In-Depth Battery Technology Analysis: A Multidimensional Comparison of Semi-Solid-State Batteries and NMC Ternary Lithium Batteries

In the current landscape of battery technology, semi-solid-state batteries and ternary lithium batteries stand out as two highly regarded “stars,” frequently chosen by manufacturers of end-user devices. While both serve the common goal of powering equipment, they differ significantly across several key dimensions. What intrinsic factors shape their unique characteristics, steering them toward distinct technological and application paths? In this article, Grepow’s team will delve into a multi-faceted analysis, guiding you beyond the surface to gain a deep understanding of the fundamental differences between semi-solid-state batteries and ternary lithium batteries.

1. What Are Semi-Solid-State Batteries and Ternary Lithium Batteries?

Semi-Solid-State Batteries

Definition: Semi-solid-state batteries represent a hybrid technology between traditional liquid batteries and fully solid-state batteries. Their electrode materials are partially or entirely solid, while the electrolyte is a mixture of solid and liquid electrolytes or a gel-like substance containing a certain amount of liquid electrolyte. Structural Features: The structure of semi-solid-state batteries resembles that of traditional liquid batteries but differs in the composition and distribution of electrodes and electrolytes. Electrodes typically use high-nickel multi-element materials or lithium-rich manganese-based materials as the cathode, and carbon-silicon anodes as the anode, enhancing energy density and charge-discharge performance. The electrolyte combines solid electrolytes with high ionic conductivity and stability—such as oxides or sulfides—with a small amount of liquid electrolyte to improve ion transport efficiency.

Ternary Lithium Batteries

Definition: Ternary lithium batteries are lithium-ion batteries with cathodes composed of nickel, manganese, and cobalt.

Structural Features: Ternary lithium batteries are typically manufactured using a laminated pouch cell process, offering high energy density and good charge-discharge performance. The cathode material is a ternary compound, while the anode often uses graphite or silicon-carbon anodes to boost capacity and charge-discharge efficiency.

2. How Do the Cycle Lifetimes of Semi-Solid-State and Ternary Lithium Batteries Differ?

Differences in Cycle Lifetime Range

• Semi-solid-state cells can achieve a cycle life exceeding 2,000 cycles, with energy densities ranging from 280–350 Wh/kg and a potential 10% improvement in cycle life.

• NMC ternary lithium batteries generally offer a cycle life of around 1,000 cycles, retaining over 80% capacity after 1,000 cycles.

Factors Influencing Cycle Lifetime

• Semi-Solid-State Batteries: The use of semi-solid electrolytes ensures more stable contact between electrodes and electrolytes, reducing electrode material shedding and side reactions during charge-discharge cycles, thus extending cycle life. Additionally, the chemical and thermal stability of semi-solid electrolytes minimizes decomposition or degradation issues during cycling, further enhancing battery longevity.

• Ternary Lithium Batteries: As traditional liquid lithium-ion batteries, the liquid electrolyte reacts continuously with electrode materials over prolonged cycles, leading to structural damage and performance decline. The high nickel content in ternary materials makes the cathode prone to structural changes—such as transitioning from a layered to a spinel structure—during charge-discharge, degrading electrochemical performance and impacting cycle life.

Impact of Cycle Life on Practical Applications

• Semi-Solid-State Batteries: Their extended cycle life suits applications with high battery lifespan demands, such as low-altitude economy (drones), electric vehicles (EVs), and energy storage stations. In EVs, a long cycle life means the battery can maintain performance throughout the vehicle’s lifespan, reducing range degradation and replacement frequency, thus lowering user costs.

• Ternary Lithium Batteries: Though their cycle life is shorter, they remain advantageous in cost-sensitive applications with less stringent lifespan requirements. For instance, consumer electronics with shorter usage cycles—typically replaced within a few years—can meet performance needs during their lifecycle, while the relatively lower cost enhances market competitiveness.

3. Why Are Semi-Solid-State Batteries Generally Safer Than Ternary Lithium Batteries?

Thermal Stability

• Semi-Solid-State Batteries: Utilizing a mix of solid electrolytes or solid and liquid electrolytes, semi-solid batteries benefit from the high thermal stability of solid electrolytes, which are non-volatile and non-flammable. They maintain performance under high temperatures, reducing the risk of thermal runaway. For example, a semi-solid battery product using in-situ curing technology for a polymer framework demonstrates excellent safety, showing no fire or explosion even in high-temperature tests.

• Ternary Lithium Batteries: Relying on liquid electrolytes, ternary lithium batteries have lower thermal stability. Under high temperatures, the electrolyte may decompose or volatilize, generating heat and gas that increase the likelihood of thermal runaway, potentially causing fires or explosions.

Suppression of Lithium Dendrite Growth

• Semi-Solid-State Batteries: Solid electrolytes provide mechanical strength to effectively suppress lithium dendrite growth and penetration. Lithium dendrites, a primary cause of internal short circuits, are mitigated by semi-solid batteries, enhancing safety. Companies like Qingtao Energy have developed semi-solid batteries with solid electrolytes that prevent dendrite formation, ensuring safe operation.

• Ternary Lithium Batteries: During charge-discharge cycles, lithium ions in ternary batteries can form dendrites on the anode surface. When these grow sufficiently, they may pierce the separator, causing short circuits and triggering thermal runaway.

Overcharge Tolerance

• Semi-Solid-State Batteries: Some semi-solid batteries exhibit good overcharge tolerance. The use of solid electrolytes can limit excessive redox reactions during overcharging, reducing risks like swelling or ignition caused by overcharge.

• Ternary Lithium Batteries: The presence of liquid electrolytes in ternary batteries makes them prone to intense chemical reactions during overcharging, generating significant heat and gas. This rapid increase in internal pressure heightens the risk of explosion.

Resistance to Compression and Puncture

• Semi-Solid-State Batteries: Some semi-solid batteries, due to their internal structure and materials, offer superior resistance to compression and puncture. For instance, BAK Battery’s semi-solid batteries excel in nail penetration tests, showing no fire, explosion, or leakage—critical for preventing safety incidents under external impact.

• Ternary Lithium Batteries: Liquid batteries are vulnerable to separator rupture or electrode contact when compressed or punctured, leading to short circuits and thermal runaway.

4. Factors Influencing the Safety of Semi-Solid-State Batteries

Electrolyte System

• Solid Electrolyte Content and Performance: The amount and quality of solid electrolyte are vital to battery safety. Too little solid electrolyte fails to isolate the cathode and anode, risking short circuits, while too much may hinder ion transport efficiency, reducing performance. Solid electrolytes with high ionic conductivity and thermal stability—such as oxide-based electrolytes—enhance safety under high temperatures while ensuring normal charge-discharge.

• Residual Liquid Electrolyte: Though reduced compared to traditional liquid batteries, residual liquid electrolyte in semi-solid batteries must be strictly controlled. Leakage during use can cause short circuits or corrosion, lowering safety. Under extreme conditions like high temperatures or overcharging, it may decompose and generate gas, increasing internal pressure and explosion risks.

Electrode Materials

• Cathode Materials: The stability and safety of cathode materials significantly impact overall battery safety. High-nickel cathodes offer high energy density but are prone to structural changes and thermal decomposition under high temperatures or overcharging, releasing oxygen and raising fire or explosion risks. Modifying or coating high-nickel cathodes to improve thermal and structural stability is crucial for safety.

• Anode Materials: Anode selection also affects safety. Silicon-based anodes, for instance, expand significantly during charge-discharge, potentially causing electrode pulverization and detachment, impacting cycle life and safety. Lithium metal anodes, despite their high theoretical capacity, may form dendrites in practice, piercing separators or solid electrolytes and causing internal short circuits.

Battery Manufacturing Process

• Interface Compatibility Between Electrolyte and Electrodes: During production, ensuring good interface compatibility between solid electrolytes and electrode materials is essential for smooth ion transport. Poor compatibility increases interface resistance, generating heat during charge-discharge and affecting safety and lifespan.

• Encapsulation Process: The quality of battery encapsulation directly relates to sealing and safety. Effective encapsulation prevents external moisture or oxygen from entering, avoiding corrosion or damage to electrodes and electrolytes. It must also provide mechanical strength to withstand compression or collisions during use, preventing structural damage and safety hazards.

Battery Management System

• Overcharge and Over-Discharge Protection: Overcharge and over-discharge protection in the battery management system (BMS) is critical for semi-solid battery safety. Overcharging triggers irreversible chemical reactions, generating heat and gas that raise temperature and pressure, posing safety risks. Effective protection mechanisms cut off charging circuits to prevent overcharge.

• Thermal Management: Heat generated during charge-discharge can overheat the battery, impacting performance and safety if not dissipated effectively. BMS thermal management modules, using fans or cooling pipes, ensure the battery operates within a safe temperature range, enhancing longevity and safety.

Usage Environment and Conditions

• Temperature: Extreme high or low temperatures affect semi-solid battery safety. High temperatures accelerate chemical reactions, risking thermal runaway, while low temperatures reduce charge-discharge efficiency, potentially damaging electrodes and impacting lifespan and safety. Measures like enhanced cooling in high temperatures or preheating in low temperatures are necessary.

• External Impact: Compression, collision, or puncture during use can damage internal structures, causing short circuits or leaks. Battery design and manufacturing must prioritize resistance to external impact—using high-strength casings and optimized internal structures—to ensure safety.

Conclusion

In the realm of battery technology, semi-solid-state and ternary lithium batteries each have their strengths, catering to different devices based on specific needs. Newbettercell, with over 20 years of expertise in rechargeable battery R&D and manufacturing, produces semi-solid-state batteries with voltage options from 4S (14.8V) to 18S (68.4V) and capacities up to 84Ah. Our diverse product line suits various application scenarios. For questions or special requirements, feel free to contact us via online customer service, phone, or message—we’ll respond promptly with dedicated support.