Solid-State Batteries Today: What’s Real, What’s Semi-Solid, and Why the Industry Uses the Same Term

Solid-state batteries (SSBs) have become one of the most discussed developments in energy storage, with the potential to influence how batteries are designed and used.

Even so, the industry is still working towards a shared definition, and there is currently no single formal certification that verifies a battery as “solid-state”. This article walks through today’s SSB landscape, explains why the terminology is used so broadly, and outlines what it could mean for Renogy going forward.

Industry Situation: What “Solid-State” Means in Today’s Market

The Simplest Definition

To understand what “solid-state batteries” are, it helps to start with the basics of a standard lithium-ion battery. Put simply, a conventional lithium-ion battery includes an anode, a cathode, a separator, and an electrolyte (typically a liquid). During charging, lithium ions move from the positive electrode, through the electrolyte and separator, and settle into the negative electrode. During discharge, the flow reverses.

“Solid-state batteries”, as the name suggests, replace this traditional liquid electrolyte with solid or semi-solid materials.

The Key Realities in 2025

When we discuss "solid-state batteries," what are we truly talking about? In most discussions, people instinctively envision the "All-Solid-State Battery" (ASSB)—the industry’s "holy grail." In this ideal form, the battery contains no liquid electrolyte whatsoever, a milestone that researchers and manufacturers are eagerly pursuing.

However, it is crucial to distinguish between this conceptual ideal and this current reality. Clarifying this gap helps consumers look past marketing hype and understand what this new technology can actually deliver today.

First, true all-solid-state Batteries are still largely in the R&D phase. They have yet to achieve widespread commercial use in electric vehicles (EVs), wearables, or grid-scale storage. According to Marija Maisch of pv magazine, major global manufacturers like Toyota and Nissan remain in the pilot production phase as of 2025, with large-scale manufacturing not expected until 2030. Even Solid Power, a leader in the field, does not anticipate mass production until the second half of 2026.

Consequently, most "solid-state" batteries currently in the consumer market are actually "semi-solid-state." Recent developments from Chinese EV makers highlight this trend. For instance, NIO launched the ET7 in June 2024, featuring a 150kWh semi-solid-state battery (a hybrid of liquid and solid electrolytes) capable of an estimated 609-mile (981km) range (Tim Levin, 2024). Similarly, SAIC Motor’s MG4, released this September, utilizes semi-solid-state technology from QingTao Energy (Florian Treiss, 2025). This technical breakthrough allows the battery to pass nail-penetration tests without smoking or catching fire, effectively eliminating the risk of spontaneous combustion.

Furthermore, the industry is exploring various technical paths to bring solid-state technology to life. Some companies focus on replacing flammable liquid electrolytes with solid materials. QuantumScape, for example, uses oxide ceramics that do not melt during a puncture, preventing the chain reaction of thermal runaway. Meanwhile, CATL is pursuing multiple avenues, including oxides and sulfides, to achieve a technical breakthrough.

In addition to searching for the ideal solid-state electrolyte, several research teams are approaching the challenge from a different angle: innovating the battery’s cathode and anode materials. Colorado-based Solid Power is a prime example; they use high-silicon anodes to boost charging speeds and ensure performance in cold temperatures. They are also exploring lithium-metal anodes, which could dramatically increase energy density, reducing battery weight while extending the range and efficiency of future EVs.

Why “Solid-State” and “Semi-Solid-State” Are Often Grouped Together

Given the R&D and market realities mentioned above, it is clear why "solid-state battery" has become an umbrella term used throughout the industry and media. There are two primary reasons for this:

Reason 1: Divergent Technical Pathways

Currently, companies and research institutions are pursuing vastly different technical routes based on their specific expertise and market positioning. For example, solid electrolytes range from sulfide to oxide systems. When combined with various anode and cathode materials, this results in a wide array of technical configurations. Furthermore, the industry lacks a consensus on the definition of "solid." One company may label a battery "solid-state" if its liquid content is below 10wt%, while another may insist that it must be entirely liquid-free. This diverse pathways make it impossible to establish a single, unified technical specification.

Reason 2: Incremental Commercialization

A significant engineering gap exists between "all-solid-state" lab prototypes and mass-produced commercial batteries. To bridge this gap, "semi-solid" or "hybrid solid-liquid" batteries have emerged as the most practical, near-term solution for vehicle integration. These transitional solutions retain some liquid electrolyte to address challenges such as ionic conductivity and high interfacial impedance. Regardless of whether a battery is "all-solid-state" or "semi-solid-state," the shared goal is clear: to gradually reduce, and eventually eliminate, flammable liquid electrolytes that lead to lithium dendrite growth.

Why There’s No “Official Stamped Solid-State Certification” Today

When shopping for a new refrigerator or washing machine, people often look for the "Energy Star" label to verify energy efficiency. Since the debut of solid-state battery products, consumers have frequently asked if there is a similar official "seal of approval" for solid-state technology. Unfortunately, no such industry-wide certification exists yet. This is simply because R&D paths are so diverse that the industry has not yet settled on a unified definition or set of testing conditions. As all-solid-state batteries move into true mass production, standardized definitions and certifications will follow.

However, the absence of an SSB-specific certificate does not mean these products lack safety credentials. Take Renogy’s solid-state batteries, for example: before they ever leave the factory, they must pass the same rigorous testing as any traditional battery. They are fully certified under standards such as CE, FCC, RoHS, R10, and UN38.3, ensuring complete safety during both transportation and daily use.

The Benefits of Solid State

With major EV manufacturers and research institutions investing significant funding and talent into solid-state batteries (SSBs), a practical question follows: what changes could this bring in real use? To explore that, we’ll look at three areas most people care about: safety, energy density, and cycle life.

Safety with Solid State Batteries

Most conventional lithium batteries rely on a liquid electrolyte to carry ions back and forth between the anode and cathode, which is what allows the battery to deliver power. If the cell is abused, for example through a short circuit, overcharging, or physical impact, heat can rise quickly. In the worst cases, this escalation can trigger thermal runaway, where the electrolyte becomes part of the problem and may ignite, and in extreme events the cell can vent violently or rupture.

Solid-state development is largely driven by the goal of reducing flammable liquid content inside the cell. By using non-combustible electrolyte materials such as ceramics or polymers, and by shifting away from the thin, lower-strength separator films commonly found in liquid cells (often PP/PE), designers aim to remove a key contributor to fire risk. Put simply, it is about taking away a major fuel source. In theory, that can improve stability in harsh test scenarios, including puncture, high-impact events, or overcharge conditions.

Still, it is important to keep the message grounded. A solid electrolyte can improve safety potential, but it does not make any battery “risk-free”. Real-world safety comes from the complete design: strong mechanical construction, an intelligent BMS, protective circuitry, and correct operation by the user.

Energy Density of Solid State Batteries

Put simply, energy density describes how much energy a battery can store relative to its weight or volume. The higher the energy density, the further an electric vehicle can travel, or the longer a phone can run on a single charge.

In traditional liquid-based batteries, common chemistries such as graphite and lithium cobalt oxide (LCO) are widely used, but they can limit how much energy fits into a given size. Solid-state cell designs may support higher-capacity electrode materials, including lithium-metal anodes.

Lithium metal is difficult to use in liquid systems due to safety and stability concerns, but solid-state designs may offer a more stable pathway. Even then, the energy density an all-solid-state battery can reach depends on the materials chosen and the cell engineering approach used by each manufacturer.

The Longevity of Solid State Batteries

When we talk about battery durability, it is usually best understood through two measures: cycle life and long-term stability. Cycle life refers to how many full charge-discharge cycles a battery can complete before capacity drops to a set level (often around 80% of its original capacity). Long-term stability describes how well the battery resists ageing across different environments. Several key factors have the biggest impact on overall lifespan:

Depth of Discharge (DoD): Fully draining a battery from 100% to 0% generally causes more wear than partial cycling (for example, operating between 90% and 30%). Shallower cycles are typically better for long-term health. For lead-acid users, a common recommendation is to keep Depth of Discharge at or below 50%.
Temperature: Temperature extremes can shorten battery life. High heat is often the biggest driver, as it accelerates internal reactions and degradation. Very cold conditions can also reduce performance. In conventional lithium batteries, cold-weather use can contribute to lithium dendrite formation, needle-like structures that can damage internal layers and increase the risk of faults.
Charge/Discharge Rates: Frequent ultra-fast charging or sustained high-power discharge adds stress to the cell chemistry, which can reduce usable life over time.

In theory, solid-state designs can offer durability advantages because a more stable internal structure may reduce unwanted side reactions. Just as importantly, a solid electrolyte can help suppress lithium dendrite growth, which is one reason the industry expects potential gains in cycle life and long-term stability.

Renogy’s Solid-State Approach

How Renogy Uses the Term “Solid-State”

Renogy has chosen a practical middle-ground approach. The hybrid solid-liquid cells we use incorporate oxide-polymer solid materials to reduce the amount of liquid electrolyte inside the battery.

Compared to traditional lithium-ion batteries (typically 25% to 35% liquid by weight), Renogy’s semi-solid cells reduce liquid content by about 70%, keeping it at roughly 10% by weight. With more solid material in the cell, thermal resistance improves and temperature rises more slowly. Even as heat continues to build, the risk of thermal runaway is greatly reduced. In addition, the cathode and anode in these hybrid cells are coated with a high-melting-point solid-state electrolyte that withstands temperatures up to 572°F (300°C).

In the event of external impacts or punctures, the cell remains stable and resists ignition or explosion. This provides an important safety upgrade for demanding off-grid environments such as RV and marine applications, where reliability matters.

Why Combine This Approach with LiFePO4 (LFP)

Beyond semi-solid cell design, Renogy uses Lithium Iron Phosphate (LFP), a market-proven chemistry known for stability and strong performance compared with lead-acid alternatives.

Safety is further supported by our proprietary BMS, which includes 60+ intelligent protections designed to balance strong safety with a smooth user experience. For added redundancy, we include Active Backup Protection via self-control fuses, which disconnect the circuit during abnormalities to help prevent permanent damage.

By combining semi-solid technology with LFP chemistry and layered protection, Renogy has pioneered a smart, portable solid-state battery designed for mobile energy storage.

Our Commitment to Solid-State Technology

As solid-state technology moves from the lab into real products, Renogy is committed to providing a clear and honest roadmap for customers and partners, built on three pillars:

Transparency: We commit to clear, accurate technical definitions. By avoiding hype and unclear jargon, we aim to give you the facts needed to make informed choices.
Targeted Innovation: Our R&D focuses on demanding off-grid applications such as RVs, boats, and home backup systems. The goal is to solve energy storage challenges where reliability and resilience matter most.
True Accessibility: We aim to bring advanced battery technology to a wider audience. For us, accessibility means more than price. It means making next-generation tech widely available without sacrificing quality or safety, supported by optimised manufacturing and supply chain capability.

Takeaways

When exploring products that use emerging solid-state technology, the key takeaway is simple: there is currently no unified “solid-state” certification standard. With diverse technical pathways and a gradual commercial ramp-up, “solid-state battery” is widely used as an umbrella term covering a range of evolving designs.

To find reliable power solutions for your needs, we invite you to explore Renogy’s battery portfolio. You can also speak directly with our technical support team, or browse our educational resources on off-grid battery systems.

FAQs

1. Is there an official certification for “solid-state batteries”?

No. There is currently no official, unified global standard or certification that formally defines or "stamps" a product as a solid-state battery.

2. What’s the difference between solid-state and semi-solid-state?

An all-solid-state battery contains zero liquid electrolyte. A semi-solid-state battery is a hybrid that replaces most, but not all, of the liquid with solid materials (such as polymers or ceramics) to improve safety and performance.

3. Are any fully all-solid-state (zero-liquid) large batteries available today?

No. True all-solid-state batteries (ASSBs) are still in the laboratory and pilot production phases. Most major manufacturers do not expect large-scale commercial production until 2026–2030.

4. Does “solid-state” automatically mean safer?

Theoretically, yes, because it removes flammable liquids. However, absolute safety is a "holistic engineering" challenge that still depends on the battery's physical design, its battery management system (BMS), and proper user habits.

5. Why do brands use the term differently?

The term is used broadly because there is no consensus on definitions. Some brands call a battery "solid-state" if the liquid content is below 10wt%, while others believe it must be 0wt%. Additionally, companies are pursuing various material paths (e.g., sulfides vs. oxides).

6. What should I look for when comparing batteries?

Look for technical transparency and established safety credentials (like CE, FCC, and UN38.3). Beyond standard certifications, focus on the integrated safety design: the battery chemistry (e.g., LFP), the BMS, and other features or technologies that match your needs.

References

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