Stable Cathode Electrolyte Interface Research Articles

Surface Coating of NCM523 Cathode Electrodes by the Difunctional Block Copolymer/Lithium Salt Composites.

Nickel-rich layered oxide cathodes, such as LiNi0.5Co0.2Mn0.3O2 (NCM523), are prevalent in high-power batteries owing to their high energy density. However, these cathodes suffer from undesirable side reactions occurring at the cathode/liquid electrolyte interface, leading to inferior interface stability and poor cycle life. To address these issues, herein, an amphiphilic diblock copolymer poly(dimethylsiloxane)-block-poly(acrylic acid) (PDMS-b-PAA) along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is utilized for modifying the electrode surface. This modification causes a thin and stable cathode-electrolyte interface (CEI) on the surface of NCM523 particles, as evidenced by XPS, TEM, and EIS analysis. The introduction of this modified interface successfully suppresses the capacity fading of NCM523. After 200 cycles at a rate of 1.0 C, the capacity of the modified NCM523 cathode is 108.7 mAh g-1, with a capacity retention of 82.8%, while the control samples without the polymer modification display a capacity retention of 72.7%. These results outline the distinct advantage of electrode surface modification with diblock copolymers/LiTFSI for the stabilization of Ni-rich layered oxide cathodes.

Double-Salts Super Concentrated Carbonate Electrolyte Boosting Electrochemical Performance of Ni-Rich LiNi0.90Co0.05Mn0.05O2 Lithium Metal Batteries.

Current lithium-ion batteries cannot meet the requirement of higher energy density with further large-scale application of electrical vehicles. Lithium metal batteries combined with Ni-rich layered oxides cathode are expected as the one of promising solutions, while the poor electrode and electrolyte interface impedes the commercial development of lithium metal batteries. A new double-salts super concentrated (DSSC) carbonate electrolyte is proposed to improve the electrochemical performance of LiNi0.90Co0.05Mn0.05O2 (NCM9055)||Li metal battery which exhibits stable cycling performance with the capacity retention of 93.04% and reversible capacity of 173.8 mAh g-1 after 100 cycles at 1 C, while cells with conventional 1m diluted electrolyte remains only 60.55% and capacity of 114.2 mAh g-1. The double salts synergistic effect in super concentrated electrolyte promotes the formation for more balanced stable cathode electrolyte interface (CEI) inorganic compounds of CFx, LiNOx, SOF2, Li2SO4, and less LiF by X-ray photoelectron spectroscopy (XPS)test, and the uniform 2-3nm rock-salt phase protection layer on the cathode surface by transmission electron microscope (TEM) characterization, improving the cycling performance of the Ni-rich NCM9055 layered oxide cathode. The DSSC electrolyte also can relief the Li dendrite growth on Li metal anode, as well as exhibit better flame retardance, promoting the application of more safety Ni-rich NCM9055||Li metal batteries.

Dynamically constructing robust cathode-electrolyte-interphase on nickel-rich cathode by organic boron additive for high-performance lithium-ion batteries

Nickel-rich ternary cathode materials LiNi0.8Co0.1Mn0.1O2 (NCM811) have attracted broad attention due to their high voltage and high energy density for lithium-ion batteries. However, rapid capacity decay due to unstable particle surface inhibit the application. Artificial cathode electrolyte interface (CEI) is undoubtedly a more effective and simpler way to solve this issue. Here, stable and highly conductive in situ CEI is designed using a low-cost organic boron additive isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (ITD). Higher occupied molecular orbital energy endows ITD ability to participate in forming CEI. ITD-contained CEI can reduce nickel dissolving, resulting in a lower self-discharge rate, which is benefit from the uniform and stable CEI on the NCM811 surface. As expected, ITD-based CEI can restrain NCM811crystal cracking in Li||NCM811 half batteries, improving capacity retention from 29.4 % to 93.0 % after 200 cycles at 1C (1C = 200 mA g−1). It is worth mentioning that ITD–derived CEI is conducive to ion migration, which improve the rate capacity retention from 91.5 % to 95.5 %.

Pentafluorophenyl diethoxy phosphate: An electrolyte additive for high-voltage cathodes of lithium-ion batteries

Increasing the upper limit of the charging voltage in commercial lithium-ion batteries (LIBs) can enable them to have a higher energy density, but during high-voltage charging and discharging, the electrolyte will accelerate the decomposition, and the interfacial adverse reaction among the cathode and electrolyte is serious, which corrodes the cathode active material and consumes excessive electrolyte, and ultimately lead to a shorter service life of lithium-ion batteries. To address this issue, an electrolyte additive with properties suitable for high voltage cathodes, named pentafluorophenyl diethoxy phosphate (FPOP), was synthesized in this work and successfully applied to LiNi0.8Co0.1Mn0.1O2 cathode (NCM-811). Density Functional Theory (DFT) computations reveal that the FPOP additive undergoes preferential oxidation and self-polymerizes on the NCM-811 cathode surface to establishing a safeguarding film at the cathode-electrolyte interface (CEI). This film effectively inhibits detrimental side reactions. The electrochemical performance test data indicated that the retention rate of discharge-specific capacity in batteries was markedly enhanced with 0.1 wt% of FPOP when added to the standard electrolyte. Specifically, after subjecting the batteries to 200 cycles at a current of 0.2C and under voltages ranging from 4.2 V to 4.5 V, the retention of discharge ratio capacity increased by 37.6 %, 39.2 %, 26.9 %, and 37.1 % correspondingly. Morphology characterization and spectroscopic characterization showed that FPOP could not only construct a stable CEI film by oxidation during the first stages of lithium precipitation but also remove HF by strongly binding to the HF in the electrolyte or dissociating H+ and F− from HF, which ultimately enhanced the batteries' capacity to operate effectively at elevated voltage levels. Therefore, incorporating FPOP as an additive in electrolyte presents a cost-efficient approach to achieving elevated energy density.

BF4- Tailoring Solvation Chemistry of Ether-Based Electrolytes to Construct Stable Electrode/Electrolyte Interfaces for Sodium-Ion Full Batteries.

The ether-based electrolytes show excellent performance on anodes in sodium-ion batteries (SIBs), but they still show poor compatibility with the cathodes. Here, ether electrolytes with NaBF4 as the main salt or additive were applied in NFM//HC full cells and showed enhanced performance than the electrolyte with NaPF6. Then, BF4- was found to have a stronger interaction with Na+, which could reduce the solvation of Na+ with the solvent, thus inducing the formation of the cathode electrolyte interface (CEI) and solid electrolyte interface (SEI) layers rich in inorganic species. Moreover, the morphology, structure, composition, and solubility of CEI and SEI were explored, concluding that NaBF4 could induce more stable CEI and SEI layers rich in B-containing species and inorganics. This work proposes using NaBF4 as the main salt or additive to improve the performance of ether electrolytes in NFM//HC full cells, which provides a strategy to improve the compatibility of ether-based electrolytes and cathodes.

In Situ Formation of a LiBO2 Coating Layer and Spinel Phase for Ni-Rich Cathode Materials from a Boric Acid-Etched Precursor.

Ni-rich cathode materials exhibit superior energy densities and have attracted interest among both research and industrial fields; whereas, their practical application is hindered by the intrinsic drawbacks brought by the high nickel content such as structural instability and rapid capacity fading. Herein, in situ formation of a LiBO2 coating layer and spinel phase layer is achieved on the surface of a Ni-rich cathode material via a boric acid etching method at the precursor state. The spinel phase is considered to have a 3D lithium diffusion tunnel and hence faster diffusion kinetics. Moreover, the LiBO2 layer possesses excellent (electro)chemical inertness and can suppress electrolyte decomposition, resulting in a more inorganic and stable cathode-electrolyte interface. The surface reconstructed sample exhibits better cyclic stability (93.3% capacity retention vs 85.3% for the pristine sample at 1 C for 100 cycles) and rate performance. The superiority of this surface reconstruction is demonstrated by a series of electrochemical techniques and characterization methods including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), post-mortem X-ray photoelectron spectroscopy (XPS) analysis, and density functional theory (DFT) calculations.

Elastic Interfacial Layer Enabled the High-Temperature Performance of Lithium-Ion Batteries Via Utilization of Synthetic Fluorosulfate Additive

The key to producing high-energy Li-ion cells is ensuring the interfacial stability of Si-containing anodes and Ni-rich cathodes. Herein, 4-(allyloxy) phenyl fluorosulfate (APFS), a multi-functional electrolyte additive that forms a mechanical strain-adaptive solid electrolyte interphase (SEI) comprising LiF and polymeric species, and a thermally stable cathode–electrolyte interface containing S–O and S–F species. The radical copolymerization of vinylene carbonate (VC) with APFS via electrochemical initiation creates a spatially deformable polymeric SEI on the SiG-C (30 wt.% graphite + 70 wt.% SiC composite) anode, with large volume changes during cycling. Moreover, the APFS-promoted interfacial layers reduce Ni dissolution and deposition. Furthermore, APFS deactivates the Lewis acid PF5, thereby inhibiting hydrolyses that produce unwanted HF. These results indicate that the combined use of VC with APFS allows capacity retentions of 72.5% with a high capacity of 143.5 mAh g−1 in SiG-C/LiNi0.8Co0.1Mn0.1O2 full cells after 300 cycles at 45 °C.

Transitioning Towards Asymmetric Gel Polymer Electrolytes for Lithium Batteries: Progress and Prospects

AbstractThe utilization of liquid electrolytes (LEs) concerns inevitable dendrite growth and safety issues. In contrast, solid polymer electrolytes suffer from unsettled low ionic conductivity and interfacial impedance issues. The intermediary gel polymer electrolytes (GPEs) improve safety by incorporating a sturdy polymer matrix and ionic conductivity as an advantage of percolating LEs responsible for gelation. The overall stability and compatibility of GPEs with different electrode materials depend on the polymers, plasticizers, and precursors utilized. No single polymer has a wide energy gap to exhibit stability against Li metal anodes and oxidative stability against high‐voltage cathodes. Thereafter, symmetric GPEs (SGPEs) possess limitations while simultaneously satisfying the two electrode requirements, which hinders their practical applications. Asymmetric GPEs (ASGPEs) generally comprise a bilayer or gradient structure, wherein the side contacting the cathode is modified to promote oxidative stability for a stable cathode electrolyte interface (CEI). The corresponding side in contact with the anode is modified to be mechanically and chemically compatible with dendritic lithium. Overall, asymmetric structural engineering enables electrode compatibility while maintaining the physical competency of GPEs. Herein, the focus is to summarize the current transition from SGPEs to asymmetric ones, which promotes multifunctionality while overcoming specific constraints associated with the electrodes.

Fluorine grafted gel polymer electrolyte by in situ construction for high-voltage lithium metal batteries

Gel polymer electrolytes (GPEs) are promising candidates for next generation lithium metal batteries (LMBs) due to their reassuring safety and high ionic conductivity at room temperature. However, they are still plagued by incompatible interfaces and poor compatibility with Ni-rich cathodes, imposing great restrictions on the scalability of high-voltage cathodes. To overcome these problems, a GPE with a polyacrylonitrile porous membrane, together with 2,2,3,4,4,4-hexafluorobutyl acrylate grafted pentaerythritol tetraacrylate, is fabricated via in-situ thermal polymerization. By virtue of the effective transport channels provided by PAN and PETEA molecules, our GPE exhibits both a high lithium-ion transference number and a high ionic conductivity of 0.87 and 4.06 × 10−3 S cm−1, respectively at 30 °C. Moreover, the GPE ensures a high electrochemical window, stable at potentials up to 5.35 V, enabling the application of LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes. Due to the uniform cathode electrolyte interface (CEI) formed by our GPE on the surface of NCM811, the assembled NCM811|GPE|Li batteries present an excellent cycling life of 300 cycles in the voltage range of 3 ∼ 4.5 V with a capacity retention of 84% at 2C. Our study provides a novel strategy for constructing fast Li+ transport channels and stable CEI membranes in LMBs operating at high voltages.

Olivine-based nano-filling layer empowering Ni-rich layered cathodes with enhanced surface stability and thermal shock resistance

Irreversible phase transition and nerve-racking thermal runaway of NCM811 especially cycled at high charge cut-off potential hinder its full-scale commercialization. In this study, we use a facile and powerful surface modification strategy to construct modified NCM811 whose ravines are completely filled/embedded by sand-milled LiMn0.6Fe0.4PO4 (LMFP), forming the nano-filled NCM811 (LMFP@NCM811). By virtue of this compact & uniform LMFP layer, a thin and stable cathode-electrolyte interface (CEI) layer can be established on the surface of LMFP@NCM811, which leads to prominent electrochemical properties with a high capacity retention of ∼ 80% after 450 cycles at 100 mAh/g. Moreover, due to the intrinsic stability of olivine structure (LMFP), the LMFP-embedded NCM811 showcases admirable thermal stability and thermal shock resistance at high de-lithiation state. We believe that such success at the performance improvement of Ni-rich ternary cathodes can provide a good guidance for future work to achieve more efficient energy storage and utilization.

Cathode Electrolyte Interface Engineering by Gradient Fluorination for High‐Performance Lithium Rich Cathode

AbstractDespite their ultrahigh specific capacity, lithium‐rich layered oxide cathodes are still plagued by challenges such as poor cycle stability and notorious voltage decay, which are primarily attributed to surface issues such as the release of lattice oxygen and interfacial side reactions. In this study, a facial strategy of gradient fluorination is adopted to construct a thin but robust LiF‐rich cathode electrolyte interface (CEI), highly enhancing the stability of the interface of lithium‐rich oxides. Experimental results and theoretical calculations both demonstrate that the stable CEI not only promotes oxygen participation in redox reactions and simultaneously inhibits oxygen release and structural transition, but also facilitates the transport kinetics of lithium ions. As a result, the gradient fluorinated lithium‐rich cathode delivers highly enhanced rate performance (133 mAh g−1 at 5 C), superior cycling stability with a capacity retention of 81.9% after 100 cycles at 1 C (250 mAh g−1), and alleviated voltage fade (only 1.75 mV per cycle). Moreover, a unique formation mechanism for LiF‐rich surfaces is proposed according to theoretical calculations. This work not only provides a fresh understanding of the CEI formation mechanism, but also show a promising avenue for designing LiF‐rich CEIs applicable to other layered oxide cathodes.

Elastic Interfacial Layer Enabled the High‐Temperature Performance of Lithium‐Ion Batteries via Utilization of Synthetic Fluorosulfate Additive

AbstractThe key to producing high‐energy Li‐ion cells is ensuring the interfacial stability of Si‐containing anodes and Ni‐rich cathodes. Herein, 4‐(allyloxy)phenyl fluorosulfate (APFS), a multi‐functional electrolyte additive that forms a mechanical strain‐adaptive solid electrolyte interphase (SEI) comprising LiF and polymeric species, and a thermally stable cathode–electrolyte interface containing SO and SF species. The radical copolymerization of vinylene carbonate (VC) with APFS via electrochemical initiation creates a spatially deformable polymeric SEI on the SiG‐C (30 wt.% graphite + 70 wt.% SiC composite) anode, with large volume changes during cycling. Moreover, the APFS‐promoted interfacial layers reduce Ni dissolution and deposition. Furthermore, APFS deactivates the Lewis acid PF5, thereby inhibiting hydrolyses that produce unwanted HF. These results indicate that the combined use of VC with APFS allows capacity retentions of 72.5% with a high capacity of 143.5 mAh g−1 in SiG‐C/LiNi0.8Co0.1Mn0.1O2 full cells after 300 cycles at 45 °C.

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.

Carboxylate-derived conductive, sodium-ion storable surface of Prussian Blue with a stable cathode-electrolyte interface

Considering the high binding affinity between carboxylate ligands (−O–CO) and alkaline Na ions, Prussian blue (PB) with a carboxylate-derived conductive, Na-ion storable surface is developed as a cathode material for Na-ion rechargeable batteries. Here, citric acid (CA) (C6H8O7) is introduced as a carboxylate source because, in a neutral aqueous solution, it loses two H ions of each molecule to reach an acid-base equilibrium and is stabilized in a chemical form with two −O–CO ligands that are accompanied by two delocalized electrons. Consequently, these functional groups newly formed from CA remain on the surfaces of PB particles even when PB is co-precipitated using CA and sodium citrate as dual chelating agents. Specifically, they strongly bind to high-spin Fe (FeHS) ions on the PB surface, providing additional active sites for Na-ion storage via a quasi-reversible, surface redox process (i.e., FeHS–R–C–O– ↔ FeHS–R–C–O–Na) in the low-voltage region close to 3.0 V (vs. Na+/Na). During charge/discharge cycling, inserted Na ions prefer to be stored in the activated surface sites instead of being used to produce unstable by-products by electrolyte decomposition, which resultantly inhibits the thick growth of cathode-electrolyte interface (CEI) layers on the PB particles. As a result, 2 wt% CA-assisted PB exhibits high first discharge capacity (∼110 mA h g−1) and low average capacity decay rate (−0.39 mA h g−1/cycle) at a current density of 0.2 C.

Cathode-Electrolyte Interface Modification by Binder Engineering for High-Performance Aqueous Zinc-Ion Batteries.

A stable cathode-electrolyte interface (CEI) is crucial for aqueous zinc-ion batteries (AZIBs), but it is less investigated. Commercial binder poly(vinylidene fluoride) (PVDF) is widely used without scrutinizing its suitability and cathode-electrolyte interface (CEI) in AZIBs. A water-soluble binder is developed that facilitated the in situ formation of a CEI protecting layer tuning the interfacial morphology. By combining a polysaccharide sodium alginate (SA) with a hydrophobic polytetrafluoroethylene (PTFE), the surface morphology, and charge storage kinetics can be confined from diffusion-dominated to capacitance-controlled processes. The underpinning mechanism investigates experimentally in both kinetic and thermodynamic perspectives demonstrate that the COO- from SA acts as an anionic polyelectrolyte facilitating the adsorption of Zn2+ ; meanwhile fluoride atoms on PTFE backbone provide hydrophobicity to break desolvation penalty. The hybrid binder is beneficial in providing a higher areal flux of Zn2+ at the CEI, where the Zn-Birnessite MnO2 battery with the hybrid binder exhibits an average specific capacity 45.6% higher than that with conventional PVDF binders; moreover, a reduced interface activation energy attained fosters a superior rate capability and a capacity retention of 99.1% in 1000 cycles. The hybrid binder also reduces the cost compared to the PVDF/NMP, which is a universal strategy to modify interface morphology.

Effect of fluoroethylene carbonate additive on the low–temperature performance of lithium–ion batteries

• FEC increased the ionic conductivity and electrochemical stability of electrolyte. • The inclusion of FEC enables Li||LCO cell to work efficiently at −40 °C. • The production of a highly fluorinated interfacial coating can be aided by the FEC. • FEC shows the advantage of high rate discharge at low temperature. The operation of lithium–ion batteries (LIBs) at low temperature is hampered by decreased electrical conductivity and delayed electrode reaction kinetics. Due to its positive solid electrolyte interphase (SEI) formation properties, fluoroethylene carbonate (FEC) is one of the most widely researched additives for LIBs. Herein, charge–discharge tests, electrochemical impedance spectroscopy scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X–ray photoelectron spectroscopy (XPS) were used to investigate the effect of FEC on LCO/Li cells. According to SEM, TEM and XPS results, the addition of FEC results in the formation of a thin and stable cathode–electrolyte interface (CEI) film on the surface of the LCO electrode. Charge–discharge curves show that adding FEC to the electrolyte reduces polarization while increasing the discharge capacity. At −40 °C, the discharge capacity in electrolyte with 10 wt% FEC is 75.3 % that at room temperature and only 46.8 % without FEC at 1C. LiF is the main component of the FEC electrochemistry that forms a CEI, which has a low interfacial resistance and improves the ionic conductivity of the electrolyte, thus facilitating the performance of the battery at low temperature.

Stability Enhancement and Microstructural Modification of Ni-Rich Cathodes via Halide Doping.

Elemental doping is an effective strategy to modify surface and bulk chemistry in NMC cathode materials. By adding small amounts of lithium halide salts during the calcination process, the Ni-rich NMC811 cathode is doped with Br, Cl, or F halogens. The dopant type has a significant impact on the lithiation process and heavily influences the final cathode porosity and surface morphology. Utilizing a variety of electrochemical, surface, and bulk characterization techniques, it is demonstrated that an initial content of 5 mol % LiBr or LiCl in the lithium source is effective in improving capacity retention while also providing excellent rate performance. The improvements are attributed to a substantial increase in specific surface area, the formation of a stable cathode electrolyte interface (CEI) layer, and suppressed surface reconstruction. In addition, the particle microstructure is better equipped to handle cyclic volume changes with increased values of critical crack lengths. Overall, it is demonstrated that anion doping via the addition of lithium halide salts is a facile approach toward Ni-rich NMC modification for enhanced cathode performance.

Unraveling the Stable Cathode Electrolyte Interface in all Solid‐State Thin‐Film Battery Operating at 5 V

AbstractSpinel‐type LiNi0.5Mn1.5O4 (LNMO) is one of the most promising 5 V‐class cathode materials for Li‐ion batteries that can achieve high energy density and low production costs. However, in liquid electrolyte cells, the high voltage causes continuous cell degradation through the oxidative decomposition of carbonate‐based liquid electrolytes. In contrast, some solid‐state electrolytes have a wide electrochemical stability range and can withstand the required oxidative potential. In this work, a thin‐film battery consisting of an LNMO cathode with a solid lithium phosphorus oxynitride (LiPON) electrolyte is tested and their interface before and after cycling is characterized. With Li metal as the anode, this system can deliver stable performance for 600 cycles with an average Coulombic efficiency >99%. Neutron depth profiling indicates a slight overlithiated layer at the interface prior to cycling, a result that is consistent with the excess charge capacity measured during the first cycle. Cryogenic electron microscopy further reveals intimate contact between LNMO and LiPON without noticeable structure and chemical composition evolution after extended cycling, demonstrating the superior stability of LiPON against a high voltage cathode. Consequently, design guidelines are proposed for interface engineering that can accelerate the commercialization of a high voltage cell with solid or liquid electrolytes.

Layered Oxide Cathode-Electrolyte Interface towards Na-Ion Batteries: Advances and Perspectives.

With the ever increasing demand for low-cost and economic sustainable energy storage, Na-ion batteries have received much attention for the application on large-scale energy storage for electric grids because of the worldwide distribution and natural abundance of sodium element, low solvation energy of Na+ ion in the electrolyte and the low cost of Al as current collectors. Starting from a brief comparison with Li-ion batteries, this review summarizes the current understanding of layered oxide cathode/electrolyte interphase in NIBs, and discusses the related degradation mechanisms, such as surface reconstruction and transition metal dissolution. Recent advances in constructing stable cathode electrolyte interface (CEI) on layered oxide cathode are systematically summarized, including surface modification of layered oxide cathode materials and formulation of electrolyte. Urgent challenges are detailed in order to provide insight into the imminent developments of NIBs.

Pushing Lithium Cobalt Oxides to 4.7 V by Lattice‐Matched Interfacial Engineering

AbstractThe utilization of high‐voltage LiCoO2 is imperative to break the bottleneck of the practical energy density of lithium‐ion batteries. However, LiCoO2 suffers from severe structural and interfacial degradation at >4.55 V. Herein, a novel lattice‐matched LiCoPO4 coating is rationally designed for LiCoO2 which works at 4.6 V (vs Li/Li+) or above. This LiCoPO4 coating, derived by an in situ chemical reaction, grows epitaxially on LiCoO2 crystallite with strong bonding and complete coverage to LiCoO2, ensuring a stable cathode–electrolyte interface with fewer side reactions and alleviated intergranular cracking and phase collapse during repeated high‐voltage lithiation/delithiation processes. In addition, the formed strong covalent P–O tetrahedron configuration at the interface effectively decreases the surface oxygen activity of LiCoO2, further suppressing oxygen release and irreversible phase transition. Therefore, the LiCoPO4‐LiCoO2ǁLi cells display excellent capacity retention of 87% after 300 cycles at 4.6 V and stable operation at 4.6 V/55 °C or 4.7 V/30 °C. The strategy of lattice‐matching growth affords a new way to impact the development of high‐voltage LiCoO2 and beyond.