Small-dose electrolyte additives are widely used to enhance battery performance, yet rational additive selection for the stabilization of lithium metal (Li°) electrodes remains challenging. Coulombic efficiency (CE) measurements in asymmetric Li°||Cu° cells serve as critical evaluative metrics, but the resulting CE values often deviate from expectations based on additive structure alone. Herein, we delve into the design of fluorinated electrolyte additives by combining statistical analysis of Li°||Cu° cycling data with compositional characterization as well as atomistic and chemical simulations. Our results demonstrate that nonafluorobutanesulfonyl fluoride, as an electrolyte additive, induces only a marginal effect on the Aurbach CE values during short-term cycling tests of Li°||Cu° cells. Intriguingly, during extended-cycling, statistical analysis reveals that the same additive exhibits divergent effects in electrolyte families based on bis(trifluoromethanesulfonyl)imide (TFSI-) and bis(fluorosulfonyl)imide (FSI-) anions. These differences arise from the interplay between the film-forming chemistry of the fluorinated additive and the active involvement of TFSI- and FSI- anions, which collectively modulate the chemical and electrochemical features of the resulting solid-electrolyte interphases (SEI) on Li°. This work elucidates how additive functionality translates into interphase chemistry and provides a statistically robust framework for screening electrolyte additives for practical lithium metal batteries.

Stress-induced fractures are recognized as a primary cause of degradation in a wide range of positive electrode active materials during battery operation. However, the state-of-the-art mechanistic understanding and strategy development often overlook the brittle nature of these materials, as well as the dynamic and localized characteristics of mechanical stress during the charge and discharge cycles of the cell. Here we present a shape-memory polymer nanocoating method using initiated chemical vapour deposition to dynamically delocalize concentrated stresses in various positive electrode active materials, including Ni-rich layered oxides with different Ni contents and LiFePO4. Fracture simulations and surface-to-bulk physicochemical characterizations collectively show that the balanced stiffness and deformability of the shape-memory polymer nanocoating on the positive electrode material effectively mitigate stress gradients and the consequent surface reconstruction, chemical heterogeneity and intergranular cracking during battery operation. In particular, when a polymeric nanocoated nickel-rich layered oxide positive electrode active material (90 at% of Ni) is tested in non-aqueous lithium metal coin cell configuration at 25 °C, the cells can be consistently charged and discharged over long cycles at moderate (for example, 1,000 cycles at 400 mA g-1) and high (for example, 500 cycles at 1 A g-1) specific currents.

Ni-rich layered oxide cathode materials have emerged as promising candidates for next-generation mainstream high-energy nonaqueous lithium-based batteries because of their inherent advantages in terms of specific capacity. However, the delicate layered structure is more susceptible to both crystal and morphological structure degradation under electro-chemo-mechanical stresses at high states of delithiation, leading to an unsustainable cycle life and vulnerable safety hazards. To address these issues, 20 extensively utilized doping elements are incorporated into a LiNi _0.9 Co _0.1 Mn _0.1 O _2 (NCM90) cathode to generate a critical dataset with 20 descriptors comprising its intrinsic, structural and morphological features. Furthermore, we develop a designed multidimensional graph differential neural network (MDGNN) model trained on the former dataset to fit the doping laws, which results in an error rate in predicting two key performance metrics, e.g. specific capacity and capacity retention, of an arbitrary dopant-modified NCM90 cathode. Combined with the MDGNN model and traditional chemical principle, 1.2 mol% Al ^3+ , 0.3 mol% Zr ^4+ and 0.5 mol% Sb ^5+ are elaborately doped into the NCM90 cathode to stabilize its electrochemical and thermal properties, and the related operation mechanism is systematically investigated via characterization. The developed 7.3 Ah Al1.2Zr0.3Sb0.5-NCM90||graphite pouch cell attains 87.3% capacity retention after 3000 cycles at 1.0/1.0 C, verifying the practical feasibility of our MDGNN model. These results open a viable avenue for the data-driven design of high-performance battery materials.

Defect engineering has been used for centuries to enhance the mechanical strength of metals and alloys, but its application to cathodes remains largely unexplored. Conventional cathode synthesis aims for defect-free crystals to maximize capacity, but such structures degrade easily through interlayer gliding and microcracking, both of which are reported for single-crystal LiNi0.8Mn0.1Co0.1O2 (SC-NMC811). Dopant substitution or surface coating has been explored to address these issues but introduce foreign elements that complicate recycling. Here, we present a scalable method to introduce a controlled amount (<5%) of Li/Ni anti-site defects that act as “rivets” to suppress interlayer gliding. This moderate defect level enhances the shear strength of SC-NMC811 by 88% and inhibits oxygen loss. The optimized cathodes retain 88.1% capacity after 1,800 cycles (4.3 V) and 80.1% after 900 cycles (4.7 V) using a standard carbonate-based electrolyte. This exceeds conventional SC-NMC811 cycling stability without relying on complicated synthesis procedures or introducing dopants that complicate the recycling process.

Next-generation rechargeable batteries require materials that offer enhanced electrochemical capabilities. Achieving these goals depends on understanding the fundamental principles governing these materials, which presents challenges associated to the complex interactions between composition, structural characteristics and electrochemical performance in battery materials. Despite intensive research, progress remains limited regarding effective strategies to mitigate the degradation of fragile alkali-metal-deficient frameworks arising from lattice stress and structural or chemo-mechanical instability upon cycling. In this Review, we explore the importance of chemical heterogeneity in rechargeable battery materials. We discuss how heterogeneity at atomic scale, nano-domains and up to phase-segregated levels within particles can enhance the electrochemical properties of battery materials beyond those of their homogeneous counterparts. Introducing chemical heterogeneity, principles and mechanisms can be unlocked to develop materials with improved structural stability, ion conductivity, redox activity, and phase transition characteristics, driving progress in battery technology. Finally, we outline the challenges and strategies for developing the future battery materials.

The synergy between salt anion and inorganic fillers can effectively modulate the basic properties of composite polymer electrolytes (CPEs). In this work, we herein continue the exploration of the chemical and electrochemical stability of the CPEs comprising a super anion (i.e., sTFSI-) and nano-sized alumina against lithium metal (Li degrees) electrode, and systematically investigate the cycling stability of the Li degrees electrode, Li degrees deposition morphology, and surface composition of the as-formed interphases. Our results suggest significant differences in the interfacial behavior of the sTFSI-based CPEs in comparison to the classic sulfonimide [i.e., bis(trifluoromethanesulfonyl)imide anion, TFSI-] systems, primarily due to the distinct interaction mechanisms for two anions with different characteristics. Benefiting from the inherent strong negative charge delocalization of sTFSI-anion, it possesses greater reduction stability in the presence of inorganic fillers and plays a dominant role in the interfacial reactions on Li degrees surface, supporting superior cycle life for Li degrees electrode and more uniform deposition morphology. This work reveals the critical role of anions and inorganic fillers in modulating the interfacial reactions and film-formation processes between polymer electrolyte and negative electrode, providing important insights for enhancing the performances of solid-state batteries, not limited to lithium systems.

Silicon-based materials stand as tantalizing battery anodes for markedly advancing performance indicators of today's rechargeable lithium-ion batteries; however, their structural degradations, together with detestable side reactions residing in electrode-electrolyte interphases, greatly hinder the delivery of energy promises under practical conditions. Herein, we introduce the spatiotemporally coupled sulfur chemistry as an effective antidote to cope with the volume change and structural integrity of near-full silicon anodes, and concurrently modulate inherent properties of electrode-electrolyte interphases layers enlisting elasticity and ion diffusivity. The sulfur regulated approach is readily achieved by overlaying silicon with a homogenous layer of elemental sulfur, which is highly compatible with present production facilities for lithium-ion batteries industry. The prototype LiNi0.9Co0.05Mn0.05O2 | |Si90+ pouch cell at ampere-hour level (7.3 Ah) delivers great performances assessed simultaneously by energy density (1190 Wh L-1 for cell), specific energy (416 Wh kg-1 for cell), and cycle life (80% capacity retention after 1700 cycles). In light of the significantly improved battery performance and practical applicability, the sulfur regulated Si90+ anodes thus could be considered as a game-changer for offering reliable power source and rapidly turning emerging applications into reality.

Cracking in Ni-rich layered cathode materials represents a major degradation mechanism that rapidly diminishes electrochemical performance. However, the exact origins of cracking in these materials, particularly in polycrystalline form, remain controversial due to coupled mechanical-electrochemical effects. Here, through combined thermal and electrochemical investigations, we reveal that polycrystalline LiNi0.9Co0.05Mn0.05O2 (NCM90) cathodes exhibit intrinsic mechanical toughness, tolerating thermal cycling strains up to 7% (v/v) without significant cracking, especially when composed of small primary particles, even without external modification. Further studies demonstrate that NCM90 also maintains a crack-free morphology in EC/DMC electrolyte at 55 degrees C in the absence of LiPF6. However, introducing LiPF6 induces severe particle fracture due to associated formation of HF, particularly in cathodes with larger primary particles, consistent with electrochemical degradation trends. Our findings identify HF-induced attack on polycrystalline NCM90 as the primary driver of cracking, particularly for cycling at elevated temperatures. Consequently, HF-resistant oxide doping emerges as the most effective strategy for enhancing structural stability while improving electrochemical performance, offering a practical and efficient solution for stabilizing Ni-rich cathodes.

Alloy anodes can offer high energy densities of Na-ion batteries (NIBs) but suffer from poor cycling performance. Conventional strategies to mitigate the volume expansion often sacrifice the capacity delivery and material scalability, while the underlying mechanisms governing the cycling stability and practical applicability remain unrevealed. Here we design a scalable micrometre-scale Sn anode for ampere-hour-level NIBs, which delivers a high volumetric energy density of 453 Wh l(-1) and realizes fast charging (similar to 15 min) over 600 cycles. Notably, the Sn-based cell exhibits superior low-temperature performance compared with the LiFePO4/graphite cell. Multiscale characterizations combined with machine learning-assisted quantitative analyses reveal that the adequate and continuous topological morphological evolution of the Sn particles, synergistically reinforced by the cross-linked networks of single-walled carbon nanotubes, ensures stable electrical connection and high active material utilization throughout the cycle life. This work clarifies the structure-stability-performance correlation of alloy-based anodes and highlights their great potential for next-generation high-energy NIBs.

Ni-rich layered cathode materials are promising for high-energy-density lithium-ion batteries; however, their severe capacity degradation hampers large-scale applications. While metal doping has emerged as a viable strategy to enhance structural stability, the reported effects of dopants remain controversial, primarily due to differences in synthesis conditions and precursor reactivity. Herein, we propose a dual-parameter strategy integrating primary particle morphology and Li/Ni disorder across a broad sintering temperature range (700-900 degrees C). Under this strategy, LiNi0.90Co0.06Mn0.04O2 (NCM90) cathode materials achieve optimal structural and electrochemical performance with two exemplary dopants (1 mol% Nb and W). However, the optimized sintering temperature for Nb-NCM90 cathode materials is 750 degrees C, whereas W-NCM90 require 850 degrees C. Detailed morphological analysis reveals that a critical primary particle density governs capacity retention. Below the critical primary particle density (33.82 particles per mu m2 for the Nb-NCM90 and 11.69 particles per mu m2 for the W-NCM90), all cathode materials exhibit excellent capacity retention due to limited strain building up during cycling, but low reversible capacity associated with severe Li/Ni disorder. In contrast, above the critical primary particle density, these cathode materials demonstrate rapid capacity fading attributed to high strain accumulation during cycling, despite high initial capacity associated with low Li/Ni disorder. These findings highlight the synergistic interplay between primary particle density and Li/Ni disorder in achieving both high-capacity retention and reversible capacity.

Composite polymer electrolytes (CPEs), harmonizing the advantageous features of organic and inorganic components, appear to be a tantalizing solution to enhance inherent safety and energy density of today's rechargeable lithium batteries. In light of the significant impact of salt anions on electrolyte properties, we herein delve into a family of CPEs based on a super-delocalized sulfonimide anion (i.e., sTFSI(-)) and inorganic nanofillers (i.e., alumina), to provide more precise molecular design and property turning of solid-state electrolytes and their batteries. The fundamental properties of sTFSI-based CPEs are systematically investigated and compared with those based on classical bis(trifluoromethanesulfonyl)imide anion (i.e., TFSI-), enlisting surface morphology, phase transition, and ion transport, etc. Our results show that the content of nanosized Al2O3 filler serves as a critical factor affecting the mechanical properties and crystallization behavior of the resulting CPEs. The replacement of TFSI- with sTFSI(-) anion enables a higher portion of nanosized Al2O3 filler (>10 wt%) in the resulting CPEs, at only a minor expense of the ionic conductivity. This work unveils significant synergy between salt anions and inorganic fillers in modulating fundamental properties of polymer electrolytes, offering critical insights into the performance enhancement of the polymer-based solid-state batteries.

ABSTRACT Polycrystalline Ni‐rich layered oxides are promising cathodes for Li‐ion batteries of high‐power density and long cycle life. However, their practical application is still hindered by the sluggish Li+ diffusion rate and reaction inhomogeneity during redox cycles. In this work, LiNi0.9Co0.05Mn0.05O2 (NCM9055) cathode with a desired internal radial structure was designed and successfully synthesized using Nb2O5 as a dual‐functional structural and interfacial modulator. During calcination, the Nb2O5 reacts to form an intergranular LiNbO3 phase at grain boundaries. This phase, forming before high‐temperature grain growth, acts as a structural modulator to preserve the desirable radial alignment of primary particles by impeding random grain growth. It also functions as an interfacial conductor, creating fast Li+ diffusion pathways along the grain boundaries. These structural and interfacial modifications synergistically mitigate chemical inhomogeneity and relieve accumulated strain during cycling. Consequently, the Nb‐modified NCM9055 exhibits superior electrochemical performance, delivering an excellent rate capacity (152.4 mA h g−1 at 10 C) and robust cycling stability under high‐rate conditions (83.0% capacity retention after 500 cycles at 5C). These findings clarify the mechanism of Nb modulation and demonstrate a robust strategy for preserving desirable microstructures in high‐rate, Ni‐rich cathode materials.

Electrolyte solidification holds great promise in addressing safety concerns. Nevertheless, integrating high electrochemical stability and intrinsic interfacial compatibility remains challenging for high-voltage lithium metal batteries. Herein, we report an ion-percolative quasi-solid electrolyte via concentration-driven self-assembly. At a concentration threshold (LiFSI(FEC)x, x = 0.37), the system triggers spontaneous crystallization of LiFSI to form a rigid, nonflammable framework at room temperature and generates dispersed [LiFSI-FEC] ionic clusters that simultaneously percolate within grain boundaries. This unique ion-percolative architecture (nano-LiFSI skeleton + [LiFSI-FEC] cluster network) enables autonomous Li-ion highways between dynamic clusters along grain boundaries of salt. The optimized electrolyte achieves a high ionic conductivity of 2.3 × 10-4 S/cm and an exceptional Li⁺ transference number (0.75) at room temperature. This electrolyte provides a satisfying tradeoff between nonflammability, electrochemical windows, ionic conductivity, and mechanical properties, simultaneously achieving perfect compatibility with the lithium metal anode and 4.6 V high-voltage cathodes.

High-voltage layered oxide combined with silicon-base anode materials represents a promising candidate for the next-generation lithium-ion batteries. However, the strong catalytic nature of oxide surface renders severe electrolyte decomposition at the interface, accumulation of the acidic products (e.g. HF) and even damage to anode interphase. Here, we introduce the multiple-cyano-ligand salt as an electrolyte additive to regulate the harsh interphase of high-voltage LiCoO2. By tuning the non-metal centers bridged to cyano ligand, the tetracyanoborate (TCB) salt was identified with strong electrochemical stability and water tolerance. Strong adsorption of cyano groups efficiently deactivates the lattice oxygen, thereby inhibiting solvent dehydrogenation and subsequent decomposition. Moreover, the ligand exchange reaction between cyano and fluorine endows the TCB anion with acid-scavenging capability. With the addition of 1 wt% of potassium TCB salt as a multifunctional additive, a high-voltage LCO-Si/C pouch cell (4.5 V vs. Si/C) achieves excellent cycling stability, retaining 92.5 % of its initial capacity after 500 cycles. Furthermore, benefiting from the cyano- and LiF-rich interphases, the high-voltage LCO-Si/C full cell exhibits stable electrochemical performance even at elevated temperatures (45 degrees C). This work provides a new molecule design strategy for functional additives targeting high-voltage cathode materials.

O2-type LixCoO2 (O2-LCO) has recently attracted significant attention as a promising cathode material with superior electrochemical performance compared to its conventional O3-type counterpart. Due to its metastable nature, O2-LCO is typically synthesized via ion exchange under relatively mild thermal conditions; however, the structural evolution and resultant phase composition during this process, which critically affect the material's performance, remain insufficiently understood. Here, we systematically elucidate the interplay between composition, structure, and electrochemical performance in metastable LiCoO2 synthesized via molten-salt ion exchange. We show that the Na content in the precursor not only dictates the final Li content in the product but also thermodynamically governs the phase transition pathway. Comprehensive long-range and local structural characterizations reveal the composite nature of ion-exchanged LCO, comprising T#2, O2, and O3 phases, with their relative fractions determined by the initial Na content. Electrochemical measurements, supported by theoretical calculations, indicate that the optimal phase composite maximizes both Li content and T#2 fraction while suppressing O3 formation, thereby enhancing Li+ diffusion kinetics and structural compatibility. These insights provide a fundamental basis for phase engineering in metastable cathode materials and practical guidelines for designing high-performance layered oxide cathodes.

Elevating the charging voltage of layered oxide cathodes to achieve higher capacity induces phase transitions associated with transition metal slab gliding, which significantly impacts the material's structural stability. Doping with inert elements is commonly employed to delay such phase transitions to higher voltages. However, these electrochemically inactive elements do not participate in redox reactions, thereby compromising lithium storage capacity. This compromise raises a critical and underexplored issue regarding whether doped materials with reduced capacity still maintain an advantage in energy density. In this study, using LiCoO2 as a model material, it was observed that an increase in the concentration of Al dopant indeed delayed the onset voltage of the H1-3 phase transition. However, the extent of delithiation associated with this phase transition remains largely unchanged. When the discharge capacity is controlled to just below the threshold for the global H1-3 phase transition, the undoped material demonstrates even superior capacity retention and rate performance compared to the doped samples, at a lower charging cutoff voltage. Comprehensive experimental characterizations and theoretical calculations reveal that the doping-induced structural defects hinder Li+ conduction and promote oxygen release, consequently accelerating performance degradation. This study suggests that in the development of high-voltage layered oxide cathodes, it is crucial to prioritize enhancing material capacity. Additionally, it is imperative to meticulously assess the adverse effects of doping, as industrial preparation methods often lead to nonideal dopant incorporation, causing undesirable structural defects that are particularly harmful to the reversibility of high-voltage phase transitions.

Prussian blue analogues (PBAs) are promising electrode candidates for aqueous batteries because the inevitable interstitial water is generally thought to have little impact on battery performance. Currently, mounting researches have focused on optimizing PBA properties by varying transition metal composition, but less attention has been paid to interstitial water, especially in alkali metal-ion deficient PBAs with large cavities. Here, we employ the water-rich K0.01Mn[Cr(CN)6]0.74·4.75H2O as the negative electrode to study the effect of interstitial water. It is found that during de-potassiation, the electrode undergoes dehydration, which negatively impacts kinetics, distorts structure, and raises charging potential. A cation-self-shielding strategy involving Dihydroxyacetone (DHA) in the electrolyte to secure the water-rich state is then proposed. The built 1.82 V all-Prussian blue aqueous K-ion battery delivers a high practical specific energy of ~76 Wh kg-1 over 1.5 V (based on the total mass of active materials in both electrodes). This study reveals the significance of interstitial water on the kinetics of PBA negative electrodes and promotes the exploration of water-containing electrodes to develop high-voltage aqueous rechargeable batteries for energy storage applications.

Pairing high-energy nickel-rich cathodes with current collectors as anodes presents a compelling strategy to significantly boost the specific energy of rechargeable lithium-ion batteries, driving progress toward a transportation revolution. However, the limited active lithium inventory sourced by the cathodes tend to be rapidly consumed by irreversible Li plating/stripping and interfacial side reactions. To address these limitations, we propose a dual-gradient metal layer as an innovative solution to mitigate active Li loss by promoting uniform Li deposition and in situ formation of a stable solid electrolyte interphase. The operation of these batteries is investigated using a combination of electrochemical and chemical techniques to differentiate dead Li and interphase-bound Li inventory loss as well as material characterization methods to analyse the plated Li and interfacial composition and morphology. The developed dual gradient metal layer-based 600 mAh LiNi0.9Co0.05Mn0.05O2 | |Cu pouch cells achieve an areal capacity of 7.25 mAh cm-2 and deliver an 80% capacity retention over 160 cycles. We show that the proposed approach is compatible with a range of different metal materials, offering a promising path toward next generation long-lasting, high-energy, initially active material-free anode based Li metal batteries.

Despite its high theoretical capacity and the lowest electrode potential, the lithium metal (Li°) anode possesses significant volume changes and narrow external pressure tolerance upon cycling, hindering its commercial applications in all-solid-state lithium batteries (ASSLBs). Herein, the concept of topology fortified anode (TFA) materials is introduced, featuring a 3D lithiophilic Li5B4 skeleton combined with an ingeniously optimized fraction of electroactive lithium phase, along with broadened external pressure tolerance to synergistically enhance the electrochemical performance of ASSLBs. The unique topological design of the TFA materials empowers them with robust mechanical stability and fast lithium diffusivity, achieving near-zero volume changes along with a fivefold improvement in external pressure tolerance compared to Li°. An archetypal TFA-based symmetric cell demonstrates 3.6-fold higher critical current density than its Li°-based counterpart, sustaining stable cycling for >6,000 h at 2 mAh cm-2. When paired with a high-capacity of FeS2 cathode, the archetypal TFA-based full cells achieve 62% active lithium utilization (9.5 mAh cm-2), and ≈70% capacity retention after 800 cycles at a high current density of 3.07 mA cm-2. The findings provide a revolutionary design approach for high-energy anodes in ASSLBs, advancing not only their development but also battery technologies beyond lithium chemistry.