Ceramic-Coated Li-Ion Electrodes Without Melting Separators
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Solution Overview
Problem
Lithium-ion batteries face safety hazards due to internal short circuits and limited cycle life caused by the melting of organic polymer separator membranes, which also increase internal resistance and reduce thermal stability.
Innovation Solution
A lithium-ion battery design with a ceramic coating on the electrodes replaces the traditional separator membrane, using ceramic powder and a binder to form a 6-9 μm thick coating, enhancing safety and cycle life by preventing direct short circuits and improving thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an organic polymer separator membrane is used to isolate electrodes, then the battery can prevent short circuits and ensure safety, but the separator membrane melts or carbonizes under abnormal conditions causing safety hazards and increases internal resistance
Solution Approach 1:
The patent changes the material parameter of the separator from organic polymer to inorganic ceramic coating. The ceramic coating maintains structural stability at high temperatures (resisting melting and carbonization) while providing electrical insulation to prevent short circuits, thus resolving the contradiction between safety performance and thermal stability
Solution Approach 2:
The patent uses a composite structure where a ceramic coating layer is applied on the electrode surface. This composite design combines the electrical insulation properties of ceramic materials with the conductive properties of the electrode, allowing the ceramic coating to function as both protective layer and separator, improving thermal stability while maintaining safety
2Reliability
If the separator membrane thickness is increased to improve isolation, then short circuit prevention is enhanced, but the internal resistance increases and cycle life is limited
Solution Approach 1:
The patent optimizes the thickness parameter of the ceramic coating to 6-9 μm. This thin coating provides sufficient electrical insulation to prevent short circuits while minimizing resistance to lithium ion transport, thereby extending cycle life without compromising short circuit prevention capability
3Use of energy by moving object
If no separator membrane is used to increase energy density, then volumetric specific energy improves, but direct short circuit between electrodes occurs causing safety hazards
Solution Approach 1:
The patent merges the functions of the electrode and separator by applying a ceramic coating directly on the electrode surface. The coating serves dual purposes: maintaining electrode functionality while providing separation and insulation, eliminating the need for a separate separator membrane and increasing energy density while ensuring safety
Solution Approach 2:
The patent applies a ceramic coating with optimized thickness (6-9 μm) that provides sufficient electrical insulation to prevent short circuits. This thin coating minimizes space occupation, allowing high volumetric specific energy while maintaining safety performance
4Device complexity
If lithium-ion batteries are designed without tabs to simplify structure, then internal impedance is reduced and processing is easier, but large short-circuit current is generated during internal short circuits causing thermal runaway
Solution Approach 1:
The patent applies preliminary protective action by coating the electrode surface with ceramic material before assembly. This pre-established protective layer prevents internal short circuits and limits short-circuit current generation, addressing the safety issue of tabless battery design before it can manifest as a problem
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ceramic coating increases safety performance, extends cycle life, and enhances thermal stability while maintaining high volumetric specific energy, achieving ≥70% average capacity efficiency after ≥600 cycles and improved thermal stability at 130°C.
Implementation Method 1
the ceramic coating with a specific thickness formed on an electrode can replace the battery separator membrane... preventing the direct short circuit between the cathode electrode and the anode electrode
Implementation Method 2
to allow the lithium ions in the electrolyte to freely pass between the cathode electrode and the anode electrode. The lithium ion conductivity is directly related to the overall performance of the lithium-ion battery
Data Source
AI summary
The present invention provides an electrode ceramic coating comprising a ceramic powder and a binder, wherein the thickness of the ceramic coating is 6 μm-9 μm, preferably 7 μm-9 μm, more preferably 8 μm-9 μm. The present invention further provides an lithium-ion battery comprising a cathode electrode, an anode electrode, electrolyte and a housing, wherein the cathode electrode includes a cathode collector and a cathode active material coated thereon, the anode electrode includes an anode collector and an anode active material coated thereon, and wherein the cathode electrode and the anode electrode face each other, and at least one of surfaces of the cathode electrode and the anode electrode that face each other has a ceramic coating. The ceramic coating can replace the battery separator membrane in the conventional sense, and can improve the cycle life and the thermal stability of the lithium-ion battery.