficient ion‐percolation network. As a result, the composite electrolyte demonstrates an effective room‐temperature Li+ conductivity of 1.52 × 10–4 S cm–1 and a high cutoff voltage of up to 4.7 V versus Li+/Li to support stable operation of all‐solid‐state Li‐LiCoO2 batteries.

Phosphate-Rich Interface for a Highly Stable and Safe 4.6V LiCoO2 Cathode.

Increasing the upper cut-off voltage of LiCoO2 (LCO) is one of the most efficient strategies to gain high-energy density for current lithium-ion batteries. However, surface instability is expected to be exaggerated with increasing voltage arising from the high reactivity between the delithiated LCO and electrolytes, leading to serious safety concerns. This work is aimed to construct a physically and chemically stable phosphate-rich cathode-electrolyte interface (CEI) on the LCO particles to mitigate this issue. This phosphate-rich CEI is generated during the electrochemical activation by using fluoroethylene carbonate and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyletherare as the solvents. Both solvents also demonstrate high thermal stability, reducing the intrinsic flammability of the commercial organic electrolyte, thereby eliminating the safety concern in the LCO-based systems upon high-voltage operation. This stable CEI layer on the particle surface can also enhance the surface structure by blocking direct contact between LCO and electrolyte, improving the cycling stability. Therefore, by using the proposed electrolyte, the LCO cathode exhibits a high-capacity retention of 76.1% after 200 cycles at a high cut-off voltage of 4.6V. This work provides a novel insight into the rational design of high-voltage and safe battery systems by adopting the flame-retardant electrolyte.

P2-Type Moisture-Stable and High-Voltage-Tolerable Cathodes for High-Energy and Long-Life Sodium-Ion Batteries.

P2-Na0.67Ni0.33Mn0.67O2 represents a promising cathode for Na-ion batteries, but it suffers from severe structural degradation upon storing in a humid atmosphere and cycling at a high cutoff voltage. Here we propose an in situ construction to achieve simultaneous material synthesis and Mg/Sn cosubstitution of Na0.67Ni0.33Mn0.67O2 via one-pot solid-state sintering. The materials exhibit superior structural reversibility and moisture insensitivity. In-operando XRD reveals an essential correlation between cycling stability and phase reversibility, whereas Mg substitution suppressed the P2-O2 phase transition by forming a new Z phase, and Mg/Sn cosubstitution enhanced the P2-Z transition reversibility benefiting from strong Sn-O bonds. DFT calculations disclosed high chemical tolerance to moisture, as the adsorption energy to H2O was lower than that of the pure Na0.67Ni0.33Mn0.67O2. A representative Na0.67Ni0.23Mg0.1Mn0.65Sn0.02O2 cathode exhibits high reversible capacities of 123 mAh g-1 (10 mA g-1), 110 mAh g-1 (200 mA g-1), and 100 mAh g-1 (500 mA g-1) and a high capacity retention of 80% (500 mA g-1, 500 cycles).