[Deep Professional Expansion] Bronze Phase TiO 2O (B) Nanotubes Modified PEO-Based Solid Electrolyte: [Deep Professional Expansion] Bronze Phase TiO 2O (B) Nanotubes Modified PEO-Based Solid Electrolyte:
New mechanism of interface conduction and bottom principle of ultra-long-life all-solid-state battery New mechanism of interface conduction and bottom principle of ultra-long-life all-solid-state battery
(Do not repeat the original text, pure mechanism depth expansion) (Do not repeat the original text, pure mechanism depth expansion)
1. The scientific nature of crystal phase selection: Why is it? 1. The scientific nature of crystal phase selection: Why is it bronze phase TiO (B) bronze phase TiO (B) instead of ordinary anatase/rutile?, instead of ordinary anatase/rutile?
Conventional titanium dioxide (anatase TiO 2 (A), rutile TiO 2 (R)) is often used as PEO composite electrolyte filler, but conventional titanium dioxide (anatase TiO 2 (A), rutile TiO 2 (R)) is often used as PEO composite electrolyte filler, but there are generally poor dispersibility, weak interaction with polymer, limited promotion of lithium salt dissociation, insufficient interfacial stability Poor dispersibility, weak interaction with polymer, limited promotion of lithium salt dissociation, insufficient interfacial stability and other problems. Breakthrough selection of this research. The breakthrough selection of bronze phase titanium dioxide (B) bronze phase titanium dioxide (B) , its core scientific value lies in:, its core scientific value lies in:
Crystal structure is unique, with natural "lithium ion channel" Crystal structure is unique, with natural "lithium ion channel" TiO (B) belongs to monoclinic crystal system, TiO octahedron with open tunneling structure and distortion, TiO (B) belongs to monoclinic crystal system, TiO octahedron with open tunneling structure and distortion, lattice oxygen arrangement is looser, ion diffusion barrier is lower, ion diffusion barrier is lower , itself has weak ion conduction ability, can be formed with PEO chain, itself has weak ion conduction ability, can form continuous ion conduction path with PEO chain continuous ion conduction path Strong>, while ordinary anatase/rutile is a close-packed structure, only as a physical filler, almost no contribution to ion conduction., while ordinary anatase/rutile is a close-packed structure, only as a physical filler, almost no contribution to ion conduction.
The surface coordination is unsaturated, forming a reinforcement interface with the PEO chain. The surface coordination is unsaturated, forming a reinforcement interface with the PEO chain. The surface Ti coordination environment is unsaturated, and the surface Ti coordination environment can be formed with ether oxygen (C-O-C) in PEO. The surface Ti coordination environment is unsaturated, and the surface Ti coordination environment can be formed with ether oxygen (C-O-C) in PEO. Ti ← O coordination bond Ti ← O coordination bond , this strong interaction energy:, this strong interaction energy:
Forced to disrupt the regular arrangement of PEO chains, forcibly disrupt the regular arrangement of PEO chains, significantly inhibit crystallization ;
Reduce the activation energy of segment motion to improve the ion transport efficiency in the amorphous region; reduce the activation energy of segment motion to improve the ion transport efficiency in the amorphous region;
Avoid filler agglomeration, avoid filler agglomeration of nanotubes in PEO, and achieve uniform dispersion of nanotubes in PEO Uniform dispersion ...
Nanotube morphology brings about a three-dimensional continuous conductive network Nanotube morphology brings about a three-dimensional continuous conductive network One-dimensional nanotube structure can be inside the electrolyte One-dimensional nanotube structure can be inside the electrolyte Construct a through-type conductive path Construct a through-type conductive path , lithium ions can not only jump between PEO chains, but also migrate rapidly along the TiO (B) tube wall/interface, forming Lithium ions can not only jump between PEO chains, but also migrate rapidly along the TiO (B) tube wall/interface, forming bulk conduction + interfacial conduction + filler conduction + interfacial conduction + filler conduction 's triple channel, which cannot be achieved by ordinary particle TiO 2O.'s triple channel, which cannot be achieved by ordinary particle TiO 2O.
Exclusive view: Exclusive view: TiO (B) is not a simple "inert filler", but a real "functional interface regulator + ion conduction booster" TiO (B) is not a simple "inert filler", but a real "functional interface regulator + ion conduction booster" , which is the core premise that the system can achieve high conductivity, high stability and long life at the same time., which is the core premise that the system can achieve high conductivity, high stability and long life at the same time.
II. New mechanism of interface conduction: how to achieve "ultrafast ion transport" at TiO (B) - PEO interface II. New mechanism of interface conduction: how to achieve "ultrafast ion transport" at TiO (B) - PEO interface
Lithium-ion conduction dependence in traditional PEO electrolytes Lithium-ion conduction dependence in traditional PEO electrolytes ether-oxygen coordination-discoordination ether-oxygen coordination-discoordination chain movement, slow speed and large crystallization obstacle. After the introduction of TiO (B), the chain movement of the system appeared, slow speed and large crystallization obstacle. After the introduction of TiO (B), the system appeared new interfacial conduction mechanism New interfacial conduction mechanism :
The interface region becomes the lithium-ion high-speed channel The interface region becomes the interface layer of the lithium-ion high-speed channel in the contact between TiO 2O (B) and PEO, the polymer chain is highly perturbed and the crystallinity is greatly reduced, forming the interface layer in the contact between TiO 2O (B) and PEO, the polymer chain is highly perturbed and the crystallinity is greatly reduced, forming the interface region of high free volume, high segment motility, high segment motility . Simulation confirms: the interface region of this region. Simulations confirm that the concentration of lithium ions in this region is 2-3 times that of bulk PEO, and the concentration of lithium ions is 2-3 times that of bulk PEO , and the migration energy barrier is significantly reduced., the migration energy barrier is significantly reduced.
TiO 2 (B) promotes deep dissociation of lithium salts TiO 2 (B) promotes deep dissociation of lithium salts TiO 2 (B) surface has Lewis acidic check point, but TiO 2 (B) surface has Lewis acidic check point, can preferentially bind to TFSI + anion preferentially bind to TFSI + anion , weaken the Li-TFSI + interaction, so that more Li is involved in conduction in the form of free ions , rather than in the form of ion pairs/ion clusters. This directly explains: participation in conduction, rather than "invalid existence" in the form of ion pairs/ion clusters This directly explains:
Ionic conductivity from 0.128 → 0.262 mS/cm Ionic conductivity from 0.128 → 0.262 mS/cm
Lithium ion migration number from 0.31 → 0.40 Lithium ion migration number from 0.31 → 0.40
Reduces the complexation energy of Li
In-depth conclusion: In-depth conclusion: The real breakthrough of this system is not the "addition of fillers", but the establishment of a "new mechanism for ultrafast ion transport at the TiO (B) -PEO interface", which upgrades the composite electrolyte from "segment-dominated" to "interface-dominated" conduction mode. The real breakthrough of this system is not the "addition of fillers", but the establishment of a "new mechanism for ultrafast ion transport at the TiO (B) -PEO interface", which upgrades the composite electrolyte from "segment-dominated" to "interface-dominated" conduction mode.
III. In-situ generation of rich LiF interfaces: the core guarantee of 3100 ultra-long cycles III. In-situ generation of rich LiF interfaces: the core guarantee of 3100 ultra-long cycles
One of the most valuable findings of this study is that TiO (B) can induce the generation of a dense, uniform, LiF-rich interface layer (SEI) in situ. TiO (B) can induce the generation of a dense, uniform, LiF-rich interface layer (SEI) in situ. , which is the key to achieving 2350 hours of symmetrical battery and 3100 full battery cycles., which is the key to achieving 2350 hours of symmetrical battery and 3100 full battery cycles.
1. Why is the LiF-rich interface the "best interface for lithium metal anode"? 1. Why is the LiF-rich interface the "best interface for lithium metal anode"?
LiF has LiF has extremely high interfacial stability, low electronic conductivity, high interfacial strength extremely high interfacial stability, low electronic conductivity, high interfacial strength ;
Energy Blocking electron tunneling Blocking electron tunneling , inhibiting side reactions and electrolyte continuous decomposition;, inhibiting side reactions and electrolyte continuous decomposition;
Energy Homogenization of lithium ion flux Homogenization of lithium ion flux makes lithium deposition dense, smooth, and dendritic;, makes lithium deposition dense, smooth, and dendritic;
Wide electrochemical window to withstand high voltage cathode long-term cycling. Wide electrochemical window to withstand high voltage cathode long-term cycling.
2. How does TiO (B) induce the in situ generation of LiF-rich interfaces? 2. How does TiO (B) induce the in situ generation of LiF-rich interfaces?
The mechanism is not simple physical adsorption, but the mechanism is not simple physical adsorption, but interface chemistry synergy interface chemistry synergy :
TiO 2O (B) surface Lewis acid check point TiO 2O (B) surface Lewis acid check point promotes TFSI decomposition promotes TFSI decomposition , preferentially produces F species;, preferentially produces F species;
Ti and F form strong Ti-F bonds, Ti and F form strong Ti-F bonds, guide LiF to nucleate preferentially at the interface, and guide LiF to nucleate preferentially and grow uniformly at the interface ;;
At the same time, a small amount of electronic insulating phases such as Li 🥰 N are generated at the interface, which further stabilizes the interface structure.
TOF-SIMS, Cryo-TEM Direct Confirmation: TOF-SIMS, Cryo-TEM Direct Confirmation: Interface forms uniform, crack-free, LiF-rich seamless interface layer Interface forms uniform, crack-free, LiF-rich seamless interface layer , lithium ions can pass quickly, electrons are blocked, and lithium deposition is completely flat., lithium ions can pass quickly, electrons are blocked, and lithium deposition is completely flat.
Exclusive point of view: The traditional strategy relies on additives and additives to strengthen the manufacturing interface, which is easy to segregate and unstable; the system relies on the strong manufacturing interface, which is easy to segregate and unstable; the system relies on the TiO (B) interface chemical in situ induction of TiO (B) interface chemical in situ induction to achieve self-healing, uniform, stable, long-term self-healing, uniform, stable, long-term rich LiF interface, is a true "intelligent interface".
4. Ultra-long cycle dynamics: Why can it achieve 3100 cycles with only 0.0077% attenuation per cycle? 4. Ultra-long cycle dynamics: Why can it achieve 3100 cycles with only 0.0077% attenuation per cycle?
The PEO-lithium metal full battery in the industry usually decays rapidly after a few hundred cycles, while the system realizes that the PEO-lithium metal full battery in the industry usually decays rapidly after a few hundred cycles, and the system realizes 3100 cycles at 1C rate, 3100 cycles at capacity retention rate of 93%, and capacity retention rate of 93% . Behind it is quadruple stability mechanism quadruple stability mechanism Synergy:
LiF-rich interface completely inhibits side reactions LiF-rich interface completely inhibits side reactions Interface layer is stable, does not continue to consume active lithium and electrolyte, battery interface layer is stable, does not continue to consume active lithium and electrolyte, battery Self-attenuation extremely low Self-attenuation extremely low
...Lithium ion flux uniformity, complete elimination of lithium dendrite Lithium ion flux uniformity, complete elimination of lithium dendrite COMSOL simulation proves that: TiO (B) makes lithium ions on the electrode surface COMSOL simulation proves that: TiO (B) makes lithium ions on the electrode surface distribution highly uniform distribution highly uniform , no local current accumulation, lithium deposition is always dense and smooth., no local current accumulation, lithium deposition is always dense and smooth.
Electrolyte mechanical strength improvement, inhibit dendrite puncture electrolyte mechanical strength improvement, inhibit dendrite puncture Young's modulus from 7.57 MPa → 18.9 MPa, strength improvement means that Young's modulus from 7.57 MPa → 18.9 MPa, strength improvement means stronger physical resistance to dendrite, stronger physical resistance to dendrite , more suitable for long-term cycling.
High voltage stability broadens application scenarios High voltage stability broadens application scenarios The electrochemical window expands to 5.0 V5.0 V , which can match high voltage cathodes such as high nickel ternary, laying the foundation for the next generation of high specific energy solid state batteries., can match high voltage cathodes such as high nickel ternary, laying the foundation for the next generation of high specific energy solid state batteries.
In-depth conclusion: In-depth conclusion: This is not a "performance improvement", but a "mechanism revolution": upgrade from "passive anti-dendrite" to "actively guided uniform deposition + in-situ construction of stable interface". This is not a "performance improvement", but a "mechanism revolution": upgrade from "passive anti-dendrite" to "actively guided uniform deposition + in-situ construction of stable interface".
5. Dual value of academia and industrialization: Why can this work be sent to Nano Energy? 5. Dual value of academia and industrialization: Why can this work be sent to Nano Energy?
The interface function of bronze phase TiO 2O (B) in solid electrolytes is clarified for the first time. The interface function of bronze phase TiO 2O (B) in solid electrolytes is clarified for the first time.
Break through traditional filler thinking, establish a breakthrough in traditional filler thinking, and establish a crystal phase-interface-conductance-stable crystal phase-interface-conductance-stability structure-activity relationship.Proposed a new model of "interface-dominated ion conduction" Proposed a new model of "interface-dominated ion conduction" Provide a new design idea for the conductivity improvement of PEO-based solid-state electrolytes. Provide a new design idea for the conductivity improvement of PEO-based solid-state electrolytes.
True industrialized ultra-long cycle performance True industrialized ultra-long cycle performance 3100 cycles, 2350 hours symmetrical battery, high critical current density (1.6 mA cm ²), 3100 cycles, 2350 hours symmetrical battery, high critical current density (1.6 mA cm ²), Close to automotive solid-state battery durability requirements Close to automotive solid-state battery durability requirements ...
The process is simple and scalable. The process is simple and scalable. Hydrothermal preparation of TiO (B) nanotubes + solution pouring composite requires no expensive equipment and is compatible with existing coating production lines. Hydrothermal preparation of TiO (B) nanotubes + solution pouring composite requires no expensive equipment and is compatible with existing coating production lines.
6. Summary (highly concise, can be used directly for papers/presentations) 6. Summary (highly concise, can be used directly for papers/presentations)
TiO (B) is not an ordinary filler, but an integrated material of interface regulation and ion conduction function; TiO (B) is not an ordinary filler, but an integrated material of interface regulation and ion conduction function;
The new mechanism of interface conduction greatly improves the conductance and migration number, breaking the bottleneck of low room temperature conductivity of PEO; the new mechanism of interface conduction greatly improves the conductivity and migration number, breaking the bottleneck of low room temperature conductivity of PEO;
In-situ LiF-rich interface realizes uniform lithium deposition, dendritic-free, ultra-stable, and ultra-long life; in-situ LiF-rich interface realizes uniform lithium deposition, dendritic-free, ultra-stable, and ultra-long life;
The quadruple synergy mechanism enables the whole battery to achieve 3100 ultra-long cycles, which is close to the practical level; the quadruple synergy mechanism enables the whole battery to achieve 3100 ultra-long cycles, which is close to the practical level;
Provides a new paradigm and scientific basis for the industrialization of PEO-based solid-state electrolytes. Provides a new paradigm and scientific basis for the industrialization of PEO-based solid-state electrolytes.
